[PATCH v2 2/5] H4 line discipline enhancements

[Ilya Faenson <ifaenson@broadcom.com>]

Added the ability to flow control the UART and improved the
UART baud rate setting.

Signed-off-by: Ilya Faenson <ifaenson@broadcom.com>
---
 drivers/bluetooth/hci_ldisc.c | 66 +++++++++++++++++++++++++++++++++++++++++--
 drivers/bluetooth/hci_uart.h  |  1 +
 2 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index ac87346..f86e973 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -266,20 +266,82 @@ static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
 	return 0;
 }
 
+/* Flow control or un-flow control the device */
+void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
+{
+	struct tty_struct *tty = hu->tty;
+	struct ktermios ktermios;
+	int status;
+	unsigned int set = 0;
+	unsigned int clear = 0;
+
+	if (enable) {
+		/* Disable hardware flow control */
+		ktermios = tty->termios;
+		ktermios.c_cflag &= ~CRTSCTS;
+		status = tty_set_termios(tty, &ktermios);
+		BT_DBG("Disabling hardware flow control: %s", status ?
+		       "failed" : "success");
+
+		/* Clear RTS to prevent the device from sending */
+		/* Most UARTs need OUT2 to enable interrupts */
+		status = tty->driver->ops->tiocmget(tty);
+		BT_DBG("Current tiocm 0x%x", status);
+
+		set &= ~(TIOCM_OUT2 | TIOCM_RTS);
+		clear = ~set;
+		set &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
+		       TIOCM_OUT2 | TIOCM_LOOP;
+		clear &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
+			 TIOCM_OUT2 | TIOCM_LOOP;
+		status = tty->driver->ops->tiocmset(tty, set, clear);
+		BT_DBG("Clearing RTS: %s", status ? "failed" : "success");
+	} else {
+		/* Set RTS to allow the device to send again */
+		status = tty->driver->ops->tiocmget(tty);
+		BT_DBG("Current tiocm 0x%x", status);
+
+		set |= (TIOCM_OUT2 | TIOCM_RTS);
+		clear = ~set;
+		set &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
+		       TIOCM_OUT2 | TIOCM_LOOP;
+		clear &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
+			 TIOCM_OUT2 | TIOCM_LOOP;
+		status = tty->driver->ops->tiocmset(tty, set, clear);
+		BT_DBG("Setting RTS: %s", status ? "failed" : "success");
+
+		/* Re-enable hardware flow control */
+		ktermios = tty->termios;
+		ktermios.c_cflag |= CRTSCTS;
+		status = tty_set_termios(tty, &ktermios);
+		BT_DBG("Enabling hardware flow control: %s", status ?
+		       "failed" : "success");
+	}
+}
+
 void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed)
 {
 	struct tty_struct *tty = hu->tty;
 	struct ktermios ktermios;
 
+	/* Bring the UART into a known state with a given baud rate */
 	ktermios = tty->termios;
 	ktermios.c_cflag &= ~CBAUD;
-	ktermios.c_cflag |= BOTHER;
+	ktermios.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
+			    | INLCR | IGNCR | ICRNL | IXON);
+	ktermios.c_oflag &= ~OPOST;
+	ktermios.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
+	ktermios.c_cflag &= ~(CSIZE | PARENB | CBAUD);
+	ktermios.c_cflag |= CS8;
+	ktermios.c_cflag |= CRTSCTS;
 	tty_termios_encode_baud_rate(&ktermios, speed, speed);
 
 	/* tty_set_termios() return not checked as it is always 0 */
 	tty_set_termios(tty, &ktermios);
 
-	BT_DBG("%s: New tty speed: %d", hu->hdev->name, tty->termios.c_ispeed);
+	BT_DBG("%s: New tty speeds: %d/%d, cflag: 0x%x", hu->hdev->name,
+	       tty->termios.c_ispeed, tty->termios.c_ospeed,
+	       tty->termios.c_cflag);
 }
 
 static int hci_uart_setup(struct hci_dev *hdev)
diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h
index e9f970c..8ef1881 100644
--- a/drivers/bluetooth/hci_uart.h
+++ b/drivers/bluetooth/hci_uart.h
@@ -100,6 +100,7 @@ int hci_uart_unregister_proto(const struct hci_uart_proto *p);
 int hci_uart_tx_wakeup(struct hci_uart *hu);
 int hci_uart_init_ready(struct hci_uart *hu);
 void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed);
+void hci_uart_set_flow_control(struct hci_uart *hu, bool enable);
 
 #ifdef CONFIG_BT_HCIUART_H4
 int h4_init(void);
-- 
1.9.1