[PATCH v3 0/3] ASoC: qcom: enable audio on stage-2 protected DSPs (mDSP)

[PATCH v3 0/3] ASoC: qcom: enable audio on stage-2 protected DSPs (mDSP)

[Ajay Kumar Nandam]

On platforms such as Qualcomm Shikra, audio is served by the modem DSP
(mDSP) rather than the ADSP. The mDSP runs in a stage-2 protected context
and cannot use the SMMU, so the PCM buffers it consumes must live in
reserved-memory carveouts that are handed to the consumer VMIDs via a
hypervisor (SCM) memory assignment. This series adds that access model to
the q6apm DAI driver and its binding, alongside the existing stage-1/SMMU
(iommus) path, which is left untouched.

The driver detects the mDSP target at runtime from the GPR domain_id
(GPR_DOMAIN_ID_MODEM) and enables the SCM assignment path automatically.
VMIDs are hardcoded in the driver (HLOS + MSS_MSA + LPASS) rather than
read from DT, following the consensus from v2 review discussion with
Krzysztof Kozlowski and Srinivas Kandagatla.

Tested on Qualcomm Shikra with mDSP audio playback and capture.

Prior versions:
v1 (VMID binding + driver + GPR domain):
  https://lore.kernel.org/all/20260609064038.492641-1-ajay.nandam@oss.qualcomm.com/
v1 (memory-region binding + DTS):
  https://lore.kernel.org/all/20260618113509.2025881-1-ajay.nandam@oss.qualcomm.com/
v2:
  https://lore.kernel.org/all/20260826-a2a-shikra-vmid-v5-v2-0-c3dc62354eee@oss.qualcomm.com/

Changes since v2:
- Drop qcom,vmids DT property entirely; VMIDs are static per SoC and
  hardcoded in the driver (HLOS, MSS_MSA, LPASS). This addresses
  Krzysztof's concern that qcom,vmids is "not a hardware property at
  all" and does not belong in DT. (Krzysztof Kozlowski)
- Drop oneOf / dependentRequired constraints from the binding since
  qcom,vmids no longer exists. memory-region is simply optional.
- Detect mDSP from GPR domain_id (GPR_DOMAIN_ID_MODEM) instead of
  keying off a DT property. No new compatible needed.
- Add QCOM_SCM_VMID_LPASS to the SCM destination list alongside
  HLOS and MSS_MSA — required for the mDSP firmware to access
  buffers.
- Switch reserved-memory path from snd_pcm_set_managed_buffer_all()
  to snd_pcm_set_fixed_buffer_all() so the carveout is not subject
  to the preallocate_dma module param. (Mark Brown)
- Use per-item descriptions for memory-region in the DT binding
  instead of free-form text. (Krzysztof Kozlowski)
- Drop reserved-memory node from the binding example.
  (Krzysztof Kozlowski)
- Register devm cleanup action before SCM assigns so probe-error
  paths do not leak HLOS memory access.
- Reorder series: g_apm fix (1/3), GPR domain (2/3), SCM assign
  (3/3) for cleaner bisection.

Signed-off-by: Ajay Kumar Nandam <ajay.nandam@oss.qualcomm.com>
---
Ajay Kumar Nandam (3):
      ASoC: qcom: q6apm: clear g_apm on driver removal
      ASoC: qcom: qdsp6: generalize GPR service domain
      ASoC: qcom: q6apm-dai: add SCM buffer assignment for mDSP platforms

 .../devicetree/bindings/sound/qcom,q6apm-dai.yaml  |  12 +-
 sound/soc/qcom/Kconfig                             |   1 +
 sound/soc/qcom/qdsp6/audioreach.c                  |  12 +-
 sound/soc/qcom/qdsp6/audioreach.h                  |  22 +-
 sound/soc/qcom/qdsp6/q6apm-dai.c                   | 260 +++++++++++++++++++--
 sound/soc/qcom/qdsp6/q6apm.c                       |   9 +-
 sound/soc/qcom/qdsp6/q6apm.h                       |   2 +-
 sound/soc/qcom/qdsp6/q6prm.c                       |   2 +
 8 files changed, 287 insertions(+), 33 deletions(-)
---
base-commit: 3d5670d672ae08b8c534b7beed6f57c8b44e7b43
change-id: 20260918-vmid-v3-cad97e0eb7bb

Best regards,
--  
Ajay Kumar Nandam <ajay.nandam@oss.qualcomm.com>

[PATCH v3 1/3] ASoC: qcom: q6apm: clear g_apm on driver removal

[Ajay Kumar Nandam]

The global g_apm pointer is set during apm_probe() but never cleared
in apm_remove(). After the driver is removed the devm-managed struct
q6apm is freed, leaving g_apm dangling. A subsequent call to
q6apm_is_adsp_ready() dereferences the freed pointer.

Clear g_apm in apm_remove() before the component is unregistered so
that q6apm_is_adsp_ready() returns false instead of triggering a
use-after-free.

