Bluetooth: btusb: Use the cmd_timeout method to reset the Intel BT chip

If the platform provides it, use the reset gpio to reset the Intel BT
chip, as part of cmd_timeout handling. This has been found helpful on
Intel bluetooth controllers where the firmware gets stuck and the only
way out is a hard reset pin provided by the platform.
Signed-off-by: Rajat Jain <rajatja@google.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/btusb.c

@@ -29,6 +29,7 @@
 #include <linux/of_device.h>
 #include <linux/of_irq.h>
 #include <linux/suspend.h>
+#include <linux/gpio/consumer.h>
 #include <asm/unaligned.h>
 
 #include <net/bluetooth/bluetooth.h>
@@ -439,6 +440,7 @@ static const struct dmi_system_id btusb_needs_reset_resume_table[] = {
 #define BTUSB_BOOTING		9
 #define BTUSB_DIAG_RUNNING	10
 #define BTUSB_OOB_WAKE_ENABLED	11
+#define BTUSB_HW_RESET_ACTIVE	12
 
 struct btusb_data {
 	struct hci_dev       *hdev;
@@ -476,6 +478,8 @@ struct btusb_data {
 	struct usb_endpoint_descriptor *diag_tx_ep;
 	struct usb_endpoint_descriptor *diag_rx_ep;
 
+	struct gpio_desc *reset_gpio;
+
 	__u8 cmdreq_type;
 	__u8 cmdreq;
 
@@ -489,8 +493,41 @@ struct btusb_data {
 	int (*setup_on_usb)(struct hci_dev *hdev);
 
 	int oob_wake_irq;   /* irq for out-of-band wake-on-bt */
+	unsigned cmd_timeout_cnt;
 };
 
+
+static void btusb_intel_cmd_timeout(struct hci_dev *hdev)
+{
+	struct btusb_data *data = hci_get_drvdata(hdev);
+	struct gpio_desc *reset_gpio = data->reset_gpio;
+
+	if (++data->cmd_timeout_cnt < 5)
+		return;
+
+	if (!reset_gpio) {
+		bt_dev_err(hdev, "No way to reset. Ignoring and continuing");
+		return;
+	}
+
+	/*
+	 * Toggle the hard reset line if the platform provides one. The reset
+	 * is going to yank the device off the USB and then replug. So doing
+	 * once is enough. The cleanup is handled correctly on the way out
+	 * (standard USB disconnect), and the new device is detected cleanly
+	 * and bound to the driver again like it should be.
+	 */
+	if (test_and_set_bit(BTUSB_HW_RESET_ACTIVE, &data->flags)) {
+		bt_dev_err(hdev, "last reset failed? Not resetting again");
+		return;
+	}
+
+	bt_dev_err(hdev, "Initiating HW reset via gpio");
+	gpiod_set_value(reset_gpio, 1);
+	mdelay(100);
+	gpiod_set_value(reset_gpio, 0);
+}
+
 static inline void btusb_free_frags(struct btusb_data *data)
 {
 	unsigned long flags;
@@ -2915,6 +2952,7 @@ static int btusb_probe(struct usb_interface *intf,
 		       const struct usb_device_id *id)
 {
 	struct usb_endpoint_descriptor *ep_desc;
+	struct gpio_desc *reset_gpio;
 	struct btusb_data *data;
 	struct hci_dev *hdev;
 	unsigned ifnum_base;
@@ -3028,6 +3066,15 @@ static int btusb_probe(struct usb_interface *intf,
 
 	SET_HCIDEV_DEV(hdev, &intf->dev);
 
+	reset_gpio = gpiod_get_optional(&data->udev->dev, "reset",
+					GPIOD_OUT_LOW);
+	if (IS_ERR(reset_gpio)) {
+		err = PTR_ERR(reset_gpio);
+		goto out_free_dev;
+	} else if (reset_gpio) {
+		data->reset_gpio = reset_gpio;
+	}
+
 	hdev->open   = btusb_open;
 	hdev->close  = btusb_close;
 	hdev->flush  = btusb_flush;
@@ -3082,6 +3129,7 @@ static int btusb_probe(struct usb_interface *intf,
 		hdev->shutdown = btusb_shutdown_intel;
 		hdev->set_diag = btintel_set_diag_mfg;
 		hdev->set_bdaddr = btintel_set_bdaddr;
+		hdev->cmd_timeout = btusb_intel_cmd_timeout;
 		set_bit(HCI_QUIRK_STRICT_DUPLICATE_FILTER, &hdev->quirks);
 		set_bit(HCI_QUIRK_SIMULTANEOUS_DISCOVERY, &hdev->quirks);
 		set_bit(HCI_QUIRK_NON_PERSISTENT_DIAG, &hdev->quirks);
@@ -3094,6 +3142,7 @@ static int btusb_probe(struct usb_interface *intf,
 		hdev->hw_error = btintel_hw_error;
 		hdev->set_diag = btintel_set_diag;
 		hdev->set_bdaddr = btintel_set_bdaddr;
+		hdev->cmd_timeout = btusb_intel_cmd_timeout;
 		set_bit(HCI_QUIRK_STRICT_DUPLICATE_FILTER, &hdev->quirks);
 		set_bit(HCI_QUIRK_SIMULTANEOUS_DISCOVERY, &hdev->quirks);
 		set_bit(HCI_QUIRK_NON_PERSISTENT_DIAG, &hdev->quirks);
@@ -3226,6 +3275,8 @@ static int btusb_probe(struct usb_interface *intf,
 	return 0;
 
 out_free_dev:
+	if (data->reset_gpio)
+		gpiod_put(data->reset_gpio);
 	hci_free_dev(hdev);
 	return err;
 }
@@ -3269,6 +3320,9 @@ static void btusb_disconnect(struct usb_interface *intf)
 	if (data->oob_wake_irq)
 		device_init_wakeup(&data->udev->dev, false);
 
+	if (data->reset_gpio)
+		gpiod_put(data->reset_gpio);
+
 	hci_free_dev(hdev);
 }