[PATCH v5 04/13] HID: asus: add gamepad configuration

[Denis Benato <denis.benato@linux.dev>]

Add the base configuration structures for the gamepad configuration,
detect capabilities and initialize the device in a known state.

Assisted-by: opencode:glm-5.2
Assisted-by: Claude:claude-fable-5
Signed-off-by: Denis Benato <denis.benato@linux.dev>
Signed-off-by: Luke Jones <luke@ljones.dev>
Signed-off-by: Jonathan LoBue <jlobue10@gmail.com>
---
 drivers/hid/hid-asus.c | 401 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 398 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
index 129cec7e27ec..4714ebb4a543 100644
--- a/drivers/hid/hid-asus.c
+++ b/drivers/hid/hid-asus.c
@@ -22,6 +22,7 @@
 
 #include <linux/acpi.h>
 #include <linux/cleanup.h>
+#include <linux/device.h>
 #include <linux/dmi.h>
 #include <linux/hid.h>
 #include <linux/jiffies.h>
@@ -34,6 +35,7 @@
 #include <linux/usb.h> /* For to_usb_interface for T100 touchpad intf check */
 #include <linux/power_supply.h>
 #include <linux/stddef.h>
+#include <linux/sysfs.h>
 #include <linux/leds.h>
 #include <linux/unaligned.h>
 
@@ -176,6 +178,45 @@ struct asus_touchpad_info {
 	int report_size;
 };
 
+struct ally_config {
+	/* Must be locked if the data is being changed */
+	struct mutex config_mutex;
+	bool initialized;
+
+	/* Device capabilities flags */
+	bool is_ally_x;
+	bool xbox_controller_support;
+	bool user_cal_support;
+	bool turbo_support;
+	bool resp_curve_support;
+	bool dir_to_btn_support;
+	bool gyro_support;
+	bool anti_deadzone_support;
+
+	/* Current settings */
+	bool xbox_controller_enabled;
+	u8 gamepad_mode;
+	u8 left_deadzone;
+	u8 left_outer_threshold;
+	u8 right_deadzone;
+	u8 right_outer_threshold;
+	u8 left_anti_deadzone;
+	u8 right_anti_deadzone;
+	u8 left_trigger_min;
+	u8 left_trigger_max;
+	u8 right_trigger_min;
+	u8 right_trigger_max;
+};
+
+/*
+ * The Ally configuration is allocated when the controller first appears and
+ * is released only on module removal: the embedded controller can disappear
+ * and re-enumerate at any time (it powers off during suspend when powersave
+ * is enabled), and on re-probe the driver must re-apply the recorded
+ * configuration instead of factory defaults.
+ */
+static struct ally_config *ally_config;
+
 struct ally_handheld {
 	/* All read/write to IN interfaces must lock */
 	struct mutex intf_mutex;
@@ -197,6 +238,8 @@ struct ally_handheld {
 	unsigned long cad_last_event_time;
 
 	struct delayed_work resume_work;
+
+	struct ally_config *config;
 };
 
 struct asus_drvdata {
@@ -590,11 +633,20 @@ static int ally_gamepad_send_receive_packet(struct ally_handheld *ally,
  * responsibility to free the buffer using kfree().
  *
  * Return: the newly allocated buffer containing the command, or NULL on
- * allocation failure
+ * allocation failure or if the payload would not fit in the report
  */
 static u8 *ally_alloc_cmd(u8 cmd, const u8 *payload, u8 payload_size)
 {
-	u8 *hidbuf = kzalloc(ROG_ALLY_REPORT_SIZE, GFP_KERNEL);
+	u8 *hidbuf;
+
+	/*
+	 * The payload is written after the 4-byte command header:
+	 * reject one that would spill past the end of the report.
+	 */
+	if (payload_size > ROG_ALLY_REPORT_SIZE - 4)
+		return NULL;
+
+	hidbuf = kzalloc(ROG_ALLY_REPORT_SIZE, GFP_KERNEL);
 
 	if (!hidbuf)
 		return NULL;
@@ -610,6 +662,272 @@ static u8 *ally_alloc_cmd(u8 cmd, const u8 *payload, u8 payload_size)
 	return hidbuf;
 }
 