Fixes: 5477518b8a0e ("ASoC: qdsp6: audioreach: add q6apm support")
Signed-off-by: Ajay Kumar Nandam <ajay.nandam@oss.qualcomm.com>
---
 sound/soc/qcom/qdsp6/q6apm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sound/soc/qcom/qdsp6/q6apm.c b/sound/soc/qcom/qdsp6/q6apm.c
index 641d6d243229..12c6dfe4c58e 100644
--- a/sound/soc/qcom/qdsp6/q6apm.c
+++ b/sound/soc/qcom/qdsp6/q6apm.c
@@ -894,6 +894,7 @@ static int apm_probe(gpr_device_t *gdev)
 
 static void apm_remove(gpr_device_t *gdev)
 {
+	g_apm = NULL;
 	of_platform_depopulate(&gdev->dev);
 	snd_soc_unregister_component(&gdev->dev);
 }

-- 
2.34.1

[PATCH v3 2/3] ASoC: qcom: qdsp6: generalize GPR service domain

[Ajay Kumar Nandam]

AudioReach builds APM and PRM command packets with the GPR destination
domain hardcoded to GPR_DOMAIN_ID_ADSP. This assumes audio is always
served by the ADSP, which is true for all currently supported targets.

On platforms such as Qualcomm Shikra, audio is served by the modem DSP
(mDSP) instead. The GPR node in DT already describes which DSP backs
the service via its qcom,domain property (e.g. GPR_DOMAIN_ID_MODEM),
and the GPR core exposes it as gdev->domain_id. But the AudioReach
packet builders ignore this and always target the ADSP, so every
APM/PRM command is routed to the wrong DSP on mDSP targets and audio
does not function.

Fix this by reading the GPR destination domain from gdev->domain_id
and stamping it in the send helpers (q6apm_send_cmd_sync,
audioreach_graph_send_cmd_sync, q6prm_send_cmd_sync) just before
dispatch. This centralizes the domain decision at the send layer
rather than threading it through every packet-allocation call site.
For the small number of async data-path sends that bypass the sync
helpers (write, read, compr, EOS), the domain is stamped inline
before gpr_send_port_pkt(). When no domain is available the helper
falls back to GPR_DOMAIN_ID_ADSP, so all existing ADSP targets
remain unchanged.

Co-developed-by: Pratyush Meduri <mpratyus@qti.qualcomm.com>
Signed-off-by: Pratyush Meduri <mpratyus@qti.qualcomm.com>
Signed-off-by: Ajay Kumar Nandam <ajay.nandam@oss.qualcomm.com>
---
 sound/soc/qcom/qdsp6/audioreach.c | 12 +++++++++---
 sound/soc/qcom/qdsp6/audioreach.h | 22 +++++++++++++++-------
 sound/soc/qcom/qdsp6/q6apm.c      |  8 +++++++-
 sound/soc/qcom/qdsp6/q6apm.h      |  2 +-
 sound/soc/qcom/qdsp6/q6prm.c      |  2 ++
 5 files changed, 34 insertions(+), 12 deletions(-)

diff --git a/sound/soc/qcom/qdsp6/audioreach.c b/sound/soc/qcom/qdsp6/audioreach.c
index e6e9eb2e85aa..f7ae6d0db7e7 100644
--- a/sound/soc/qcom/qdsp6/audioreach.c
+++ b/sound/soc/qcom/qdsp6/audioreach.c
@@ -579,10 +579,10 @@ EXPORT_SYMBOL_GPL(audioreach_alloc_graph_pkt);
 int audioreach_send_cmd_sync(struct device *dev, gpr_device_t *gdev,
 			     struct gpr_ibasic_rsp_result_t *result, struct mutex *cmd_lock,
 			     gpr_port_t *port, wait_queue_head_t *cmd_wait,
-			     const struct gpr_pkt *pkt, uint32_t rsp_opcode)
+			     struct gpr_pkt *pkt, uint32_t rsp_opcode)
 {
 
-	const struct gpr_hdr *hdr = &pkt->hdr;
+	struct gpr_hdr *hdr = &pkt->hdr;
 	int rc;
 
 	mutex_lock(cmd_lock);
@@ -622,10 +622,12 @@ int audioreach_send_cmd_sync(struct device *dev, gpr_device_t *gdev,
 }
 EXPORT_SYMBOL_GPL(audioreach_send_cmd_sync);
 
-int audioreach_graph_send_cmd_sync(struct q6apm_graph *graph, const struct gpr_pkt *pkt,
+int audioreach_graph_send_cmd_sync(struct q6apm_graph *graph, struct gpr_pkt *pkt,
 				   uint32_t rsp_opcode)
 {
 
+	pkt->hdr.dest_domain = audioreach_gpr_dest_domain(graph->apm->gdev);
+
 	return audioreach_send_cmd_sync(graph->dev, NULL,  &graph->result, &graph->lock,
 					graph->port, &graph->cmd_wait, pkt, rsp_opcode);
 }
@@ -970,6 +972,8 @@ int audioreach_compr_set_param(struct q6apm_graph *graph,
 	if (rc)
 		return rc;
 
