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.
Signed-off-by: Crescent CY Hsieh <[email protected]>
---
Changes from v4 to v5:
- Revise commit message.
- Delete RS422 checks within uart_set_rs485_termination().
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.
v4: https://lore.kernel.org/all/[email protected]/
v3: https://lore.kernel.org/all/[email protected]/
v2: https://lore.kernel.org/all/[email protected]/
v1: https://lore.kernel.org/all/[email protected]/
---
drivers/tty/serial/serial_core.c | 7 +++++++
include/uapi/linux/serial.h | 19 +++++++++++--------
2 files changed, 18 insertions(+), 8 deletions(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 831d03361..db1ebed7f 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) ==
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
On Tue, Nov 21, 2023 at 05:51:22PM +0800, Crescent CY Hsieh wrote:
> --- 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)
You just broke userspace by changing the flags for existing values :(
Please be much more careful in the future, do not do "cleanup" patches
along with a "add a new feature" patch, as it would have been much more
obvious as to what happened here if you had done that.
thanks,
greg k-h
On 21.11.23 at 10:51, 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.
>
> Signed-off-by: Crescent CY Hsieh <[email protected]>
>
> ---
> Changes from v4 to v5:
> - Revise commit message.
> - Delete RS422 checks within uart_set_rs485_termination().
>
> 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.
>
> v4: https://lore.kernel.org/all/[email protected]/
> v3: https://lore.kernel.org/all/[email protected]/
> v2: https://lore.kernel.org/all/[email protected]/
> v1: https://lore.kernel.org/all/[email protected]/
>
> ---
> drivers/tty/serial/serial_core.c | 7 +++++++
> include/uapi/linux/serial.h | 19 +++++++++++--------
> 2 files changed, 18 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 831d03361..db1ebed7f 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);
Does not RS422 also require termination resistors? So what about SER_RS485_TERMINATE_BUS?
Regards,
Lino