+/**
+ * ally_check_capability() - Check if a specific capability is supported
+ * @hdev: HID device
+ * @ally: ally handheld structure
+ * @check_cmd: capability command code to query
+ *
+ * Return: true if the capability is supported, false otherwise
+ */
+static bool ally_check_capability(struct hid_device *hdev, struct ally_handheld *ally,
+				  enum ally_command_codes check_cmd)
+{
+	u8 payload[] = { 0x00 };
+	int ret;
+
+	u8 *buf __free(kfree) = ally_alloc_cmd(check_cmd, payload, sizeof(payload));
+	if (!buf) {
+		hid_err(hdev, "Failed to allocate buffer for capability check.\n");
+		return false;
+	}
+
+	ret = ally_gamepad_send_receive_packet(ally, hdev, buf, ROG_ALLY_REPORT_SIZE);
+	if (ret < 0) {
+		hid_err(hdev, "Failed to check capability 0x%02x: %d\n", check_cmd, ret);
+		return false;
+	}
+
+	return buf[1] == HID_ALLY_FEATURE_CODE_PAGE && buf[2] == check_cmd &&
+	       buf[4] == 0x01;
+}
+
+static int ally_detect_capabilities(struct hid_device *hdev, struct ally_handheld *ally,
+				    struct ally_config *cfg)
+{
+	if (!hdev || !cfg || !ally)
+		return -EINVAL;
+
+	scoped_guard(mutex, &cfg->config_mutex) {
+		cfg->is_ally_x = (hdev->product == USB_DEVICE_ID_ASUSTEK_ROG_NKEY_ALLY_X);
+
+		cfg->xbox_controller_support =
+			ally_check_capability(hdev, ally, CMD_CHECK_XBOX_SUPPORT);
+		cfg->user_cal_support =
+			ally_check_capability(hdev, ally, CMD_CHECK_USER_CAL_SUPPORT);
+		cfg->turbo_support =
+			ally_check_capability(hdev, ally, CMD_CHECK_TURBO_SUPPORT);
+		cfg->resp_curve_support =
+			ally_check_capability(hdev, ally, CMD_CHECK_RESP_CURVE_SUPPORT);
+		cfg->dir_to_btn_support =
+			ally_check_capability(hdev, ally, CMD_CHECK_DIR_TO_BTN_SUPPORT);
+		cfg->gyro_support =
+			ally_check_capability(hdev, ally, CMD_CHECK_GYRO_TO_JOYSTICK);
+		cfg->anti_deadzone_support =
+			ally_check_capability(hdev, ally, CMD_CHECK_ANTI_DEADZONE);
+	}
+
+	return 0;
+}
+
+static int ally_set_xbox_controller(struct hid_device *hdev,
+				    struct ally_handheld *ally,
+				    struct ally_config *cfg, bool enabled)
+{
+	u8 payload[] = { enabled ? 0x01 : 0x00 };
+	int ret;
+
+	if (!cfg || !cfg->xbox_controller_support)
+		return -ENODEV;
+
+	u8 *buf __free(kfree) = ally_alloc_cmd(CMD_SET_XBOX_CONTROLLER, payload, sizeof(payload));
+	if (!buf)
+		return -ENOMEM;
+
+	ret = ally_gamepad_send_packet(ally, hdev, buf, ROG_ALLY_REPORT_SIZE);
+	if (ret < 0) {
+		hid_err(hdev, "Failed to set Xbox controller mode: %d\n", ret);
+		return ret;
+	}
+
+	cfg->xbox_controller_enabled = enabled;
+	return 0;
+}
+
+/**
+ * ally_get_config() - Get the configuration of the Ally device
+ * @ally: ally handheld structure
+ *
+ * Fetch the configuration published by hid_asus_ally_probe() under
+ * ally_data_lock: the pointer is also cleared by hid_asus_ally_remove(),
+ * so reading it without the lock would race with interface removal.
+ *
+ * The returned configuration outlives the sysfs callbacks using it: it is
+ * allocated once on the ally probe path and released only on module
+ * removal, when every sysfs attribute referencing it is gone.
+ *
+ * Return: the ally config, or NULL if no configuration is published
+ */
+static struct ally_config *ally_get_config(struct ally_handheld *ally)
+{
+	struct ally_config *cfg;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ally_data_lock, flags);
+	cfg = ally->config;
+	spin_unlock_irqrestore(&ally_data_lock, flags);
+
+	return cfg;
+}
+
+static ssize_t xbox_controller_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	struct hid_device *hdev = to_hid_device(dev);
+	struct asus_drvdata *drvdata = hid_get_drvdata(hdev);
+	struct ally_handheld *ally = drvdata->rog_ally;
+	struct ally_config *cfg;
+
+	if (!ally)
+		return -ENODEV;
+
+	cfg = ally_get_config(ally);
+	if (!cfg)
+		return -ENODEV;
+
