HID: amd_sfh: Allow configuring whether HPD is enabled or disabled

Human presence detection (HPD) sensor uses a camera to determine when
user is physically in front of the machine.  This might not be a
desirable behavior because it can (for example) cause the machine to
wake on approach.

Add a new sysfs file "hpd" that will control whether this sensor is
enabled. Use the value of this sysfs file to turn off HPD and prevent
it from re-enabling after resume from suspend.

Cc: Pratap Nirujogi <pratap.nirujogi@amd.com>
Tested-by: Anson Tsao <anson.tsao@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

Author: superm1

Documentation/ABI/testing/sysfs-driver-amd-sfh

@@ -0,0 +1,13 @@
+What:		/sys/bus/pci/drivers/pcie_mp2_amd/*/hpd
+Date:		April 2025
+Contact:	mario.limonciello@amd.com
+Description:
+		Human presence detection (HPD) enable/disable.
+		When HPD is enabled, the device will be able to detect the
+		presence of a human and will send an interrupt that can be
+		used to wake the system from a low power state.
+		When HPD is disabled, the device will not be able to detect
+		the presence of a human.
+
+		Access: Read/Write
+		Valid values: enabled/disabled

drivers/hid/amd-sfh-hid/amd_sfh_common.h

@@ -42,6 +42,7 @@ struct amd_mp2_sensor_info {
 
 struct sfh_dev_status {
 	bool is_hpd_present;
+	bool is_hpd_enabled;
 	bool is_als_present;
 	bool is_sra_present;
 };

drivers/hid/amd-sfh-hid/amd_sfh_pcie.c

@@ -18,6 +18,7 @@
 #include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/slab.h>
+#include <linux/string_choices.h>
 
 #include "amd_sfh_pcie.h"
 #include "sfh1_1/amd_sfh_init.h"
@@ -330,6 +331,57 @@ static const struct dmi_system_id dmi_nodevs[] = {
 	{ }
 };
 
+static ssize_t hpd_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct amd_mp2_dev *mp2 = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%s\n", str_enabled_disabled(mp2->dev_en.is_hpd_enabled));
+}
+
+static ssize_t hpd_store(struct device *dev,
+			 struct device_attribute *attr,
+			 const char *buf, size_t count)
+{
+	struct amd_mp2_dev *mp2 = dev_get_drvdata(dev);
+	bool enabled;
+	int ret;
+
+	ret = kstrtobool(buf, &enabled);
+	if (ret)
+		return ret;
+
+	mp2->sfh1_1_ops->toggle_hpd(mp2, enabled);
+
+	return count;
+}
+static DEVICE_ATTR_RW(hpd);
+
+static umode_t sfh_attr_is_visible(struct kobject *kobj, struct attribute *attr, int idx)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct amd_mp2_dev *mp2 = dev_get_drvdata(dev);
+
+	if (!mp2->sfh1_1_ops || !mp2->dev_en.is_hpd_present)
+		return 0;
+
+	return attr->mode;
+}
+
+static struct attribute *sfh_attrs[] = {
+	&dev_attr_hpd.attr,
+	NULL,
+};
+
+static struct attribute_group sfh_attr_group = {
+	.attrs = sfh_attrs,
+	.is_visible = sfh_attr_is_visible,
+};
+
+static const struct attribute_group *amd_sfh_groups[] = {
+	&sfh_attr_group,
+	NULL,
+};
+
 static void sfh1_1_init_work(struct work_struct *work)
 {
 	struct amd_mp2_dev *mp2 = container_of(work, struct amd_mp2_dev, work);
@@ -341,6 +393,11 @@ static void sfh1_1_init_work(struct work_struct *work)
 
 	amd_sfh_clear_intr(mp2);
 	mp2->init_done = 1;
+
+	rc = sysfs_update_group(&mp2->pdev->dev.kobj, &sfh_attr_group);
+	if (rc)
+		dev_warn(&mp2->pdev->dev, "failed to update sysfs group\n");
+
 }
 
 static void sfh_init_work(struct work_struct *work)
@@ -487,6 +544,7 @@ static struct pci_driver amd_mp2_pci_driver = {
 	.driver.pm	= &amd_mp2_pm_ops,
 	.shutdown	= amd_sfh_shutdown,
 	.remove		= amd_sfh_remove,
+	.dev_groups	= amd_sfh_groups,
 };
 module_pci_driver(amd_mp2_pci_driver);
 

