Add support for Qualcomm serial slave devices. Probe the serial device,
retrieve its maximum speed and register a new hci uart device.

Signed-off-by: Thierry Escande <thierry.esca...@linaro.org>
---
 drivers/bluetooth/Kconfig   |   2 +-
 drivers/bluetooth/hci_qca.c | 102 +++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 101 insertions(+), 3 deletions(-)

diff --git a/drivers/bluetooth/Kconfig b/drivers/bluetooth/Kconfig
index 07e55cd8f8c8..c2a6a7ebd14b 100644
--- a/drivers/bluetooth/Kconfig
+++ b/drivers/bluetooth/Kconfig
@@ -195,7 +195,7 @@ config BT_HCIUART_BCM
 
 config BT_HCIUART_QCA
        bool "Qualcomm Atheros protocol support"
-       depends on BT_HCIUART
+       depends on BT_HCIUART_SERDEV
        select BT_HCIUART_H4
        select BT_QCA
        help
diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index 05ec530b8a3a..ca5428898702 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -29,7 +29,11 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/clk.h>
 #include <linux/debugfs.h>
+#include <linux/gpio/consumer.h>
+#include <linux/of.h>
+#include <linux/serdev.h>
 
 #include <net/bluetooth/bluetooth.h>
 #include <net/bluetooth/hci_core.h>
@@ -50,6 +54,9 @@
 #define IBS_TX_IDLE_TIMEOUT_MS         2000
 #define BAUDRATE_SETTLE_TIMEOUT_MS     300
 
+/* divclk4 rate */
+#define DIVCLK4_RATE_32KHZ     32768
+
 /* HCI_IBS transmit side sleep protocol states */
 enum tx_ibs_states {
        HCI_IBS_TX_ASLEEP,
@@ -111,6 +118,12 @@ struct qca_data {
        u64 votes_off;
 };
 
+struct qca_serdev {
+       struct hci_uart  serdev_hu;
+       struct gpio_desc *bt_en;
+       struct clk       *divclk4;
+};
+
 static void __serial_clock_on(struct tty_struct *tty)
 {
        /* TODO: Some chipset requires to enable UART clock on client
@@ -386,6 +399,7 @@ static void hci_ibs_wake_retrans_timeout(struct timer_list 
*t)
 /* Initialize protocol */
 static int qca_open(struct hci_uart *hu)
 {
+       struct qca_serdev *qcadev;
        struct qca_data *qca;
 
        BT_DBG("hu %p qca_open", hu);
@@ -444,6 +458,13 @@ static int qca_open(struct hci_uart *hu)
        timer_setup(&qca->tx_idle_timer, hci_ibs_tx_idle_timeout, 0);
        qca->tx_idle_delay = IBS_TX_IDLE_TIMEOUT_MS;
 
+       if (hu->serdev) {
+               serdev_device_open(hu->serdev);
+
+               qcadev = serdev_device_get_drvdata(hu->serdev);
+               gpiod_set_value(qcadev->bt_en, 1);
+       }
+
        BT_DBG("HCI_UART_QCA open, tx_idle_delay=%u, wake_retrans=%u",
               qca->tx_idle_delay, qca->wake_retrans);
 
@@ -512,6 +533,7 @@ static int qca_flush(struct hci_uart *hu)
 /* Close protocol */
 static int qca_close(struct hci_uart *hu)
 {
+       struct qca_serdev *qcadev;
        struct qca_data *qca = hu->priv;
 
        BT_DBG("hu %p qca close", hu);
@@ -525,6 +547,13 @@ static int qca_close(struct hci_uart *hu)
        destroy_workqueue(qca->workqueue);
        qca->hu = NULL;
 
+       if (hu->serdev) {
+               serdev_device_close(hu->serdev);
+
+               qcadev = serdev_device_get_drvdata(hu->serdev);
+               gpiod_set_value(qcadev->bt_en, 0);
+       }
+
        kfree_skb(qca->rx_skb);
 
        hu->priv = NULL;
@@ -885,6 +914,14 @@ static int qca_set_baudrate(struct hci_dev *hdev, uint8_t 
baudrate)
        return 0;
 }
 
