Bluetooth: hci_bcm: Add support for FW loading in autobaud mode

Use the presence of a DT property, "brcm,requires-autobaud-mode", to enable
startup in autobaud mode. If the property is present, the device is started
in autobaud mode by asserting RTS (BT_UART_CTS_N) prior to powering on the
device.

Also prevent the use of unsupported commands for devices started in
autobaud mode. Only a limited subset of HCI commands are supported in
autobaud mode.

Some devices (e.g. CYW5557x) require autobaud mode to enable FW loading.
Autobaud mode can also be required on some boards where the controller
device is using a non-standard baud rate in normal mode when first powered
on.

Signed-off-by: Hakan Jansson <hakan.jansson@infineon.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 13 insertions, 3 deletions

diff --git a/drivers/bluetooth/hci_bcm.c b/drivers/bluetooth/hci_bcm.c
index 785f445dd60d..4309654f95a5 100644
--- a/drivers/bluetooth/hci_bcm.c
+++ b/drivers/bluetooth/hci_bcm.c
@@ -99,6 +99,7 @@ struct bcm_device_data {
  * @no_early_set_baudrate: don't set_baudrate before setup()
  * @drive_rts_on_open: drive RTS signal on ->open() when platform requires it
  * @pcm_int_params: keep the initial PCM configuration
+ * @use_autobaud_mode: start Bluetooth device in autobaud mode
  */
 struct bcm_device {
 	/* Must be the first member, hci_serdev.c expects this. */
@@ -136,6 +137,7 @@ struct bcm_device {
 #endif
 	bool			no_early_set_baudrate;
 	bool			drive_rts_on_open;
+	bool			use_autobaud_mode;
 	u8			pcm_int_params[5];
 };
 
@@ -472,7 +474,9 @@ static int bcm_open(struct hci_uart *hu)
 
 out:
 	if (bcm->dev) {
-		if (bcm->dev->drive_rts_on_open)
+		if (bcm->dev->use_autobaud_mode)
+			hci_uart_set_flow_control(hu, false);	/* Assert BT_UART_CTS_N */
+		else if (bcm->dev->drive_rts_on_open)
 			hci_uart_set_flow_control(hu, true);
 
 		hu->init_speed = bcm->dev->init_speed;
@@ -564,6 +568,7 @@ static int bcm_setup(struct hci_uart *hu)
 {
 	struct bcm_data *bcm = hu->priv;
 	bool fw_load_done = false;
+	bool use_autobaud_mode = (bcm->dev ? bcm->dev->use_autobaud_mode : 0);
 	unsigned int speed;
 	int err;
 
@@ -572,7 +577,7 @@ static int bcm_setup(struct hci_uart *hu)
 	hu->hdev->set_diag = bcm_set_diag;
 	hu->hdev->set_bdaddr = btbcm_set_bdaddr;
 
-	err = btbcm_initialize(hu->hdev, &fw_load_done);
+	err = btbcm_initialize(hu->hdev, &fw_load_done, use_autobaud_mode);
 	if (err)
 		return err;
 
@@ -616,7 +621,7 @@ static int bcm_setup(struct hci_uart *hu)
 		btbcm_write_pcm_int_params(hu->hdev, &params);
 	}
 
-	err = btbcm_finalize(hu->hdev, &fw_load_done);
+	err = btbcm_finalize(hu->hdev, &fw_load_done, use_autobaud_mode);
 	if (err)
 		return err;
 
@@ -1197,6 +1202,11 @@ static int bcm_acpi_probe(struct bcm_device *dev)
 
 static int bcm_of_probe(struct bcm_device *bdev)
 {
+	bdev->use_autobaud_mode = device_property_read_bool(bdev->dev,
+							    "brcm,requires-autobaud-mode");
+	if (bdev->use_autobaud_mode)
+		bdev->no_early_set_baudrate = true;
+
 	device_property_read_u32(bdev->dev, "max-speed", &bdev->oper_speed);
 	device_property_read_u8_array(bdev->dev, "brcm,bt-pcm-int-params",
 				      bdev->pcm_int_params, 5);