[PATCH v12 09/17] HID: asus: add support to force feedback

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

Unlike ROG ally the X version and following ones uses DInput protocol
and the force feedback needs to be implemented as its protocol is
vendor-specific, therefore add support for FF_RUMBLE with magnitude
scaling on a work-queue based approach to avoid using possibly
sleeping calls in atomic context.

Signed-off-by: Denis Benato <denis.benato@linux.dev>
Signed-off-by: Khamunetri Clark <khamunetriclark@gmail.com>
Co-developed-by: Luke Jones <luke@ljones.dev>
Signed-off-by: Luke Jones <luke@ljones.dev>
---
 drivers/hid/Kconfig    |   1 +
 drivers/hid/hid-asus.c | 143 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 144 insertions(+)

diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 2481bc01c435..dd411f6eff4f 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -189,6 +189,7 @@ config HID_ASUS
 	depends on USB_HID
 	depends on LEDS_CLASS
 	depends on ASUS_WMI || ASUS_WMI=n
+	select INPUT_FF_MEMLESS
 	select POWER_SUPPLY
 	help
 	Support for Asus notebook built-in keyboard and touchpad via i2c, and
diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
index 783c78160277..3ade3dbda72e 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/compiler.h>
 #include <linux/compiler_attributes.h>
 #include <linux/container_of.h>
 #include <linux/ctype.h>
@@ -30,6 +31,7 @@
 #include <linux/hid.h>
 #include <linux/jiffies.h>
 #include <linux/kstrtox.h>
+#include <linux/limits.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
@@ -210,6 +212,23 @@ struct asus_touchpad_info {
 	int report_size;
 };
 
+/* Output report 0x0D on the gamepad interface. */
+struct ally_ff_data {
+	u8 enable;
+	u8 magnitude_left;
+	u8 magnitude_right;
+	u8 magnitude_strong;
+	u8 magnitude_weak;
+	u8 pulse_sustain_10ms;
+	u8 pulse_release_10ms;
+	u8 loop_count;
+} __packed;
+
+struct ally_ff_report {
+	u8 report_id;
+	struct ally_ff_data ff;
+} __packed;
+
 struct ally_intf {
 	struct hid_device *hdev;
 	/* HID-core evdev of this interface. Reports for it land here. */
@@ -219,6 +238,14 @@ struct ally_intf {
 	u8 cad_state;
 	unsigned long cad_last_event_time;
 	struct delayed_work resume_work;
+	struct {
+		/* Guards live, update, and packet. */
+		spinlock_t lock;
+		bool live;
+		bool update;
+		struct ally_ff_report packet;
+		struct work_struct work;
+	} ff;
 };
 
 struct asus_drvdata {
@@ -325,10 +352,15 @@ enum ally_command_codes {
 	CMD_SET_ANTI_DEADZONE           = 0x18,
 };
 
+/* Rumble magnitudes use the hardware's 0..100 intensity range. */
+#define ALLY_FF_MAX_INTENSITY 100
+
 static const u8 ally_force_feedback_off[] = {
 	0x0D, 0x0F, 0x00, 0x00, 0x00, 0x00, 0xFF, 0x00, 0xEB
 };
 
+static_assert(sizeof(struct ally_ff_report) == sizeof(ally_force_feedback_off));
+
 /*
  * Each Ally interface owns its own ally_intf. A report is delivered on the
  * evdev of the interface that received it. Nothing here points at another
@@ -2184,6 +2216,84 @@ static struct input_dev *ally_x_alloc_input_dev(struct hid_device *hdev,
 	return input_dev;
 }
 
