[PATCH v4 5/9] misc: amd-sbi: Add support for mailbox error codes

[Akshay Gupta <akshay.gupta@amd.com>]

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 userspace.

Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>
Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
---
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 92d33d589bdc..b4f292303ed4 100644
--- a/drivers/misc/amd-sbi/rmi-core.c
+++ b/drivers/misc/amd-sbi/rmi-core.c
@@ -27,13 +27,15 @@
 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)
@@ -74,6 +76,9 @@ 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]
@@ -89,12 +94,17 @@ 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 dc926327629d..4207aa08b660 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