platform/x86/amd/pmf: Add heartbeat signal support

PMF driver can send periodic heartbeat signals to OEM BIOS. When BIOS does
not receive the signal after a period of time, it can infer that AMDPMF
has hung or failed to load.

In this situation, BIOS can fallback to legacy operations. OEM can modify
the time interval of the signal or completely disable signals through
ACPI Method.
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Link: https://lore.kernel.org/r/20220802151149.2123699-6-Shyam-sundar.S-k@amd.comSigned-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/amd/pmf/acpi.c

@@ -103,6 +103,22 @@ int apmf_get_static_slider_granular(struct amd_pmf_dev *pdev,
 									 data, sizeof(*data));
 }
 
+static void apmf_sbios_heartbeat_notify(struct work_struct *work)
+{
+	struct amd_pmf_dev *dev = container_of(work, struct amd_pmf_dev, heart_beat.work);
+	union acpi_object *info;
+
+	dev_dbg(dev->dev, "Sending heartbeat to SBIOS\n");
+	info = apmf_if_call(dev, APMF_FUNC_SBIOS_HEARTBEAT, NULL);
+	if (!info)
+		goto out;
+
+	schedule_delayed_work(&dev->heart_beat, msecs_to_jiffies(dev->hb_interval * 1000));
+
+out:
+	kfree(info);
+}
+
 static int apmf_if_verify_interface(struct amd_pmf_dev *pdev)
 {
 	struct apmf_verify_interface output;
@@ -131,15 +147,23 @@ static int apmf_get_system_params(struct amd_pmf_dev *dev)
 	if (err)
 		return err;
 
-	dev_dbg(dev->dev, "system params mask:0x%x flags:0x%x cmd_code:0x%x\n",
+	dev_dbg(dev->dev, "system params mask:0x%x flags:0x%x cmd_code:0x%x heartbeat:%d\n",
 		params.valid_mask,
 		params.flags,
-		params.command_code);
+		params.command_code,
+		params.heartbeat_int);
 	params.flags = params.flags & params.valid_mask;
+	dev->hb_interval = params.heartbeat_int;
 
 	return 0;
 }
 
+void apmf_acpi_deinit(struct amd_pmf_dev *pmf_dev)
+{
+	if (pmf_dev->hb_interval)
+		cancel_delayed_work_sync(&pmf_dev->heart_beat);
+}
+
 int apmf_acpi_init(struct amd_pmf_dev *pmf_dev)
 {
 	int ret;
@@ -156,6 +180,12 @@ int apmf_acpi_init(struct amd_pmf_dev *pmf_dev)
 		goto out;
 	}
 
+	if (pmf_dev->hb_interval) {
+		/* send heartbeats only if the interval is not zero */
+		INIT_DELAYED_WORK(&pmf_dev->heart_beat, apmf_sbios_heartbeat_notify);
+		schedule_delayed_work(&pmf_dev->heart_beat, 0);
+	}
+
 out:
 	return ret;
 }

drivers/platform/x86/amd/pmf/core.c

@@ -279,6 +279,7 @@ static int amd_pmf_remove(struct platform_device *pdev)
 
 	mutex_destroy(&dev->lock);
 	amd_pmf_deinit_features(dev);
+	apmf_acpi_deinit(dev);
 	amd_pmf_dbgfs_unregister(dev);
 	kfree(dev->buf);
 	return 0;

drivers/platform/x86/amd/pmf/pmf.h

@@ -17,6 +17,7 @@
 /* APMF Functions */
 #define APMF_FUNC_VERIFY_INTERFACE			0
 #define APMF_FUNC_GET_SYS_PARAMS			1
+#define APMF_FUNC_SBIOS_HEARTBEAT			4
 #define APMF_FUNC_STATIC_SLIDER_GRANULAR       9
 
 /* Message Definitions */
@@ -53,6 +54,7 @@ struct apmf_system_params {
 	u32 valid_mask;
 	u32 flags;
 	u8 command_code;
+	u32 heartbeat_int;
 } __packed;
 
 enum amd_stt_skin_temp {
@@ -91,6 +93,8 @@ struct amd_pmf_dev {
 	enum platform_profile_option current_profile;
 	struct platform_profile_handler pprof;
 	struct dentry *dbgfs_dir;
+	int hb_interval; /* SBIOS heartbeat interval */
+	struct delayed_work heart_beat;
 };
 
 struct apmf_sps_prop_granular {
@@ -116,6 +120,7 @@ struct amd_pmf_static_slider_granular {
 
 /* Core Layer */
 int apmf_acpi_init(struct amd_pmf_dev *pmf_dev);
+void apmf_acpi_deinit(struct amd_pmf_dev *pmf_dev);
 int is_apmf_func_supported(struct amd_pmf_dev *pdev, unsigned long index);
 int amd_pmf_send_cmd(struct amd_pmf_dev *dev, u8 message, bool get, u32 arg, u32 *data);
 int amd_pmf_get_power_source(void);