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 <redacted>
---
v5: Rename the hook to cmd_timeout, and wait for 5 timeouts before
   resetting the device.
v4: Use data->flags instead of clearing the quirk in btusb_hw_reset()
v3: Better error handling for gpiod_get_optional()
v2: Handle the EPROBE_DEFER case.

drivers/bluetooth/btusb.c | 54 +++++++++++++++++++++++++++++++++++++++
1 file changed, 54 insertions(+)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 4761499db9ee..8949ea30a1bc 100644
--- a/drivers/bluetooth/btusb.c
+++ b/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 +493,39 @@ struct btusb_data {

	int (*setup_on_usb)(struct hci_dev *hdev);

	int oob_wake_irq;   /* irq for out-of-band wake-on-bt */
+	unsigned num_cmd_timeout;

+
+	/*
+	 * 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 +2950,7 @@ 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 +3064,15 @@ 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;

@@ -3085,6 +3130,8 @@ static int btusb_probe(struct usb_interface *intf,

		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);
+		if (data->reset_gpio)
+			hdev->cmd_timeout = btusb_intel_cmd_timeout;
	}

	if (id->driver_info & BTUSB_INTEL_NEW) {

@@ -3097,6 +3144,8 @@ static int btusb_probe(struct usb_interface *intf,

		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);
+		if (data->reset_gpio)
+			hdev->cmd_timeout = btusb_intel_cmd_timeout;
	}

	if (id->driver_info & BTUSB_MARVELL)

@@ -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);
}