HID: magicmouse: Handle touch controller resets on SPI devices

On at least some SPI devices (e.g. recent Apple Silicon machines), the
Broadcom touch controller is prone to crashing. When this happens, the
STM eventually notices and resets it. It then notifies the driver via
HID report 0x60, and the driver needs to re-enable MT mode to make
things work again.

This poses an additional issue: the hidinput core will close the
low-level transport while the device is closed, which can cause us to
miss a reset notification. To fix this, override the input open/close
callbacks and send the MT enable every time the HID device is opened,
instead of only once on probe. This should increase general robustness,
even if the reset mechanism doesn't work for some reason, so it's worth
doing it for USB devices too. MTP devices are exempt since they do not
require the MT enable at all.

Signed-off-by: Hector Martin <marcan@marcan.st>

Author: marcan

drivers/hid/hid-magicmouse.c

@@ -61,6 +61,7 @@ MODULE_PARM_DESC(report_undeciphered, "Report undeciphered multi-touch state fie
 #define MOUSE2_REPORT_ID   0x12
 #define DOUBLE_REPORT_ID   0xf7
 #define SPI_REPORT_ID      0x02
+#define SPI_RESET_REPORT_ID 0x60
 #define MTP_REPORT_ID      0x75
 #define USB_BATTERY_TIMEOUT_SEC 60
 
@@ -176,6 +177,50 @@ struct magicmouse_sc {
 	struct magicmouse_input_ops input_ops;
 };
 
+static int magicmouse_enable_multitouch(struct hid_device *hdev);
+
+static int magicmouse_open(struct input_dev *dev)
+{
+	struct hid_device *hdev = input_get_drvdata(dev);
+	struct magicmouse_sc *msc = hid_get_drvdata(hdev);
+	int ret;
+
+	ret = hid_hw_open(hdev);
+	if (ret)
+		return ret;
+
+	/*
+	 * Some devices repond with 'invalid report id' when feature
+	 * report switching it into multitouch mode is sent to it.
+	 *
+	 * This results in -EIO from the _raw low-level transport callback,
+	 * but there seems to be no other way of switching the mode.
+	 * Thus the super-ugly hacky success check below.
+	 */
+	ret = magicmouse_enable_multitouch(hdev);
+	if (ret != -EIO && ret < 0) {
+		hid_err(hdev, "unable to request touch data (%d)\n", ret);
+		return ret;
+	}
+	if (ret == -EIO && (hdev->product == USB_DEVICE_ID_APPLE_MAGICMOUSE2 ||
+			    hdev->product == USB_DEVICE_ID_APPLE_MAGICMOUSE2_USBC)) {
+		schedule_delayed_work(&msc->work, msecs_to_jiffies(500));
+	}
+
+	/*
+	 * MT enable is usually not required after the first time, so don't
+	 * consider it fatal.
+	 */
+	return 0;
+}
+
+static void magicmouse_close(struct input_dev *dev)
+{
+	struct hid_device *hdev = input_get_drvdata(dev);
+
+	hid_hw_close(hdev);
+}
+
 static int magicmouse_firm_touch(struct magicmouse_sc *msc)
 {
 	int touch = -1;
@@ -706,12 +751,19 @@ static int magicmouse_raw_event_mtp(struct hid_device *hdev,
 static int magicmouse_raw_event_spi(struct hid_device *hdev,
 		struct hid_report *report, u8 *data, int size)
 {
+	struct magicmouse_sc *msc = hid_get_drvdata(hdev);
 	const size_t hdr_sz = sizeof(struct tp_mouse_report);
 
-	if (size < hdr_sz)
+	if (!size)
 		return 0;
 
-	if (data[0] != SPI_REPORT_ID)
+	if (data[0] == SPI_RESET_REPORT_ID) {
+		hid_info(hdev, "Touch controller was reset, re-enabling touch mode\n");
+		schedule_delayed_work(&msc->work, msecs_to_jiffies(10));
+		return 1;
+	}
+
+	if (data[0] != SPI_REPORT_ID || size < hdr_sz)
 		return 0;
 
 	return magicmouse_raw_event_mtp(hdev, report, data + hdr_sz, size - hdr_sz);
@@ -904,10 +956,17 @@ static int magicmouse_setup_input_usb(struct input_dev *input,
 	 */
 	__clear_bit(EV_REP, input->evbit);
 
