Commit 90bc07cc authored by Chen-Yu Tsai's avatar Chen-Yu Tsai Committed by Marcel Holtmann
Browse files

Bluetooth: hci_bcm: Add support for LPO clock 



The Broadcom Bluetooth controllers support a secondary LPO clock at
32.768 kHz. This external clock provides low power timing, and also
a way to detect the frequency of the main reference clock. On many
designs without NVRAM and a non-default reference clock, this must
be used or the controller will not function correctly.

Tested-by: default avatarOndrej Jirman <megous@megous.com>
Signed-off-by: default avatarChen-Yu Tsai <wens@csie.org>
Signed-off-by: default avatarMarcel Holtmann <marcel@holtmann.org>
parent 55dbfcd0

drivers/bluetooth/hci_bcm.c

+36 −5
Original line number Diff line number Diff line
@@ -72,7 +72,8 @@ 
 * @btpu: Apple ACPI method to drive BT_REG_ON pin high ("Bluetooth Power Up")

 * @btpd: Apple ACPI method to drive BT_REG_ON pin low ("Bluetooth Power Down")

 * @txco_clk: external reference frequency clock used by Bluetooth device

 * @clk_enabled: whether @txco_clk is prepared and enabled

 * @lpo_clk: external LPO clock used by Bluetooth device

 * @clk_enabled: whether clocks are prepared and enabled

 * @init_speed: default baudrate of Bluetooth device;

 *	the host UART is initially set to this baudrate so that

 *	it can configure the Bluetooth device for @oper_speed
@@ -103,6 +104,7 @@ struct bcm_device { 
#endif



	struct clk		*txco_clk;

	struct clk		*lpo_clk;

	bool			clk_enabled;



	u32			init_speed;
@@ -215,21 +217,34 @@ static int bcm_gpio_set_power(struct bcm_device *dev, bool powered) 
	int err;



	if (powered && !dev->clk_enabled) {

		err = clk_prepare_enable(dev->txco_clk);

		/* LPO clock needs to be 32.768 kHz */

		err = clk_set_rate(dev->lpo_clk, 32768);

		if (err) {

			dev_err(dev->dev, "Could not set LPO clock rate\n");

			return err;

		}



		err = clk_prepare_enable(dev->lpo_clk);

		if (err)

			return err;



		err = clk_prepare_enable(dev->txco_clk);

		if (err)

			goto err_lpo_clk_disable;

	}



	err = dev->set_shutdown(dev, powered);

	if (err)

		goto err_clk_disable;

		goto err_txco_clk_disable;



	err = dev->set_device_wakeup(dev, powered);

	if (err)

		goto err_revert_shutdown;



	if (!powered && dev->clk_enabled)

	if (!powered && dev->clk_enabled) {

		clk_disable_unprepare(dev->txco_clk);

		clk_disable_unprepare(dev->lpo_clk);

	}



	dev->clk_enabled = powered;
@@ -237,9 +252,12 @@ static int bcm_gpio_set_power(struct bcm_device *dev, bool powered) 


err_revert_shutdown:

	dev->set_shutdown(dev, !powered);

err_clk_disable:

err_txco_clk_disable:

	if (powered && !dev->clk_enabled)

		clk_disable_unprepare(dev->txco_clk);

err_lpo_clk_disable:

	if (powered && !dev->clk_enabled)

		clk_disable_unprepare(dev->lpo_clk);

	return err;

}
@@ -934,6 +952,19 @@ static int bcm_get_resources(struct bcm_device *dev) 
	if (IS_ERR(dev->txco_clk))

		dev->txco_clk = NULL;



	dev->lpo_clk = devm_clk_get(dev->dev, "lpo");

	if (dev->lpo_clk == ERR_PTR(-EPROBE_DEFER))

		return PTR_ERR(dev->lpo_clk);



	if (IS_ERR(dev->lpo_clk))

		dev->lpo_clk = NULL;



	/* Check if we accidentally fetched the lpo clock twice */

	if (dev->lpo_clk && clk_is_match(dev->lpo_clk, dev->txco_clk)) {

		devm_clk_put(dev->dev, dev->txco_clk);

		dev->txco_clk = NULL;

	}



	dev->device_wakeup = devm_gpiod_get_optional(dev->dev, "device-wakeup",

						     GPIOD_OUT_LOW);

	if (IS_ERR(dev->device_wakeup))

CRA Git | Maintained and supported by SUSTech CRA and CCSE