+static inline void host_set_baudrate(struct hci_uart *hu, unsigned int speed)
+{
+       if (hu->serdev)
+               serdev_device_set_baudrate(hu->serdev, speed);
+       else
+               hci_uart_set_baudrate(hu, speed);
+}
+
 static int qca_setup(struct hci_uart *hu)
 {
        struct hci_dev *hdev = hu->hdev;
@@ -905,7 +942,7 @@ static int qca_setup(struct hci_uart *hu)
                speed = hu->proto->init_speed;
 
        if (speed)
-               hci_uart_set_baudrate(hu, speed);
+               host_set_baudrate(hu, speed);
 
        /* Setup user speed if needed */
        speed = 0;
@@ -924,7 +961,7 @@ static int qca_setup(struct hci_uart *hu)
                                   ret);
                        return ret;
                }
-               hci_uart_set_baudrate(hu, speed);
+               host_set_baudrate(hu, speed);
        }
 
        /* Setup patch / NVM configurations */
@@ -958,12 +995,73 @@ static struct hci_uart_proto qca_proto = {
        .dequeue        = qca_dequeue,
 };
 
+static int qca_serdev_probe(struct serdev_device *serdev)
+{
+       struct qca_serdev *qcadev;
+
+       qcadev = devm_kzalloc(&serdev->dev, sizeof(*qcadev), GFP_KERNEL);
+       if (!qcadev)
+               return -ENOMEM;
+
+       qcadev->serdev_hu.serdev = serdev;
+       serdev_device_set_drvdata(serdev, qcadev);
+
+       qcadev->bt_en = devm_gpiod_get(&serdev->dev, "bt-disable-n",
+                                      GPIOD_OUT_LOW);
+       if (IS_ERR(qcadev->bt_en)) {
+               dev_err(&serdev->dev, "failed to acquire bt-disable-n gpio\n");
+               return PTR_ERR(qcadev->bt_en);
+       }
+
+       gpiod_set_value(qcadev->bt_en, 0);
+
+       qcadev->divclk4 = devm_clk_get(&serdev->dev, NULL);
+       if (IS_ERR(qcadev->divclk4)) {
+               dev_err(&serdev->dev, "failed to acquire divclk4\n");
+               return PTR_ERR(qcadev->divclk4);
+       }
+
+       clk_set_rate(qcadev->divclk4, DIVCLK4_RATE_32KHZ);
+       clk_prepare_enable(qcadev->divclk4);
+
+       return hci_uart_register_device(&qcadev->serdev_hu, &qca_proto);
+}
+
+static void qca_serdev_remove(struct serdev_device *serdev)
+{
+       struct qca_serdev *qcadev = serdev_device_get_drvdata(serdev);
+
+       hci_uart_unregister_device(&qcadev->serdev_hu);
+
+       clk_disable(qcadev->divclk4);
+       clk_unprepare(qcadev->divclk4);
+}
+
+static const struct of_device_id qca_bluetooth_of_match[] = {
+       { .compatible = "qcom,qca6174-bt" },
+       { },
+};
+MODULE_DEVICE_TABLE(of, qca_bluetooth_of_match);
+
+static struct serdev_device_driver qca_serdev_driver = {
+       .probe = qca_serdev_probe,
+       .remove = qca_serdev_remove,
+       .driver = {
+               .name = "hci_uart_qca",
+               .of_match_table = qca_bluetooth_of_match,
+       },
+};
+
 int __init qca_init(void)
 {
+       serdev_device_driver_register(&qca_serdev_driver);
+
        return hci_uart_register_proto(&qca_proto);
 }
 
 int __exit qca_deinit(void)
 {
+       serdev_device_driver_unregister(&qca_serdev_driver);
+
        return hci_uart_unregister_proto(&qca_proto);
 }
-- 
2.14.1

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