[PATCH v2 1/2] drm/xe/i2c: Expose AMC Alert reason sysfs

[Badal Nilawar <badal.nilawar@intel.com>]

AMC raises an SMBUS alert before performing a power removal or
power-cycle operation. The xe driver then places the device into
vendor-specific wedge mode until the recovery is performed.

Expose a read-only xe_amc_alert_reason sysfs attribute to help users
identify the required recovery action.

Assisted-by: Claude:claude-opus-4.8
Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
---
v2:
 - Created sysfs during i2c probe time
 - Fix Documentation (Rodrigo)
v3:
 - Keep limited information in "DOC:" section (Michal)
 - Handle AMC alert none and unknown cases, document
   in ABI
 - Clear i2c->amc on sysfs creation failure (Sashiko)
---
 .../ABI/testing/sysfs-driver-intel-xe-amc     | 25 ++++++
 drivers/gpu/drm/xe/xe_amc.c                   | 78 ++++++++++++++++---
 2 files changed, 93 insertions(+), 10 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-driver-intel-xe-amc

diff --git a/Documentation/ABI/testing/sysfs-driver-intel-xe-amc b/Documentation/ABI/testing/sysfs-driver-intel-xe-amc
new file mode 100644
index 000000000000..3bae78d1e0d9
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-intel-xe-amc
@@ -0,0 +1,25 @@
+What:		/sys/bus/pci/drivers/xe/.../xe_amc_alert_reason
+Date:		September 2026
+KernelVersion:	7.4
+Contact:	intel-xe@lists.freedesktop.org
+Description:
+		This file exposes the reason for the most recent Add-In
+		Management Controller (AMC) alert on Intel Xe platforms.
+
+		An AMC alert is delivered via an SMBUS interrupt and causes the
+		device to be wedged, requiring vendor-specific recovery. This
+		attribute is created when such an alert is handled and is
+		available to all users as read-only.
+
+		Read returns a single line containing one of the following
+		alert reasons:
+
+			none
+				No AMC alert has been received
+			unknown
+				AMC alert received but with invalid reason code
+			firmware_download
+			thermal_trip
+			oob_request
+			oob_reset
+			catastrophic
diff --git a/drivers/gpu/drm/xe/xe_amc.c b/drivers/gpu/drm/xe/xe_amc.c
index edd50bf8261e..bb9d260f800f 100644
--- a/drivers/gpu/drm/xe/xe_amc.c
+++ b/drivers/gpu/drm/xe/xe_amc.c
@@ -18,6 +18,7 @@
 #include "xe_device.h"
 #include "xe_i2c.h"
 #include "xe_mmio.h"
+#include "xe_printk.h"
 
 /**
  * DOC: Add-In Management Controller (AMC)
@@ -43,19 +44,23 @@ enum xe_amc_alert {
 	AMC_ALERT_OOB_REQUEST,
 	AMC_ALERT_OOB_RESET,
 	AMC_ALERT_CATERR,
+	AMC_ALERT_NONE = U8_MAX,
 };
 
 static const char * const amc_alert[] = {
-	[AMC_ALERT_FW_DOWNLOAD]		= "Firmware Download",
-	[AMC_ALERT_THERMAL_TRIP]	= "Thermal Trip",
-	[AMC_ALERT_OOB_REQUEST]		= "OOB Request",
-	[AMC_ALERT_OOB_RESET]		= "OOB Reset",
-	[AMC_ALERT_CATERR]		= "Catastrophic",
+	[AMC_ALERT_UNKNOWN]		= "unknown",
+	[AMC_ALERT_FW_DOWNLOAD]		= "firmware_download",
+	[AMC_ALERT_THERMAL_TRIP]	= "thermal_trip",
+	[AMC_ALERT_OOB_REQUEST]		= "oob_request",
+	[AMC_ALERT_OOB_RESET]		= "oob_reset",
+	[AMC_ALERT_CATERR]		= "catastrophic",
+	[AMC_ALERT_NONE]		= "none",
 };
 
 struct xe_amc {
 	struct xe_i2c *i2c;
 	struct work_struct work;
+	u8 alert_reason;
 };
 
 struct amc_header {
@@ -104,6 +109,42 @@ static const struct amc_request amc_get_alert_reason = {
 	},
 };
 
