Hi, On 13.11.23 10:41, Crescent CY Hsieh wrote: > 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. Commit messages should use the imperative form. > > 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)) Is this check needed at all? If no termination GPIO is specified, gpiod_set_value_cansleep() does nothing. If a termination GPIO is specified it will be deasserted in case of RS422 (since for the RS422 case the SER_RS485_TERMINATE_BUS flag is deleted in uart_sanitize_serial_rs485()). This seems like a good behaviour to me, so IMO the above check is not needed. > > 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. All of the above flags are only effective if RS485_ENABLED is set, so no need to mention this explicitly for the MODE_RS422 flag. > */ > 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; Regards, Lino
