[PATCH v3 0/4] ASoC: add ESS Technology ES9039Q2M codec driver

[PATCH v3 0/4] ASoC: add ESS Technology ES9039Q2M codec driver

[Karl Asseily]

This series adds support for the ESS Technology ES9039Q2M, a 32-bit
two-channel audio DAC with an asynchronous sample rate converter,
controlled over I2C. The part also has a hardware mode strapped by
HW0/HW1/HW2 with no control bus at all; this driver implements the
software mode that MODE = GND selects.

Two things about the part shape the driver:

 - Selecting an input format takes two registers, not one. INPUT_SEL
   chooses the port; SYS MODE CONFIG enables the matching decoder, and at
   reset only ENABLE_TDM_DECODE is set. Selecting DoP without also
   enabling ENABLE_DOP_DECODE leaves the part hunting for a marker with
   the marker decoder switched off, so it finds nothing and mutes. The
   driver writes both.

 - Several registers have non-zero reserved defaults - register 88 reads
   0xb8 at reset - so every write is read-modify-write.

The programmable FIR coefficient controls are write-only by design.
PROG_COEFF_OUT is documented as a coefficient readback but is not a RAM
read port: it returns the last coefficient written, whatever address is
selected in PROG_COEFF_ADDR. Measured with the driver out of the path,
five sequences, ten reads, all returning the same value. A get() built on
that register would return something with the shape of data and none of
its meaning, so there is none.

Every control has been verified against the silicon rather than against
the driver's own read-back - written through ALSA, then read over raw I2C
- and DSD, DoP and S/PDIF input are all implemented and tested on
hardware.

ESS Technology has no bindings in the tree today, so the series also adds
the vendor prefix, taken from the company's domain esstech.com.

Link to v1: https://lore.kernel.org/r/20260820062626.39218-1-karl@asseily.com
Link to v2: https://lore.kernel.org/r/20260821043859.171871-1-karl@asseily.com

Changes in v3:

 - Fix the MCLK selection introduced in v2. hw_params() called
   clk_set_rate() for 256 * FS unconditionally, which is above the part's
   50 MHz MCLK maximum for any rate over 192 kHz, and the rate the clock
   settled on was never re-checked against that ceiling. The ratio is now
   taken from the highest that fits.

 - Decide 64FS mode from the MCLK/FS ratio in use rather than from a rate
   threshold. The 128 * FS floor was applied even in 64FS mode, where the
   datasheet asks for 64 * FS, so the 768 kHz this driver advertises in
   SNDRV_PCM_RATE_8000_768000 could never be reached - 128 * 768000 is
   98.304 MHz. Register 0[6] is keyed to the ratio, not the rate: 384 kHz
   from 24.576 MHz needs it as much as 768 kHz from 49.152 MHz does. The
   asynchronous floor is also strictly greater than 130 * FS now, as
   Table 7 note 1 has it.

 - The mute and DoP controls moved their shadow state before the I2C
   write and left it moved if the write failed. Both short-circuit on "no
   change", so a retry with the same value was a no-op and the control
   stayed permanently at odds with the register. They now restore the old
   value on failure.

 - Enable the datapath at component probe. SYSTEM_CONFIG[1] is clear at
   reset, so in software mode the analogue output was dead until
   something outside the driver set that bit. Written after the mute and
   never before it.

 - Add system suspend and resume. Where a board feeds the part a
   free-running oscillator, nothing in the system can gate its clock and
   it stayed fully clocked through suspend; suspend now clears
   ENABLE_DAC_CLK and resume resynchronises the cache. Resume mutes
   first, because regcache_sync() walks registers in ascending address
   order and would otherwise restore DAC_MODE in register 0 long before
   the mute in register 86, on any board that removes the part's
   supplies.

 - Remove board-specific references from the comments - measurement
   attributions, dates, and two pointers at a repository outside the
   tree. No functional change.

 - Note on what is and is not tested: everything at 176.4 kHz and below
   runs on the board this driver was written for. The paths above it are
   derived from the datasheet and not measured - that board feeds the
   part a fixed 24.576 MHz oscillator as a clock consumer and cannot
   reach them.

Changes in v2:

 - Accept SND_SOC_DAIFMT_CBP_CFP rather than requiring CBC_CFC. v1
   rejected every provider mode but consumer, which was one board's choice
   written into the driver. CBP_CFP now programs PCM_MASTER_MODE,
   hw_params() calls clk_set_rate() to pull MCLK to a multiple of the
   sample rate where the clock allows it, and the datasheet's two MCLK
   floors are applied separately - 128 x Fs synchronous, 130 x Fs
   asynchronous - instead of 130 x Fs unconditionally, which had been
   refusing 192 kHz on synchronous boards that can carry it.

 - ES9039_DECODE_MASK did not cover ENABLE_SPDIF_DECODE. hw_params() uses
   that mask to enable one decoder and clear the rest, so the S/PDIF
   decoder stayed enabled alongside whichever decoder was selected.

 - mute_stream() and the "Master Playback Switch" control both wrote
   ES9039_DAC_MUTE and overwrote each other. Each now records its own
   intent and the register is written from the union of the two.

 - The DoP control returns -EBUSY while a stream is open rather than
   half-applying a change hw_params() will not re-run, and both halves of
   automatic DoP detection go through one helper under a mutex, so
   AUTO_INPUT_SEL and ENABLE_DOP_DECODE can no longer disagree.

 - Status controls use the symbolic source-bit names rather than bare
   BIT() values. Doing so found a bug: "Clock Fault" read bit 7 of
   register 235, which is reserved, rather than BCK_WS_FAIL_SOURCE in
   register 234, and could never have reported a fault.

 - The volume put() raises VOLUME_HOLD around the pair of channel writes
   and drops it afterwards, which is what the bit is for. A stereo change
   previously left the channels briefly at different levels.

 - Rename the vendor prefix from "ess" to "esstech", after Krzysztof
   Kozlowski pointed out that ESS Technology's domain is esstech.com. The
   binding file, its $id and the compatible string follow.

 - The harmonic correction controls keep their names rather than gaining a
   "Volume" suffix. The justification in the comment was wrong - TLV data
   is not what decides - but they cancel distortion rather than set a
   level, so the name stands and the comment now says why.

 - Style: the header block is one C++ comment, and the "return ret ? ret :
   1" ternaries are plain conditionals.

 - Add the Assisted-by tag that
   Documentation/process/coding-assistants.rst asks for, which v1 omitted.
   This driver was developed with AI assistance. The board it was written
   against, the register-level measurements quoted above, and the
   responsibility for what is in it, are mine.

v2 has had a run on the board the driver was written for.

Karl Asseily (4):
  dt-bindings: vendor-prefixes: add ESS Technology
  ASoC: dt-bindings: add ESS Technology ES9039Q2M
  ASoC: es9039q2m: add ESS Technology ES9039Q2M codec driver
  MAINTAINERS: add entry for the ES9039Q2M codec driver

 .../bindings/sound/esstech,es9039q2m.yaml     |   61 +
 .../devicetree/bindings/vendor-prefixes.yaml  |    2 +
 MAINTAINERS                                   |    7 +
 sound/soc/codecs/Kconfig                      |   14 +
 sound/soc/codecs/Makefile                     |    2 +
 sound/soc/codecs/es9039q2m.c                  | 1831 +++++++++++++++++
 6 files changed, 1917 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/sound/esstech,es9039q2m.yaml
 create mode 100644 sound/soc/codecs/es9039q2m.c

-- 
2.34.1

[PATCH v3 1/4] dt-bindings: vendor-prefixes: add ESS Technology

[Karl Asseily]

Add the vendor prefix for ESS Technology, Inc., maker of the SABRE family
of audio DACs. The prefix follows the company's domain, esstech.com.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Karl Asseily <karl@asseily.com>
---

Notes:
    v2: rename the vendor prefix to esstech, after the company domain

 Documentation/devicetree/bindings/vendor-prefixes.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/vendor-prefixes.yaml b/Documentation/devicetree/bindings/vendor-prefixes.yaml
index ba200296937..ff4a85f4cbd 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.yaml
+++ b/Documentation/devicetree/bindings/vendor-prefixes.yaml
@@ -559,6 +559,8 @@ patternProperties:
     description: Seiko Epson Corp.
   "^esp,.*":
     description: Espressif Systems Co. Ltd.
+  "^esstech,.*":
+    description: ESS Technology, Inc.
   "^est,.*":
     description: ESTeem Wireless Modems
   "^eswin,.*":
-- 
2.34.1

[PATCH v3 2/4] ASoC: dt-bindings: add ESS Technology ES9039Q2M

[Karl Asseily]

Add a binding for the ES9039Q2M, a 32-bit two-channel audio DAC with an
asynchronous sample rate converter.

The part selects between two control personalities with its MODE pin:
hardware mode, strapped by HW0/HW1/HW2 with no control bus at all, and
software mode over I2C or SPI. This binding describes software mode over
I2C, which MODE = GND selects.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Karl Asseily <karl@asseily.com>
---

Notes:
    v2: rename the binding to esstech,es9039q2m and update its $id and compatible

 .../bindings/sound/esstech,es9039q2m.yaml     | 61 +++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/sound/esstech,es9039q2m.yaml

diff --git a/Documentation/devicetree/bindings/sound/esstech,es9039q2m.yaml b/Documentation/devicetree/bindings/sound/esstech,es9039q2m.yaml
new file mode 100644
index 00000000000..c1d03d3a855
--- /dev/null
+++ b/Documentation/devicetree/bindings/sound/esstech,es9039q2m.yaml
@@ -0,0 +1,61 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/sound/esstech,es9039q2m.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ESS Technology ES9039Q2M audio DAC
+
+maintainers:
+  - Karl Asseily <karl@asseily.com>
+
+description:
+  The ES9039Q2M is a 32-bit two-channel audio DAC supporting PCM to 768 kHz,
+  DSD64 to DSD1024, DoP and S/PDIF. It is controlled over I2C or SPI when the
+  MODE pin selects software mode; this binding covers the I2C interface. The
+  part contains an asynchronous sample rate converter, so the system clock need
+  not be synchronous with the audio bit or frame clocks.
+
+allOf:
+  - $ref: dai-common.yaml#
+
+properties:
+  compatible:
+    const: esstech,es9039q2m
+
+  reg:
+    description:
+      I2C address, selected by the ADDR0 and ADDR1 pins - 0x48, 0x49, 0x4a or
+      0x4b for GND/GND, GND/AVDD, AVDD/GND and AVDD/AVDD respectively.
+    enum: [ 0x48, 0x49, 0x4a, 0x4b ]
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    const: mclk
+
+  "#sound-dai-cells":
+    const: 0
+
+required:
+  - compatible
+  - reg
+  - "#sound-dai-cells"
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        audio-codec@48 {
+            compatible = "esstech,es9039q2m";
+            reg = <0x48>;
+            #sound-dai-cells = <0>;
+            clocks = <&dac_mclk>;
+            clock-names = "mclk";
+        };
+    };
-- 
2.34.1

[PATCH v3 3/4] ASoC: es9039q2m: add ESS Technology ES9039Q2M codec driver

[Karl Asseily]

The ES9039Q2M is a 32-bit two-channel audio DAC with an asynchronous
sample rate converter. It selects between two control personalities with
its MODE pin: hardware mode, strapped by HW0/HW1/HW2 with no control bus
at all, and software mode over I2C or SPI. This driver implements
software mode over I2C, which MODE = GND selects.

Three properties of the part shape the driver:

 - The ASRC in front of the DAC means MCLK need not be synchronous with
   BCLK or LRCK, so a board can feed it a fixed oscillator and never
   touch the clock again. The driver derives which case it is in rather
   than assuming one: the part runs synchronously when it drives the bus
   clocks itself, or when the MCLK it was given can be set to a
   multiple of the sample rate, and asynchronously only when a fixed
   oscillator feeds it as a clock consumer. The datasheet's MCLK floor
   differs between the two - 128 x Fs synchronous, 130 x Fs asynchronous
   - and where the clock is fixed a startup constraint derives the
   maximum rate from the MCLK actually present rather than advertising
   rates the hardware cannot honour.

 - Selecting an input format takes two registers, not one. Register 57
   INPUT_SEL chooses which port to listen to; register 1 SYS MODE CONFIG
   enables the corresponding decoder, and at reset only ENABLE_TDM_DECODE
   is set. Selecting DoP without also enabling ENABLE_DOP_DECODE leaves
   the part hunting for a marker with the marker decoder switched off, so
   it finds no valid DoP and mutes. The driver sets both.

 - Several registers have non-zero reserved defaults - register 88 reads
   0xb8 at reset - so every write is read-modify-write.

The datapath is off at reset and the driver turns it on at component
probe. SYSTEM_CONFIG[1] is clear when the part comes out of reset, so in
software mode nothing enables it at power-up and the analogue output
stays dead until the driver writes that bit. It is written after the mute
and never before it: bringing the datapath up into an unmuted part whose
volume registers still sit at their 0 dB reset value is the thump the
mute is there to prevent. Note when testing that a warm reboot does not
reset this part - registers and coefficient RAM both survive one, and
only removing power clears them - so the previous boot's value can hide
whether the write happened at all.