+	pkt->hdr.dest_domain = audioreach_gpr_dest_domain(graph->apm->gdev);
+
 	return gpr_send_port_pkt(graph->port, pkt);
 }
 EXPORT_SYMBOL_GPL(audioreach_compr_set_param);
@@ -1489,6 +1493,8 @@ int audioreach_shared_memory_send_eos(struct q6apm_graph *graph)
 
 	eos->policy = WR_SH_MEM_EP_EOS_POLICY_LAST;
 
+	pkt->hdr.dest_domain = audioreach_gpr_dest_domain(graph->apm->gdev);
+
 	return gpr_send_port_pkt(graph->port, pkt);
 }
 EXPORT_SYMBOL_GPL(audioreach_shared_memory_send_eos);
diff --git a/sound/soc/qcom/qdsp6/audioreach.h b/sound/soc/qcom/qdsp6/audioreach.h
index 62a2fd79bbcb..2ae7b402a137 100644
--- a/sound/soc/qcom/qdsp6/audioreach.h
+++ b/sound/soc/qcom/qdsp6/audioreach.h
@@ -912,14 +912,19 @@ struct audioreach_module_config {
 };
 
 /* Packet Allocation routines */
-void *audioreach_alloc_apm_cmd_pkt(int pkt_size, uint32_t opcode, uint32_t
-				    token);
+static inline u16 audioreach_gpr_dest_domain(gpr_device_t *gdev)
+{
+	return gdev && gdev->domain_id ? gdev->domain_id : GPR_DOMAIN_ID_ADSP;
+}
+
+void *audioreach_alloc_apm_cmd_pkt(int pkt_size, uint32_t opcode,
+				   uint32_t token);
 void audioreach_set_default_channel_mapping(u8 *ch_map, int num_channels);
 void *audioreach_alloc_cmd_pkt(int payload_size, uint32_t opcode,
 			       uint32_t token, uint32_t src_port,
 			       uint32_t dest_port);
 void *audioreach_alloc_apm_pkt(int pkt_size, uint32_t opcode, uint32_t token,
-				uint32_t src_port);
+			       uint32_t src_port);
 void *audioreach_alloc_pkt(int payload_size, uint32_t opcode,
 			   uint32_t token, uint32_t src_port,
 			   uint32_t dest_port);
@@ -930,10 +935,13 @@ int audioreach_tplg_init(struct snd_soc_component *component);
 
 /* Module specific */
 void audioreach_graph_free_buf(struct q6apm_graph *graph);
-int audioreach_send_cmd_sync(struct device *dev, gpr_device_t *gdev, struct gpr_ibasic_rsp_result_t *result,
-			     struct mutex *cmd_lock, gpr_port_t *port, wait_queue_head_t *cmd_wait,
-			     const struct gpr_pkt *pkt, uint32_t rsp_opcode);
-int audioreach_graph_send_cmd_sync(struct q6apm_graph *graph, const struct gpr_pkt *pkt,
+int audioreach_send_cmd_sync(struct device *dev, gpr_device_t *gdev,
+			     struct gpr_ibasic_rsp_result_t *result,
+			     struct mutex *cmd_lock, gpr_port_t *port,
+			     wait_queue_head_t *cmd_wait,
+			     struct gpr_pkt *pkt, uint32_t rsp_opcode);
+int audioreach_graph_send_cmd_sync(struct q6apm_graph *graph,
+				   struct gpr_pkt *pkt,
 				   uint32_t rsp_opcode);
 int audioreach_set_media_format(struct q6apm_graph *graph,
 				const struct audioreach_module *module,
diff --git a/sound/soc/qcom/qdsp6/q6apm.c b/sound/soc/qcom/qdsp6/q6apm.c
index 12c6dfe4c58e..1845eb7b5739 100644
--- a/sound/soc/qcom/qdsp6/q6apm.c
+++ b/sound/soc/qcom/qdsp6/q6apm.c
@@ -29,11 +29,13 @@ struct apm_graph_mgmt_cmd {
 
 static struct q6apm *g_apm;
 
-int q6apm_send_cmd_sync(struct q6apm *apm, const struct gpr_pkt *pkt,
+int q6apm_send_cmd_sync(struct q6apm *apm, struct gpr_pkt *pkt,
 			uint32_t rsp_opcode)
 {
 	gpr_device_t *gdev = apm->gdev;
 
+	pkt->hdr.dest_domain = audioreach_gpr_dest_domain(gdev);
+
 	return audioreach_send_cmd_sync(&gdev->dev, gdev, &apm->result, &apm->lock,
 					NULL, &apm->wait, pkt, rsp_opcode);
 }
@@ -502,6 +504,8 @@ int q6apm_write_async(struct q6apm_graph *graph, uint32_t len, uint32_t msw_ts,
 
 	mutex_unlock(&graph->lock);
 
+	pkt->hdr.dest_domain = audioreach_gpr_dest_domain(graph->apm->gdev);
+
 	return gpr_send_port_pkt(graph->port, pkt);
 }
 EXPORT_SYMBOL_GPL(q6apm_write_async);
@@ -536,6 +540,8 @@ int q6apm_read(struct q6apm_graph *graph)
 
 	mutex_unlock(&graph->lock);
 
