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SubjectRe: [PATCH 2/8] serial: 8250: Add ioctl to enable auto rs485 mode with some Exar UARTs
Hi Wolfram,

Il 16/11/2011 17:24, Wolfram Sang ha scritto:
> 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;

This else branch may be removed, since the structure has been already memsetted to 0.

Claudio


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