[PATCH v15 07/18] HID: asus: add joysticks anti-deadzone configuration

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

ROG Ally devices allow configuring the anti-deadzone parameter for
the resistive joysticks devices as over time those develops drift,
therefore allow userspace to configure the anti-deadzone by exposing
relevant sysfs attributes.

Signed-off-by: Denis Benato <denis.benato@linux.dev>
Co-developed-by: Luke Jones <luke@ljones.dev>
Signed-off-by: Luke Jones <luke@ljones.dev>
---
 drivers/hid/hid-asus.c | 157 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 157 insertions(+)

diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
index 5b8b4e2a901e..85641e36c922 100644
--- a/drivers/hid/hid-asus.c
+++ b/drivers/hid/hid-asus.c
@@ -107,6 +107,9 @@ MODULE_DESCRIPTION("Asus HID Keyboard and TouchPad");
 #define ASUS_ALLY_INNER_THRESHOLD_MIN 0
 #define ASUS_ALLY_INNER_THRESHOLD_MAX 50
 
+#define ASUS_ALLY_ANTI_DEADZONE_MIN 0
+#define ASUS_ALLY_ANTI_DEADZONE_MAX 100
+
 #define ASUS_ALLY_TRIGGER_RANGE_LOWER_MIN 0
 #define ASUS_ALLY_TRIGGER_RANGE_LOWER_MAX 50
 #define ASUS_ALLY_TRIGGER_RANGE_UPPER_MIN 70
@@ -851,6 +854,9 @@ static struct ally_prefs {
 	u8 left_trigger_max;
 	u8 right_trigger_min;
 	u8 right_trigger_max;
+
+	u8 left_anti_deadzone;
+	u8 right_anti_deadzone;
 } ally_prefs = {
 	.lock = __MUTEX_INITIALIZER(ally_prefs.lock),
 };
@@ -1334,11 +1340,153 @@ static struct device_attribute dev_attr_right_joystick_outer_threshold =
 static struct device_attribute dev_attr_right_joystick_outer_threshold_range =
 	__ATTR(outer_threshold_range, 0444, right_joystick_outer_threshold_range_show, NULL);
 
