This patch series is an attempt to simplify rs485 implementation in drivers
by moving the following tasks out of the drivers into the serial core:
- ensure sane RTS settings: in case of an invalid configuration (both RTS
after send and RTS on send set or both unset) enable RTS on send and
disable RTS after send
- nullify the padding field of the serial_rs485 struct before it is
returned to userspace
- copy the configuration stored in the serial_rs485 struct to the port
configuration if setting the configuration in the driver was successfull
- limit the RTS delay to 100ms
Redundant code has been removed from the following drivers for now:
- atmel
- fsl_lpuart
- amba
- imx
- max310x
- omap-serial
- sc16is7xx
- stm32-usart
The code has been tested with the amba pl011 driver. This series applies
against Gregs tty-testing branch.
Changes in v2:
- use a makro for max RTS delays and comment it (as requested by Jiri)
- add a comment concerning the memset of a structures padding field - correct
typos in the commit message (found by Uwe)
- rephrase all commit messages to make more clear that function
uart_set_rs485_config() has been extended by checks and other functionalities
(as requested by Uwe)
Changes in v3:
- add warning messages if the serial core corrects RS485 values (as requested by
Lukas Wunner)
- dont expose the macro for max RTS delays to userspace (as requested by Greg)
Changes in v4:
- use ratelimit warning messages and also print device, uart port name and line
(as requested by Jiri)
In uart_set_rs485_config() the serial core already nullifies the padding
field of the passed serial_rs485 struct before returning it to userspace.
Doing the same in the drivers rs485_config() function is redundant, so
remove the concerning memset in this function.
Signed-off-by: Lino Sanfilippo <[email protected]>
---
drivers/tty/serial/max310x.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c
index 3112b4a05448..a0b6ea52d133 100644
--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -1037,7 +1037,6 @@ static int max310x_rs485_config(struct uart_port *port,
rs485->flags &= SER_RS485_RTS_ON_SEND | SER_RS485_RX_DURING_TX |
SER_RS485_ENABLED;
- memset(rs485->padding, 0, sizeof(rs485->padding));
port->rs485 = *rs485;
schedule_work(&one->rs_work);
--
2.35.1
In uart_set_rs485_config() the serial core already clamps the RTS delays.
It also assigns the passed serial_rs485 struct to the uart port.
So remove these tasks from the drivers rs485_config() function to avoid
redundancy.
Signed-off-by: Lino Sanfilippo <[email protected]>
---
drivers/tty/serial/omap-serial.c | 13 +++----------
1 file changed, 3 insertions(+), 10 deletions(-)
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 8d5ffa196097..46f4d4cacb6e 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1336,18 +1336,11 @@ serial_omap_config_rs485(struct uart_port *port, struct serial_rs485 *rs485)
up->ier = 0;
serial_out(up, UART_IER, 0);
- /* Clamp the delays to [0, 100ms] */
- rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U);
- rs485->delay_rts_after_send = min(rs485->delay_rts_after_send, 100U);
-
- /* store new config */
- port->rs485 = *rs485;
-
if (up->rts_gpiod) {
/* enable / disable rts */
- val = (port->rs485.flags & SER_RS485_ENABLED) ?
+ val = (rs485->flags & SER_RS485_ENABLED) ?
SER_RS485_RTS_AFTER_SEND : SER_RS485_RTS_ON_SEND;
- val = (port->rs485.flags & val) ? 1 : 0;
+ val = (rs485->flags & val) ? 1 : 0;
gpiod_set_value(up->rts_gpiod, val);
}
@@ -1358,7 +1351,7 @@ serial_omap_config_rs485(struct uart_port *port, struct serial_rs485 *rs485)
/* If RS-485 is disabled, make sure the THR interrupt is fired when
* TX FIFO is below the trigger level.
*/
- if (!(port->rs485.flags & SER_RS485_ENABLED) &&
+ if (!(rs485->flags & SER_RS485_ENABLED) &&
(up->scr & OMAP_UART_SCR_TX_EMPTY)) {
up->scr &= ~OMAP_UART_SCR_TX_EMPTY;
serial_out(up, UART_OMAP_SCR, up->scr);
--
2.35.1
In uart_set_rs485_config() the serial core already
- ensures that only one of both options RTS on send or RTS after send is
set
- nullifies the padding field of the passed serial_rs485 struct
- clamps the RTS delays
- assigns the passed serial_rs485 struct to the uart port
So remove these tasks from the code of the drivers rs485_config() function
to avoid redundancy.
