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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: Ondrej Jirman <megous@megous.com>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This commit is contained in:
Chen-Yu Tsai 2018-12-17 12:04:42 +08:00 committed by Marcel Holtmann
parent 55dbfcd0f6
commit 90bc07cc59
1 changed files with 36 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
drivers/bluetooth/hci_bcm.c
View File

@ -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))