Add "SER_RS485_MODE_RS422" flag to struct serial_rs485, so that serial port can switch interface into RS422 if supported by using ioctl command "TIOCSRS485". By treating RS422 as a mode of RS485, which means while enabling RS422 there are two flags need to be set (SER_RS485_ENABLED and SER_RS485_MODE_RS422), it would make things much easier. For example some places that checks for "SER_RS485_ENABLED" won't need to be rewritten. There are only two things need to be noticed: - While enabling RS422, other RS485 flags should not be set. - RS422 doesn't need to deal with termination, so while disabling RS485 or enabling RS422, uart_set_rs485_termination() shall return. Signed-off-by: Crescent CY Hsieh <crescentcy.hsieh@xxxxxxxx> --- Changes from v3 to v4: - Include 'linux/const.h' header in '/include/uapi/linux/serial.h' - Replace BIT() with _BITUL() which defined in '/include/uapi/linux/const.h' Changes from v2 to v3: - Remove "SER_RS422_ENABLED" flag from legacy flags. - Revise "SER_RS422_ENABLED" into "SER_RS485_MODE_RS422". - Remove the code which checks the conflicts between SER_RS485_ENABLED and SER_RS422_ENABLED. - Add return check in uart_set_rs485_termination(). Changes from v1 to v2: - Revise the logic that checks whether RS422/RS485 are enabled simultaneously. v3: https://lore.kernel.org/all/20231108060719.11775-1-crescentcy.hsieh@xxxxxxxx/ v2: https://lore.kernel.org/all/20231101064404.45711-1-crescentcy.hsieh@xxxxxxxx/ v1: https://lore.kernel.org/all/20231030053632.5109-1-crescentcy.hsieh@xxxxxxxx/ --- drivers/tty/serial/serial_core.c | 11 ++++++++++- include/uapi/linux/serial.h | 19 +++++++++++-------- 2 files changed, 21 insertions(+), 9 deletions(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 831d03361..777f091a4 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1376,6 +1376,13 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4 return; } + /* Clear other RS485 flags and return if enabling RS422 */ + if (rs485->flags & SER_RS485_MODE_RS422) { + memset(rs485, 0, sizeof(*rs485)); + rs485->flags |= (SER_RS485_ENABLED | SER_RS485_MODE_RS422); + return; + } + /* Pick sane settings if the user hasn't */ if ((supported_flags & (SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND)) && !(rs485->flags & SER_RS485_RTS_ON_SEND) == @@ -1400,7 +1407,9 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4 static void uart_set_rs485_termination(struct uart_port *port, const struct serial_rs485 *rs485) { - if (!(rs485->flags & SER_RS485_ENABLED)) + /* Return while disabling RS485 or enabling RS422 */ + if (!(rs485->flags & SER_RS485_ENABLED) || + (rs485->flags & SER_RS485_ENABLED && rs485->flags & SER_RS485_MODE_RS422)) return; gpiod_set_value_cansleep(port->rs485_term_gpio, diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h index 53bc1af67..9086367db 100644 --- a/include/uapi/linux/serial.h +++ b/include/uapi/linux/serial.h @@ -11,6 +11,7 @@ #ifndef _UAPI_LINUX_SERIAL_H #define _UAPI_LINUX_SERIAL_H +#include <linux/const.h> #include <linux/types.h> #include <linux/tty_flags.h> @@ -137,17 +138,19 @@ struct serial_icounter_struct { * * %SER_RS485_ADDRB - Enable RS485 addressing mode. * * %SER_RS485_ADDR_RECV - Receive address filter (enables @addr_recv). Requires %SER_RS485_ADDRB. * * %SER_RS485_ADDR_DEST - Destination address (enables @addr_dest). Requires %SER_RS485_ADDRB. + * * %SER_RS485_MODE_RS422 - Enable RS422. Requires %SER_RS485_ENABLED. */ struct serial_rs485 { __u32 flags; -#define SER_RS485_ENABLED (1 << 0) -#define SER_RS485_RTS_ON_SEND (1 << 1) -#define SER_RS485_RTS_AFTER_SEND (1 << 2) -#define SER_RS485_RX_DURING_TX (1 << 4) -#define SER_RS485_TERMINATE_BUS (1 << 5) -#define SER_RS485_ADDRB (1 << 6) -#define SER_RS485_ADDR_RECV (1 << 7) -#define SER_RS485_ADDR_DEST (1 << 8) +#define SER_RS485_ENABLED _BITUL(0) +#define SER_RS485_RTS_ON_SEND _BITUL(1) +#define SER_RS485_RTS_AFTER_SEND _BITUL(2) +#define SER_RS485_RX_DURING_TX _BITUL(3) +#define SER_RS485_TERMINATE_BUS _BITUL(4) +#define SER_RS485_ADDRB _BITUL(5) +#define SER_RS485_ADDR_RECV _BITUL(6) +#define SER_RS485_ADDR_DEST _BITUL(7) +#define SER_RS485_MODE_RS422 _BITUL(8) __u32 delay_rts_before_send; __u32 delay_rts_after_send; -- 2.34.1
