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    Subject[PATCH RESEND 2/8] serial: 8250: Add ioctl to enable auto rs485 mode with some Exar UARTs
    Date
    From: Matthias Fuchs <mfuchs@ma-fu.de>

    Some Exar UARTs support an auto rs485 mode. In this mode
    the UART's RTS# pin is activated during transmitting and
    can be used to enable a rs485 line driver. This has nothing
    to do with attempts to do this by manually asserting/
    deasserting handshake lines in software.

    Signed-off-by: Matthias Fuchs <mfuchs@ma-fu.de>

    [wsa] Replaced 0xbf with define, saved some line-breaks.

    Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
    ---
    drivers/tty/serial/8250.c | 68 ++++++++++++++++++++++++++++++++++++++++++++
    include/linux/serial_reg.h | 1 +
    2 files changed, 69 insertions(+), 0 deletions(-)

    diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
    index f8f2320..920b4df 100644
    --- a/drivers/tty/serial/8250.c
    +++ b/drivers/tty/serial/8250.c
    @@ -38,6 +38,7 @@
    #include <linux/nmi.h>
    #include <linux/mutex.h>
    #include <linux/slab.h>
    +#include <linux/uaccess.h>

    #include <asm/io.h>
    #include <asm/irq.h>
    @@ -2698,6 +2699,72 @@ serial8250_type(struct uart_port *port)
    return uart_config[type].name;
    }

    +static int serial8250_ioctl_port(struct uart_port *port,
    + unsigned int cmd, unsigned long arg)
    +{
    + struct uart_8250_port *up = (struct uart_8250_port *)port;
    + unsigned long flags;
    +
    + switch (cmd) {
    + case TIOCSRS485:
    + {
    + struct serial_rs485 rs485ctrl;
    + unsigned char fctr, lcr;
    +
    + if (port->type != PORT_16850)
    + return -ENOTTY;
    +
    + if (copy_from_user(&rs485ctrl, (struct serial_rs485 *)arg,
    + sizeof(rs485ctrl)))
    + return -EFAULT;
    +
    + spin_lock_irqsave(&up->port.lock, flags);
    + lcr = serial_inp(up, UART_LCR);
    + serial_outp(up, UART_LCR, UART_LCR_CONF_MODE_B);
    + fctr = serial_inp(up, UART_FCTR);
    + if (rs485ctrl.flags & SER_RS485_ENABLED)
    + fctr |= UART_FCTR_RS485;
    + else
    + fctr &= ~UART_FCTR_RS485;
    + serial_outp(up, UART_FCTR, fctr);
    + serial_outp(up, UART_LCR, lcr);
    + spin_unlock_irqrestore(&up->port.lock, flags);
    + return 0;
    + }
    +
    + case TIOCGRS485:
    + {
    + struct serial_rs485 rs485ctrl;
    + unsigned char lcr;
    +
    + if (port->type != PORT_16850)
    + return -ENOTTY;
    +
    + memset(&rs485ctrl, 0, sizeof(rs485ctrl));
    +
    + spin_lock_irqsave(&up->port.lock, flags);
    + lcr = serial_inp(up, UART_LCR);
    + serial_outp(up, UART_LCR, UART_LCR_CONF_MODE_B);
    + if (serial_inp(up, UART_FCTR) & UART_FCTR_RS485)
    + rs485ctrl.flags = SER_RS485_ENABLED;
    + else
    + rs485ctrl.flags = 0;
    + serial_outp(up, UART_LCR, lcr);
    + spin_unlock_irqrestore(&up->port.lock, flags);
    +
    + if (copy_to_user((struct serial_rs485 *)arg, &rs485ctrl,
    + sizeof(rs485ctrl)))
    + return -EFAULT;
    + return 0;
    + }
    +
    + default:
    + return -ENOIOCTLCMD;
    + }
    +
    + return 0;
    +}
    +
    static struct uart_ops serial8250_pops = {
    .tx_empty = serial8250_tx_empty,
    .set_mctrl = serial8250_set_mctrl,
    @@ -2717,6 +2784,7 @@ static struct uart_ops serial8250_pops = {
    .request_port = serial8250_request_port,
    .config_port = serial8250_config_port,
    .verify_port = serial8250_verify_port,
    + .ioctl = serial8250_ioctl_port,
    #ifdef CONFIG_CONSOLE_POLL
    .poll_get_char = serial8250_get_poll_char,
    .poll_put_char = serial8250_put_poll_char,
    diff --git a/include/linux/serial_reg.h b/include/linux/serial_reg.h
    index 8ce70d7..fb37c4f 100644
    --- a/include/linux/serial_reg.h
    +++ b/include/linux/serial_reg.h
    @@ -201,6 +201,7 @@
    #define UART_FCTR_RTS_8DELAY 0x03
    #define UART_FCTR_IRDA 0x04 /* IrDa data encode select */
    #define UART_FCTR_TX_INT 0x08 /* Tx interrupt type select */
    +#define UART_FCTR_RS485 0x08 /* Auto RS485 mode */
    #define UART_FCTR_TRGA 0x00 /* Tx/Rx 550 trigger table select */
    #define UART_FCTR_TRGB 0x10 /* Tx/Rx 650 trigger table select */
    #define UART_FCTR_TRGC 0x20 /* Tx/Rx 654 trigger table select */
    --
    1.7.7.3


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