Bluetooth: Add delayed init sequence support for UART controllers

This patch makes it possible to have UART drivers perform an internal
initialization before calling hci_register_dev. This allows moving a lot
of init code from user space (hciattach) to the kernel side, thereby
creating a more controlled/robust initialization process.

Signed-off-by: Johan Hedberg <[e-mail]>
Signed-off-by: Gustavo Padovan <[e-mail]>

drivers/bluetooth/hci_ldisc.c

···
 	return 0;
 }
 
+static void hci_uart_init_work(struct work_struct *work)
+{
+	struct hci_uart *hu = container_of(work, struct hci_uart, init_ready);
+	int err;
+
+	if (!test_and_clear_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags))
+		return;
+
+	err = hci_register_dev(hu->hdev);
+	if (err < 0) {
+		BT_ERR("Can't register HCI device");
+		hci_free_dev(hu->hdev);
+		hu->hdev = NULL;
+		hu->proto->close(hu);
+	}
+
+	set_bit(HCI_UART_REGISTERED, &hu->flags);
+}
+
+int hci_uart_init_ready(struct hci_uart *hu)
+{
+	if (!test_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags))
+		return -EALREADY;
+
+	schedule_work(&hu->init_ready);
+
+	return 0;
+}
+
 /* ------- Interface to HCI layer ------ */
 /* Initialize device */
 static int hci_uart_open(struct hci_dev *hdev)
···
 	hu->tty = tty;
 	tty->receive_room = 65536;
 
+	INIT_WORK(&hu->init_ready, hci_uart_init_work);
+
 	spin_lock_init(&hu->rx_lock);
 
 	/* Flush any pending characters in the driver and line discipline. */
···
 
 	if (test_and_clear_bit(HCI_UART_PROTO_SET, &hu->flags)) {
 		if (hdev) {
-			hci_unregister_dev(hdev);
+			if (test_bit(HCI_UART_REGISTERED, &hu->flags))
+				hci_unregister_dev(hdev);
 			hci_free_dev(hdev);
 		}
 		hu->proto->close(hu);
···
 	else
 		hdev->dev_type = HCI_BREDR;
 
+	if (test_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags))
+		return 0;
+
 	if (hci_register_dev(hdev) < 0) {
 		BT_ERR("Can't register HCI device");
 		hci_free_dev(hdev);
 		return -ENODEV;
 	}
+
+	set_bit(HCI_UART_REGISTERED, &hu->flags);
 
 	return 0;
 }

drivers/bluetooth/hci_uart.h

···
 #define HCI_UART_RAW_DEVICE	0
 #define HCI_UART_RESET_ON_INIT	1
 #define HCI_UART_CREATE_AMP	2
+#define HCI_UART_INIT_PENDING	3
 
 struct hci_uart;
 
···
 	unsigned long		flags;
 	unsigned long		hdev_flags;
 
+	struct work_struct	init_ready;
+
 	struct hci_uart_proto	*proto;
 	void			*priv;
 
···
 
 /* HCI_UART proto flag bits */
 #define HCI_UART_PROTO_SET	0
+#define HCI_UART_REGISTERED	1
 
 /* TX states  */
 #define HCI_UART_SENDING	1
···
 int hci_uart_register_proto(struct hci_uart_proto *p);
 int hci_uart_unregister_proto(struct hci_uart_proto *p);
 int hci_uart_tx_wakeup(struct hci_uart *hu);
+int hci_uart_init_ready(struct hci_uart *hu);
 
 #ifdef CONFIG_BT_HCIUART_H4
 int h4_init(void);