2023-10-30 05:38:25

by Crescent CY Hsieh

Subject: [PATCH] tty: serial: Add RS422 flag to struct serial_rs485

Add "SER_RS422_ENABLED" flag within struct serial_rs485, so that serial
port can switching interface into RS422 if supported by using ioctl
command "TIOCSRS485".

In case of interfaces confliction, add checks within
uart_sanitize_serial_rs485() such that only one of RS422/RS485 is set.

Signed-off-by: Crescent CY Hsieh <[email protected]>
---
drivers/tty/serial/serial_core.c | 19 +++++++++++++++++--
include/uapi/linux/serial.h | 4 ++++
2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 831d03361..afbffa9dd 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1305,7 +1305,7 @@ static int uart_get_icount(struct tty_struct *tty,

#define SER_RS485_LEGACY_FLAGS (SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | \
SER_RS485_RTS_AFTER_SEND | SER_RS485_RX_DURING_TX | \
- SER_RS485_TERMINATE_BUS)
+ SER_RS485_TERMINATE_BUS | SER_RS422_ENABLED)

static int uart_check_rs485_flags(struct uart_port *port, struct serial_rs485 *rs485)
{
@@ -1371,11 +1371,26 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4
{
u32 supported_flags = port->rs485_supported.flags;

- if (!(rs485->flags & SER_RS485_ENABLED)) {
+ if (!(rs485->flags & (SER_RS485_ENABLED | SER_RS422_ENABLED))) {
memset(rs485, 0, sizeof(*rs485));
return;
}

+ /* Pick sane setting if the user enables both interfaces */
+ if (rs485->flags & (SER_RS485_ENABLED | SER_RS422_ENABLED)) {
+ dev_warn_ratelimited(port->dev,
+ "%s (%d): Invalid serial interface setting, using RS485 instead\n",
+ port->name, port->line);
+ rs485->flags &= ~SER_RS422_ENABLED;
+ }
+
+ /* Clear other bits and return if RS422 is enabled */
+ if (rs485->flags & SER_RS422_ENABLED) {
+ memset(rs485, 0, sizeof(*rs485));
+ rs485->flags |= SER_RS422_ENABLED;
+ 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..427609fd5 100644
--- a/include/uapi/linux/serial.h
+++ b/include/uapi/linux/serial.h
@@ -137,6 +137,8 @@ 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_RS422_ENABLED - RS422 enabled.
*/
struct serial_rs485 {
__u32 flags;
@@ -149,6 +151,8 @@ struct serial_rs485 {
#define SER_RS485_ADDR_RECV (1 << 7)
#define SER_RS485_ADDR_DEST (1 << 8)

+#define SER_RS422_ENABLED (1 << 9)
+
__u32 delay_rts_before_send;
__u32 delay_rts_after_send;

--
2.34.1

2023-10-30 06:57:45

by Jiri Slaby

Subject: Re: [PATCH] tty: serial: Add RS422 flag to struct serial_rs485

On 30. 10. 23, 6:36, Crescent CY Hsieh wrote:
> @@ -1371,11 +1371,26 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4
> {
> u32 supported_flags = port->rs485_supported.flags;
>
> - if (!(rs485->flags & SER_RS485_ENABLED)) {
> + if (!(rs485->flags & (SER_RS485_ENABLED | SER_RS422_ENABLED))) {
> memset(rs485, 0, sizeof(*rs485));
> return;
> }
>
> + /* Pick sane setting if the user enables both interfaces */
> + if (rs485->flags & (SER_RS485_ENABLED | SER_RS422_ENABLED)) {

This would have to be:
if (rs485->flags & (SER_RS485_ENABLED | SER_RS422_ENABLED) ==
SER_RS485_ENABLED | SER_RS422_ENABLED)

But your previous version:
rs485->flags & SER_RS485_ENABLED && rs485->flags & SER_RS422_ENABLED
looked better in this case.

thanks,
--
js
suse labs