DoP is detected by the part rather than announced by the host:
AUTO_INPUT_SEL is enabled and both the TDM and DoP decoders run, so a
player can simply send DoP-encoded PCM. That is the only way DoP works in
practice, because no player can select a DAC mode through a kcontrol
first, and material sent to a part that is not looking for the marker
renders as the near-silent hiss the DoP design deliberately degrades to.

The programmable FIR coefficient controls are write-only by design. The
part has a PROG_COEFF_OUT register described as "Programmable FIR
coefficient readback", but it is not a RAM read port: it returns the last
coefficient written, whatever address is selected in PROG_COEFF_ADDR.
Measured by writing two different coefficients to addresses 0 and 1 and
reading them back five ways - plain, with a settle delay, with
PROG_COEFF_EN set, with the address written twice, and with a
write-enable pulse after the address. All ten reads returned the value
written to address 1. A get() built on that register would return
something with the shape of data and none of its meaning, so there is
none.

Every control was verified against the silicon rather than against the
driver's own read-back: written through ALSA, then read from the chip
over raw I2C. That covers the eight filter shapes, the modulator
bandwidth, the IIR bandwidth, the four signed 16-bit THD compensation
coefficients at both extremes of their range, and the automute enable,
time, level and off-level fields including the neighbouring
MUTE_RAMP_TO_GND bit that shares a register with the 11-bit time field.
The coefficient upload, whose RAM cannot be read back, was verified from
the I2C bus itself.

System suspend gates the part's internal clock tree. Where the part is
clocked from the SoC, system suspend stops its clock as a side effect and
there is nothing for a driver to do; where the board feeds it a
free-running oscillator - which the ASRC makes an attractive design,
since MCLK then need not track BCLK or LRCK - nothing in the system can
gate that clock and the part stays fully clocked for the whole of
suspend. Clearing ENABLE_DAC_CLK is the only part of its consumption
software can reach; the analogue supplies are the board's business.
Measured on an RK3588 board with a fixed 24.576 MHz oscillator, system
suspend power fell from 1.98 W to 1.95 W and followed the register in
both directions across an A/B.

Resume mutes the part before regcache_sync(), because the sync walks
registers in ascending address order. A board that keeps the supplies up
needs nothing, but one that removes them brings the part back at reset
defaults - DAC_MODE clear, both channels unmuted, both volume registers
at 0 dB - and the sync would set DAC_MODE in register 0 and only restore
the real mute in register 86, lighting the datapath up at full scale in
between.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Karl Asseily <karl@asseily.com>
---

Notes:
    v3:
    - fix the MCLK selection added in v2. clk_set_rate() asked for 256 * FS
      unconditionally, which is above the part's 50 MHz maximum for anything
      over 192 kHz, and the rate the clock settled on was not re-checked. The
      ratio is now the highest of 512/256/128/64 that fits
    - 64FS mode is decided from the MCLK/FS ratio in use rather than from a
      rate threshold, so the advertised 768 kHz is reachable instead of always
      failing the 128 * FS floor, and the asynchronous floor is strictly
      greater than 130 * FS as the datasheet has it
    - the mute and DoP controls restore their shadow state if the register
      write fails. Both short-circuit on "no change", so a retry with the same
      value was a no-op and the control stayed permanently at odds with the
      register
    - enable the datapath at component probe. SYSTEM_CONFIG[1] is clear at
      reset, so in software mode the analogue output was dead until something
      outside the driver set that bit. Written after the mute, never before it
    - add system suspend and resume. Suspend clears ENABLE_DAC_CLK, which
      gates the internal clock tree and is all that software can reach where
      MCLK is a free-running oscillator the system cannot gate. Resume mutes
      before regcache_sync(), because the sync walks registers in ascending
      address order and would otherwise restore DAC_MODE in register 0 long
      before the mute in register 86, on any board that removes the part's
      supplies
    - comments: board-specific measurement attributions, dates and two
      pointers outside the tree removed. No functional change
    v2: address Mark Brown's review of v1
    - make the whole header block a C++ comment
    - ES9039_DECODE_MASK now covers S/PDIF. hw_params() uses it to enable one
      decoder and clear the rest, so omitting it left S/PDIF enabled alongside
      whichever decoder was selected
    - plain conditionals in place of "return ret ? ret : 1"
    - mute_stream() and the Master Playback Switch no longer both write
      ES9039_DAC_MUTE. Each records its intent and the register is written from
      the union, so neither can override the other
    - the DoP control returns -EBUSY while a stream is open rather than
      half-applying a change hw_params() will not re-run
    - the status controls use the symbolic source bits; TDM_VALID gained one
    - the harmonic correction controls keep their names. The TLV justification
      was wrong and is gone, but they cancel distortion rather than set a level
    - clocking, which was one mistake in three places. SND_SOC_DAIFMT_CBP_CFP is
      accepted and programs PCM_MASTER_MODE; clk_set_rate() pulls MCLK to
      256 * FS when the clock is settable; synchronous operation is derived
      rather than assumed; and the MCLK floor is 128 * FS synchronous or
      130 * FS asynchronous, not 130 unconditionally, so a synchronous board is
      no longer refused rates it can carry
    - fix the Clock Fault control, which read the byte above the status bit and
      so could never report a fault
    - hold both DoP bits consistent under a mutex, and use VOLUME_HOLD so the
      two channel volumes latch together

 sound/soc/codecs/Kconfig     |   14 +
 sound/soc/codecs/Makefile    |    2 +
 sound/soc/codecs/es9039q2m.c | 1831 ++++++++++++++++++++++++++++++++++
 3 files changed, 1847 insertions(+)
 create mode 100644 sound/soc/codecs/es9039q2m.c

diff --git a/sound/soc/codecs/Kconfig b/sound/soc/codecs/Kconfig
index e78d725e61e..fefda526277 100644
--- a/sound/soc/codecs/Kconfig
+++ b/sound/soc/codecs/Kconfig
@@ -123,6 +123,7 @@ config SND_SOC_ALL_CODECS
 	imply SND_SOC_ES8328_I2C
 	imply SND_SOC_ES8375
 	imply SND_SOC_ES8389
+	imply SND_SOC_ES9039Q2M
 	imply SND_SOC_ES9356
 	imply SND_SOC_ES7134
 	imply SND_SOC_ES7241
@@ -1317,6 +1318,19 @@ config SND_SOC_ES8389
 	tristate "Everest Semi ES8389 CODEC"
 	depends on I2C
 