+	pkt->hdr.dest_domain = audioreach_gpr_dest_domain(graph->apm->gdev);
+
 	return gpr_send_port_pkt(graph->port, pkt);
 }
 EXPORT_SYMBOL_GPL(q6apm_read);
diff --git a/sound/soc/qcom/qdsp6/q6apm.h b/sound/soc/qcom/qdsp6/q6apm.h
index 5cb51ca491dc..9092359ccf90 100644
--- a/sound/soc/qcom/qdsp6/q6apm.h
+++ b/sound/soc/qcom/qdsp6/q6apm.h
@@ -147,7 +147,7 @@ int q6apm_alloc_fragments(struct q6apm_graph *graph,
 int q6apm_free_fragments(struct q6apm_graph *graph, unsigned int dir);
 int q6apm_unmap_memory_fixed_region(struct device *dev, unsigned int graph_id);
 /* Helpers */
-int q6apm_send_cmd_sync(struct q6apm *apm, const struct gpr_pkt *pkt,
+int q6apm_send_cmd_sync(struct q6apm *apm, struct gpr_pkt *pkt,
 			uint32_t rsp_opcode);
 
 /* Callback for graph specific */
diff --git a/sound/soc/qcom/qdsp6/q6prm.c b/sound/soc/qcom/qdsp6/q6prm.c
index 04892fb4423f..f93383078eb1 100644
--- a/sound/soc/qcom/qdsp6/q6prm.c
+++ b/sound/soc/qcom/qdsp6/q6prm.c
@@ -51,6 +51,8 @@ struct prm_cmd_release_rsc {
 
 static int q6prm_send_cmd_sync(struct q6prm *prm, struct gpr_pkt *pkt, uint32_t rsp_opcode)
 {
+	pkt->hdr.dest_domain = audioreach_gpr_dest_domain(prm->gdev);
+
 	return audioreach_send_cmd_sync(prm->dev, prm->gdev, &prm->result, &prm->lock,
 					NULL, &prm->wait, pkt, rsp_opcode);
 }

-- 
2.34.1

[PATCH v3 3/3] ASoC: qcom: q6apm-dai: add SCM buffer assignment for mDSP platforms

[Ajay Kumar Nandam]

On platforms such as Qualcomm Shikra, audio is served by the modem DSP
(mDSP) which runs in a stage-2 protected context. Unlike ADSP targets
where SMMU-mapped system RAM is directly accessible, the mDSP cannot
reach the PCM buffers unless they are explicitly SCM-assigned to the
appropriate Virtual Machine IDs (VMIDs). Without this assignment, audio
does not function on these platforms.

At probe time, the driver reads the GPR domain_id from the parent APM
device to determine which DSP serves audio. When domain_id matches
GPR_DOMAIN_ID_ADSP the existing SMMU/iommus path is taken and no new
code is exercised. When domain_id matches GPR_DOMAIN_ID_MODEM, the
driver verifies that qcom_scm is available (deferring otherwise) and
that iommus is absent (the two mechanisms are mutually exclusive), then
enables the SCM assignment path.

In the SCM path the driver parses the optional memory-region entries in
DT. The first entry (memory-region[0] / audio_heap_mem) is the
control-path carveout used by the DSP firmware for command traffic; since
the mDSP operates on stage-2 protected memory, this carveout must be
SCM-assigned at probe time itself for the firmware to function. It is
SCM-assigned to HLOS (retained as source owner, RW) plus MSS_MSA and
LPASS (consumer VMIDs, both RW) and restored to HLOS-only ownership via
devm_add_action_or_reset() at device removal. The second entry
(memory-region[1]) is the data-path buffer pool from which per-stream
DMA buffers are carved out. This pool is attached via
of_reserved_mem_device_init_by_idx() so that PCM buffers allocate
directly from the carveout instead of system RAM. Individual buffer
slices are SCM-assigned in pcm_new() after allocation and unassigned in
pcm_free(), so only the actively used slices are shared with the modem
and unused carveout memory remains HLOS-owned.

The VMIDs are static per SoC and hardcoded in the driver (HLOS, MSS_MSA,
LPASS) rather than read from DT, following the upstream pattern used by
rmtfs_mem and qcom_q6v5_pas. Buffer constraints are capped at
reserved_buf_size when the data-path pool is present, and
snd_pcm_set_fixed_buffer_all() is used for both paths so the carveout is
not subject to the preallocate_dma module parameter.

The DT binding is updated to add an optional memory-region property (1-2
entries) and to make iommus optional (removed from the required list),
since mDSP platforms have neither IOMMU nor VMID DT properties.

All new code paths are gated on use_scm_assign (false when domain_id is
not GPR_DOMAIN_ID_MODEM), ensuring existing ADSP/iommus targets are
completely unaffected.

