@@ -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,
@@ -137,17 +137,19 @@ 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 BIT(0)
+#define SER_RS485_RTS_ON_SEND BIT(1)
+#define SER_RS485_RTS_AFTER_SEND BIT(2)
+#define SER_RS485_RX_DURING_TX BIT(3)
+#define SER_RS485_TERMINATE_BUS BIT(4)
+#define SER_RS485_ADDRB BIT(5)
+#define SER_RS485_ADDR_RECV BIT(6)
+#define SER_RS485_ADDR_DEST BIT(7)
+#define SER_RS485_MODE_RS422 BIT(8)
__u32 delay_rts_before_send;
__u32 delay_rts_after_send;
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@moxa.com> --- 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. v2: https://lore.kernel.org/all/20231101064404.45711-1-crescentcy.hsieh@moxa.com/ v1: https://lore.kernel.org/all/20231030053632.5109-1-crescentcy.hsieh@moxa.com/ --- drivers/tty/serial/serial_core.c | 11 ++++++++++- include/uapi/linux/serial.h | 18 ++++++++++-------- 2 files changed, 20 insertions(+), 9 deletions(-)