Adds "gamepad_mode" attribute to second generation OneXPlayer
configuration HID devices. This attribute initiates a mode shift in the
device MCU that puts it into a state where all events are routed to an
hidraw interface instead of the xpad evdev interface. This allows for
debugging the hardware input mapping added in the next patch.

Signed-off-by: Derek J. Clark <derekjohn.clark@gmail.com>
---
v2:
  - Rename to gamepad_mode & show relevant gamepad modes instead of
    using a debug enable/disable paradigm, to match other drivers.
---
 drivers/hid/hid-oxp.c | 130 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 130 insertions(+)

diff --git a/drivers/hid/hid-oxp.c b/drivers/hid/hid-oxp.c
index 25214356163e..c62952537d98 100644
--- a/drivers/hid/hid-oxp.c
+++ b/drivers/hid/hid-oxp.c
@@ -33,6 +33,7 @@
 enum oxp_function_index {
 	OXP_FID_GEN1_RGB_SET =		0x07,
 	OXP_FID_GEN1_RGB_REPLY =	0x0f,
+	OXP_FID_GEN2_TOGGLE_MODE =	0xb2,
 	OXP_FID_GEN2_STATUS_EVENT =	0xb8,
 };
 
@@ -41,11 +42,22 @@ static struct oxp_hid_cfg {
 	struct hid_device *hdev;
 	struct mutex cfg_mutex; /*ensure single synchronous output report*/
 	u8 rgb_brightness;
+	u8 gamepad_mode;
 	u8 rgb_effect;
 	u8 rgb_speed;
 	u8 rgb_en;
 } drvdata;
 
+enum oxp_gamepad_mode_index {
+	OXP_GP_MODE_XINPUT = 0x00,
+	OXP_GP_MODE_DEBUG = 0x03,
+};
+
+static const char *const oxp_gamepad_mode_text[] = {
+	[OXP_GP_MODE_XINPUT] = "xinput",
+	[OXP_GP_MODE_DEBUG] = "debug",
+};
+
 enum oxp_feature_en_index {
 	OXP_FEAT_DISABLED,
 	OXP_FEAT_ENABLED,
@@ -181,6 +193,32 @@ static int oxp_hid_raw_event_gen_1(struct hid_device *hdev,
 	return 0;
 }
 
+static int oxp_gen_2_property_out(enum oxp_function_index fid, u8 *data, u8 data_size);
+
+static void oxp_mcu_init_fn(struct work_struct *work)
+{
+	u8 gp_mode_data[3] = { OXP_GP_MODE_DEBUG, 0x01, 0x02 };
+	int ret;
+
+	/* Cycle the gamepad mode */
+	ret = oxp_gen_2_property_out(OXP_FID_GEN2_TOGGLE_MODE, gp_mode_data, 3);
+	if (ret)
+		dev_err(&drvdata.hdev->dev,
+			"Error: Failed to set gamepad mode: %i\n", ret);
+
+	/* Remainder only applies for xinput mode */
+	if (drvdata.gamepad_mode == OXP_GP_MODE_DEBUG)
+		return;
+
+	gp_mode_data[0] = OXP_GP_MODE_XINPUT;
+	ret = oxp_gen_2_property_out(OXP_FID_GEN2_TOGGLE_MODE, gp_mode_data, 3);
+	if (ret)
+		dev_err(&drvdata.hdev->dev,
+			"Error: Failed to set gamepad mode: %i\n", ret);
+}
+
+static DECLARE_DELAYED_WORK(oxp_mcu_init, oxp_mcu_init_fn);
+
 static int oxp_hid_raw_event_gen_2(struct hid_device *hdev,
 				   struct hid_report *report, u8 *data,
 				   int size)
@@ -191,6 +229,14 @@ static int oxp_hid_raw_event_gen_2(struct hid_device *hdev,
 	if (data[0] != OXP_FID_GEN2_STATUS_EVENT)
 		return 0;
 
+	/* Sent ~6s after resume event, indicating the MCU has fully reset.
+	 * Re-apply our settings after this has been received.
+	 */
+	if (data[3] == OXP_EFFECT_MONO_TRUE) {
+		mod_delayed_work(system_wq, &oxp_mcu_init, msecs_to_jiffies(50));
+		return 0;
+	}
+
 	if (data[3] != OXP_GET_PROPERTY)
 		return 0;
 
@@ -288,6 +334,77 @@ static int oxp_gen_2_property_out(enum oxp_function_index fid, u8 *data,
 				footer_size);
 }
 
+static ssize_t gamepad_mode_store(struct device *dev,
+				  struct device_attribute *attr, const char *buf,
+				  size_t count)
+{
+	u16 up = get_usage_page(drvdata.hdev);
+	u8 data[3] = { 0x00, 0x01, 0x02 };
+	int ret = -EINVAL;
+	int i;
+
+	if (up != GEN2_USAGE_PAGE)
+		return ret;
+
+	for (i = 0; i < ARRAY_SIZE(oxp_gamepad_mode_text); i++) {
+		if (oxp_gamepad_mode_text[i] && sysfs_streq(buf, oxp_gamepad_mode_text[i])) {
+			ret = i;
+			break;
+		}
+	}
+	if (ret < 0)
+		return ret;
+
+	data[0] = ret;
+
+	ret = oxp_gen_2_property_out(OXP_FID_GEN2_TOGGLE_MODE, data, 3);
+	if (ret)
+		return ret;
+
+	drvdata.gamepad_mode = data[0];
+
+	return count;
+}
+
+static ssize_t gamepad_mode_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%s\n", oxp_gamepad_mode_text[drvdata.gamepad_mode]);
+}
+static DEVICE_ATTR_RW(gamepad_mode);
+
+static ssize_t gamepad_mode_index_show(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	ssize_t count = 0;
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(oxp_gamepad_mode_text); i++) {
+		if (!oxp_gamepad_mode_text[i] ||
+		    oxp_gamepad_mode_text[i][0] == '\0')
+			continue;
+
+		count += sysfs_emit_at(buf, count, "%s ", oxp_gamepad_mode_text[i]);
+	}
+
+	if (count)
+		buf[count - 1] = '\n';
+
+	return count;
+}
+static DEVICE_ATTR_RO(gamepad_mode_index);
+
+static struct attribute *oxp_cfg_attrs[] = {
+	&dev_attr_gamepad_mode.attr,
+	&dev_attr_gamepad_mode_index.attr,
+	NULL,
+};
+
+static const struct attribute_group oxp_cfg_attrs_group = {
+	.attrs = oxp_cfg_attrs,
+};
+
 static int oxp_rgb_status_store(u8 enabled, u8 speed, u8 brightness)
 {
 	u16 up = get_usage_page(drvdata.hdev);
@@ -733,7 +850,20 @@ static int oxp_cfg_probe(struct hid_device *hdev, u16 up)
 		dev_warn(drvdata.led_mc->led_cdev.dev,
 			 "Failed to query RGB initial state: %i\n", ret);
 
+	/* Below features are only implemented in gen 2 */
+	if (up != GEN2_USAGE_PAGE)
+		return 0;
+
 skip_rgb:
+	mod_delayed_work(system_wq, &oxp_mcu_init, msecs_to_jiffies(50));
+
+	drvdata.gamepad_mode = OXP_GP_MODE_XINPUT;
+
+	ret = devm_device_add_group(&hdev->dev, &oxp_cfg_attrs_group);
+	if (ret)
+		return dev_err_probe(&hdev->dev, ret,
+				     "Failed to attach configuration attributes\n");
+
 	return 0;
 }
 
-- 
2.53.0