Signed-off-by: Ajay Kumar Nandam <ajay.nandam@oss.qualcomm.com>
---
 .../devicetree/bindings/sound/qcom,q6apm-dai.yaml  |  12 +-
 sound/soc/qcom/Kconfig                             |   1 +
 sound/soc/qcom/qdsp6/q6apm-dai.c                   | 260 +++++++++++++++++++--
 3 files changed, 252 insertions(+), 21 deletions(-)

diff --git a/Documentation/devicetree/bindings/sound/qcom,q6apm-dai.yaml b/Documentation/devicetree/bindings/sound/qcom,q6apm-dai.yaml
index 9e5b30d9c6e6..7d0415f2463a 100644
--- a/Documentation/devicetree/bindings/sound/qcom,q6apm-dai.yaml
+++ b/Documentation/devicetree/bindings/sound/qcom,q6apm-dai.yaml
@@ -20,9 +20,19 @@ properties:
     minItems: 1
     maxItems: 2
 
+  memory-region:
+    minItems: 1
+    maxItems: 2
+    items:
+      - description:
+          Control-path buffer (audio_heap_mem) for platforms where the DSP
+          runs in a stage-2 protected context (e.g. modem-DSP).
+      - description:
+          Data-path buffer pool from which per-stream DMA buffers are
+          allocated.
+
 required:
   - compatible
-  - iommus
 
 additionalProperties: false
 
diff --git a/sound/soc/qcom/Kconfig b/sound/soc/qcom/Kconfig
index e6e24f3b9922..991feb317940 100644
--- a/sound/soc/qcom/Kconfig
+++ b/sound/soc/qcom/Kconfig
@@ -102,6 +102,7 @@ config SND_SOC_QDSP6_ASM_DAI
 config SND_SOC_QDSP6_APM_DAI
 	tristate
 	select SND_SOC_COMPRESS
+	select QCOM_SCM
 
 config SND_SOC_QDSP6_APM_LPASS_DAI
 	tristate
diff --git a/sound/soc/qcom/qdsp6/q6apm-dai.c b/sound/soc/qcom/qdsp6/q6apm-dai.c
index bf1f872a09f4..24f920a7c60d 100644
--- a/sound/soc/qcom/qdsp6/q6apm-dai.c
+++ b/sound/soc/qcom/qdsp6/q6apm-dai.c
@@ -1,20 +1,24 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (c) 2021, Linaro Limited
 
-#include <linux/init.h>
+#include <dt-bindings/firmware/qcom,scm.h>
+#include <dt-bindings/soc/qcom,gpr.h>
+#include <linux/dma-mapping.h>
 #include <linux/err.h>
+#include <linux/firmware/qcom/qcom_scm.h>
+#include <linux/init.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_reserved_mem.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
-#include <sound/soc.h>
-#include <sound/soc-dapm.h>
 #include <linux/spinlock.h>
 #include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+#include <sound/soc-dapm.h>
 #include <asm/div64.h>
 #include <asm/dma.h>
-#include <linux/dma-mapping.h>
-#include <sound/pcm_params.h>
 #include "q6apm.h"
 
 #define DRV_NAME "q6apm-dai"
@@ -36,6 +40,16 @@
 #define COMPR_PLAYBACK_MIN_NUM_FRAGMENTS (4)
 #define SID_MASK_DEFAULT	0xF
 
+#define Q6APM_MAX_SCM_REGIONS	16
+#define Q6APM_POOL_MAX_STREAMS	8
+
+struct q6apm_scm_region {
+	phys_addr_t addr;
+	size_t size;
+	u64 src_perms;
+	bool assigned;
+};
+
 static const struct snd_compr_codec_caps q6apm_compr_caps = {
 	.num_descriptors = 1,
 	.descriptor[0].max_ch = 2,
@@ -84,9 +98,88 @@ struct q6apm_dai_rtd {
 };
 
 struct q6apm_dai_data {
+	struct device *dev;
 	long long sid;
+	bool use_scm_assign;
+	bool has_reserved_mem;
+	size_t reserved_buf_size;
+	struct q6apm_scm_region scm_regions[Q6APM_MAX_SCM_REGIONS];
+	int num_scm_regions;
 };
 