+/**
+ * DOC: AMC Alert Reason
+ *
+ * On Intel Xe platforms, AMC sends an alert notification via an SMBUS interrupt
+ * to notify events such as firmware download, thermal trip or a
+ * catastrophic error. See enum xe_amc_alert for the full list of reasons.
+ * Upon an AMC alert the device is wedged and requires vendor-specific recovery.
+ *
+ * See Documentation/ABI/testing/sysfs-driver-intel-xe-amc for the ABI
+ * specification.
+ */
+
+static ssize_t xe_amc_alert_reason_show(struct device *dev,
+					struct device_attribute *attr, char *buf)
+{
+	struct xe_device *xe = pdev_to_xe_device(to_pci_dev(dev));
+	struct xe_amc *amc = xe->i2c->amc;
+
+	return sysfs_emit(buf, "%s\n", amc_alert[amc->alert_reason]);
+}
+static DEVICE_ATTR_RO(xe_amc_alert_reason);
+
+static void xe_amc_remove_alert_sysfs(struct xe_i2c *i2c)
+{
+	struct device *dev = i2c->drm_dev;
+
+	device_remove_file(dev, &dev_attr_xe_amc_alert_reason);
+}
+
+static int xe_amc_create_alert_sysfs(struct xe_i2c *i2c)
+{
+	struct device *dev = i2c->drm_dev;
+
+	return device_create_file(dev, &dev_attr_xe_amc_alert_reason);
+}
+
 static void xe_amc_work(struct work_struct *work)
 {
 	const struct amc_request *request = &amc_get_alert_reason;
@@ -158,12 +199,19 @@ static void xe_amc_work(struct work_struct *work)
 	case AMC_ALERT_THERMAL_TRIP:
 	case AMC_ALERT_OOB_REQUEST:
 	case AMC_ALERT_OOB_RESET:
-	case AMC_ALERT_CATERR:
-		dev_warn(amc->i2c->drm_dev, "AMC Alert: %s\n", amc_alert[alert_reason]);
-		xe_device_declare_wedged(i2c_client_to_xe_device(client));
+	case AMC_ALERT_CATERR: {
+		struct xe_device *xe = i2c_client_to_xe_device(client);
+
+		dev_warn(amc->i2c->drm_dev,
+			 "AMC Alert: %s (%u)\n", amc_alert[alert_reason], alert_reason);
+		amc->alert_reason = alert_reason;
+		xe_device_set_wedged_method(xe, DRM_WEDGE_RECOVERY_VENDOR);
+		xe_device_declare_wedged(xe);
 		break;
+	}
 	default:
-		dev_warn(amc->i2c->drm_dev, "unknown AMC alert: %d\n", alert_reason);
+		amc->alert_reason = AMC_ALERT_UNKNOWN;
+		dev_warn(amc->i2c->drm_dev, "AMC Alert: unknown (%u)\n", alert_reason);
 		break;
 	}
 }
@@ -176,6 +224,7 @@ void xe_amc_handle_alert(struct xe_i2c *i2c)
 int xe_amc_init(struct xe_i2c *i2c)
 {
 	struct xe_amc *amc;
+	int ret;
 
 	amc = kzalloc_obj(*amc);
 	if (!amc)
@@ -185,13 +234,22 @@ int xe_amc_init(struct xe_i2c *i2c)
 	i2c->amc = amc;
 	amc->i2c = i2c;
 
-	return 0;
+	amc->alert_reason = AMC_ALERT_NONE;
+	ret = xe_amc_create_alert_sysfs(i2c);
+	if (ret) {
+		kfree(i2c->amc);
+		i2c->amc = NULL;
+	}
+
+	return ret;
 }
 
 void xe_amc_exit(struct xe_i2c *i2c)
 {
 	if (i2c->amc) {
+		xe_amc_remove_alert_sysfs(i2c);
 		cancel_work_sync(&i2c->amc->work);
 		kfree(i2c->amc);
+		i2c->amc = NULL;
 	}
 }
-- 
2.54.0