Several drivers that support setting the RS485 configuration via userspace
implement one or more of the following tasks:
- in case of an invalid RTS configuration (both RTS after send and RTS on
send set or both unset) fall back to enable RTS on send and disable RTS
after send
- nullify the padding field of the returned serial_rs485 struct
- copy the configuration into the uart port struct
- limit RTS delays to 100 ms
Move these tasks into the serial core to make them generic and to provide
a consistent behaviour among all drivers.
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@xxxxxx>
---
drivers/tty/serial/serial_core.c | 18 ++++++++++++++++++
include/uapi/linux/serial.h | 3 +++
2 files changed, 21 insertions(+)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 846192a7b4bf..a4f7e847d414 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1282,8 +1282,26 @@ static int uart_set_rs485_config(struct uart_port *port,
if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
return -EFAULT;
+ /* pick sane settings if the user hasn't */
+ if (!(rs485.flags & SER_RS485_RTS_ON_SEND) ==
+ !(rs485.flags & SER_RS485_RTS_AFTER_SEND)) {
+ rs485.flags |= SER_RS485_RTS_ON_SEND;
+ rs485.flags &= ~SER_RS485_RTS_AFTER_SEND;
+ }
+
+ rs485.delay_rts_before_send = min_t(unsigned int,
+ rs485.delay_rts_before_send,
+ SER_RS485_MAX_RTS_DELAY);
+ rs485.delay_rts_after_send = min_t(unsigned int,
+ rs485.delay_rts_after_send,
+ SER_RS485_MAX_RTS_DELAY);
+ /* Return clean padding area to userspace */
+ memset(rs485.padding, 0, sizeof(rs485.padding));
+
spin_lock_irqsave(&port->lock, flags);
ret = port->rs485_config(port, &rs485);
+ if (!ret)
+ port->rs485 = rs485;
spin_unlock_irqrestore(&port->lock, flags);
if (ret)
return ret;
diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
index fa6b16e5fdd8..859045a53231 100644
--- a/include/uapi/linux/serial.h
+++ b/include/uapi/linux/serial.h
@@ -128,6 +128,9 @@ struct serial_rs485 {
(if supported) */
__u32 delay_rts_before_send; /* Delay before send (milliseconds) */
__u32 delay_rts_after_send; /* Delay after send (milliseconds) */
+#define SER_RS485_MAX_RTS_DELAY 100 /* Max time with active
+ RTS before/after
+ data sent (msecs) */
__u32 padding[5]; /* Memory is cheap, new structs
are a royal PITA .. */
};
base-commit: 802d00bd774b77fe132e9e83462b96fb9919411c
--
2.34.1