Signed-off-by: Lino Sanfilippo <[email protected]>
---
drivers/tty/serial/amba-pl011.c | 16 +---------------
1 file changed, 1 insertion(+), 15 deletions(-)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 51ecb050ae40..de2c4dc6257e 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2170,25 +2170,11 @@ static int pl011_rs485_config(struct uart_port *port,
struct uart_amba_port *uap =
container_of(port, struct uart_amba_port, port);
- /* 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;
- }
- /* clamp the delays to [0, 100ms] */
- rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U);
- rs485->delay_rts_after_send = min(rs485->delay_rts_after_send, 100U);
- memset(rs485->padding, 0, sizeof(rs485->padding));
-
if (port->rs485.flags & SER_RS485_ENABLED)
pl011_rs485_tx_stop(uap);
- /* Set new configuration */
- port->rs485 = *rs485;
-
/* Make sure auto RTS is disabled */
- if (port->rs485.flags & SER_RS485_ENABLED) {
+ if (rs485->flags & SER_RS485_ENABLED) {
u32 cr = pl011_read(uap, REG_CR);
cr &= ~UART011_CR_RTSEN;
--
2.35.1
In uart_set_rs485_config() the serial core already ensures that only one of
both options RTS on send or RTS after send is set. It also assigns the
passed serial_rs485 struct to the uart port.
So remove the check and the assignment from the drivers rs485_config()
function to avoid redundancy.
Signed-off-by: Lino Sanfilippo <[email protected]>
---
drivers/tty/serial/stm32-usart.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 87b5cd4c9743..f886976daef6 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -107,8 +107,6 @@ static int stm32_usart_config_rs485(struct uart_port *port,
stm32_usart_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
- port->rs485 = *rs485conf;
-
rs485conf->flags |= SER_RS485_RX_DURING_TX;
if (rs485conf->flags & SER_RS485_ENABLED) {
@@ -128,13 +126,10 @@ static int stm32_usart_config_rs485(struct uart_port *port,
rs485conf->delay_rts_after_send,
baud);
- if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
+ if (rs485conf->flags & SER_RS485_RTS_ON_SEND)
cr3 &= ~USART_CR3_DEP;
- rs485conf->flags &= ~SER_RS485_RTS_AFTER_SEND;
- } else {
+ else
cr3 |= USART_CR3_DEP;
- rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
- }
writel_relaxed(cr3, port->membase + ofs->cr3);
writel_relaxed(cr1, port->membase + ofs->cr1);
--
2.35.1
In uart_set_rs485_config() the serial core already ensures that only one of
both options RTS on send or RTS after send is set. It also assigns the
passed serial_rs485 struct to the uart port.
So remove the check and the assignment from the drivers rs485_config()
function to avoid redundancy.
Signed-off-by: Lino Sanfilippo <[email protected]>
---
drivers/tty/serial/fsl_lpuart.c | 32 --------------------------------
1 file changed, 32 deletions(-)
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 87789872f400..8fea7fd915d2 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1377,19 +1377,6 @@ static int lpuart_config_rs485(struct uart_port *port,
/* Enable auto RS-485 RTS mode */
modem |= UARTMODEM_TXRTSE;
- /*
- * RTS needs to be logic HIGH either during transfer _or_ after
- * transfer, other variants are not supported by the hardware.
- */
-
- if (!(rs485->flags & (SER_RS485_RTS_ON_SEND |
- SER_RS485_RTS_AFTER_SEND)))
- rs485->flags |= SER_RS485_RTS_ON_SEND;
-
- if (rs485->flags & SER_RS485_RTS_ON_SEND &&
- rs485->flags & SER_RS485_RTS_AFTER_SEND)
- rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
-
/*
* The hardware defaults to RTS logic HIGH while transfer.
* Switch polarity in case RTS shall be logic HIGH
@@ -1402,9 +1389,6 @@ static int lpuart_config_rs485(struct uart_port *port,
modem |= UARTMODEM_TXRTSPOL;
}
- /* Store the new configuration */
- sport->port.rs485 = *rs485;
-
writeb(modem, sport->port.membase + UARTMODEM);
return 0;
}
@@ -1428,19 +1412,6 @@ static int lpuart32_config_rs485(struct uart_port *port,
/* Enable auto RS-485 RTS mode */
modem |= UARTMODEM_TXRTSE;
- /*
- * RTS needs to be logic HIGH either during transfer _or_ after
- * transfer, other variants are not supported by the hardware.