+	guard(mutex)(&cfg->config_mutex);
+
+	if (!cfg->xbox_controller_support)
+		return -ENODEV;
+
+	return sysfs_emit(buf, "%d\n", cfg->xbox_controller_enabled ? 1 : 0);
+}
+
+static ssize_t xbox_controller_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	struct hid_device *hdev = to_hid_device(dev);
+	struct asus_drvdata *drvdata = hid_get_drvdata(hdev);
+	struct ally_handheld *ally = drvdata->rog_ally;
+	struct ally_config *cfg;
+	bool enabled;
+	int ret;
+
+	if (!ally)
+		return -ENODEV;
+
+	cfg = ally_get_config(ally);
+	if (!cfg)
+		return -ENODEV;
+
+	ret = kstrtobool(buf, &enabled);
+	if (ret)
+		return ret;
+
+	guard(mutex)(&cfg->config_mutex);
+
+	if (!cfg->xbox_controller_support)
+		return -ENODEV;
+
+	ret = ally_set_xbox_controller(hdev, ally, cfg, enabled);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static DEVICE_ATTR_RW(xbox_controller);
+
+static struct attribute *ally_config_attrs[] = {
+	&dev_attr_xbox_controller.attr,
+	NULL
+};
+
+static const struct attribute_group ally_attr_groups[] = {
+	{
+		.attrs = ally_config_attrs,
+	},
+};
+
+/**
+ * ally_config_create() - Initialize configuration and create sysfs entries
+ * @hdev: HID device
+ * @ally: non-NULL ally device data with uninitialized config pointer
+ *
+ * Return: valid pointer on success, error pointer on failure
+ */
+static struct ally_config *ally_config_create(struct hid_device *hdev, struct ally_handheld *ally)
+{
+	struct ally_config *cfg;
+	int ret, sysfs_i;
+
+	/*
+	 * Allocate the configuration only once and keep it until module
+	 * removal: the controller can disappear and re-enumerate while
+	 * suspended, and the recorded settings must survive that to be
+	 * re-applied when the controller comes back.
+	 */
+	if (!ally_config) {
+		ally_config = kzalloc_obj(*ally_config, GFP_KERNEL);
+		if (!ally_config)
+			return ERR_PTR(-ENOMEM);
+
+		mutex_init(&ally_config->config_mutex);
+	}
+
+	cfg = ally_config;
+
+	ret = ally_detect_capabilities(hdev, ally, cfg);
+	if (ret < 0) {
+		hid_err(hdev, "Failed to detect Ally capabilities: %d\n", ret);
+		goto ally_config_create_err;
+	}
+
+	if (!cfg->initialized) {
+		cfg->gamepad_mode = 0x01;
+		cfg->left_deadzone = 10;
+		cfg->left_outer_threshold = 90;
+		cfg->right_deadzone = 10;
+		cfg->right_outer_threshold = 90;
+	}
+
+	for (sysfs_i = 0; sysfs_i < ARRAY_SIZE(ally_attr_groups); sysfs_i++) {
+		ret = sysfs_create_group(&hdev->dev.kobj,
+					 &ally_attr_groups[sysfs_i]);
+		if (ret < 0) {
+			hid_err(hdev, "Failed to create sysfs group '%s': %d\n",
+				ally_attr_groups[sysfs_i].name ?: "", ret);
+			goto ally_config_create_sysfs_err;
+		}
+	}
+
+	/* So far the only hardware this is supported is the Ally 1 */
+	if (cfg->xbox_controller_support) {
+		ret = ally_set_xbox_controller(hdev, ally, cfg, true);
+		if (ret < 0)
+			hid_warn(hdev, "Failed to set default Xbox controller mode: %d\n",
+				ret);
+	}
+
+	cfg->initialized = true;
+
+	return cfg;
+ally_config_create_sysfs_err:
+	/* The sysfs groups are not devm-managed: undo the created ones. */
+	while (sysfs_i-- > 0)
+		sysfs_remove_group(&hdev->dev.kobj, &ally_attr_groups[sysfs_i]);
+
+ally_config_create_err:
+	return ERR_PTR(ret);
+}
+
+/**
+ * ally_config_remove() - Clean up configuration resources
+ * @hdev: HID device
+ * @cfg: ally config to clean up, may be NULL
+ */
+static void ally_config_remove(struct hid_device *hdev, struct ally_config *cfg)
+{
+	int i;
+
+	if (!cfg || !cfg->initialized)
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(ally_attr_groups); i++)
+		sysfs_remove_group(&hdev->dev.kobj, &ally_attr_groups[i]);
+}
+
 /**
  * ally_gamepad_check_ready() - Wait for the gamepad MCU to report ready
  * @ally: ally handheld structure
@@ -874,6 +1192,7 @@ static int ally_x_setup_input(struct hid_device *hdev, struct ally_handheld *all
 
