[PATCH v3] soc: qcom: rpmh-rsc: Update CMD_MSGID_LEN to 4 bytes for read request

[Maulik Shah <maulik.shah@oss.qualcomm.com>]

Newer SoC like hawi with RSC version v4.5 support 4 byte message read
request instead of default 8 byte on older SoCs. The write request
continues to be 8 bytes.

The CMD_MSGID_LEN field is [3:0] bits. Describe the length bits as a
GENMASK() and use FIELD_PREP() when programming 4-byte or 8-byte message
length.

Tested-by: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com> #Hawi
Signed-off-by: Maulik Shah <maulik.shah@oss.qualcomm.com>
---
Changes in v3:
- Drop patch-2 as it may wait for a while to get more comments.
- No changes to patch-1.
- Drop cover letter for single change
- Link to v2: https://patch.msgid.link/20260911-rsc_read-v2-0-98675c248278@oss.qualcomm.com

Changes in v2:
- Define CMD_MSGID_LEN as a field and use FIELD_PREP() for lengths.
- Keep the read length selection explicit for RSC v4.5 and newer.
- Keep Tested-by for patch-1.
- No changes to patch-2.
- Link to v1: https://patch.msgid.link/20260910-rsc_read-v1-0-c9b7fa3cdde2@oss.qualcomm.com

To: Bjorn Andersson <andersson@kernel.org>
To: Konrad Dybcio <konradybcio@kernel.org>
To: Maulik Shah <maulik.shah@oss.qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
To: Mark Brown <broonie@kernel.org>
To: Kamal Wadhwa <kamal.wadhwa@oss.qualcomm.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
---
 drivers/soc/qcom/rpmh-rsc.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
index c4542318eac4..c5ed9874bb67 100644
--- a/drivers/soc/qcom/rpmh-rsc.c
+++ b/drivers/soc/qcom/rpmh-rsc.c
@@ -7,6 +7,7 @@
 #define pr_fmt(fmt) "%s " fmt, KBUILD_MODNAME
 
 #include <linux/atomic.h>
+#include <linux/bitfield.h>
 #include <linux/cpu_pm.h>
 #include <linux/delay.h>
 #include <linux/interrupt.h>
@@ -86,7 +87,7 @@ enum {
 #define TCS_AMC_MODE_TRIGGER		BIT(24)
 
 /* TCS CMD register bit mask */
-#define CMD_MSGID_LEN			8
+#define CMD_MSGID_LEN			GENMASK(3, 0)
 #define CMD_MSGID_RESP_REQ		BIT(8)
 #define CMD_MSGID_WRITE			BIT(16)
 #define CMD_STATUS_ISSUED		BIT(8)
@@ -499,13 +500,20 @@ static void __tcs_buffer_write(struct rsc_drv *drv, int tcs_id, int cmd_id,
 			       const struct tcs_request *msg)
 {
 	u32 msgid;
-	u32 cmd_msgid = CMD_MSGID_LEN;
+	u32 cmd_msgid;
 	u32 cmd_enable = 0;
 	struct tcs_cmd *cmd;
 	int i, j;
 
 	/* Convert all commands to RR when the request has wait_for_compl set */
-	cmd_msgid |= msg->wait_for_compl ? CMD_MSGID_RESP_REQ : 0;
+	cmd_msgid = msg->wait_for_compl ? CMD_MSGID_RESP_REQ : 0;
+
+	if (msg->is_read && (drv->ver.major > 4 ||
+	     (drv->ver.major == 4 && drv->ver.minor >= 5)))
+		cmd_msgid |= FIELD_PREP(CMD_MSGID_LEN, 4);
+	else
+		cmd_msgid |= FIELD_PREP(CMD_MSGID_LEN, 8);
+
 	if (!msg->is_read)
 		cmd_msgid |= CMD_MSGID_WRITE;
 

---
base-commit: c68a982815dcce5464e3bf2a31ac94f5146c04ca
change-id: 20260910-rsc_read-27d689e37cb5

Best regards,
--  
Maulik Shah <maulik.shah@oss.qualcomm.com>