+config SND_SOC_ES9039Q2M
+	tristate "ESS Technology ES9039Q2M CODEC"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  Enable support for the ESS Technology ES9039Q2M, a 32-bit
+	  two-channel audio DAC with an asynchronous sample rate converter,
+	  supporting PCM, DSD, DoP and S/PDIF input. This driver covers the
+	  I2C control interface, which the MODE pin selects.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called snd-soc-es9039q2m.
+
 config SND_SOC_ES9356
 	tristate "Everest Semi ES9356 CODEC SDW"
 	depends on SND_SOC_SDCA
diff --git a/sound/soc/codecs/Makefile b/sound/soc/codecs/Makefile
index 9287a602d41..1679c3ffc63 100644
--- a/sound/soc/codecs/Makefile
+++ b/sound/soc/codecs/Makefile
@@ -140,6 +140,7 @@ snd-soc-es8328-i2c-y := es8328-i2c.o
 snd-soc-es8328-spi-y := es8328-spi.o
 snd-soc-es8375-y := es8375.o
 snd-soc-es8389-y := es8389.o
+snd-soc-es9039q2m-y := es9039q2m.o
 snd-soc-es9356-y := es9356.o
 snd-soc-framer-y := framer-codec.o
 snd-soc-fs-amp-lib-y := fs-amp-lib.o
@@ -586,6 +587,7 @@ obj-$(CONFIG_SND_SOC_ES8328_I2C)+= snd-soc-es8328-i2c.o
 obj-$(CONFIG_SND_SOC_ES8328_SPI)+= snd-soc-es8328-spi.o
 obj-$(CONFIG_SND_SOC_ES8375)    += snd-soc-es8375.o
 obj-$(CONFIG_SND_SOC_ES8389)    += snd-soc-es8389.o
+obj-$(CONFIG_SND_SOC_ES9039Q2M)	+= snd-soc-es9039q2m.o
 obj-$(CONFIG_SND_SOC_ES9356)    += snd-soc-es9356.o
 obj-$(CONFIG_SND_SOC_FRAMER)	+= snd-soc-framer.o
 obj-$(CONFIG_SND_SOC_FS_AMP_LIB)+= snd-soc-fs-amp-lib.o
diff --git a/sound/soc/codecs/es9039q2m.c b/sound/soc/codecs/es9039q2m.c
new file mode 100644
index 00000000000..4edaab87e3f
--- /dev/null
+++ b/sound/soc/codecs/es9039q2m.c
@@ -0,0 +1,1831 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// ESS Technology ES9039Q2M 32-bit 2-channel audio DAC
+//
+// Copyright (C) 2026 Karl Asseily <karl@asseily.com>
+//
+// Every register number, bit field and default in this file was taken from
+// ES9039Q2M datasheet v0.2.3 and then verified by reading the defaults back off
+// a live part over I2C.
+//
+// The part has two control personalities selected by the MODE pin: hardware
+// mode (strapped by HW0/HW1/HW2, no bus at all) and software mode (I2C or SPI).
+// This driver implements software mode over I2C, which MODE = GND selects.
+//
+// Three properties shape the driver:
+//
+//  - There is an ASRC in front of the DAC, so MCLK need not be synchronous with
+//    BCLK or LRCK. A board may feed it a fixed oscillator, or may run it
+//    synchronously and let the part generate BCLK and WS; both are supported.
+//
+//  - INPUT_SEL chooses PCM / DSD / DoP / S/PDIF. It does NOT choose I2S vs
+//    left-justified - that is TDM_LJ_MODE in register 60, and there is no
+//    right-justified mode to map onto at all.
+//
+//  - Several registers have non-zero reserved defaults (register 88 reads
+//    0xb8 at reset), so every write here is read-modify-write.
+
+#include <linux/bitfield.h>
+#include <linux/cleanup.h>
+#include <linux/clk.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/regmap.h>
+
+#include <sound/control.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+#include <sound/tlv.h>
+
+/* ------------------------------------------------- read/write registers ---- */
+
+#define ES9039_SYSTEM_CONFIG		0x00	/* reg 0 */
+#define   ES9039_DAC_MODE		BIT(1)	/* CLEAR at reset - datapath off */
+#define   ES9039_64FS_MODE		BIT(6)
+
+/*
+ * Register 1 selects which DECODERS are running, and it is separate from
+ * INPUT_SEL in register 57, which only says which port to listen to. Both are
+ * needed: on reset only ENABLE_TDM_DECODE is set, so selecting DoP as the input
+ * while leaving bit 2 clear leaves the part hunting for a marker with the
+ * marker decoder switched off. It then finds no valid DoP and mutes - silence,
+ * DOP_VALID reading 0, and nothing anywhere saying why. Measured on hardware.
+ */
+#define ES9039_SYS_MODE			0x01	/* reg 1, reset 0xb1 */
+#define   ES9039_ENABLE_TDM_DECODE	BIT(0)	/* set at reset */
+#define   ES9039_ENABLE_DSD_DECODE	BIT(1)
+#define   ES9039_ENABLE_DOP_DECODE	BIT(2)
+#define   ES9039_ENABLE_SPDIF_DECODE	BIT(3)
+#define   ES9039_SYNC_MODE		BIT(6)	/* 0 = ASYNC */
+#define   ES9039_ENABLE_DAC_CLK		BIT(7)	/* set at reset */
+/*
+ * Every decoder the part has. hw_params() enables one of these and clears the
+ * rest, so leaving S/PDIF out of the mask would have left its decoder running
+ * alongside the selected one.
+ */
+#define   ES9039_DECODE_MASK		(ES9039_ENABLE_TDM_DECODE | \
+					 ES9039_ENABLE_DSD_DECODE | \
+					 ES9039_ENABLE_DOP_DECODE | \
+					 ES9039_ENABLE_SPDIF_DECODE)
+
+#define ES9039_AUTO_FS_DETECT		0x03	/* reg 3 */
+#define   ES9039_AUTO_FS_DETECT_EN	BIT(7)
+
+#define ES9039_CLOCK_CONFIG		0x04	/* reg 4, MASTER_BCK_DIV */
+
+#define ES9039_INPUT_SEL		0x39	/* reg 57 */
+#define   ES9039_AUTO_INPUT_SEL		BIT(0)
+#define   ES9039_INPUT_SEL_MASK		GENMASK(2, 1)
+#define     ES9039_INPUT_PCM		0x0
+#define     ES9039_INPUT_DSD		0x1
+#define     ES9039_INPUT_DOP		0x2
+#define     ES9039_INPUT_SPDIF		0x3
+#define   ES9039_PCM_MASTER_MODE	BIT(4)
+#define   ES9039_DSD_MASTER_MODE	BIT(5)
+#define   ES9039_DSD_FAULT_DETECT	BIT(6)	/* set at reset */
+
+#define ES9039_MASTER_ENC		0x3a	/* reg 58 */
+#define   ES9039_BCK_INV		BIT(6)
+
+#define ES9039_TDM_CH_NUM		0x3b	/* reg 59, slots = value + 1 */
+#define   ES9039_TDM_CH_NUM_MASK	GENMASK(4, 0)
+
+#define ES9039_TDM_CONFIG1		0x3c	/* reg 60 */
+#define   ES9039_TDM_VALID_EDGE		BIT(6)
+#define   ES9039_TDM_LJ_MODE		BIT(7)	/* 0 = standard I2S */
+
+#define ES9039_TDM_CONFIG2		0x3d	/* reg 61 */
+#define   ES9039_TDM_BIT_WIDTH_MASK	GENMASK(6, 5)
+#define     ES9039_WIDTH_32		0x0
+#define     ES9039_WIDTH_24		0x1
+#define     ES9039_WIDTH_16		0x2
+
+#define ES9039_MONITOR_CFG		0x3e	/* reg 62 */
+#define   ES9039_DISABLE_PCM_DC		BIT(3)
+#define   ES9039_ENABLE_BCK_MONITOR	BIT(4)	/* set at reset */
+#define   ES9039_ENABLE_WS_MONITOR	BIT(5)	/* set at reset */
+#define   ES9039_DISABLE_DSD_MUTE	BIT(6)
+#define   ES9039_DISABLE_DSD_DC		BIT(7)
+
+#define ES9039_VOLUME_CH1		0x4a	/* reg 74, 0x00 = 0 dB */
+#define ES9039_VOLUME_CH2		0x4b	/* reg 75, 0xff = -127.5 dB */
+#define   ES9039_VOL_MAX		0xff
+
+#define ES9039_VOL_RATE_UP		0x52	/* reg 82 */
+#define ES9039_VOL_RATE_DOWN		0x53	/* reg 83 */
+
+#define ES9039_DAC_MUTE			0x56	/* reg 86, 1 = muted */
+#define   ES9039_MUTE_CH1		BIT(0)
+#define   ES9039_MUTE_CH2		BIT(1)
+#define   ES9039_MUTE_BOTH		(ES9039_MUTE_CH1 | ES9039_MUTE_CH2)
+
+#define ES9039_DAC_INVERT		0x57	/* reg 87 */
+
+#define ES9039_FILTER_SHAPE		0x58	/* reg 88, [7:3] reset to 10111 */
+#define   ES9039_FILTER_SHAPE_MASK	GENMASK(2, 0)
+#define     ES9039_FILTER_APODIZING	1	/* linear phase apodizing fast */
+
+#define ES9039_IIR_SPDIF		0x59	/* reg 89 */
+#define   ES9039_IIR_BW_MASK		GENMASK(2, 0)
+#define   ES9039_VOLUME_HOLD		BIT(3)
+#define   ES9039_SPDIF_SEL_MASK		GENMASK(7, 4)
+
+#define ES9039_DAC_PATH			0x5a	/* reg 90 */
+#define   ES9039_BYPASS_FIR2X		BIT(0)
+#define   ES9039_BYPASS_FIR4X		BIT(1)
+#define   ES9039_BYPASS_IIR		BIT(2)
+
+#define ES9039_THD_C2			0x5b	/* regs 91-94: CH1 lo, CH2 hi */
+#define ES9039_THD_C3			0x6b	/* regs 107-110 */
+
+#define ES9039_AUTOMUTE_EN		0x7b	/* reg 123, both set at reset */
+#define ES9039_AUTOMUTE_TIME		0x7c	/* regs 124-125 */
+#define   ES9039_AUTOMUTE_TIME_MASK	GENMASK(10, 0)
+#define   ES9039_MUTE_RAMP_TO_GND	BIT(11)	/* set at reset */
+#define ES9039_AUTOMUTE_LEVEL		0x7e	/* regs 126-127 */
+#define ES9039_AUTOMUTE_OFF_LEVEL	0x80	/* regs 128-129 */
+
+#define ES9039_SOFT_RAMP		0x82	/* reg 130, valid 0..12 */
+#define   ES9039_SOFT_RAMP_MASK		GENMASK(4, 0)
+#define   ES9039_SOFT_RAMP_MAX		12
+
+#define ES9039_NSMOD			0x83	/* reg 131 */
+#define   ES9039_NSMOD_WIDE_BW_MASK	GENMASK(4, 1)
+#define     ES9039_NSMOD_DEFAULT	0x4
+#define     ES9039_NSMOD_WIDE		0xc
+
+#define ES9039_PROG_RAM_CTRL		0x87	/* reg 135 */
+#define   ES9039_PROG_COEFF_EN		BIT(0)
+#define   ES9039_PROG_COEFF_WE		BIT(1)
+
+#define ES9039_PROG_RAM_ADDR		0x89	/* reg 137 */
+#define   ES9039_PROG_ADDR_MASK		GENMASK(6, 0)
+#define   ES9039_PROG_STAGE_4X		BIT(7)
+
+#define ES9039_PROG_RAM_DATA		0x8a	/* regs 138-140, 24-bit signed */
+
+#define ES9039_LAST_RW			0x8e	/* reg 145 */
+
+/* ----------------------------------------------------- readback registers -- */
+
+#define ES9039_READBACK_BASE		0xe0	/* reg 224 */
+
+#define ES9039_CHIP_ID			0xe1	/* reg 225 */
+#define   ES9039_CHIP_ID_ES9039Q2M	0x63
+
+#define ES9039_IRQ_SOURCES		0xea	/* regs 234-235, 16-bit */
+#define   ES9039_SRC_VOL_MIN_MASK	GENMASK(1, 0)
+#define   ES9039_SRC_AUTOMUTE_MASK	GENMASK(3, 2)
+#define   ES9039_SRC_SS_RAMP_MASK	GENMASK(5, 4)
+#define   ES9039_SRC_DOP_VALID		BIT(6)
+#define   ES9039_SRC_BCK_WS_FAIL	BIT(7)
+#define   ES9039_SRC_TDM_VALID		BIT(11)
+
+#define ES9039_AUTO_FS_READ		0xef	/* reg 239 */
+#define   ES9039_FS_DIV_MASK		GENMASK(5, 0)
+#define   ES9039_FS_HALF_DIV		BIT(6)
+#define   ES9039_FS_DIV_VALID		BIT(7)
+
+#define ES9039_AUTOMUTE_READ		0xf2	/* reg 242 */
+
+#define ES9039_INPUT_STREAM_READ	0xf5	/* reg 245 */
+#define   ES9039_RD_INPUT_SEL_MASK	GENMASK(1, 0)
+#define   ES9039_RD_DOP_VALID		BIT(2)
+#define   ES9039_RD_TDM_VALID		BIT(3)
+#define   ES9039_RD_SPDIF_VALID		BIT(4)
+
+#define ES9039_MAX_REGISTER		0xfb	/* reg 251 */
+
+/* Programmable oversampling FIR: 128 taps in the 2x stage, 32 in the 4x. */
+#define ES9039_FIR2X_TAPS		128
+#define ES9039_FIR4X_TAPS		32
+#define ES9039_COEFF_BYTES		3
+
+/* ------------------------------------------------------------------ private */
+
+struct es9039q2m_priv {
+	struct regmap *regmap;
+	struct clk *mclk;
+	unsigned int mclk_rate;
+	unsigned int fmt;
+	unsigned int stream_rate;	/* last rate from hw_params */
+	unsigned int bclk_ratio;	/* bit clocks per frame, 0 = unknown */
+
+	/*
+	 * Serialises dop_auto against hw_params(), which reads it while
+	 * deciding what to program. Without it a control write racing a
+	 * stream start can leave the two DoP registers disagreeing.
+	 */
+	struct mutex lock;
+	bool dop_auto;		/* let the part detect DoP itself */
+
+	/*
+	 * ES9039_DAC_MUTE has two owners and neither can hold it alone: the
+	 * "Master Playback Switch" control, and mute_stream() around stream
+	 * start and stop. Both record what they want here and the register is
+	 * written from the union, so a user unmute cannot un-mute a stopped
+	 * stream and a stream start cannot override a user mute.
+	 *
+	 * mute_stream starts FALSE and only a real mute_stream(1) sets it.
+	 * Starting it true seemed the safe choice - come up muted - but it is
+	 * not: if a card never reaches the DAI mute callbacks, the flag never
+	 * clears, and because the control now records intent rather than
+	 * writing the register there is nothing the user can do about it. The
+	 * DAC is then muted for ever and the mixer looks fine. Measured on
+	 * hardware: silent with the switch on, off, stream or no stream. Pop
+	 * suppression at probe comes from writing the register
+	 * directly instead, which is what the driver did before this rework
+	 * and is a state either owner may legitimately lift.
+	 */
+	unsigned int mute_user;	/* ES9039_MUTE_CH* the user asked for */
+	bool mute_stream;	/* ASoC has the stream muted */
+
+	bool provider;		/* part drives BCK and WS */
+	bool mclk_fixed;	/* MCLK rate cannot be changed, so ASRC it is */
+};
+
+/*
+ * Multi-byte fields are little-endian across ascending register addresses:
+ * register N holds bits [7:0], N+1 holds [15:8], and so on.
+ */
+static int es9039_read_le(struct regmap *map, unsigned int reg, int n, u32 *out)
+{
+	u8 buf[4];
+	int ret, i;
+
+	ret = regmap_bulk_read(map, reg, buf, n);
+	if (ret)
+		return ret;
+
+	*out = 0;
+	for (i = 0; i < n; i++)
+		*out |= (u32)buf[i] << (8 * i);
+
+	return 0;
+}
+
+static int es9039_write_le(struct regmap *map, unsigned int reg, int n, u32 val)
+{
+	u8 buf[4];
+	int i;
+
+	for (i = 0; i < n; i++)
+		buf[i] = (val >> (8 * i)) & 0xff;
+
+	return regmap_bulk_write(map, reg, buf, n);
+}
+
+/* ------------------------------------------------------------------ regmap */
+
+static bool es9039q2m_writeable_reg(struct device *dev, unsigned int reg)
+{
+	return reg <= ES9039_LAST_RW;