+static int ally_ff_output(struct hid_device *hdev, const void *buf, size_t len)
+{
+	u8 *dmabuf __free(kfree) = kmemdup(buf, len, GFP_KERNEL);
+
+	if (!dmabuf)
+		return -ENOMEM;
+
+	return hid_hw_output_report(hdev, dmabuf, len);
+}
+
+static int ally_ff_off(struct hid_device *hdev)
+{
+	return ally_ff_output(hdev, ally_force_feedback_off,
+			      sizeof(ally_force_feedback_off));
+}
+
+static void ally_ff_work_fn(struct work_struct *work)
+{
+	struct ally_intf *intf = container_of(work, struct ally_intf, ff.work);
+	struct ally_ff_report report;
+	bool update = false;
+	int ret;
+
+	scoped_guard(spinlock_irqsave, &intf->ff.lock) {
+		if (!intf->ff.update)
+			break;
+
+		report = intf->ff.packet;
+		intf->ff.update = false;
+		update = true;
+	}
+
+	if (!update)
+		return;
+
+	ret = ally_ff_output(intf->hdev, &report, sizeof(report));
+	if (ret < 0)
+		hid_err(intf->hdev, "Failed to send force-feedback: %d\n", ret);
+}
+
+static int ally_ff_play(struct input_dev *idev, void *data, struct ff_effect *effect)
+{
+	struct ally_intf *intf = input_get_drvdata(idev);
+
+	if (effect->type != FF_RUMBLE)
+		return 0;
+
+	guard(spinlock_irqsave)(&intf->ff.lock);
+
+	if (!intf->ff.live)
+		return 0;
+
+	intf->ff.packet.ff.magnitude_strong =
+		effect->u.rumble.strong_magnitude * ALLY_FF_MAX_INTENSITY / U16_MAX;
+	intf->ff.packet.ff.magnitude_weak =
+		effect->u.rumble.weak_magnitude * ALLY_FF_MAX_INTENSITY / U16_MAX;
+	intf->ff.update = true;
+	schedule_work(&intf->ff.work);
+	return 0;
+}
+
+static void ally_ff_quiesce(struct ally_intf *intf)
+{
+	int ret;
+
+	if (!intf || !intf->gamepad)
+		return;
+
+	scoped_guard(spinlock_irqsave, &intf->ff.lock)
+		intf->ff.live = false;
+
+	cancel_work_sync(&intf->ff.work);
+
+	ret = ally_ff_off(intf->hdev);
+	if (ret < 0)
+		hid_warn(intf->hdev, "Failed to stop force-feedback\n");
+}
+
 static int ally_x_setup_input(struct hid_device *hdev, struct ally_intf *intf)
 {
 	struct input_dev *input = ally_x_alloc_input_dev(hdev, intf);
@@ -2212,8 +2322,24 @@ static int ally_x_setup_input(struct hid_device *hdev, struct ally_intf *intf)
 	input_set_capability(input, EV_KEY, BTN_THUMBL);
 	input_set_capability(input, EV_KEY, BTN_THUMBR);
 
+	spin_lock_init(&intf->ff.lock);
+	INIT_WORK(&intf->ff.work, ally_ff_work_fn);
+	memcpy(&intf->ff.packet, ally_force_feedback_off, sizeof(intf->ff.packet));
+	intf->ff.update = false;
+	intf->ff.live = false;
+
+	input_set_capability(input, EV_FF, FF_RUMBLE);
+	ret = input_ff_create_memless(input, NULL, ally_ff_play);
+	if (ret) {
+		hid_err(hdev, "Failed to create force-feedback: %d\n", ret);
+		input_free_device(input);
+		return ret;
+	}
+
+	intf->ff.live = true;
 	ret = input_register_device(input);
 	if (ret) {
+		intf->ff.live = false;
 		hid_err(hdev, "Failed to register Ally X gamepad device: %d\n", ret);
 		input_free_device(input);
 		return ret;
@@ -2404,6 +2530,14 @@ static struct ally_intf *hid_asus_ally_probe(struct hid_device *hdev)
 			hid_err(hdev, "Failed to create Ally X gamepad device.\n");
 			return ERR_PTR(ret);
 		}
+
+		/*
+		 * This is the interface that owns the rumble output report.
+		 * Failure to silence it is not fatal.
+		 */
+		ret = ally_ff_off(hdev);
+		if (ret < 0)
+			hid_warn(hdev, "Failed to disable force-feedback: %d\n", ret);
 		break;
 	case HID_ALLY_INTF_KEYBOARD_IN:
 		break;
@@ -2426,6 +2560,13 @@ static int hid_asus_ally_reset_resume(struct hid_device *hdev, struct ally_intf
 		return 0;
 
 	ep = ally_get_endpoint_address(hdev);
+	if (ep == HID_ALLY_X_INTF_IN) {
+		ret = ally_ff_off(hdev);
+		if (ret < 0)
+			hid_warn(hdev, "Failed to disable force-feedback: %d\n", ret);
+		return 0;
+	}
+
 	if (ep != HID_ALLY_INTF_CFG_IN)
 		return 0;
 
@@ -3914,6 +4055,7 @@ static int asus_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	if (drvdata->quirks & QUIRK_ROG_ALLY_XPAD) {
 		ally_quiesce(drvdata->ally);
 		ally_sysfs_remove(hdev);
+		ally_ff_quiesce(drvdata->ally);
 	}
 
 	asus_worker_stop(drvdata->worker);
@@ -3937,6 +4079,7 @@ static void asus_remove(struct hid_device *hdev)
 	if (drvdata->quirks & QUIRK_ROG_ALLY_XPAD) {
 		ally_quiesce(drvdata->ally);
 		ally_sysfs_remove(hdev);
+		ally_ff_quiesce(drvdata->ally);
 	}
 
 	asus_worker_stop(drvdata->worker);
-- 
2.47.3