+	/*
+	 * This isn't strictly speaking needed for USB, but enabling MT on
+	 * device open is probably more robust than only doing it once on probe
+	 * even if USB devices are not known to suffer from the SPI reset issue.
+	 */
+	input->open = magicmouse_open;
+	input->close = magicmouse_close;
 	return 0;
 }
 
-static int magicmouse_setup_input_spi(struct input_dev *input,
+static int magicmouse_setup_input_mtp(struct input_dev *input,
 				      struct hid_device *hdev)
 {
 	int error;
@@ -980,6 +1039,25 @@ static int magicmouse_setup_input_spi(struct input_dev *input,
 	return 0;
 }
 
+static int magicmouse_setup_input_spi(struct input_dev *input,
+				      struct hid_device *hdev)
+{
+	int ret = magicmouse_setup_input_mtp(input, hdev);
+	if (ret)
+		return ret;
+
+	/*
+	 * Override the default input->open function to send the MT
+	 * enable every time the device is opened. This ensures it works
+	 * even if we missed a reset event due to the device being closed.
+	 * input->close is overridden for symmetry.
+	 */
+	input->open = magicmouse_open;
+	input->close = magicmouse_close;
+
+	return 0;
+}
+
 static int magicmouse_input_mapping(struct hid_device *hdev,
 		struct hid_input *hi, struct hid_field *field,
 		struct hid_usage *usage, unsigned long **bit, int *max)
@@ -1041,7 +1119,7 @@ static int magicmouse_enable_multitouch(struct hid_device *hdev)
 			feature_size = sizeof(feature_mt_trackpad2_bt);
 			feature = feature_mt_trackpad2_bt;
 			break;
-		default: /* USB_VENDOR_ID_APPLE || SPI_VENDOR_ID_APPLE */
+		default:  /* USB_VENDOR_ID_APPLE || SPI_VENDOR_ID_APPLE */
 			feature_size = sizeof(feature_mt_trackpad2_usb);
 			feature = feature_mt_trackpad2_usb;
 		}
@@ -1152,7 +1230,7 @@ static int magicmouse_probe(struct hid_device *hdev,
 	// conflicts with the report ID.
 	if (id->bus == BUS_HOST) {
 		msc->input_ops.raw_event = magicmouse_raw_event_mtp;
-		msc->input_ops.setup_input = magicmouse_setup_input_spi;
+		msc->input_ops.setup_input = magicmouse_setup_input_mtp;
 	} else if (id->bus == BUS_SPI) {
 		msc->input_ops.raw_event = magicmouse_raw_event_spi;
 		msc->input_ops.setup_input = magicmouse_setup_input_spi;
@@ -1246,22 +1324,10 @@ static int magicmouse_probe(struct hid_device *hdev,
 	if (id->bus == BUS_HOST)
 		return 0;
 
-	/*
-	 * Some devices repond with 'invalid report id' when feature
-	 * report switching it into multitouch mode is sent to it.
-	 *
-	 * This results in -EIO from the _raw low-level transport callback,
-	 * but there seems to be no other way of switching the mode.
-	 * Thus the super-ugly hacky success check below.
-	 */
-	ret = magicmouse_enable_multitouch(hdev);
-	if (ret != -EIO && ret < 0) {
-		hid_err(hdev, "unable to request touch data (%d)\n", ret);
-		goto err_stop_hw;
-	}
-	if (ret == -EIO && (id->product == USB_DEVICE_ID_APPLE_MAGICMOUSE2 ||
-			    id->product == USB_DEVICE_ID_APPLE_MAGICMOUSE2_USBC)) {
-		schedule_delayed_work(&msc->work, msecs_to_jiffies(500));
+	/* SPI devices need to watch for reset events to re-send the MT enable */
+	if (id->bus == BUS_SPI) {
+		report = hid_register_report(hdev, HID_INPUT_REPORT, SPI_RESET_REPORT_ID, 0);
+		report->size = 2;
 	}
 
 	return 0;