+}
+
+static bool es9039q2m_readable_reg(struct device *dev, unsigned int reg)
+{
+	return reg <= ES9039_LAST_RW || reg >= ES9039_READBACK_BASE;
+}
+
+static bool es9039q2m_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return reg >= ES9039_READBACK_BASE;
+}
+
+static const struct regmap_config es9039q2m_regmap = {
+	.reg_bits	= 8,
+	.val_bits	= 8,
+	.max_register	= ES9039_MAX_REGISTER,
+	.writeable_reg	= es9039q2m_writeable_reg,
+	.readable_reg	= es9039q2m_readable_reg,
+	.volatile_reg	= es9039q2m_volatile_reg,
+	.cache_type	= REGCACHE_MAPLE,
+};
+
+/* --------------------------------------------------- signed 16-bit controls */
+
+struct es9039_s16_ctl {
+	unsigned int reg;
+	unsigned int shift;	/* 0 for CH1, 16 for CH2 within the 32-bit pair */
+};
+
+static int es9039_s16_info(struct snd_kcontrol *kcontrol,
+			   struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 1;
+	uinfo->value.integer.min = S16_MIN;
+	uinfo->value.integer.max = S16_MAX;
+	return 0;
+}
+
+static int es9039_s16_get(struct snd_kcontrol *kcontrol,
+			  struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
+	struct es9039_s16_ctl *p = (void *)kcontrol->private_value;
+	u32 v;
+	int ret;
+
+	ret = es9039_read_le(priv->regmap, p->reg + (p->shift / 8), 2, &v);
+	if (ret)
+		return ret;
+
+	ucontrol->value.integer.value[0] = (s16)v;
+	return 0;
+}
+
+static int es9039_s16_put(struct snd_kcontrol *kcontrol,
+			  struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
+	struct es9039_s16_ctl *p = (void *)kcontrol->private_value;
+	long v = ucontrol->value.integer.value[0];
+	u32 old;
+	int ret;
+
+	if (v < S16_MIN || v > S16_MAX)
+		return -EINVAL;
+
+	ret = es9039_read_le(priv->regmap, p->reg + (p->shift / 8), 2, &old);
+	if (ret)
+		return ret;
+
+	if ((s16)old == (s16)v)
+		return 0;
+
+	ret = es9039_write_le(priv->regmap, p->reg + (p->shift / 8), 2,
+			      (u16)v);
+	if (ret)
+		return ret;
+
+	return 1;
+}
+
+#define ES9039_S16(xname, xreg, xshift)					\
+{									\
+	.iface	= SNDRV_CTL_ELEM_IFACE_MIXER,				\
+	.name	= xname,						\
+	.info	= es9039_s16_info,					\
+	.get	= es9039_s16_get,					\
+	.put	= es9039_s16_put,					\
+	.private_value = (unsigned long)&(struct es9039_s16_ctl)	\
+			 { .reg = xreg, .shift = xshift },		\
+}
+
+/* ------------------------------------------------- multi-register integers */
+
+struct es9039_wide_ctl {
+	unsigned int reg;
+	unsigned int bytes;
+	unsigned int mask;
+	unsigned int max;
+};
+
+static int es9039_wide_info(struct snd_kcontrol *kcontrol,
+			    struct snd_ctl_elem_info *uinfo)
+{
+	struct es9039_wide_ctl *p = (void *)kcontrol->private_value;
+
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 1;
+	uinfo->value.integer.min = 0;
+	uinfo->value.integer.max = p->max;
+	return 0;
+}
+
+static int es9039_wide_get(struct snd_kcontrol *kcontrol,
+			   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
+	struct es9039_wide_ctl *p = (void *)kcontrol->private_value;
+	u32 v;
+	int ret;
+
+	ret = es9039_read_le(priv->regmap, p->reg, p->bytes, &v);
+	if (ret)
+		return ret;
+
+	ucontrol->value.integer.value[0] = v & p->mask;
+	return 0;
+}
+
+static int es9039_wide_put(struct snd_kcontrol *kcontrol,
+			   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
+	struct es9039_wide_ctl *p = (void *)kcontrol->private_value;
+	long v = ucontrol->value.integer.value[0];
+	u32 old;
+	int ret;
+
+	if (v < 0 || v > p->max)
+		return -EINVAL;
+
+	ret = es9039_read_le(priv->regmap, p->reg, p->bytes, &old);
+	if (ret)
+		return ret;
+
+	if ((old & p->mask) == (u32)v)
+		return 0;
+
+	/* Preserve the bits outside the field - reg 124 carries MUTE_RAMP. */
+	ret = es9039_write_le(priv->regmap, p->reg, p->bytes,
+			      (old & ~p->mask) | (u32)v);
+	if (ret)
+		return ret;
+
+	return 1;
+}
+
+#define ES9039_WIDE(xname, xreg, xbytes, xmask, xmax)			\
+{									\
+	.iface	= SNDRV_CTL_ELEM_IFACE_MIXER,				\
+	.name	= xname,						\
+	.info	= es9039_wide_info,					\
+	.get	= es9039_wide_get,					\
+	.put	= es9039_wide_put,					\
+	.private_value = (unsigned long)&(struct es9039_wide_ctl)	\
+			 { .reg = xreg, .bytes = xbytes,		\
+			   .mask = xmask, .max = xmax },		\
+}
+
+/* ------------------------------------------------ programmable FIR upload --
+ *
+ * Write-only, deliberately. The chip has a PROG_COEFF_OUT register (248-246)
+ * described only as "Programmable FIR coefficient readback", but it is not a
+ * RAM read port: it returns the LAST COEFFICIENT WRITTEN, whatever address is
+ * selected in PROG_COEFF_ADDR. Measured over raw I2C with this driver out of
+ * the path - two different coefficients written to
+ * addresses 0 and 1, then read back with five different sequences (plain, with
+ * a settle delay, with PROG_COEFF_EN set, with the address written twice, and
+ * with a WE pulse after the address). All ten reads returned the value written
+ * to address 1.
+ *
+ * A get() built on that register would return something with the shape of data
+ * and none of its meaning, so there is no get(). If ESS documents a real
+ * readback sequence, add one.
+ */
+
+/*
+ * Per-control data rides in our own struct with the soc_bytes_ext EMBEDDED,
+ * recovered by container_of. Not in soc_bytes_ext.dobj: that field belongs to
+ * the topology subsystem and only exists under CONFIG_SND_SOC_TOPOLOGY, so a
+ * driver stashing its own data there fails to build on any config without it.
+ */
+struct es9039_fir_ctl {
+	struct soc_bytes_ext be;
+	unsigned int taps;
+	bool stage_4x;
+};
+
+static int es9039_fir_put(struct snd_kcontrol *kcontrol,
+			  const unsigned int __user *bytes, unsigned int size)
+{
+	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
+	struct soc_bytes_ext *be = (void *)kcontrol->private_value;
+	struct es9039_fir_ctl *p = container_of(be, struct es9039_fir_ctl, be);
+	u8 *buf;
+	int ret, i;
+
+	if (size != p->taps * ES9039_COEFF_BYTES)
+		return -EINVAL;
+
+	buf = memdup_user(bytes, size);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	/*
+	 * PROG_COEFF_WE is a per-coefficient strobe, not a gate held open
+	 * across the upload. The datasheet's sequence is address, data, raise
+	 * WE, lower WE, once per coefficient. Holding it high for the whole
+	 * loop also appears to work on ES9039Q2M silicon, but "appears to
+	 * work" is not a specification.
+	 */
+	for (i = 0; i < p->taps; i++) {
+		ret = regmap_write(priv->regmap, ES9039_PROG_RAM_ADDR,
+				   (p->stage_4x ? ES9039_PROG_STAGE_4X : 0) |
+				   FIELD_PREP(ES9039_PROG_ADDR_MASK, i));
+		if (ret)
+			goto out;
+
+		ret = regmap_bulk_write(priv->regmap, ES9039_PROG_RAM_DATA,
+					&buf[i * ES9039_COEFF_BYTES],
+					ES9039_COEFF_BYTES);
+		if (ret)
+			goto out;
+
+		ret = regmap_update_bits(priv->regmap, ES9039_PROG_RAM_CTRL,
+					 ES9039_PROG_COEFF_WE,
+					 ES9039_PROG_COEFF_WE);
+		if (ret)
+			goto out;
+
+		ret = regmap_update_bits(priv->regmap, ES9039_PROG_RAM_CTRL,
+					 ES9039_PROG_COEFF_WE, 0);
+		if (ret)
+			goto out;
+	}
+
+out:
+	regmap_update_bits(priv->regmap, ES9039_PROG_RAM_CTRL,
+			   ES9039_PROG_COEFF_WE, 0);
+	kfree(buf);
+	if (ret)
+		return ret;
+
+	return 1;
+}
+
+static struct es9039_fir_ctl es9039_fir2x = {
+	.be = { .max = ES9039_FIR2X_TAPS * ES9039_COEFF_BYTES,
+		.put = es9039_fir_put },
+	.taps = ES9039_FIR2X_TAPS,
+};
+
+static struct es9039_fir_ctl es9039_fir4x = {
+	.be = { .max = ES9039_FIR4X_TAPS * ES9039_COEFF_BYTES,
+		.put = es9039_fir_put },
+	.taps = ES9039_FIR4X_TAPS,
+	.stage_4x = true,
+};
+
+#define ES9039_FIR(xname, xctl)						\
+{									\
+	.iface	= SNDRV_CTL_ELEM_IFACE_MIXER,				\
+	.name	= xname,						\
+	.info	= snd_soc_bytes_info_ext,				\
+	.tlv.c	= snd_soc_bytes_tlv_callback,				\
+	.access	= SNDRV_CTL_ELEM_ACCESS_TLV_WRITE |			\
+		  SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK,			\
+	.private_value = (unsigned long)&(xctl).be,			\
+}
+
+/* ------------------------------------------------------- status (read-only) */
+
+struct es9039_stat_ctl {
+	unsigned int reg;
+	unsigned int mask;
+	unsigned int max;
+};
+
+static int es9039_stat_info(struct snd_kcontrol *kcontrol,
+			    struct snd_ctl_elem_info *uinfo)
+{
+	struct es9039_stat_ctl *p = (void *)kcontrol->private_value;
+
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 1;
+	uinfo->value.integer.min = 0;
+	uinfo->value.integer.max = p->max;
+	return 0;
+}
+
+static int es9039_stat_get(struct snd_kcontrol *kcontrol,
+			   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
+	struct es9039_stat_ctl *p = (void *)kcontrol->private_value;
+	unsigned int v;
+	int ret;
+
+	ret = regmap_read(priv->regmap, p->reg, &v);
+	if (ret)
+		return ret;
+
+	ucontrol->value.integer.value[0] =
+		(v & p->mask) >> (ffs(p->mask) - 1);
+	return 0;
+}
+
+#define ES9039_STAT(xname, xreg, xmask, xmax)				\
+{									\
+	.iface	= SNDRV_CTL_ELEM_IFACE_MIXER,				\
+	.name	= xname,						\
+	.access	= SNDRV_CTL_ELEM_ACCESS_READ |				\
+		  SNDRV_CTL_ELEM_ACCESS_VOLATILE,			\
+	.info	= es9039_stat_info,					\
+	.get	= es9039_stat_get,					\
+	.private_value = (unsigned long)&(struct es9039_stat_ctl)	\
+			 { .reg = xreg, .mask = xmask, .max = xmax },	\
+}
+
+/*
+ * Detected sample rate.
+ *
+ * When the part's own rate detector has a valid ratio, use it - it is measured
+ * from the incoming frame clock and is the ground truth:
+ *
+ *   FS = Y * SYS_CLK / ((X + 1) * (128 >> 64FS_MODE))
+ *
+ * with X = IDAC_DIV_AUTO and Y = 2 when IDAC_HALF_DIV_AUTO reports a
+ * half-integer multiple.
+ *
+ * That detector is UNAVAILABLE on any board running the DAC asynchronously -
+ * register 3[7] AUTO_FS_DETECT carries the note "Cannot be used in ASYNC mode".
+ * A board feeding a free-running oscillator and letting the ASRC absorb the
+ * difference is precisely that case, and it is the preferable design, so the
+ * detector reading 0 there is expected rather than a fault. Fall back to the
+ * rate the stream was opened at, which is what a front panel wants to show.
+ * Reports 0 only when nothing is playing and the chip has no lock either.
+ */
+static int es9039_rate_info(struct snd_kcontrol *kcontrol,
+			    struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 1;
+	uinfo->value.integer.min = 0;
+	uinfo->value.integer.max = 1536000;
+	return 0;
+}
+
+static int es9039_rate_get(struct snd_kcontrol *kcontrol,
+			   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
+	unsigned int fsreg, sysreg, div, y, den;
+	int ret;
+
+	ucontrol->value.integer.value[0] = priv->stream_rate;
+
+	if (!priv->mclk_rate)
+		return 0;
+
+	ret = regmap_read(priv->regmap, ES9039_AUTO_FS_READ, &fsreg);
+	if (ret)
+		return ret;
+
+	if (!(fsreg & ES9039_FS_DIV_VALID))
+		return 0;	/* async mode: keep the stream rate set above */
+
+	ret = regmap_read(priv->regmap, ES9039_SYSTEM_CONFIG, &sysreg);
+	if (ret)
+		return ret;
+
+	div = FIELD_GET(ES9039_FS_DIV_MASK, fsreg) + 1;
+	y   = (fsreg & ES9039_FS_HALF_DIV) ? 2 : 1;
+	den = div * ((sysreg & ES9039_64FS_MODE) ? 64 : 128);
+
+	ucontrol->value.integer.value[0] =
+		DIV_ROUND_CLOSEST(priv->mclk_rate * y, den);
+	return 0;
+}
+
+static const char * const es9039_stream_texts[] = {
+	"PCM", "DSD", "DoP", "S/PDIF",
+};
+
+static int es9039_stream_info(struct snd_kcontrol *kcontrol,
+			      struct snd_ctl_elem_info *uinfo)
+{
+	return snd_ctl_enum_info(uinfo, 1, ARRAY_SIZE(es9039_stream_texts),
+				 es9039_stream_texts);
+}
+
+static int es9039_stream_get(struct snd_kcontrol *kcontrol,
+			     struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
+	unsigned int v;
+	int ret;
+
+	ret = regmap_read(priv->regmap, ES9039_INPUT_STREAM_READ, &v);
+	if (ret)
+		return ret;
+
+	ucontrol->value.enumerated.item[0] =
+		FIELD_GET(ES9039_RD_INPUT_SEL_MASK, v);
+	return 0;
+}
+
+/* ----------------------------------------------------------------- controls */
+
+static const DECLARE_TLV_DB_SCALE(es9039_vol_tlv, -12750, 50, 1);
+
+static const char * const es9039_filter_texts[] = {
+	"Minimum Phase",
+	"Linear Phase Apodizing Fast Roll-Off",
+	"Linear Phase Fast Roll-Off",
+	"Linear Phase Fast Roll-Off Low Ripple",
+	"Linear Phase Slow Roll-Off",
+	"Minimum Phase Fast Roll-Off",
+	"Minimum Phase Slow Roll-Off",