+static int q6apm_dai_scm_assign(struct q6apm_dai_data *pdata,
+				phys_addr_t addr, size_t size)
+{
+	struct qcom_scm_vmperm dst[] = {
+		{ .vmid = QCOM_SCM_VMID_HLOS, .perm = QCOM_SCM_PERM_RW },
+		{ .vmid = QCOM_SCM_VMID_MSS_MSA, .perm = QCOM_SCM_PERM_RW },
+		{ .vmid = QCOM_SCM_VMID_LPASS, .perm = QCOM_SCM_PERM_RW },
+	};
+	struct q6apm_scm_region *r;
+	u64 src = BIT(QCOM_SCM_VMID_HLOS);
+	int ret;
+
+	if (pdata->num_scm_regions >= Q6APM_MAX_SCM_REGIONS)
+		return -ENOSPC;
+
+	ret = qcom_scm_assign_mem(addr, size, &src, dst, ARRAY_SIZE(dst));
+	if (ret)
+		return ret;
+
+	r = &pdata->scm_regions[pdata->num_scm_regions++];
+	r->addr = addr;
+	r->size = size;
+	r->src_perms = src;
+	r->assigned = true;
+
+	return 0;
+}
+
+static void q6apm_dai_scm_unassign(struct q6apm_dai_data *pdata,
+				    phys_addr_t addr)
+{
+	struct qcom_scm_vmperm hlos = {
+		.vmid = QCOM_SCM_VMID_HLOS,
+		.perm = QCOM_SCM_PERM_RW,
+	};
+	int i;
+
+	for (i = 0; i < pdata->num_scm_regions; i++) {
+		if (pdata->scm_regions[i].addr != addr ||
+		    !pdata->scm_regions[i].assigned)
+			continue;
+
+		if (qcom_scm_assign_mem(addr, pdata->scm_regions[i].size,
+					&pdata->scm_regions[i].src_perms,
+					&hlos, 1)) {
+			dev_err(pdata->dev, "SCM unassign %pa failed\n", &addr);
+			return;
+		}
+
+		pdata->scm_regions[i].assigned = false;
+		pdata->num_scm_regions--;
+		pdata->scm_regions[i] = pdata->scm_regions[pdata->num_scm_regions];
+		return;
+	}
+}
+
+static void q6apm_dai_scm_cleanup(void *data)
+{
+	struct q6apm_dai_data *pdata = data;
+	int i;
+
+	for (i = pdata->num_scm_regions - 1; i >= 0; i--) {
+		if (pdata->scm_regions[i].assigned)
+			q6apm_dai_scm_unassign(pdata,
+					       pdata->scm_regions[i].addr);
+	}
+}
+
+static void q6apm_dai_reserved_mem_release(void *data)
+{
+	of_reserved_mem_device_release(data);
+}
+
 static const struct snd_pcm_hardware q6apm_dai_hardware_capture = {
 	.info =                 (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_BLOCK_TRANSFER |
 				 SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_INTERLEAVED |
@@ -409,8 +502,11 @@ static int q6apm_dai_open(struct snd_soc_component *component,
 	}
 
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		size_t buf_max = pdata->has_reserved_mem ? pdata->reserved_buf_size :
+							   BUFFER_BYTES_MAX;
+
 		ret = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_BUFFER_BYTES,
-						   BUFFER_BYTES_MIN, BUFFER_BYTES_MAX);
+						   BUFFER_BYTES_MIN, buf_max);
 		if (ret < 0) {
 			dev_err(dev, "constraint for buffer bytes min max ret = %d\n", ret);
 			goto err;
@@ -431,17 +527,20 @@ static int q6apm_dai_open(struct snd_soc_component *component,
 	}
 
 	runtime->private_data = prtd;
-	runtime->dma_bytes = BUFFER_BYTES_MAX;
+	runtime->dma_bytes = pdata->has_reserved_mem ? pdata->reserved_buf_size :
+						       BUFFER_BYTES_MAX;
 	if (pdata->sid < 0)
 		prtd->phys = substream->dma_buffer.addr;
 	else
 		prtd->phys = substream->dma_buffer.addr | (pdata->sid << 32);
 
 	if (q6apm_is_graph_in_push_pull_mode(prtd->graph)) {
+		size_t buf_max = pdata->has_reserved_mem ? pdata->reserved_buf_size :
+							   BUFFER_BYTES_MAX;
 		void *pos_buffer;
 
-		prtd->pos_phys = prtd->phys + BUFFER_BYTES_MAX;
-		pos_buffer = (void *)(substream->dma_buffer.area + BUFFER_BYTES_MAX);
+		prtd->pos_phys = prtd->phys + buf_max;
+		pos_buffer = (void *)(substream->dma_buffer.area + buf_max);
 		prtd->pos_buffer = (struct sh_mem_pull_push_mode_position_buffer *)(pos_buffer);
 	}
 
@@ -535,6 +634,7 @@ static int q6apm_dai_memory_map(struct snd_soc_component *component,
 {
 	struct q6apm_dai_data *pdata;
 	struct device *dev = component->dev;
+	size_t buf_max;
 	phys_addr_t phys;
 	int ret;
 
@@ -544,20 +644,23 @@ static int q6apm_dai_memory_map(struct snd_soc_component *component,
 		return -EINVAL;
 	}
 
+	buf_max = pdata->has_reserved_mem ? pdata->reserved_buf_size :
+					    BUFFER_BYTES_MAX;
+
 	if (pdata->sid < 0)
 		phys = substream->dma_buffer.addr;
 	else
 		phys = substream->dma_buffer.addr | (pdata->sid << 32);
 
-	ret = q6apm_map_memory_fixed_region(dev, graph_id, phys, BUFFER_BYTES_MAX);
+	ret = q6apm_map_memory_fixed_region(dev, graph_id, phys, buf_max);
 	if (ret < 0)
 		dev_err(dev, "Audio Start: Buffer Allocation failed rc = %d\n",	ret);
 
 	if (is_push_pull) {
 		if (pdata->sid < 0)
-			phys = substream->dma_buffer.addr + BUFFER_BYTES_MAX;
+			phys = substream->dma_buffer.addr + buf_max;
 		else
-			phys = (substream->dma_buffer.addr + BUFFER_BYTES_MAX) | (pdata->sid << 32);
+			phys = (substream->dma_buffer.addr + buf_max) | (pdata->sid << 32);
 
 		ret = q6apm_map_pos_buffer(dev, graph_id, phys, POS_BUFFER_BYTES);
 		if (ret < 0)
@@ -572,20 +675,22 @@ static int q6apm_dai_memory_map(struct snd_soc_component *component,
 static int q6apm_dai_pcm_new(struct snd_soc_component *component, struct snd_soc_pcm_runtime *rtd)
 {
 	struct snd_soc_dai *cpu_dai = snd_soc_rtd_to_cpu(rtd, 0);
+	struct q6apm_dai_data *pdata;
 	struct snd_pcm *pcm = rtd->pcm;
-	/*
-	 * Allocate one extra page as a workaround for a DSP bug where 32-bit
-	 * address arithmetic can overflow when the buffer is placed near the
-	 * end of the addressable range.
-	 */
 	int size = BUFFER_BYTES_MAX + PAGE_SIZE;
 	int graph_id, ret;
 	bool is_push_pull;
 	struct snd_pcm_substream *substream = NULL;
 