+/**
+ * ally_set_anti_deadzone() - Send the joystick anti-deadzone values to the device
+ * @hdev: HID device the packet is sent on
+ * @left: Anti-deadzone of the left joystick
+ * @right: Anti-deadzone of the right joystick
+ *
+ * Context: Caller must hold ally_prefs.lock.
+ *
+ * Return: 0 on success, -%EOPNOTSUPP if the device does not support
+ * anti-deadzone, -%ENOMEM if the command buffer cannot be allocated, or a
+ * negative error code if sending the packet fails.
+ */
+static int ally_set_anti_deadzone(struct hid_device *hdev, u8 left, u8 right)
+{
+	const u8 payload[] = { left, right };
+	size_t buf_len;
+	int ret;
+
+	if (!ally_prefs.anti_deadzone_support) {
+		hid_dbg(hdev, "Anti-deadzone not supported on this device\n");
+		return -EOPNOTSUPP;
+	}
+
+	u8 *buf __free(kfree) = ally_alloc_cmd(hdev, CMD_SET_ANTI_DEADZONE,
+					       payload, sizeof(payload),
+					       &buf_len);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = ally_gamepad_send_packet(hdev, buf, buf_len);
+	if (ret < 0) {
+		hid_err(hdev, "Failed to set anti-deadzone values: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+/* Indices into ally_anti_deadzones[] */
+enum ally_joystick {
+	ALLY_LEFT_JOYSTICK,
+	ALLY_RIGHT_JOYSTICK,
+};
+
+static u8 *const ally_anti_deadzones[] = {
+	[ALLY_LEFT_JOYSTICK]  = &ally_prefs.left_anti_deadzone,
+	[ALLY_RIGHT_JOYSTICK] = &ally_prefs.right_anti_deadzone,
+};
+
+static ssize_t ally_anti_deadzone_show(struct device *dev, char *buf,
+				       enum ally_joystick which)
+{
+	guard(mutex)(&ally_prefs.lock);
+
+	if (!ally_prefs.anti_deadzone_support) {
+		hid_dbg(to_hid_device(dev), "Anti-deadzone not supported on this device\n");
+		return -EOPNOTSUPP;
+	}
+
+	return sysfs_emit(buf, "%u\n", *ally_anti_deadzones[which]);
+}
+
+static ssize_t ally_anti_deadzone_store(struct device *dev, const char *buf,
+					size_t count, enum ally_joystick which,
+					const char *group)
+{
+	u8 value, dz[ARRAY_SIZE(ally_anti_deadzones)];
+	struct hid_device *hdev = to_hid_device(dev);
+	unsigned int i;
+	int ret;
+
+	ret = kstrtou8(buf, 10, &value);
+	if (ret || value > ASUS_ALLY_ANTI_DEADZONE_MAX)
+		return -EINVAL;
+
+	scoped_guard(mutex, &ally_prefs.lock) {
+		if (!ally_prefs.anti_deadzone_support) {
+			hid_dbg(hdev, "Anti-deadzone not supported on this device\n");
+			return -EOPNOTSUPP;
+		}
+
+		for (i = 0; i < ARRAY_SIZE(dz); i++)
+			dz[i] = *ally_anti_deadzones[i];
+		dz[which] = value;
+
+		ret = ally_set_anti_deadzone(hdev, dz[ALLY_LEFT_JOYSTICK],
+					dz[ALLY_RIGHT_JOYSTICK]);
+		if (ret)
+			return ret;
+
+		*ally_anti_deadzones[which] = value;
+	}
+
+	sysfs_notify(&dev->kobj, group, "anti_deadzone");
+
+	return count;
+}
+
+/* Generates <side>_joystick_anti_deadzone_{show,store,range_show}. */
+#define ALLY_ANTI_DEADZONE_FUNCS(side, SIDE)						\
+static ssize_t side##_joystick_anti_deadzone_show(struct device *dev,			\
+						struct device_attribute *attr,		\
+						char *buf)				\
+{											\
+	return ally_anti_deadzone_show(dev, buf, ALLY_##SIDE##_JOYSTICK);		\
+}											\
+											\
+static ssize_t side##_joystick_anti_deadzone_store(struct device *dev,			\
+						struct device_attribute *attr,		\
+						const char *buf, size_t count)		\
+{											\
+	return ally_anti_deadzone_store(dev, buf, count, ALLY_##SIDE##_JOYSTICK,	\
+					#side "_joystick_axis");			\
+}											\
+											\
+static ssize_t side##_joystick_anti_deadzone_range_show(struct device *dev,		\
+							struct device_attribute *attr,	\
+							char *buf)			\
+{											\
+	return sysfs_emit(buf, "%u %u\n", ASUS_ALLY_ANTI_DEADZONE_MIN,			\
+			  ASUS_ALLY_ANTI_DEADZONE_MAX);					\
+}
+
+ALLY_ANTI_DEADZONE_FUNCS(left, LEFT)
+ALLY_ANTI_DEADZONE_FUNCS(right, RIGHT)
+
+static struct device_attribute dev_attr_left_joystick_anti_deadzone =
+	__ATTR(anti_deadzone, 0644, left_joystick_anti_deadzone_show,
+	       left_joystick_anti_deadzone_store);
+
+static struct device_attribute dev_attr_left_joystick_anti_deadzone_range =
+	__ATTR(anti_deadzone_range, 0444, left_joystick_anti_deadzone_range_show, NULL);
+
+static struct device_attribute dev_attr_right_joystick_anti_deadzone =
+	__ATTR(anti_deadzone, 0644, right_joystick_anti_deadzone_show,
+	       right_joystick_anti_deadzone_store);
+
+static struct device_attribute dev_attr_right_joystick_anti_deadzone_range =
+	__ATTR(anti_deadzone_range, 0444, right_joystick_anti_deadzone_range_show, NULL);
+
 static struct attribute *left_joystick_axis_attrs[] = {
 	&dev_attr_left_joystick_inner_threshold.attr,
 	&dev_attr_left_joystick_outer_threshold.attr,
 	&dev_attr_left_joystick_inner_threshold_range.attr,
 	&dev_attr_left_joystick_outer_threshold_range.attr,
+	&dev_attr_left_joystick_anti_deadzone.attr,
+	&dev_attr_left_joystick_anti_deadzone_range.attr,
 	NULL
 };
 
@@ -1347,6 +1495,8 @@ static struct attribute *right_joystick_axis_attrs[] = {
 	&dev_attr_right_joystick_outer_threshold.attr,
 	&dev_attr_right_joystick_inner_threshold_range.attr,
 	&dev_attr_right_joystick_outer_threshold_range.attr,
+	&dev_attr_right_joystick_anti_deadzone.attr,
+	&dev_attr_right_joystick_anti_deadzone_range.attr,
 	NULL
 };
 
@@ -1925,6 +2075,13 @@ static int hid_asus_ally_init(struct hid_device *hdev)
 			hid_warn(hdev, "Failed to restore trigger ranges: %d\n", ret);
 	}
 
+	if (ally_prefs.initialized && ally_prefs.anti_deadzone_support) {
+		ret = ally_set_anti_deadzone(hdev, ally_prefs.left_anti_deadzone,
+					     ally_prefs.right_anti_deadzone);
+		if (ret < 0)
+			hid_warn(hdev, "Failed to restore anti-deadzone: %d\n", ret);
+	}
+
 	return 0;
 }
 
-- 
2.47.3