+	"Minimum Phase Slow Roll-Off Low Dispersion",
+};
+
+static SOC_ENUM_SINGLE_DECL(es9039_filter_enum, ES9039_FILTER_SHAPE, 0,
+			    es9039_filter_texts);
+
+/* IIR_BW is a multiple of the datapath bandwidth, not a frequency. */
+static const char * const es9039_iir_texts[] = {
+	"Reserved", "BW x8", "BW x4", "BW x2", "BW", "BW /2", "BW /4", "BW /8",
+};
+
+static SOC_ENUM_SINGLE_DECL(es9039_iir_enum, ES9039_IIR_SPDIF, 0,
+			    es9039_iir_texts);
+
+static const char * const es9039_nsmod_texts[] = {
+	"Default", "Wide Bandwidth",
+};
+
+static const unsigned int es9039_nsmod_values[] = {
+	ES9039_NSMOD_DEFAULT, ES9039_NSMOD_WIDE,
+};
+
+static SOC_VALUE_ENUM_SINGLE_DECL(es9039_nsmod_enum, ES9039_NSMOD, 1,
+				  GENMASK(3, 0), es9039_nsmod_texts,
+				  es9039_nsmod_values);
+
+static int es9039_dop_get(struct snd_kcontrol *kcontrol,
+			  struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
+
+	ucontrol->value.integer.value[0] = priv->dop_auto;
+	return 0;
+}
+
+/*
+ * Automatic DoP detection is two bits in two registers, and they are one
+ * setting: AUTO_INPUT_SEL lets the part choose a decoder from the data, and
+ * ENABLE_DOP_DECODE is what gives it a DoP decoder to choose. Enabling the
+ * first without the second leaves the part hunting for a marker it has no
+ * decoder for, whereupon it finds no valid DoP and mutes.
+ *
+ * Everything that changes the setting goes through here, so the pair can
+ * never be written apart. Callers hold priv->lock.
+ */
+static int es9039_apply_dop(struct es9039q2m_priv *priv, bool on)
+{
+	int ret;
+
+	ret = regmap_update_bits(priv->regmap, ES9039_SYS_MODE,
+				 ES9039_ENABLE_DOP_DECODE,
+				 on ? ES9039_ENABLE_DOP_DECODE : 0);
+	if (ret)
+		return ret;
+
+	return regmap_update_bits(priv->regmap, ES9039_INPUT_SEL,
+				  ES9039_AUTO_INPUT_SEL,
+				  on ? ES9039_AUTO_INPUT_SEL : 0);
+}
+
+/* Caller holds priv->lock. */
+static int es9039_apply_mute(struct es9039q2m_priv *priv)
+{
+	unsigned int val = priv->mute_user;
+
+	if (priv->mute_stream)
+		val = ES9039_MUTE_BOTH;
+
+	return regmap_update_bits(priv->regmap, ES9039_DAC_MUTE,
+				  ES9039_MUTE_BOTH, val);
+}
+
+/*
+ * The control is inverted - 1 means playing - so a zero here is a mute
+ * request. It reports priv->mute_user rather than the register, because the
+ * register also carries the stream mute and the user did not ask for that.
+ */
+static int es9039_mute_get(struct snd_kcontrol *kcontrol,
+			   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
+
+	guard(mutex)(&priv->lock);
+
+	ucontrol->value.integer.value[0] = !(priv->mute_user & ES9039_MUTE_CH1);
+	ucontrol->value.integer.value[1] = !(priv->mute_user & ES9039_MUTE_CH2);
+
+	return 0;
+}
+
+static int es9039_mute_put(struct snd_kcontrol *kcontrol,
+			   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
+	unsigned int val = 0, old;
+	int ret;
+
+	if (!ucontrol->value.integer.value[0])
+		val |= ES9039_MUTE_CH1;
+	if (!ucontrol->value.integer.value[1])
+		val |= ES9039_MUTE_CH2;
+
+	guard(mutex)(&priv->lock);
+
+	if (val == priv->mute_user)
+		return 0;
+
+	/*
+	 * Commit to the register first. If the write fails and the shadow has
+	 * already moved, get() reports a mute the part is not in and the
+	 * val == mute_user test above turns a retry with the same value into a
+	 * no-op, leaving the control permanently wrong.
+	 */
+	old = priv->mute_user;
+	priv->mute_user = val;
+
+	ret = es9039_apply_mute(priv);
+	if (ret) {
+		priv->mute_user = old;
+		return ret;
+	}
+
+	return 1;
+}
+
+static int es9039_dop_put(struct snd_kcontrol *kcontrol,
+			  struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
+	bool on = !!ucontrol->value.integer.value[0], old;
+	int ret;
+
+	guard(mutex)(&priv->lock);
+
+	if (on == priv->dop_auto)
+		return 0;
+
+	/*
+	 * hw_params() programs the decoder and INPUT_SEL from dop_auto, so
+	 * changing it under a running stream would apply half the setting now
+	 * and the rest at the next open. Refuse instead of half-applying.
+	 */
+	if (priv->stream_rate)
+		return -EBUSY;
+
+	/* Same reasoning as es9039_mute_put(): the shadow follows the write. */
+	old = priv->dop_auto;
+	priv->dop_auto = on;
+
+	ret = es9039_apply_dop(priv, on);
+	if (ret) {
+		priv->dop_auto = old;
+		return ret;
+	}
+
+	return 1;
+}
+
+/*
+ * The two channel volumes live in separate registers, so a stereo change is
+ * two I2C writes and the channels are briefly at different levels in between.
+ * VOLUME_HOLD exists for exactly this: while it is set the part accepts writes
+ * to registers 74-75 without applying them, and clearing it applies both at
+ * once. Raise it, let the generic handler do the writes, drop it again.
+ *
+ * It is dropped unconditionally, including on the error path, because a stuck
+ * VOLUME_HOLD would silently freeze the volume control.
+ */
+static int es9039_vol_put(struct snd_kcontrol *kcontrol,
+			  struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
+	int ret;
+
+	ret = regmap_update_bits(priv->regmap, ES9039_IIR_SPDIF,
+				 ES9039_VOLUME_HOLD, ES9039_VOLUME_HOLD);
+	if (ret)
+		return ret;
+
+	ret = snd_soc_put_volsw(kcontrol, ucontrol);
+
+	regmap_update_bits(priv->regmap, ES9039_IIR_SPDIF,
+			   ES9039_VOLUME_HOLD, 0);
+
+	return ret;
+}
+
+static const struct snd_kcontrol_new es9039q2m_controls[] = {
+	/* --- level --- */
+	{
+		.iface	= SNDRV_CTL_ELEM_IFACE_MIXER,
+		.name	= "Master Playback Volume",
+		.access	= SNDRV_CTL_ELEM_ACCESS_READWRITE |
+			  SNDRV_CTL_ELEM_ACCESS_TLV_READ,
+		.info	= snd_soc_info_volsw,
+		.get	= snd_soc_get_volsw,
+		.put	= es9039_vol_put,
+		.tlv.p	= es9039_vol_tlv,
+		.private_value = SOC_DOUBLE_R_VALUE(ES9039_VOLUME_CH1,
+						    ES9039_VOLUME_CH2, 0, 0,
+						    ES9039_VOL_MAX, 1),
+	},
+	{
+		.iface	= SNDRV_CTL_ELEM_IFACE_MIXER,
+		.name	= "Master Playback Switch",
+		.info	= snd_soc_info_volsw,
+		.get	= es9039_mute_get,
+		.put	= es9039_mute_put,
+		.private_value = SOC_DOUBLE_VALUE(ES9039_DAC_MUTE, 0, 1, 0, 1,
+						  1, 0),
+	},
+	SOC_DOUBLE("DAC Invert Switch", ES9039_DAC_INVERT, 0, 1, 1, 0),
+	SOC_SINGLE("Volume Ramp Up Rate", ES9039_VOL_RATE_UP, 0, 255, 0),
+	SOC_SINGLE("Volume Ramp Down Rate", ES9039_VOL_RATE_DOWN, 0, 255, 0),
+	SOC_SINGLE("Soft Ramp Time", ES9039_SOFT_RAMP, 0,
+		   ES9039_SOFT_RAMP_MAX, 0),
+
+	/* --- reconstruction filter --- */
+	SOC_ENUM("Filter Shape", es9039_filter_enum),
+	SOC_ENUM("IIR Bandwidth", es9039_iir_enum),
+	SOC_ENUM("Modulator Bandwidth", es9039_nsmod_enum),
+	SOC_SINGLE("IIR Filter Bypass Switch", ES9039_DAC_PATH, 2, 1, 0),
+	SOC_SINGLE("FIR 2x Bypass Switch", ES9039_DAC_PATH, 0, 1, 0),
+	SOC_SINGLE("FIR 4x Bypass Switch", ES9039_DAC_PATH, 1, 1, 0),
+	SOC_SINGLE("Custom FIR Switch", ES9039_PROG_RAM_CTRL, 0, 1, 0),
+	ES9039_FIR("FIR 2x Coefficients", es9039_fir2x),
+	ES9039_FIR("FIR 4x Coefficients", es9039_fir4x),
+
+	/*
+	 * Not "... Volume", because these do not set a level. They are signed
+	 * correction coefficients for the second and third harmonic: they
+	 * cancel distortion the analogue stage adds, and turning one up does
+	 * not make anything louder. Useful values come from measuring a given
+	 * board's distortion on an analyser and solving for them; zero, the
+	 * reset value, is the only honest default until someone has.
+	 */
+	/* --- distortion compensation --- */
+	ES9039_S16("THD Compensation C2 CH1", ES9039_THD_C2, 0),
+	ES9039_S16("THD Compensation C2 CH2", ES9039_THD_C2, 16),
+	ES9039_S16("THD Compensation C3 CH1", ES9039_THD_C3, 0),
+	ES9039_S16("THD Compensation C3 CH2", ES9039_THD_C3, 16),
+
+	/* --- automute --- */
+	SOC_DOUBLE("Automute Switch", ES9039_AUTOMUTE_EN, 0, 1, 1, 0),
+	ES9039_WIDE("Automute Time", ES9039_AUTOMUTE_TIME, 2,
+		    ES9039_AUTOMUTE_TIME_MASK, 2047),
+	ES9039_WIDE("Automute Level", ES9039_AUTOMUTE_LEVEL, 2, 0xffff, 65535),
+	ES9039_WIDE("Automute Off Level", ES9039_AUTOMUTE_OFF_LEVEL, 2,
+		    0xffff, 65535),
+	SOC_SINGLE("Mute Ramp To Ground Switch", ES9039_AUTOMUTE_TIME + 1,
+		   3, 1, 0),
+	SOC_SINGLE("DSD DC Automute Switch", ES9039_MONITOR_CFG, 7, 1, 1),
+	SOC_SINGLE("DSD Mute Pattern Switch", ES9039_MONITOR_CFG, 6, 1, 1),
+	SOC_SINGLE("PCM DC Automute Switch", ES9039_MONITOR_CFG, 3, 1, 1),
+
+	/* --- stream --- */
+	/*
+	 * On by default. DoP is designed to be detected, not announced: the
+	 * player just sends it and a DoP-aware DAC notices the marker, which
+	 * is why a DAC that does not notice plays it as near-silence rather
+	 * than noise. Players rely on that, and none of them can reach into
+	 * ALSA to flip a mode first.
+	 *
+	 * Left switchable because automatic detection is a pattern match, and
+	 * anyone worried about PCM material that happens to look like DoP can
+	 * turn it off and get strictly PCM.
+	 */
+	SOC_SINGLE_BOOL_EXT("DoP Auto Detect Switch", 0,
+			    es9039_dop_get, es9039_dop_put),
+
+	/* --- status, read-only --- */
+	ES9039_STAT("Automute Active CH1", ES9039_AUTOMUTE_READ, BIT(0), 1),
+	ES9039_STAT("Automute Active CH2", ES9039_AUTOMUTE_READ, BIT(1), 1),
+	ES9039_STAT("DoP Valid", ES9039_INPUT_STREAM_READ,
+		    ES9039_RD_DOP_VALID, 1),
+	ES9039_STAT("TDM Data Valid", ES9039_INPUT_STREAM_READ,
+		    ES9039_RD_TDM_VALID, 1),
+	ES9039_STAT("SPDIF Valid", ES9039_INPUT_STREAM_READ,
+		    ES9039_RD_SPDIF_VALID, 1),
+	/*
+	 * Register 235-234 is one 16-bit word and BCK_WS_FAIL_SOURCE is bit
+	 * 7 of it, so it sits in the low byte at ES9039_IRQ_SOURCES. This
+	 * read the byte above with the same mask, which is bit 15 - reserved
+	 * - so the control could never have reported a fault. The named
+	 * constant now carries the bit rather than a bare BIT(7).
+	 *
+	 * The flag is meaningful only with the BCK and WS monitors enabled,
+	 * which they are at reset and the driver leaves alone.
+	 */
+	ES9039_STAT("Clock Fault", ES9039_IRQ_SOURCES,
+		    ES9039_SRC_BCK_WS_FAIL, 1),
+	{
+		.iface	= SNDRV_CTL_ELEM_IFACE_MIXER,
+		.name	= "Detected Sample Rate",
+		.access	= SNDRV_CTL_ELEM_ACCESS_READ |
+			  SNDRV_CTL_ELEM_ACCESS_VOLATILE,
+		.info	= es9039_rate_info,
+		.get	= es9039_rate_get,
+	},
+	{
+		.iface	= SNDRV_CTL_ELEM_IFACE_MIXER,
+		.name	= "Detected Input Format",
+		.access	= SNDRV_CTL_ELEM_ACCESS_READ |
+			  SNDRV_CTL_ELEM_ACCESS_VOLATILE,
+		.info	= es9039_stream_info,
+		.get	= es9039_stream_get,
+	},
+};
+
+/* --------------------------------------------------------------------- DAPM */
+
+static const struct snd_soc_dapm_widget es9039q2m_widgets[] = {
+	SND_SOC_DAPM_DAC("DAC", NULL, SND_SOC_NOPM, 0, 0),
+	SND_SOC_DAPM_OUTPUT("AOUTL"),
+	SND_SOC_DAPM_OUTPUT("AOUTR"),
+};
+
+static const struct snd_soc_dapm_route es9039q2m_routes[] = {
+	{ "DAC",   NULL, "Playback" },
+	{ "AOUTL", NULL, "DAC" },
+	{ "AOUTR", NULL, "DAC" },
+};
+
+/* ---------------------------------------------------------------------- DAI */
+
+/*
+ * MCLK limits, all from the datasheet:
+ *
+ *  - 50 MHz absolute maximum ("Max MCLK Frequency", electrical specification).
+ *
+ *  - Table 7 note 1: MCLK >= 128 * FS synchronous, MCLK > 130 * FS
+ *    asynchronous. The gap is small but not academic - with a 24.576 MHz
+ *    clock, 128 * FS puts 192 kHz exactly at the limit while 130 * FS puts the
+ *    ceiling at 189 kHz. Note that the asynchronous bound is strict.
+ *
+ *  - Register 0[6] ENABLE_64FS_MODE runs the interpolation path at 64FS and is
+ *    "used only for PCM high sample rates such as 768kHz with a 49.152MHz or
+ *    384kHz with 24.576MHz clock" - both of which are MCLK = 64 * FS. Since
+ *    128 * 768000 is 98.304 MHz, well over the ceiling, 64FS mode is the only
+ *    way 705.6 and 768 kHz are reachable at all.
+ */
+#define ES9039_MAX_MCLK			50000000
+#define ES9039_64FS_MCLK_FS		64
+#define ES9039_SYNC_MIN_MCLK_FS		128
+#define ES9039_ASYNC_MIN_MCLK_FS	130
+
+/*
+ * MCLK/FS ratios to try on a settable clock, highest first. 256 leaves the
+ * part inside the window its automatic clock gearing aims for - register 5[2]:
+ * "MCLK will be geared down until 128FS <= SYS_CLK < 256FS" - and 64 is 64FS
+ * mode, which only becomes the choice when nothing larger fits under 50 MHz.
+ */
+static const unsigned int es9039_mclk_ratios[] = { 512, 256, 128, 64 };
+
+/*
