From e490c9144cfaa8e2242c1e5d5187230928f27417 Mon Sep 17 00:00:00 2001 From: "Matwey V. Kornilov" Date: Mon, 1 Feb 2016 21:09:21 +0300 Subject: tty: Add software emulated RS485 support for 8250 Implementation of software emulation of RS485 direction handling is based on omap_serial driver. Before and after transmission RTS is set to the appropriate value. Note that before calling serial8250_em485_init() the caller has to ensure that UART will interrupt when shift register empty. Otherwise, emultaion cannot be used. Both serial8250_em485_init() and serial8250_em485_destroy() are idempotent functions. Signed-off-by: Matwey V. Kornilov Signed-off-by: Greg Kroah-Hartman --- include/linux/serial_8250.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include') diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h index faa0e0370ce7..434879759725 100644 --- a/include/linux/serial_8250.h +++ b/include/linux/serial_8250.h @@ -76,6 +76,12 @@ struct uart_8250_ops { void (*release_irq)(struct uart_8250_port *); }; +struct uart_8250_em485 { + struct timer_list start_tx_timer; /* "rs485 start tx" timer */ + struct timer_list stop_tx_timer; /* "rs485 stop tx" timer */ + struct timer_list *active_timer; /* pointer to active timer */ +}; + /* * This should be used by drivers which want to register * their own 8250 ports without registering their own @@ -122,6 +128,8 @@ struct uart_8250_port { /* 8250 specific callbacks */ int (*dl_read)(struct uart_8250_port *); void (*dl_write)(struct uart_8250_port *, int); + + struct uart_8250_em485 *em485; }; static inline struct uart_8250_port *up_to_u8250p(struct uart_port *up) -- cgit v1.2.3