linux-kernel - [PATCH v5 07/11] misc: amd-sbi: Add support for mailbox error codes

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Message-ID: <20250303105902.215009-8-akshay.gupta@amd.com>
Date: Mon, 3 Mar 2025 10:58:58 +0000
From: Akshay Gupta <akshay.gupta@....com>
To: <linux-hwmon@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC: <linux@...ck-us.net>, <gregkh@...uxfoundation.org>, <arnd@...db.de>,
	<shyam-sundar.s-k@....com>, <gautham.shenoy@....com>,
	<mario.limonciello@....com>, <naveenkrishna.chatradhi@....com>, Akshay Gupta
	<akshay.gupta@....com>
Subject: [PATCH v5 07/11] misc: amd-sbi: Add support for mailbox error codes

APML mailbox protocol returns additional error codes written by
SMU firmware in the out-bound register 0x37. These errors include,
invalid core, message not supported over platform and
others. This additional error codes can be used to provide more
details to user space.

Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@....com>
Signed-off-by: Akshay Gupta <akshay.gupta@....com>
---
Changes since v4:
- Previously patch 5
- Fix Documentation warning

Changes since v3:
- update ioctl comment description
 
Changes since v1:
- bifurcated from previous patch 5

 drivers/misc/amd-sbi/rmi-core.c | 12 +++++++++++-
 include/uapi/misc/amd-apml.h    |  5 +++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/amd-sbi/rmi-core.c b/drivers/misc/amd-sbi/rmi-core.c
index c39a29d90c27..642fe762cf6f 100644
--- a/drivers/misc/amd-sbi/rmi-core.c
+++ b/drivers/misc/amd-sbi/rmi-core.c
@@ -25,13 +25,15 @@
 int rmi_mailbox_xfer(struct sbrmi_data *data,
 		     struct apml_message *msg)
 {
-	unsigned int bytes;
+	unsigned int bytes, ec;
 	int i, ret;
 	int sw_status;
 	u8 byte;
 
 	mutex_lock(&data->lock);
 
+	msg->fw_ret_code = 0;
+
 	/* Indicate firmware a command is to be serviced */
 	ret = regmap_write(data->regmap, SBRMI_INBNDMSG7, START_CMD);
 	if (ret < 0)
@@ -72,6 +74,9 @@ int rmi_mailbox_xfer(struct sbrmi_data *data,
 	if (ret)
 		goto exit_unlock;
 
+	ret = regmap_read(data->regmap, SBRMI_OUTBNDMSG7, &ec);
+	if (ret || ec)
+		goto exit_clear_alert;
 	/*
 	 * For a read operation, the initiator (BMC) reads the firmware
 	 * response Command Data Out[31:0] from SBRMI::OutBndMsg_inst[4:1]
@@ -87,12 +92,17 @@ int rmi_mailbox_xfer(struct sbrmi_data *data,
 		}
 	}
 
+exit_clear_alert:
 	/*
 	 * BMC must write 1'b1 to SBRMI::Status[SwAlertSts] to clear the
 	 * ALERT to initiator
 	 */
 	ret = regmap_write(data->regmap, SBRMI_STATUS,
 			   sw_status | SW_ALERT_MASK);
+	if (ec) {
+		ret = -EPROTOTYPE;
+		msg->fw_ret_code = ec;
+	}
 exit_unlock:
 	mutex_unlock(&data->lock);
 	return ret;
diff --git a/include/uapi/misc/amd-apml.h b/include/uapi/misc/amd-apml.h
index 5721aaa0c6bd..47a057226300 100644
--- a/include/uapi/misc/amd-apml.h
+++ b/include/uapi/misc/amd-apml.h
@@ -38,6 +38,10 @@ struct apml_message {
 		__u32 mb_in[2];
 		__u8 reg_in[8];
 	} data_in;
+	/*
+	 * Error code is returned in case of soft mailbox
+	 */
+	__u32 fw_ret_code;
 } __attribute__((packed));
 
 /*
@@ -60,6 +64,7 @@ struct apml_message {
  * The APML RMI module checks whether the cmd is
  * - Mailbox message read/write(0x0~0x999)
  * - returning "-EFAULT" if none of the above
+ * "-EPROTOTYPE" error is returned to provide additional error details
  */
 #define SBRMI_IOCTL_CMD		_IOWR(SB_BASE_IOCTL_NR, 0, struct apml_message)
 
-- 
2.25.1