+	pdata = snd_soc_component_get_drvdata(component);
+	if (!pdata)
+		return -EINVAL;
+
+	if (pdata->has_reserved_mem)
+		size = pdata->reserved_buf_size + PAGE_SIZE;
+
 	graph_id = cpu_dai->driver->id;
 
-	/* Note: DSP backend dais are uni-directional ONLY(either playback or capture) */
 	if (pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream)
 		substream = pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream;
 	else  if (pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream)
@@ -603,6 +708,17 @@ static int q6apm_dai_pcm_new(struct snd_soc_component *component, struct snd_soc
 		if (ret)
 			return ret;
 
+		if (pdata->use_scm_assign) {
+			ret = q6apm_dai_scm_assign(pdata,
+						   substream->dma_buffer.addr,
+						   ALIGN(size, PAGE_SIZE));
+			if (ret) {
+				dev_err(component->dev,
+					"SCM assign buffer failed: %d\n", ret);
+				return ret;
+			}
+		}
+
 		ret = q6apm_dai_memory_map(component, substream, graph_id, is_push_pull);
 		if (ret)
 			return ret;
@@ -635,15 +751,26 @@ static void q6apm_dai_memory_unmap(struct snd_soc_component *component,
 
 static void q6apm_dai_pcm_free(struct snd_soc_component *component, struct snd_pcm *pcm)
 {
+	struct q6apm_dai_data *pdata;
 	struct snd_pcm_substream *substream;
 
+	pdata = snd_soc_component_get_drvdata(component);
+
 	substream = pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream;
-	if (substream)
+	if (substream) {
 		q6apm_dai_memory_unmap(component, substream);
+		if (pdata && pdata->use_scm_assign)
+			q6apm_dai_scm_unassign(pdata,
+					       substream->dma_buffer.addr);
+	}
 
 	substream = pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream;
-	if (substream)
+	if (substream) {
 		q6apm_dai_memory_unmap(component, substream);
+		if (pdata && pdata->use_scm_assign)
+			q6apm_dai_scm_unassign(pdata,
+					       substream->dma_buffer.addr);
+	}
 }
 
 static int q6apm_dai_compr_open(struct snd_soc_component *component,
@@ -1021,6 +1148,7 @@ static int q6apm_dai_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *node = dev->of_node;
+	struct q6apm *apm = dev_get_drvdata(dev->parent);
 	struct q6apm_dai_data *pdata;
 	struct of_phandle_args args;
 	int rc;
@@ -1029,12 +1157,104 @@ static int q6apm_dai_probe(struct platform_device *pdev)
 	if (!pdata)
 		return -ENOMEM;
 
+	pdata->dev = dev;
+
 	rc = of_parse_phandle_with_fixed_args(node, "iommus", 1, 0, &args);
 	if (rc < 0)
 		pdata->sid = -1;
 	else
 		pdata->sid = args.args[0] & SID_MASK_DEFAULT;
 
