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serial: st-asc: (De)Register GPIOD and swap Pinctrl profiles

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When hardware flow-control is disabled, manual toggling of the UART's
reset line (RTS) using userland applications (e.g. stty) is not
possible, since the ASC IP does not provide this functionality in the
same was as some other IPs do.  Thus, we have to do this manually.

This patch ensures that when HW flow-control is disabled the RTS/CTS
lines are free to be registered via the GPIO API.  It also ensures
any registered GPIO lines are unregistered when HW flow-control is
requested, allowing the IP to control them automatically.

Acked-by: Peter Griffin <peter.griffin@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lee Jones 2017-02-03 10:23:13 +00:00 committed by Greg Kroah-Hartman
parent 6929cb00a5
commit d735625648
1 changed files with 26 additions and 1 deletions
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27
drivers/tty/serial/st-asc.c
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@ -513,6 +513,8 @@ static void asc_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
{
struct asc_port *ascport = to_asc_port(port);
struct device_node *np = port->dev->of_node;
struct gpio_desc *gpiod;
unsigned int baud;
u32 ctrl_val;
tcflag_t cflag;
@ -556,9 +558,32 @@ static void asc_set_termios(struct uart_port *port, struct ktermios *termios,
ctrl_val |= ASC_CTL_PARITYODD;
/* hardware flow control */
if ((cflag & CRTSCTS))
if ((cflag & CRTSCTS)) {
ctrl_val |= ASC_CTL_CTSENABLE;
/* If flow-control selected, stop handling RTS manually */
if (ascport->rts) {
devm_gpiod_put(port->dev, ascport->rts);
ascport->rts = NULL;
pinctrl_select_state(ascport->pinctrl,
ascport->states[DEFAULT]);
}
} else {
/* If flow-control disabled, it's safe to handle RTS manually */
if (!ascport->rts && ascport->states[NO_HW_FLOWCTRL]) {
pinctrl_select_state(ascport->pinctrl,
ascport->states[NO_HW_FLOWCTRL]);
gpiod = devm_get_gpiod_from_child(port->dev, "rts",
&np->fwnode);
if (!IS_ERR(gpiod)) {
gpiod_direction_output(gpiod, 0);
ascport->rts = gpiod;
}
}
}
if ((baud < 19200) && !ascport->force_m1) {
asc_out(port, ASC_BAUDRATE, (port->uartclk / (16 * baud)));
} else {