@@ -1582,13 +1582,6 @@ static void pl011_set_mctrl(struct uart_port *port, unsigned int mctrl)
container_of(port, struct uart_amba_port, port);
unsigned int cr;
- if (port->rs485.flags & SER_RS485_ENABLED) {
- if (port->rs485.flags & SER_RS485_RTS_AFTER_SEND)
- mctrl &= ~TIOCM_RTS;
- else
- mctrl |= TIOCM_RTS;
- }
-
cr = pl011_read(uap, REG_CR);
#define TIOCMBIT(tiocmbit, uartbit) \
@@ -1812,14 +1805,8 @@ static int pl011_startup(struct uart_port *port)
cr &= UART011_CR_RTS | UART011_CR_DTR;
cr |= UART01x_CR_UARTEN | UART011_CR_RXE;
- if (port->rs485.flags & SER_RS485_ENABLED) {
- if (port->rs485.flags & SER_RS485_RTS_AFTER_SEND)
- cr &= ~UART011_CR_RTS;
- else
- cr |= UART011_CR_RTS;
- } else {
+ if (!(port->rs485.flags & SER_RS485_ENABLED))
cr |= UART011_CR_TXE;
- }
pl011_write(cr, uap, REG_CR);
@@ -144,6 +144,11 @@ uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
unsigned long flags;
unsigned int old;
+ if (port->rs485.flags & SER_RS485_ENABLED) {
+ set &= ~TIOCM_RTS;
+ clear &= ~TIOCM_RTS;
+ }
+
spin_lock_irqsave(&port->lock, flags);
old = port->mctrl;
port->mctrl = (old & ~clear) | set;
@@ -157,23 +162,10 @@ uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
static void uart_port_dtr_rts(struct uart_port *uport, int raise)
{
- int rs485_on = uport->rs485_config &&
- (uport->rs485.flags & SER_RS485_ENABLED);
- int RTS_after_send = !!(uport->rs485.flags & SER_RS485_RTS_AFTER_SEND);
-
- if (raise) {
- if (rs485_on && RTS_after_send) {
- uart_set_mctrl(uport, TIOCM_DTR);
- uart_clear_mctrl(uport, TIOCM_RTS);
- } else {
- uart_set_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
- }
- } else {
- unsigned int clear = TIOCM_DTR;
-
- clear |= (!rs485_on || RTS_after_send) ? TIOCM_RTS : 0;
- uart_clear_mctrl(uport, clear);
- }
+ if (raise)
+ uart_set_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
+ else
+ uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
}
/*
@@ -1075,11 +1067,6 @@ uart_tiocmset(struct tty_struct *tty, unsigned int set, unsigned int clear)
goto out;
if (!tty_io_error(tty)) {
- if (uport->rs485.flags & SER_RS485_ENABLED) {
- set &= ~TIOCM_RTS;
- clear &= ~TIOCM_RTS;
- }
-
uart_update_mctrl(uport, set, clear);
ret = 0;
}
@@ -2390,6 +2377,9 @@ uart_configure_port(struct uart_driver *drv, struct uart_state *state,
*/
spin_lock_irqsave(&port->lock, flags);
port->mctrl &= TIOCM_DTR;
+ if (port->rs485.flags & SER_RS485_ENABLED &&
+ !(port->rs485.flags & SER_RS485_RTS_AFTER_SEND))
+ port->mctrl |= TIOCM_RTS;
port->ops->set_mctrl(port, port->mctrl);
spin_unlock_irqrestore(&port->lock, flags);
RTS polarity of rs485-enabled ports is currently initialized on uart open via: tty_port_open() tty_port_block_til_ready() tty_port_raise_dtr_rts() # if (C_BAUD(tty)) uart_dtr_rts() uart_port_dtr_rts() There's at least three problems here: First, if no baud rate is set, RTS polarity is not initialized. That's the right thing to do for rs232, but not for rs485, which requires that RTS is deasserted unconditionally. Second, if the DeviceTree property "linux,rs485-enabled-at-boot-time" is present, RTS should be deasserted as early as possible, i.e. on probe. Otherwise it may remain asserted until first open. Third, even though RTS is deasserted on open and close, it may subsequently be asserted by uart_throttle(), uart_unthrottle() or uart_set_termios() because those functions aren't rs485-aware. (Only uart_tiocmset() is.) To address these issues, move RTS initialization from uart_port_dtr_rts() to uart_configure_port(). Prevent subsequent modification of RTS polarity by moving the existing rs485 check from uart_tiocmget() to uart_update_mctrl(). That way, RTS is initialized on probe and then remains unmodified unless the uart transmits data. If rs485 is enabled at runtime (instead of at boot) through a TIOCSRS485 ioctl(), RTS is initialized by the uart driver's ->rs485_config() callback and then likewise remains unmodified. The PL011 driver initializes RTS on uart open and prevents subsequent modification in its ->set_mctrl() callback. That code is obsoleted by the present commit, so drop it. Signed-off-by: Lukas Wunner <lukas@wunner.de> Cc: Jan Kiszka <jan.kiszka@siemens.com> Cc: Su Bao Cheng <baocheng.su@siemens.com> --- drivers/tty/serial/amba-pl011.c | 15 +------------- drivers/tty/serial/serial_core.c | 34 +++++++++++--------------------- 2 files changed, 13 insertions(+), 36 deletions(-)