+	if (apm && apm->gdev &&
+	    apm->gdev->domain_id == GPR_DOMAIN_ID_MODEM) {
+		if (!qcom_scm_is_available())
+			return -EPROBE_DEFER;
+
+		if (pdata->sid >= 0) {
+			dev_err(dev,
+				"iommus and mDSP SCM path are mutually exclusive\n");
+			return -EINVAL;
+		}
+
+		pdata->use_scm_assign = true;
+
+		rc = devm_add_action_or_reset(dev, q6apm_dai_scm_cleanup,
+					      pdata);
+		if (rc)
+			return rc;
+	}
+
+	if (pdata->use_scm_assign) {
+		int mem_count;
+
+		mem_count = of_count_phandle_with_args(node, "memory-region",
+						       NULL);
+		if (mem_count >= 1) {
+			struct device_node *mem_node;
+			struct reserved_mem *rmem;
+
+			mem_node = of_parse_phandle(node, "memory-region", 0);
+			rmem = of_reserved_mem_lookup(mem_node);
+			of_node_put(mem_node);
+			if (!rmem) {
+				dev_err(dev,
+					"memory-region[0]: lookup failed\n");
+				return -ENODEV;
+			}
+
+			rc = q6apm_dai_scm_assign(pdata, rmem->base,
+						  ALIGN(rmem->size, PAGE_SIZE));
+			if (rc) {
+				dev_err(dev,
+					"SCM assign memory-region[0] failed: %d\n",
+					rc);
+				return rc;
+			}
+		}
+
+		if (mem_count >= 2) {
+			struct device_node *mem_node;
+			struct reserved_mem *rmem;
+			size_t per_stream;
+
+			mem_node = of_parse_phandle(node, "memory-region", 1);
+			rmem = of_reserved_mem_lookup(mem_node);
+			of_node_put(mem_node);
+			if (!rmem) {
+				dev_err(dev,
+					"memory-region[1]: lookup failed\n");
+				return -ENODEV;
+			}
+
+			per_stream = rmem->size / Q6APM_POOL_MAX_STREAMS;
+			if (per_stream <= POS_BUFFER_BYTES) {
+				dev_err(dev,
+					"reserved-memory pool too small: %llu bytes\n",
+					(u64)rmem->size);
+				return -EINVAL;
+			}
+
+			rc = of_reserved_mem_device_init_by_idx(dev, node, 1);
+			if (rc) {
+				dev_err(dev,
+					"reserved-memory pool init failed: %d\n",
+					rc);
+				return rc;
+			}
+
+			rc = devm_add_action_or_reset(dev,
+						      q6apm_dai_reserved_mem_release,
+						      dev);
+			if (rc)
+				return rc;
+
+			pdata->reserved_buf_size =
+				min_t(size_t, per_stream - POS_BUFFER_BYTES,
+				      BUFFER_BYTES_MAX);
+			pdata->has_reserved_mem = true;
+		}
+	}
+
 	dev_set_drvdata(dev, pdata);
 
 	return devm_snd_soc_register_component(dev, &q6apm_fe_dai_component, NULL, 0);

-- 
2.34.1

Re: [PATCH v3 3/3] ASoC: qcom: q6apm-dai: add SCM buffer assignment for mDSP platforms

[Rob Herring]

On Fri, Sep 18, 2026 at 07:19:37PM +0530, Ajay Kumar Nandam wrote:
> On platforms such as Qualcomm Shikra, audio is served by the modem DSP
> (mDSP) which runs in a stage-2 protected context. Unlike ADSP targets
> where SMMU-mapped system RAM is directly accessible, the mDSP cannot
> reach the PCM buffers unless they are explicitly SCM-assigned to the
> appropriate Virtual Machine IDs (VMIDs). Without this assignment, audio
> does not function on these platforms.
> 
> At probe time, the driver reads the GPR domain_id from the parent APM
> device to determine which DSP serves audio. When domain_id matches
> GPR_DOMAIN_ID_ADSP the existing SMMU/iommus path is taken and no new
> code is exercised. When domain_id matches GPR_DOMAIN_ID_MODEM, the
> driver verifies that qcom_scm is available (deferring otherwise) and
> that iommus is absent (the two mechanisms are mutually exclusive), then
> enables the SCM assignment path.
> 
> In the SCM path the driver parses the optional memory-region entries in
> DT. The first entry (memory-region[0] / audio_heap_mem) is the
> control-path carveout used by the DSP firmware for command traffic; since
> the mDSP operates on stage-2 protected memory, this carveout must be
> SCM-assigned at probe time itself for the firmware to function. It is
> SCM-assigned to HLOS (retained as source owner, RW) plus MSS_MSA and
> LPASS (consumer VMIDs, both RW) and restored to HLOS-only ownership via
> devm_add_action_or_reset() at device removal. The second entry
> (memory-region[1]) is the data-path buffer pool from which per-stream
> DMA buffers are carved out. This pool is attached via
> of_reserved_mem_device_init_by_idx() so that PCM buffers allocate
> directly from the carveout instead of system RAM. Individual buffer
> slices are SCM-assigned in pcm_new() after allocation and unassigned in
> pcm_free(), so only the actively used slices are shared with the modem
> and unused carveout memory remains HLOS-owned.
> 
> The VMIDs are static per SoC and hardcoded in the driver (HLOS, MSS_MSA,
> LPASS) rather than read from DT, following the upstream pattern used by
> rmtfs_mem and qcom_q6v5_pas. Buffer constraints are capped at
> reserved_buf_size when the data-path pool is present, and
> snd_pcm_set_fixed_buffer_all() is used for both paths so the carveout is
> not subject to the preallocate_dma module parameter.
> 
> The DT binding is updated to add an optional memory-region property (1-2
> entries) and to make iommus optional (removed from the required list),
> since mDSP platforms have neither IOMMU nor VMID DT properties.
> 
> All new code paths are gated on use_scm_assign (false when domain_id is
> not GPR_DOMAIN_ID_MODEM), ensuring existing ADSP/iommus targets are
> completely unaffected.
> 
> Signed-off-by: Ajay Kumar Nandam <ajay.nandam@oss.qualcomm.com>
> ---
>  .../devicetree/bindings/sound/qcom,q6apm-dai.yaml  |  12 +-

Bindings are separate patches. Run checkpatch.pl, it will tell you this.

>  sound/soc/qcom/Kconfig                             |   1 +
>  sound/soc/qcom/qdsp6/q6apm-dai.c                   | 260 +++++++++++++++++++--
>  3 files changed, 252 insertions(+), 21 deletions(-)