drivers/hid/amd-sfh-hid/sfh1_1/amd_sfh_init.c

@@ -212,6 +212,7 @@ static int amd_sfh1_1_hid_client_init(struct amd_mp2_dev *privdata)
 			switch (cl_data->sensor_idx[i]) {
 			case HPD_IDX:
 				privdata->dev_en.is_hpd_present = true;
+				privdata->dev_en.is_hpd_enabled = true;
 				break;
 			case ALS_IDX:
 				privdata->dev_en.is_als_present = true;
@@ -255,6 +256,10 @@ static void amd_sfh_resume(struct amd_mp2_dev *mp2)
 	}
 
 	for (i = 0; i < cl_data->num_hid_devices; i++) {
+		/* leave HPD alone; policy is controlled by sysfs */
+		if (cl_data->sensor_idx[i] == HPD_IDX)
+			continue;
+
 		if (cl_data->sensor_sts[i] == SENSOR_DISABLED) {
 			info.sensor_idx = cl_data->sensor_idx[i];
 			mp2->mp2_ops->start(mp2, info);
@@ -285,8 +290,10 @@ static void amd_sfh_suspend(struct amd_mp2_dev *mp2)
 	}
 
 	for (i = 0; i < cl_data->num_hid_devices; i++) {
-		if (cl_data->sensor_idx[i] != HPD_IDX &&
-		    cl_data->sensor_sts[i] == SENSOR_ENABLED) {
+		/* leave HPD alone; policy is controlled by sysfs */
+		if (cl_data->sensor_idx[i] == HPD_IDX)
+			continue;
+		if (cl_data->sensor_sts[i] == SENSOR_ENABLED) {
 			mp2->mp2_ops->stop(mp2, cl_data->sensor_idx[i]);
 			status = amd_sfh_wait_for_response
 					(mp2, cl_data->sensor_idx[i], DISABLE_SENSOR);
@@ -304,6 +311,44 @@ static void amd_sfh_suspend(struct amd_mp2_dev *mp2)
 	amd_sfh_clear_intr(mp2);
 }
 
+void amd_sfh_toggle_hpd(struct amd_mp2_dev *mp2, bool enabled)
+{
+	struct amdtp_cl_data *cl_data = mp2->cl_data;
+	struct amd_mp2_sensor_info info;
+	int i, status;
+
+	if (mp2->dev_en.is_hpd_enabled == enabled)
+		return;
+
+	for (i = 0; i < cl_data->num_hid_devices; i++) {
+		if (cl_data->sensor_idx[i] != HPD_IDX)
+			continue;
+		info.sensor_idx = cl_data->sensor_idx[i];
+		if (enabled) {
+			mp2->mp2_ops->start(mp2, info);
+			status = amd_sfh_wait_for_response
+					(mp2, cl_data->sensor_idx[i], ENABLE_SENSOR);
+			if (status == 0)
+				status = SENSOR_ENABLED;
+			if (status == SENSOR_ENABLED)
+				cl_data->sensor_sts[i] = SENSOR_ENABLED;
+		} else {
+			mp2->mp2_ops->stop(mp2, cl_data->sensor_idx[i]);
+			status = amd_sfh_wait_for_response
+					(mp2, cl_data->sensor_idx[i], DISABLE_SENSOR);
+			if (status == 0)
+				status = SENSOR_DISABLED;
+			if (status != SENSOR_ENABLED)
+				cl_data->sensor_sts[i] = SENSOR_DISABLED;
+		}
+		dev_dbg(&mp2->pdev->dev, "toggle sid 0x%x (%s) status 0x%x\n",
+			cl_data->sensor_idx[i], get_sensor_name(cl_data->sensor_idx[i]),
+			cl_data->sensor_sts[i]);
+		break;
+	}
+	mp2->dev_en.is_hpd_enabled = enabled;
+}
+
 static void amd_mp2_pci_remove(void *privdata)
 {
 	struct amd_mp2_dev *mp2 = privdata;

drivers/hid/amd-sfh-hid/sfh1_1/amd_sfh_init.h

@@ -15,12 +15,15 @@
 
 struct amd_sfh1_1_ops {
 	int (*init)(struct amd_mp2_dev *mp2);
+	void (*toggle_hpd)(struct amd_mp2_dev *mp2, bool enable);
 };
 
 int amd_sfh1_1_init(struct amd_mp2_dev *mp2);
+void amd_sfh_toggle_hpd(struct amd_mp2_dev *mp2, bool enabled);
 
 static const struct amd_sfh1_1_ops __maybe_unused sfh1_1_ops = {
 	.init = amd_sfh1_1_init,
+	.toggle_hpd = amd_sfh_toggle_hpd,
 };
 
 #endif