diff options
Diffstat (limited to 'drivers/tty/serial/8250/8250_port.c')
| -rw-r--r-- | drivers/tty/serial/8250/8250_port.c | 41 |
1 files changed, 39 insertions, 2 deletions
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 40efcea8c6e7..73244806d701 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -615,7 +615,7 @@ EXPORT_SYMBOL_GPL(serial8250_rpm_put); * * Return 0 - success, -errno - otherwise */ -int serial8250_em485_init(struct uart_8250_port *p) +static int serial8250_em485_init(struct uart_8250_port *p) { if (p->em485) return 0; @@ -636,7 +636,6 @@ int serial8250_em485_init(struct uart_8250_port *p) return 0; } -EXPORT_SYMBOL_GPL(serial8250_em485_init); /** * serial8250_em485_destroy() - put uart_8250_port into normal state @@ -664,6 +663,44 @@ void serial8250_em485_destroy(struct uart_8250_port *p) } EXPORT_SYMBOL_GPL(serial8250_em485_destroy); +/** + * serial8250_em485_config() - generic ->rs485_config() callback + * @port: uart port + * @rs485: rs485 settings + * + * Generic callback usable by 8250 uart drivers to activate rs485 settings + * if the uart is incapable of driving RTS as a Transmit Enable signal in + * hardware, relying on software emulation instead. + */ +int serial8250_em485_config(struct uart_port *port, struct serial_rs485 *rs485) +{ + struct uart_8250_port *up = up_to_u8250p(port); + + /* clamp the delays to [0, 100ms] */ + rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U); + rs485->delay_rts_after_send = min(rs485->delay_rts_after_send, 100U); + + port->rs485 = *rs485; + + /* + * Both serial8250_em485_init() and serial8250_em485_destroy() + * are idempotent. + */ + if (rs485->flags & SER_RS485_ENABLED) { + int ret = serial8250_em485_init(up); + + if (ret) { + rs485->flags &= ~SER_RS485_ENABLED; + port->rs485.flags &= ~SER_RS485_ENABLED; + } + return ret; + } + + serial8250_em485_destroy(up); + return 0; +} +EXPORT_SYMBOL_GPL(serial8250_em485_config); + /* * These two wrappers ensure that enable_runtime_pm_tx() can be called more than * once and disable_runtime_pm_tx() will still disable RPM because the fifo is |