+ * Synchronous means the frame clock and MCLK come from the same place. That is
+ * true when the part generates BCK and WS itself, and it is true when the MCLK
+ * we were given can be set to a multiple of the sample rate. Only a fixed
+ * oscillator feeding a consumer-mode part is genuinely asynchronous, and only
+ * then does the ASRC have anything to do.
+ */
+static bool es9039_is_sync(struct es9039q2m_priv *priv)
+{
+	return priv->provider || !priv->mclk_fixed;
+}
+
+/*
+ * 64FS mode is an exact MCLK/FS ratio, not a rate threshold, and it only makes
+ * sense synchronously: at 64 * FS an asynchronous part would sit far below its
+ * own 130 * FS floor, so a fixed oscillator that happens to land on 64 * FS is
+ * a coincidence rather than a mode.
+ */
+static bool es9039_is_64fs(struct es9039q2m_priv *priv, unsigned int mclk,
+			   unsigned int rate)
+{
+	return es9039_is_sync(priv) && rate &&
+	       mclk == ES9039_64FS_MCLK_FS * rate;
+}
+
+/* The lowest MCLK this rate may run at outside 64FS mode. */
+static unsigned int es9039_min_mclk(struct es9039q2m_priv *priv,
+				    unsigned int rate)
+{
+	if (es9039_is_sync(priv))
+		return ES9039_SYNC_MIN_MCLK_FS * rate;
+
+	/* Asynchronous is strictly greater than 130 * FS, not equal to it. */
+	return ES9039_ASYNC_MIN_MCLK_FS * rate + 1;
+}
+
+static int es9039q2m_startup(struct snd_pcm_substream *substream,
+			     struct snd_soc_dai *dai)
+{
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(dai->component);
+	unsigned int max_rate;
+
+	/*
+	 * A clock whose rate can be set imposes no ceiling here: hw_params()
+	 * raises MCLK to suit the rate, and fails cleanly if it cannot.
+	 * Constraining from the rate MCLK merely happens to be idling at would
+	 * reject rates the board can carry perfectly well.
+	 */
+	if (!priv->mclk_rate || !priv->mclk_fixed)
+		return 0;
+
+	if (!es9039_is_sync(priv)) {
+		max_rate = priv->mclk_rate / ES9039_ASYNC_MIN_MCLK_FS;
+	} else if (priv->mclk_rate % ES9039_64FS_MCLK_FS == 0) {
+		/*
+		 * 64FS mode reaches exactly one rate above the ordinary
+		 * ceiling - MCLK / 64 - so admit it here and leave
+		 * hw_params() to reject anything in between, where neither
+		 * 64 * FS nor 128 * FS is satisfied.
+		 */
+		max_rate = priv->mclk_rate / ES9039_64FS_MCLK_FS;
+	} else {
+		max_rate = priv->mclk_rate / ES9039_SYNC_MIN_MCLK_FS;
+	}
+
+	return snd_pcm_hw_constraint_minmax(substream->runtime,
+					    SNDRV_PCM_HW_PARAM_RATE,
+					    8000, max_rate);
+}
+
+/*
+ * Put the clocking where it needs to be for this rate, and tell the part which
+ * of its two timing worlds it is living in.
+ *
+ * With a settable MCLK the useful thing is to pull it to an exact multiple of
+ * the sample rate: the ASRC then has nothing to correct, which is the better
+ * arrangement whenever the board can manage it. With a fixed oscillator there
+ * is nothing to pull, and the ASRC earns its keep.
+ */
+static int es9039_setup_clocking(struct es9039q2m_priv *priv,
+				 struct snd_soc_dai *dai, unsigned int rate)
+{
+	unsigned int ratio, min_mclk, div, i, target = 0;
+	bool sixtyfour;
+	int ret;
+
+	if (!priv->mclk_rate)
+		return 0;
+
+	ratio = priv->bclk_ratio ? priv->bclk_ratio : 64;
+
+	if (!priv->mclk_fixed) {
+		/*
+		 * Take the highest ratio that still fits under the 50 MHz
+		 * ceiling rather than always asking for 256 * FS, which would
+		 * put 384 kHz at 98.304 MHz and 768 kHz at 196.608 MHz. A
+		 * settable clock is synchronous by definition here - see
+		 * es9039_is_sync() - so only the synchronous floors apply.
+		 */
+		for (i = 0; i < ARRAY_SIZE(es9039_mclk_ratios); i++) {
+			unsigned int mult = es9039_mclk_ratios[i];
+
+			if (mult * rate > ES9039_MAX_MCLK)
+				continue;
+			if (mult < ES9039_SYNC_MIN_MCLK_FS &&
+			    mult != ES9039_64FS_MCLK_FS)
+				continue;
+			/*
+			 * Master mode divides MCLK down to BCK by a whole
+			 * number, so a ratio that is not a multiple of the
+			 * frame size cannot produce the bit clock.
+			 */
+			if (priv->provider && mult % ratio)
+				continue;
+
+			target = mult * rate;
+			break;
+		}
+
+		if (!target) {
+			dev_err(dai->dev,
+				"no mclk ratio for %u Hz within %u Hz\n",
+				rate, ES9039_MAX_MCLK);
+			return -EINVAL;
+		}
+
+		ret = clk_set_rate(priv->mclk, target);
+		if (ret)
+			return ret;
+
+		/* Take what the clock settled on, not what was asked for. */
+		priv->mclk_rate = clk_get_rate(priv->mclk);
+	}
+
+	if (priv->mclk_rate > ES9039_MAX_MCLK) {
+		dev_err(dai->dev, "mclk %u Hz is above the %u Hz maximum\n",
+			priv->mclk_rate, ES9039_MAX_MCLK);
+		return -EINVAL;
+	}
+
+	sixtyfour = es9039_is_64fs(priv, priv->mclk_rate, rate);
+	min_mclk = es9039_min_mclk(priv, rate);
+
+	if (!sixtyfour && priv->mclk_rate < min_mclk) {
+		dev_err(dai->dev,
+			"mclk %u Hz is below the %u Hz %u Hz needs in this mode\n",
+			priv->mclk_rate, min_mclk, rate);
+		return -EINVAL;
+	}
+
+	/*
+	 * Register 0[6]. Decided from the MCLK actually in use rather than from
+	 * the sample rate alone, because the part cares about the ratio: 384 kHz
+	 * from 24.576 MHz needs 64FS mode exactly as 768 kHz from 49.152 MHz
+	 * does. The mode also forces a minimum phase filter regardless of
+	 * FILTER_SHAPE.
+	 */
+	ret = regmap_update_bits(priv->regmap, ES9039_SYSTEM_CONFIG,
+				 ES9039_64FS_MODE,
+				 sixtyfour ? ES9039_64FS_MODE : 0);
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(priv->regmap, ES9039_SYS_MODE,
+				 ES9039_SYNC_MODE,
+				 es9039_is_sync(priv) ? ES9039_SYNC_MODE : 0);
+	if (ret)
+		return ret;
+
+	if (!priv->provider)
+		return 0;
+
+	/*
+	 * Register 4: BCK = MCLK / (MASTER_BCK_DIV + 1), and WS follows from
+	 * the frame length. An MCLK that is not a whole multiple of the bit
+	 * clock cannot produce the requested rate at all, so say so rather
+	 * than emitting something close.
+	 */
+	if (priv->mclk_rate % (ratio * rate)) {
+		dev_err(dai->dev,
+			"mclk %u Hz cannot produce %u * %u Hz bit clock\n",
+			priv->mclk_rate, ratio, rate);
+		return -EINVAL;
+	}
+
+	div = priv->mclk_rate / (ratio * rate);
+	if (div < 1 || div > 256) {
+		dev_err(dai->dev, "master bck divider %u out of range\n", div);
+		return -EINVAL;
+	}
+
+	return regmap_write(priv->regmap, ES9039_CLOCK_CONFIG, div - 1);
+}
+
+static int es9039q2m_set_fmt(struct snd_soc_dai *dai, unsigned int fmt)
+{
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(dai->component);
+	unsigned int cfg1 = 0, enc = 0;
+	int ret;
+
+	/*
+	 * Both directions are useful and which is right is a board decision,
+	 * not a driver one. Driving BCK and WS from a good MCLK is the
+	 * conventional arrangement and keeps everything synchronous; taking
+	 * them from a consumer-mode host and letting the ASRC absorb the
+	 * mismatch is what a board with a fixed oscillator wants. The part can
+	 * do either, so the driver offers either.
+	 */
+	switch (fmt & SND_SOC_DAIFMT_CLOCK_PROVIDER_MASK) {
+	case SND_SOC_DAIFMT_CBC_CFC:
+		priv->provider = false;
+		break;
+	case SND_SOC_DAIFMT_CBP_CFP:
+		if (!priv->mclk)
+			return -EINVAL;
+		priv->provider = true;
+		break;
+	default:
+		/* The part cannot split them: it drives both or neither. */
+		return -EINVAL;
+	}
+
+	ret = regmap_update_bits(priv->regmap, ES9039_INPUT_SEL,
+				 ES9039_PCM_MASTER_MODE,
+				 priv->provider ? ES9039_PCM_MASTER_MODE : 0);
+	if (ret)
+		return ret;
+
+	switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
+	case SND_SOC_DAIFMT_I2S:
+		break;
+	case SND_SOC_DAIFMT_LEFT_J:
+		cfg1 |= ES9039_TDM_LJ_MODE;
+		break;
+	default:
+		/* Register 60 offers I2S or LJ. There is no RJ mode. */
+		return -EINVAL;
+	}
+
+	switch (fmt & SND_SOC_DAIFMT_INV_MASK) {
+	case SND_SOC_DAIFMT_NB_NF:
+		break;
+	case SND_SOC_DAIFMT_IB_NF:
+		enc |= ES9039_BCK_INV;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = regmap_update_bits(priv->regmap, ES9039_TDM_CONFIG1,
+				 ES9039_TDM_LJ_MODE, cfg1);
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(priv->regmap, ES9039_MASTER_ENC,
+				 ES9039_BCK_INV, enc);
+	if (ret)
+		return ret;
+
+	priv->fmt = fmt;
+	return 0;
+}
+
+/*
+ * TDM_BIT_WIDTH describes the SLOT width on the wire, not the sample size. Those
+ * are routinely different: 16-bit samples are usually carried left-justified in
+ * 32-bit slots. Getting this wrong misaligns the channel boundaries and the
+ * result is one channel, or noise.
+ *
+ * ASoC does not hand the codec the bit clock ratio unless a machine driver sets
+ * it, so take it when offered and otherwise assume 32-bit slots - by far the
+ * most common arrangement, and what the RK3588 I2S does unconditionally
+ * (rockchip_i2s.c sets bclk_ratio = 64 at probe and never varies it with
+ * format).
+ */
+static int es9039q2m_set_bclk_ratio(struct snd_soc_dai *dai, unsigned int ratio)
+{
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(dai->component);
+
+	priv->bclk_ratio = ratio;
+	return 0;
+}
+
+static int es9039q2m_hw_params(struct snd_pcm_substream *substream,
+			       struct snd_pcm_hw_params *params,
+			       struct snd_soc_dai *dai)
+{
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(dai->component);
+	unsigned int input_sel, decode, width, slot_bits, isel;
+	bool auto_sel;
+	int ret;
+
+	/*
+	 * Held for the whole call: dop_auto decides both INPUT_SEL and
+	 * SYS_MODE below, and a kcontrol write landing between the two would
+	 * leave automatic detection enabled with no DoP decoder behind it.
+	 */
+	guard(mutex)(&priv->lock);
+
+	priv->stream_rate = params_rate(params);
+
+	ret = es9039_setup_clocking(priv, dai, priv->stream_rate);
+	if (ret)
+		return ret;
+
+	switch (params_format(params)) {
+	case SNDRV_PCM_FORMAT_DSD_U8:
+	case SNDRV_PCM_FORMAT_DSD_U16_LE:
+	case SNDRV_PCM_FORMAT_DSD_U32_LE:
+		/*
+		 * Forced, not auto-detected: the datasheet requires DSD data on
+		 * DATA1 and DATA2 for AUTO_INPUT_SEL to identify it, which a
+		 * two-channel I2S link does not provide.
+		 */
+		input_sel = ES9039_INPUT_DSD;
+		decode = ES9039_ENABLE_DSD_DECODE;
+		auto_sel = false;
+		break;
+	case SNDRV_PCM_FORMAT_S16_LE:
+	case SNDRV_PCM_FORMAT_S24_LE:
+	case SNDRV_PCM_FORMAT_S24_3LE:
+	case SNDRV_PCM_FORMAT_S32_LE:
+		/*
+		 * DoP arrives inside ordinary PCM frames and is indistinguishable
+		 * from PCM until the part finds the marker, so both decoders run
+		 * and AUTO_INPUT_SEL picks between them. INPUT_SEL is programmed
+		 * anyway as the fallback the part uses when auto-detection is
+		 * switched off.
+		 */
+		input_sel = ES9039_INPUT_PCM;
+		decode = ES9039_ENABLE_TDM_DECODE |
+			 (priv->dop_auto ? ES9039_ENABLE_DOP_DECODE : 0);
+		auto_sel = priv->dop_auto;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	slot_bits = priv->bclk_ratio ?
+		    priv->bclk_ratio / params_channels(params) : 32;
+
+	switch (slot_bits) {
+	case 16:
+		width = ES9039_WIDTH_16;
+		break;
+	case 24:
+		width = ES9039_WIDTH_24;
+		break;
+	case 32:
+		width = ES9039_WIDTH_32;
+		break;
+	default:
+		dev_err(dai->dev, "unsupported slot width %u\n", slot_bits);
+		return -EINVAL;
+	}
+
+	/*
+	 * AUTO_INPUT_SEL belongs in the value as well as the mask. It was in
+	 * the mask alone, so every hw_params quietly cleared it and undid what
+	 * the component probe had set - which is why enabling auto-detection
+	 * by hand mid-stream worked while enabling it in probe() did not.
+	 * INPUT_SEL is still programmed underneath: it is what the part falls
+	 * back to when auto-detection is switched off.
+	 */
+	isel = FIELD_PREP(ES9039_INPUT_SEL_MASK, input_sel);
+	if (auto_sel)
+		isel |= ES9039_AUTO_INPUT_SEL;
+
+	ret = regmap_update_bits(priv->regmap, ES9039_INPUT_SEL,
+				 ES9039_AUTO_INPUT_SEL | ES9039_INPUT_SEL_MASK,
+				 isel);
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(priv->regmap, ES9039_TDM_CONFIG2,
+				 ES9039_TDM_BIT_WIDTH_MASK,
+				 FIELD_PREP(ES9039_TDM_BIT_WIDTH_MASK, width));
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(priv->regmap, ES9039_TDM_CH_NUM,
+				 ES9039_TDM_CH_NUM_MASK,
+				 params_channels(params) - 1);
+	if (ret)
+		return ret;
+
+	/* Switch the right decoder on for this stream, and the others off. */
+	return regmap_update_bits(priv->regmap, ES9039_SYS_MODE,
+				  ES9039_DECODE_MASK, decode);
+}
+