 static int hid_asus_ally_init(struct hid_device *hdev, struct ally_handheld *ally)
 {
+	struct ally_config *cfg;
 	int ret;
 
 	/* Failure at this point is non-critical */
@@ -882,6 +1201,20 @@ static int hid_asus_ally_init(struct hid_device *hdev, struct ally_handheld *all
 	if (ret < 0)
 		hid_err(hdev, "Ally failed to init force-feedback off: %d\n", ret);
 
+	cfg = ally_get_config(ally);
+	if (!cfg)
+		return 0;
+
+	/* The MCU may have just been reset: restore the cached state. */
+	guard(mutex)(&cfg->config_mutex);
+
+	if (cfg->xbox_controller_enabled) {
+		ret = ally_set_xbox_controller(hdev, ally, cfg, true);
+		if (ret < 0)
+			hid_warn(hdev, "Failed to restore Xbox controller mode: %d\n",
+				 ret);
+	}
+
 	return 0;
 }
 
@@ -959,11 +1292,15 @@ static struct ally_handheld *hid_asus_ally_probe(struct hid_device *hdev)
 	unsigned long flags;
 	int ret, ep = ally_get_endpoint_address(hdev);
 	struct usb_device *udev;
+	struct ally_config *ally_cfg;
 	struct hid_input *hidinput;
 
 	if (ep < 0)
 		return ERR_PTR(ep);
 
+	if (!hid_is_usb(hdev))
+		return ERR_PTR(-ENODEV);
+
 	/*
 	 * The ROG Ally controller is integrated into a handheld PC, so at
 	 * most one device can exist and the shared global state relies on
@@ -1023,6 +1360,14 @@ static struct ally_handheld *hid_asus_ally_probe(struct hid_device *hdev)
 			return ERR_PTR(ret);
 		}
 
