[PATCH v2 2/2] hwmon: (pmbus/max20830) Add support for MAX20810, MAX20815, LTM4739, LTM4740

[Carlos Jones <carlosjr.jones@analog.com>]

From: Carlos Jones Jr <carlosjr.jones@analog.com>

Add support for additional members of the MAX20830 family:
- MAX20810: 2.7V-16V input, up to 10A output
- MAX20815: 2.7V-16V input, up to 15A output
- LTM4739:  3V-15V input, up to 10A output
- LTM4740:  3V-15V input, up to 15A output

The LTM4739 and LTM4740 are the LTM-series equivalents of the MAX20810
and MAX20815 respectively. All share the MAX20830 PMBus command set and
telemetry, so no new register handling is required; they are accepted by
matching their IC_DEVICE_ID.

The LTM4739 and LTM4740 are uModules built around the MAX20810/MAX20815
dies and report the die's IC_DEVICE_ID with a "B" suffix ("MAX20810B" /
"MAX20815B"), not the "LTM4739"/"LTM4740" names printed in their
datasheets (which are being corrected to match). Only the IDs observed on
hardware are matched; the plain datasheet IDs ("MAX20810", "MAX20815",
"LTM4739", "LTM4740") are not matched, as no part reporting them has been
observed.

Matching is via the existing adi,max20830 fallback compatible; no new
of_match entries are needed.

Signed-off-by: Carlos Jones Jr <carlosjr.jones@analog.com>
---
 Documentation/hwmon/max20830.rst | 51 ++++++++++++++++++++++++++++----
 drivers/hwmon/pmbus/max20830.c   | 10 ++++++-
 2 files changed, 54 insertions(+), 7 deletions(-)

diff --git a/Documentation/hwmon/max20830.rst b/Documentation/hwmon/max20830.rst
index b850f3b6e40d..7c4f27f40d60 100644
--- a/Documentation/hwmon/max20830.rst
+++ b/Documentation/hwmon/max20830.rst
@@ -5,6 +5,38 @@ Kernel driver max20830
 
 Supported chips:
 
+  * Analog Devices LTM4739
+
+    Prefix: 'ltm4739'
+
+    Addresses scanned: -
+
+    Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ltm4739.pdf
+
+  * Analog Devices LTM4740
+
+    Prefix: 'ltm4740'
+
+    Addresses scanned: -
+
+    Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ltm4740.pdf
+
+  * Analog Devices MAX20810
+
+    Prefix: 'max20810'
+
+    Addresses scanned: -
+
+    Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/max20810.pdf
+
+  * Analog Devices MAX20815
+
+    Prefix: 'max20815'
+
+    Addresses scanned: -
+
+    Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/max20815.pdf
+
   * Analog Devices MAX20830
 
     Prefix: 'max20830'
@@ -37,13 +69,20 @@ Author:
 Description
 -----------
 
-This driver supports hardware monitoring for Analog Devices MAX20830, MAX20830C
-and MAX20840C. These are Step-Down Switching Regulator with PMBus Interface.
+This driver supports hardware monitoring for Analog Devices MAX20810, MAX20815,
+MAX20830, MAX20830C, MAX20840C, LTM4739, and LTM4740 Step-Down Switching
+Regulators with PMBus Interface.
+
+The MAX20810 and LTM4739 are 10A fully integrated step-down DC-DC switching
+regulators (2.7V-16V and 3V-15V input respectively). The MAX20815 and LTM4740
+provide up to 15A. The MAX20830 and MAX20830C provide up to 30A. The MAX20840C
+provides up to 40A. Through the PMBus interface, all devices can monitor
+input/output voltages, output current and temperature.
 
-MAX20830, and MAX20830C are 2.7V to 16V, 30A fully integrated step-down DC-DC
-switching regulators. MAX20840C is similar but can reach 40A. Through the PMBus
-interface, these devices can monitor input/output voltages, output current and
-temperature.
+LTM4739 and LTM4740 are the LTM-family equivalents of MAX20810 and MAX20815
+respectively, sharing an identical PMBus command set. These modules report the
+underlying die's IC_DEVICE_ID by design ("MAX20810B" and "MAX20815B"
+respectively), which the driver matches during probe.
 
 The driver is a client driver to the core PMBus driver. Please see
 Documentation/hwmon/pmbus.rst for details on PMBus client drivers.
diff --git a/drivers/hwmon/pmbus/max20830.c b/drivers/hwmon/pmbus/max20830.c
index 4d25a084af09..39cce250beca 100644
--- a/drivers/hwmon/pmbus/max20830.c
+++ b/drivers/hwmon/pmbus/max20830.c
@@ -20,7 +20,15 @@ struct max20830_data {
 	u32 vout_rfb2;
 };
 
+/*
+ * IC_DEVICE_ID strings matched at probe. The LTM4739/LTM4740 uModules
+ * report their MAX die ID with a "B" suffix, not the "LTM47xx" names in
+ * their datasheets (being corrected); the plain datasheet IDs are not
+ * matched, as no such part has been observed.
+ */
 static const char * const supported_chip_ids[] = {
+	"MAX20810B",	/* LTM4739 */
+	"MAX20815B",	/* LTM4740 */
 	"MAX20830",
 	"MAX20830C",
 	"MAX20840C",
@@ -34,7 +42,7 @@ static const char * const supported_chip_ids[] = {
  * like in1_max, in1_crit, etc. will not be available. Only in1_input (the
  * scaled output voltage) is supported.
  *
- * MAX20830 uses an external resistor divider for voltage sensing:
+ * MAX20830 family uses an external resistor divider for voltage sensing:
  * - VOUT_COMMAND and VOUT_MAX set the reference voltage at the feedback pin
  * - READ_VOUT reports the feedback voltage, which needs to be scaled for actual
  *   output voltage
-- 
2.43.0