+static int es9039q2m_mute_stream(struct snd_soc_dai *dai, int mute, int dir)
+{
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(dai->component);
+	bool old;
+	int ret;
+
+	guard(mutex)(&priv->lock);
+
+	old = priv->mute_stream;
+	priv->mute_stream = mute;
+
+	ret = es9039_apply_mute(priv);
+	if (ret)
+		priv->mute_stream = old;
+
+	return ret;
+}
+
+/*
+ * stream_rate doubles as "a stream is open", which es9039_dop_put() needs in
+ * order to refuse a change it could only half-apply.
+ */
+static void es9039q2m_shutdown(struct snd_pcm_substream *substream,
+			       struct snd_soc_dai *dai)
+{
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(dai->component);
+
+	guard(mutex)(&priv->lock);
+
+	priv->stream_rate = 0;
+}
+
+static const struct snd_soc_dai_ops es9039q2m_dai_ops = {
+	.startup	 = es9039q2m_startup,
+	.shutdown	 = es9039q2m_shutdown,
+	.set_fmt	 = es9039q2m_set_fmt,
+	.set_bclk_ratio	 = es9039q2m_set_bclk_ratio,
+	.hw_params	 = es9039q2m_hw_params,
+	.mute_stream	 = es9039q2m_mute_stream,
+	.no_capture_mute = 1,
+};
+
+#define ES9039_FORMATS	(SNDRV_PCM_FMTBIT_S16_LE     | \
+			 SNDRV_PCM_FMTBIT_S24_LE     | \
+			 SNDRV_PCM_FMTBIT_S24_3LE    | \
+			 SNDRV_PCM_FMTBIT_S32_LE     | \
+			 SNDRV_PCM_FMTBIT_DSD_U8     | \
+			 SNDRV_PCM_FMTBIT_DSD_U16_LE | \
+			 SNDRV_PCM_FMTBIT_DSD_U32_LE)
+
+static struct snd_soc_dai_driver es9039q2m_dai = {
+	.name = "es9039q2m-hifi",
+	.playback = {
+		.stream_name	= "Playback",
+		.channels_min	= 2,
+		.channels_max	= 2,
+		.rates		= SNDRV_PCM_RATE_8000_768000,
+		.formats	= ES9039_FORMATS,
+	},
+	.ops = &es9039q2m_dai_ops,
+};
+
+/* ---------------------------------------------------------------- component */
+
+static int es9039q2m_component_probe(struct snd_soc_component *component)
+{
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(component);
+	int ret;
+
+	/*
+	 * Come up muted. The volume registers default to 0 dB, and an unmuted
+	 * DAC arriving into an already-powered analogue stage is how you get a
+	 * thump. ASoC unmutes via mute_stream() when a stream starts.
+	 */
+	priv->mute_user = 0;
+	priv->mute_stream = false;
+	ret = regmap_update_bits(priv->regmap, ES9039_DAC_MUTE,
+				 ES9039_MUTE_BOTH, ES9039_MUTE_BOTH);
+	if (ret)
+		return ret;
+
+	/*
+	 * Enable the datapath. SYSTEM_CONFIG[1] is clear at reset, so in
+	 * software mode nothing turns the DAC on at power-up: the analogue
+	 * output stays dead until this bit is set.
+	 *
+	 * After the mute above and never before it. Bringing the datapath up
+	 * into an unmuted part whose volume registers still sit at their 0 dB
+	 * reset value is exactly the thump the mute is there to prevent.
+	 *
+	 * Note when testing that a warm reboot does not reset this part -
+	 * registers and coefficient RAM both survive one, and only removing
+	 * power clears them - so the previous boot's value can hide whether
+	 * this write happened at all.
+	 */
+	ret = regmap_update_bits(priv->regmap, ES9039_SYSTEM_CONFIG,
+				 ES9039_DAC_MODE, ES9039_DAC_MODE);
+	if (ret)
+		return ret;
+
+	/*
+	 * VOLUME_HOLD set means "do not apply volume register writes", so its
+	 * resting state has to be clear or the volume control would appear
+	 * dead. es9039_vol_put() raises it around the pair of writes and drops
+	 * it again, which is how both channels are made to move together.
+	 */
+	ret = regmap_update_bits(priv->regmap, ES9039_IIR_SPDIF,
+				 ES9039_VOLUME_HOLD, 0);
+	if (ret)
+		return ret;
+
+	/*
+	 * Let the part identify DoP for itself. Register 57[0] AUTO_INPUT_SEL
+	 * makes it choose between PCM and DoP from the data, which is the only
+	 * way DoP can work in practice: players send DoP-encoded PCM and expect
+	 * the DAC to notice, and none of them can flip an ALSA control first.
+	 * Without this the part is told "PCM", never looks for the marker, and
+	 * renders a DoP stream as the near-silent hiss the DoP marker design
+	 * deliberately degrades to. Verified on hardware by enabling this
+	 * mid-stream and watching reg 245 flip from PCM to DoP with DOP_VALID
+	 * set.
+	 *
+	 * The datasheet's "data must be provided on the DATA2 pin" applies to
+	 * identifying DSD, whose two channels arrive on separate data lines.
+	 * DoP is ordinary stereo I2S on one line and detects correctly without
+	 * it, which the same measurement establishes.
+	 */
+	priv->dop_auto = true;
+	scoped_guard(mutex, &priv->lock)
+		ret = es9039_apply_dop(priv, true);
+	if (ret)
+		return ret;
+
+	/*
+	 * Board defaults, applied once at probe so the part is deterministic
+	 * from cold instead of inheriting whatever its reset value happens to
+	 * be. Both stay user-settable through their kcontrols; these are
+	 * defaults, not policy.
+	 *
+	 * Reconstruction filter: linear phase apodizing fast roll-off. It keeps
+	 * the sharp cut and flat passband of the plain fast linear-phase filter
+	 * while suppressing pre-ringing, and an apodizing response also
+	 * suppresses pre-ringing already baked into the source material by the
+	 * recording chain - which none of the other seven addresses. The cost
+	 * is a little stopband rejection right at the band edge, well above
+	 * where it can matter. Chosen this way because a blind A/B listening
+	 * test found no audible difference between any of the eight,
+	 * so the tie is broken on theory rather than on preference.
+	 *
+	 * Modulator: wide bandwidth, which is ESS's own recommendation. It
+	 * moves the modulator's noise further out of band and improves
+	 * linearity at high frequencies.
+	 */
+	ret = regmap_update_bits(priv->regmap, ES9039_FILTER_SHAPE,
+				 ES9039_FILTER_SHAPE_MASK,
+				 ES9039_FILTER_APODIZING);
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(priv->regmap, ES9039_NSMOD,
+				 ES9039_NSMOD_WIDE_BW_MASK,
+				 FIELD_PREP(ES9039_NSMOD_WIDE_BW_MASK,
+					    ES9039_NSMOD_WIDE));
+	if (ret)
+		return ret;
+
+	/* Let the part work out the incoming rate; the ASRC does the rest. */
+	return regmap_update_bits(priv->regmap, ES9039_AUTO_FS_DETECT,
+				  ES9039_AUTO_FS_DETECT_EN,
+				  ES9039_AUTO_FS_DETECT_EN);
+}
+
+/*
+ * System suspend.
+ *
+ * Where the part is clocked from the SoC, system suspend stops its clock as a
+ * side effect and there is nothing for a driver to do. Where the board feeds
+ * it a free-running oscillator instead - which the ASRC in front of the DAC
+ * makes an attractive design, since MCLK then need not track BCLK or LRCK -
+ * nothing in the system can gate that clock, and the part stays fully clocked
+ * for the whole of suspend.
+ *
+ * Clearing ENABLE_DAC_CLK gates the part's internal clock tree, which is the
+ * only part of its consumption software can reach. The analogue supplies are
+ * the board's business, and not every board is able to switch them.
+ *
+ * The write deliberately bypasses the cache. The cached value must keep
+ * ENABLE_DAC_CLK set, so that regcache_sync() on resume restores whatever
+ * state userspace last left the part in without this code having to remember
+ * anything itself.
+ */
+static int es9039q2m_suspend(struct snd_soc_component *component)
+{
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(component);
+	int ret;
+
+	guard(mutex)(&priv->lock);
+
+	regcache_cache_bypass(priv->regmap, true);
+	ret = regmap_update_bits(priv->regmap, ES9039_SYS_MODE,
+				 ES9039_ENABLE_DAC_CLK, 0);
+	regcache_cache_bypass(priv->regmap, false);
+
+	if (ret)
+		dev_warn(component->dev,
+			 "could not gate the DAC clock for suspend: %d\n", ret);
+
+	regcache_mark_dirty(priv->regmap);
+	regcache_cache_only(priv->regmap, true);
+
+	return 0;
+}
+
+static int es9039q2m_resume(struct snd_soc_component *component)
+{
+	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(component);
+	int ret;
+
+	guard(mutex)(&priv->lock);
+
+	regcache_cache_only(priv->regmap, false);
+
+	/*
+	 * Mute the part before anything else, and write it straight to the
+	 * hardware rather than through the cache.
+	 *
+	 * Where the board kept the supplies up this is a no-op - the part still
+	 * holds the mute state it went to sleep with. Where the board removed
+	 * them it is not: the part comes back at reset defaults, which are
+	 * DAC_MODE clear, both channels UNMUTED, and both volume registers at
+	 * 0x00, their 0 dB setting. regcache_sync() walks registers in ascending
+	 * address order, so it would set DAC_MODE in register 0 - lighting the
+	 * datapath up unmuted at full scale - and only restore the real mute in
+	 * register 86, long after. That is the thump the probe path mutes to
+	 * avoid, arriving by the other door.
+	 *
+	 * The cache is bypassed so the cached mute state is untouched; the sync
+	 * below puts it back, after the volume registers at 74 and 75.
+	 */
+	regcache_cache_bypass(priv->regmap, true);
+	ret = regmap_update_bits(priv->regmap, ES9039_DAC_MUTE,
+				 ES9039_MUTE_BOTH, ES9039_MUTE_BOTH);
+	regcache_cache_bypass(priv->regmap, false);
+
+	if (ret)
+		dev_warn(component->dev,
+			 "could not mute before resync: %d\n", ret);
+
+	ret = regcache_sync(priv->regmap);
+	if (ret)
+		dev_err(component->dev,
+			"failed to restore registers on resume: %d\n", ret);
+
+	return ret;
+}
+
+static const struct snd_soc_component_driver es9039q2m_component = {
+	.probe			= es9039q2m_component_probe,
+	.suspend		= es9039q2m_suspend,
+	.resume			= es9039q2m_resume,
+	.controls		= es9039q2m_controls,
+	.num_controls		= ARRAY_SIZE(es9039q2m_controls),
+	.dapm_widgets		= es9039q2m_widgets,
+	.num_dapm_widgets	= ARRAY_SIZE(es9039q2m_widgets),
+	.dapm_routes		= es9039q2m_routes,
+	.num_dapm_routes	= ARRAY_SIZE(es9039q2m_routes),
+	.idle_bias_on		= 1,
+	.endianness		= 1,
+};
+
+/* --------------------------------------------------------------------- I2C */
+
+static int es9039q2m_i2c_probe(struct i2c_client *i2c)
+{
+	struct device *dev = &i2c->dev;
+	struct es9039q2m_priv *priv;
+	unsigned int id;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->regmap = devm_regmap_init_i2c(i2c, &es9039q2m_regmap);
+	if (IS_ERR(priv->regmap))
+		return dev_err_probe(dev, PTR_ERR(priv->regmap),
+				     "failed to init regmap\n");
+
+	priv->mclk = devm_clk_get_optional_enabled(dev, "mclk");
+	if (IS_ERR(priv->mclk))
+		return dev_err_probe(dev, PTR_ERR(priv->mclk),
+				     "failed to get mclk\n");
+
+	if (priv->mclk) {
+		priv->mclk_rate = clk_get_rate(priv->mclk);
+		if (priv->mclk_rate > 50000000)
+			return dev_err_probe(dev, -EINVAL,
+					     "mclk %u Hz exceeds the 50 MHz maximum\n",
+					     priv->mclk_rate);
+
+		/*
+		 * A fixed-rate clock answers every rounding question with the
+		 * one rate it has. That is the board saying "this is an
+		 * oscillator, use the ASRC"; anything else can be pulled to
+		 * suit the sample rate and run synchronously.
+		 */
+		priv->mclk_fixed =
+			clk_round_rate(priv->mclk, priv->mclk_rate / 2) ==
+			priv->mclk_rate;
+	}
+
+	ret = devm_mutex_init(dev, &priv->lock);
+	if (ret)
+		return ret;
+
+	i2c_set_clientdata(i2c, priv);
+
+	ret = regmap_read(priv->regmap, ES9039_CHIP_ID, &id);
+	if (ret)
+		return dev_err_probe(dev, ret, "no response at 0x%02x\n",
+				     i2c->addr);
+
+	if (id != ES9039_CHIP_ID_ES9039Q2M)
+		return dev_err_probe(dev, -ENODEV,
+				     "unexpected chip id 0x%02x, want 0x%02x\n",
+				     id, ES9039_CHIP_ID_ES9039Q2M);
+
+	dev_info(dev, "ES9039Q2M at 0x%02x, mclk %u Hz\n",
+		 i2c->addr, priv->mclk_rate);
+
+	return devm_snd_soc_register_component(dev, &es9039q2m_component,
+					       &es9039q2m_dai, 1);
+}
+
+static const struct of_device_id es9039q2m_of_match[] = {
+	{ .compatible = "esstech,es9039q2m" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, es9039q2m_of_match);
+
+static const struct i2c_device_id es9039q2m_i2c_id[] = {
+	{ "es9039q2m" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, es9039q2m_i2c_id);
+
+static struct i2c_driver es9039q2m_i2c_driver = {
+	.driver = {
+		.name		= "es9039q2m",
+		.of_match_table	= es9039q2m_of_match,
+	},
+	.probe		= es9039q2m_i2c_probe,
+	.id_table	= es9039q2m_i2c_id,
+};
+module_i2c_driver(es9039q2m_i2c_driver);
+
+MODULE_DESCRIPTION("ASoC ES9039Q2M driver");
+MODULE_AUTHOR("Karl Asseily <karl@asseily.com>");
+MODULE_LICENSE("GPL");
-- 
2.34.1

