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serial: core: move RS485 configuration tasks from drivers into core

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commit 0ed12afa5655512ee418047fb3546d229df20aa1 upstream.

Several drivers that support setting the RS485 configuration via userspace
implement one or more of the following tasks:

- in case of an invalid RTS configuration (both RTS after send and RTS on
  send set or both unset) fall back to enable RTS on send and disable RTS
  after send

- nullify the padding field of the returned serial_rs485 struct

- copy the configuration into the uart port struct

- limit RTS delays to 100 ms

Move these tasks into the serial core to make them generic and to provide
a consistent behaviour among all drivers.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220410104642.32195-2-LinoSanfilippo@gmx.de
Signed-off-by: Daisuke Mizobuchi <mizo@atmark-techno.com>
Signed-off-by: Dominique Martinet <dominique.martinet@atmark-techno.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lino Sanfilippo 2022-04-10 12:46:34 +02:00 committed by Greg Kroah-Hartman
parent eb69c07eca
commit 4a230f65d6
1 changed files with 33 additions and 0 deletions
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33
drivers/tty/serial/serial_core.c
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@ -42,6 +42,11 @@ static struct lock_class_key port_lock_key;
#define HIGH_BITS_OFFSET ((sizeof(long)-sizeof(int))*8)
/*
* Max time with active RTS before/after data is sent.
*/
#define RS485_MAX_RTS_DELAY 100 /* msecs */
static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
struct ktermios *old_termios);
static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
@ -1326,8 +1331,36 @@ static int uart_set_rs485_config(struct uart_port *port,
if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
return -EFAULT;
/* pick sane settings if the user hasn't */
if (!(rs485.flags & SER_RS485_RTS_ON_SEND) ==
!(rs485.flags & SER_RS485_RTS_AFTER_SEND)) {
dev_warn_ratelimited(port->dev,
"%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n",
port->name, port->line);
rs485.flags |= SER_RS485_RTS_ON_SEND;
rs485.flags &= ~SER_RS485_RTS_AFTER_SEND;
}
if (rs485.delay_rts_before_send > RS485_MAX_RTS_DELAY) {
rs485.delay_rts_before_send = RS485_MAX_RTS_DELAY;
dev_warn_ratelimited(port->dev,
"%s (%d): RTS delay before sending clamped to %u ms\n",
port->name, port->line, rs485.delay_rts_before_send);
}
if (rs485.delay_rts_after_send > RS485_MAX_RTS_DELAY) {
rs485.delay_rts_after_send = RS485_MAX_RTS_DELAY;
dev_warn_ratelimited(port->dev,
"%s (%d): RTS delay after sending clamped to %u ms\n",
port->name, port->line, rs485.delay_rts_after_send);
}
/* Return clean padding area to userspace */
memset(rs485.padding, 0, sizeof(rs485.padding));
spin_lock_irqsave(&port->lock, flags);
ret = port->rs485_config(port, &rs485);
if (!ret)
port->rs485 = rs485;
spin_unlock_irqrestore(&port->lock, flags);
if (ret)
return ret;