netdev - [PATCH v4 5/5] Bluetooth: btusb: Use the hw_reset method to allow resetting the BT chip

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Date:   Fri, 18 Jan 2019 14:34:07 -0800
From:   Rajat Jain <rajatja@...gle.com>
To:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "David S. Miller" <davem@...emloft.net>,
        Dmitry Torokhov <dtor@...omium.org>,
        Rajat Jain <rajatja@...gle.com>,
        Alex Hung <alex.hung@...onical.com>,
        linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, netdev@...r.kernel.org
Cc:     rajatxjain@...il.com, dtor@...gle.com, raghuram.hegde@...el.com,
        chethan.tumkur.narayan@...el.com, sukumar.ghorai@...el.com
Subject: [PATCH v4 5/5] Bluetooth: btusb: Use the hw_reset method to allow
 resetting the BT chip

If the platform provides it, use the reset gpio to reset the BT
chip (requested by the HCI core if needed). This has been found helpful
on some of 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@...gle.com>
---
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 | 45 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 59869643cc29..7cf1e4f749e9 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_DONE	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;
 
@@ -491,6 +495,30 @@ struct btusb_data {
 	int oob_wake_irq;   /* irq for out-of-band wake-on-bt */
 };
 
+
+static void btusb_hw_reset(struct hci_dev *hdev)
+{
+	struct btusb_data *data = hci_get_drvdata(hdev);
+	struct gpio_desc *reset_gpio = data->reset_gpio;
+
+	/*
+	 * 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_DONE, &data->flags)) {
+		bt_dev_warn(hdev, "last reset failed? Not resetting again\n");
+		return;
+	}
+
+	bt_dev_dbg(hdev, "Initiating HW reset via gpio\n");
+	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 +2943,7 @@ 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 +3057,16 @@ 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->hw_reset = btusb_hw_reset;
+	}
+
 	hdev->open   = btusb_open;
 	hdev->close  = btusb_close;
 	hdev->flush  = btusb_flush;
@@ -3083,6 +3122,7 @@ 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);
+		set_bit(HCI_QUIRK_HW_RESET_ON_TIMEOUT, &hdev->quirks);
 
 		if (id->driver_info & BTUSB_INTEL) {
 			hdev->setup = btusb_setup_intel;
@@ -3223,6 +3263,8 @@ 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;
 }
@@ -3266,6 +3308,9 @@ 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);
 }
 
-- 
2.20.1.321.g9e740568ce-goog