[PATCH v3 4/4] MAINTAINERS: add entry for the ES9039Q2M codec driver

[Karl Asseily]

Add myself as maintainer of the ES9039Q2M codec driver and its binding.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Karl Asseily <karl@asseily.com>
---

Notes:
    v2: follow the binding rename

 MAINTAINERS | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 20d67cc0e7a..1095476c1d9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9699,6 +9699,13 @@ S:	Maintained
 F:	include/linux/errseq.h
 F:	lib/errseq.c
 
+ES9039Q2M AUDIO CODEC DRIVER
+M:	Karl Asseily <karl@asseily.com>
+L:	linux-sound@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/sound/esstech,es9039q2m.yaml
+F:	sound/soc/codecs/es9039q2m.c
+
 ESD CAN NETWORK DRIVERS
 M:	Stefan Mätje <stefan.maetje@esd.eu>
 R:	socketcan@esd.eu
-- 
2.34.1

Re: [PATCH v3 3/4] ASoC: es9039q2m: add ESS Technology ES9039Q2M codec driver

[Mark Brown]

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On Fri, Sep 18, 2026 at 06:13:25AM +0300, Karl Asseily wrote:
> The ES9039Q2M is a 32-bit two-channel audio DAC with an asynchronous
> sample rate converter. It selects between two control personalities with
> its MODE pin: hardware mode, strapped by HW0/HW1/HW2 with no control bus
> at all, and software mode over I2C or SPI. This driver implements
> software mode over I2C, which MODE = GND selects.

> +static int es9039_fir_put(struct snd_kcontrol *kcontrol,
> +			  const unsigned int __user *bytes, unsigned int size)
> +{
> +	struct snd_soc_component *c = snd_kcontrol_chip(kcontrol);
> +	struct es9039q2m_priv *priv = snd_soc_component_get_drvdata(c);
> +	struct soc_bytes_ext *be = (void *)kcontrol->private_value;
> +	struct es9039_fir_ctl *p = container_of(be, struct es9039_fir_ctl, be);
> +	u8 *buf;
> +	int ret, i;
> +
> +	if (size != p->taps * ES9039_COEFF_BYTES)
> +		return -EINVAL;
> +
> +	buf = memdup_user(bytes, size);
> +	if (IS_ERR(buf))
> +		return PTR_ERR(buf);
> +
> +	/*
> +	 * PROG_COEFF_WE is a per-coefficient strobe, not a gate held open
> +	 * across the upload. The datasheet's sequence is address, data, raise
> +	 * WE, lower WE, once per coefficient. Holding it high for the whole
> +	 * loop also appears to work on ES9039Q2M silicon, but "appears to
> +	 * work" is not a specification.
> +	 */
> +	for (i = 0; i < p->taps; i++) {
> +		ret = regmap_write(priv->regmap, ES9039_PROG_RAM_ADDR,
> +				   (p->stage_4x ? ES9039_PROG_STAGE_4X : 0) |
> +				   FIELD_PREP(ES9039_PROG_ADDR_MASK, i));
> +		if (ret)
> +			goto out;

...

> +out:
> +	regmap_update_bits(priv->regmap, ES9039_PROG_RAM_CTRL,
> +			   ES9039_PROG_COEFF_WE, 0);
> +	kfree(buf);
> +	if (ret)
> +		return ret;

How does this work with suspend and resume if the device is powered down
in suspend?  It looks like this is doing some windowing stuff and needs
a specific write sequence.

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Re: [PATCH v3 3/4] ASoC: es9039q2m: add ESS Technology ES9039Q2M codec driver

[Karl Asseily]

> > +out:
> > + regmap_update_bits(priv->regmap, ES9039_PROG_RAM_CTRL,
> > +   ES9039_PROG_COEFF_WE, 0);
> > + kfree(buf);
> > + if (ret)
> > + return ret;
>
> How does this work with suspend and resume if the device is powered down
> in suspend?  It looks like this is doing some windowing stuff and needs
> a specific write sequence.

You are right, and it is broken as posted.

The coefficient RAM is write-only: PROG_COEFF_OUT is documented as a
readback register but returns the last coefficient written rather than the
addressed one, as the commit message describes.  So regmap cannot cache it
and nothing else in the system holds a copy.  On a board that keeps the
part powered through suspend nothing is lost, but where the supplies go
away the RAM comes back undefined while regcache_sync() restores the
filter selection from the cache - so selecting the programmable filter
would point the interpolator at whatever the RAM powered up holding.

For v4 the driver keeps a shadow of the last upload in its private struct,
the upload loop is split into a helper, and resume calls that helper again
after regcache_sync() for any stage that was ever written.  Stages never
uploaded keep the part's own defaults.

You are right about the sequence too.  It is address, data, raise
PROG_COEFF_WE, lower it, once per coefficient - a per-coefficient strobe
rather than a gate held open across the upload.  Splitting the helper out
exposed a second problem I had missed: both FIR controls drive the same
address, data and strobe registers and nothing serialised them, so two
concurrent uploads could interleave into each other's RAM.  The mutex that
orders an upload against resume closes that as well.

For completeness: an automated review on this thread raised the same
suspend question a few hours before your mail, so the fix above was
already written and building by the time it arrived.

I will hold v4 until your review is finished rather than resending
piecemeal.

Thanks,
Karl

Re: [PATCH v3 3/4] ASoC: es9039q2m: add ESS Technology ES9039Q2M codec driver

[Mark Brown]

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On Fri, Sep 18, 2026 at 01:59:43PM +0300, Karl Asseily wrote:

> I will hold v4 until your review is finished rather than resending
> piecemeal.

I think that was pretty much it from the pass I did.

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Re: [PATCH v3 1/4] dt-bindings: vendor-prefixes: add ESS Technology

[Rob Herring]

On Fri, Sep 18, 2026 at 06:13:23AM +0300, Karl Asseily wrote:
> Add the vendor prefix for ESS Technology, Inc., maker of the SABRE family
> of audio DACs. The prefix follows the company's domain, esstech.com.
> 
> Assisted-by: Claude:claude-opus-5
> Signed-off-by: Karl Asseily <karl@asseily.com>

Missing Krzysztof's ack...

Re: [PATCH v3 2/4] ASoC: dt-bindings: add ESS Technology ES9039Q2M

[Rob Herring]

On Fri, Sep 18, 2026 at 06:13:24AM +0300, Karl Asseily wrote:
> Add a binding for the ES9039Q2M, a 32-bit two-channel audio DAC with an
> asynchronous sample rate converter.
> 
> The part selects between two control personalities with its MODE pin:
> hardware mode, strapped by HW0/HW1/HW2 with no control bus at all, and
> software mode over I2C or SPI. This binding describes software mode over
> I2C, which MODE = GND selects.
> 
> Assisted-by: Claude:claude-opus-5
> Signed-off-by: Karl Asseily <karl@asseily.com>

Missing Krzysztof's R-by, but sashiko is right here. You should be some 
supplies.

Rob