+		ally_cfg = ally_config_create(hdev, &ally_drvdata);
+		if (IS_ERR(ally_cfg)) {
+			hid_err(hdev, "Failed to create Ally cfg: %ld\n",
+				PTR_ERR(ally_cfg));
+			ally_put_udev_if_orphaned();
+			return ERR_PTR(PTR_ERR(ally_cfg));
+		}
+
 		ret = hid_asus_ally_init(hdev, &ally_drvdata);
 		if (ret < 0) {
 			ally_put_udev_if_orphaned();
@@ -1030,6 +1375,7 @@ static struct ally_handheld *hid_asus_ally_probe(struct hid_device *hdev)
 		}
 
 		spin_lock_irqsave(&ally_data_lock, flags);
+		ally_drvdata.config = ally_cfg;
 		ally_drvdata.cfg_hdev = hdev;
 		spin_unlock_irqrestore(&ally_data_lock, flags);
 		break;
@@ -1066,7 +1412,9 @@ static struct ally_handheld *hid_asus_ally_probe(struct hid_device *hdev)
 static void hid_asus_ally_remove(struct hid_device *hdev, struct ally_handheld *ally)
 {
 	struct input_dev *x_input = NULL;
+	struct ally_config *cfg = NULL;
 	unsigned long flags;
+	bool owns_cfg;
 
 	if (!ally)
 		return;
@@ -1096,8 +1444,25 @@ static void hid_asus_ally_remove(struct hid_device *hdev, struct ally_handheld *
 		ally->keyboard_input = NULL;
 		ally->keyboard_hdev = NULL;
 	}
+
+	owns_cfg = ally->cfg_hdev == hdev;
+	if (owns_cfg) {
+		cfg = ally->config;
+		ally->cfg_hdev = NULL;
+		ally->config = NULL;
+	}
+
 	spin_unlock_irqrestore(&ally_data_lock, flags);
 
+	/*
+	 * The config teardown removes sysfs groups and takes sleeping locks:
+	 * it must not run under ally_data_lock. The config pointer has been
+	 * unpublished above, so no new sysfs callback can find it while the
+	 * groups are being removed.
+	 */
+	if (owns_cfg)
+		ally_config_remove(hdev, cfg);
+
 	if (x_input)
 		input_unregister_device(x_input);
 
@@ -1124,6 +1489,16 @@ static int hid_asus_ally_reset_resume(struct hid_device *hdev, struct ally_handh
 	if (ep != HID_ALLY_INTF_CFG_IN)
 		return 0;
 
+	/*
+	 * This function assumes the asus-specific initialization
+	 * to have been performed already at this point.
+	 */
+	ret = ally_gamepad_check_ready(ally, hdev);
+	if (ret < 0) {
+		hid_err(hdev, "ROG Ally device is not ready: %d\n", ret);
+		return ret;
+	}
+
 	ret = hid_asus_ally_init(hdev, ally);
 	if (ret < 0)
 		return ret;
@@ -2707,7 +3082,27 @@ static struct hid_driver asus_driver = {
 	.event			= asus_event,
 	.raw_event		= asus_raw_event
 };
-module_hid_driver(asus_driver);
+static int __init asus_init(void)
+{
+	return hid_register_driver(&asus_driver);
+}
+
+/*
+ * The Ally configuration is not tied to any device lifetime: interface
+ * removal keeps it so that it can be re-applied on re-probe. Release it
+ * only when the module itself is removed, once no sysfs attribute can
+ * reach it anymore.
+ */
+static void __exit asus_exit(void)
+{
+	hid_unregister_driver(&asus_driver);
+
+	kfree(ally_config);
+	ally_config = NULL;
+}
+
+module_init(asus_init);
+module_exit(asus_exit);
 
 MODULE_IMPORT_NS("ASUS_WMI");
 MODULE_LICENSE("GPL");
-- 
2.47.3