- */
-
- if (!(rs485->flags & (SER_RS485_RTS_ON_SEND |
- SER_RS485_RTS_AFTER_SEND)))
- rs485->flags |= SER_RS485_RTS_ON_SEND;
-
- if (rs485->flags & SER_RS485_RTS_ON_SEND &&
- rs485->flags & SER_RS485_RTS_AFTER_SEND)
- rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
-
/*
* The hardware defaults to RTS logic HIGH while transfer.
* Switch polarity in case RTS shall be logic HIGH
@@ -1453,9 +1424,6 @@ static int lpuart32_config_rs485(struct uart_port *port,
modem |= UARTMODEM_TXRTSPOL;
}
- /* Store the new configuration */
- sport->port.rs485 = *rs485;
-
lpuart32_write(&sport->port, modem, UARTMODIR);
return 0;
}
--
2.35.1
In uart_set_rs485_config() the serial core already ensures that only one of
both options RTS on send or RTS after send is set.
So remove this check from the drivers rs485_config() function to avoid
redundancy.
Signed-off-by: Lino Sanfilippo <[email protected]>
---
drivers/tty/serial/sc16is7xx.c | 10 ----------
1 file changed, 10 deletions(-)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index e857fb61efbf..bb939d2877db 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1134,16 +1134,6 @@ static int sc16is7xx_config_rs485(struct uart_port *port,
struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
if (rs485->flags & SER_RS485_ENABLED) {
- bool rts_during_rx, rts_during_tx;
-
- rts_during_rx = rs485->flags & SER_RS485_RTS_AFTER_SEND;
- rts_during_tx = rs485->flags & SER_RS485_RTS_ON_SEND;
-
- if (rts_during_rx == rts_during_tx)
- dev_err(port->dev,
- "unsupported RTS signalling on_send:%d after_send:%d - exactly one of RS485 RTS flags should be set\n",
- rts_during_tx, rts_during_rx);
-
/*
* RTS signal is handled by HW, it's timing can't be influenced.
* However, it's sometimes useful to delay TX even without RTS
--
2.35.1
In uart_set_rs485_config() the serial core already assigns the passed
serial_rs485 struct to the uart port.
So remove the assignment in the drivers rs485_config() function to avoid
reduncancy.
Acked-by: Uwe Kleine-König <[email protected]>
Signed-off-by: Lino Sanfilippo <[email protected]>
---
drivers/tty/serial/imx.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index fd38e6ed4fda..e934880febe8 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1937,8 +1937,6 @@ static int imx_uart_rs485_config(struct uart_port *port,
rs485conf->flags & SER_RS485_RX_DURING_TX)
imx_uart_start_rx(port);
- port->rs485 = *rs485conf;
-
return 0;
}
--
2.35.1
In uart_set_rs485_config() the serial core already assigns the passed
serial_rs485 struct to the uart port.
So remove the assignment from the drivers rs485_config() function to avoid
redundancy.
Acked-by: Richard Genoud <[email protected]>
Signed-off-by: Lino Sanfilippo <[email protected]>
---
drivers/tty/serial/atmel_serial.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 3a45e4fc7993..dd1c7e4bd1c9 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -299,11 +299,9 @@ static int atmel_config_rs485(struct uart_port *port,
/* Resetting serial mode to RS232 (0x0) */
mode &= ~ATMEL_US_USMODE;
- port->rs485 = *rs485conf;
-
if (rs485conf->flags & SER_RS485_ENABLED) {
dev_dbg(port->dev, "Setting UART to RS485\n");
- if (port->rs485.flags & SER_RS485_RX_DURING_TX)
+ if (rs485conf->flags & SER_RS485_RX_DURING_TX)
atmel_port->tx_done_mask = ATMEL_US_TXRDY;
else
atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
--
2.35.1
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 <[email protected]>
---
drivers/tty/serial/serial_core.c | 33 ++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 6a8963caf954..108b389e6e12 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -42,6 +42,11 @@ static struct lock_class_key port_lock_key;
#define HIGH_BITS_OFFSET ((sizeof(long)-sizeof(int))*8)
+/*
+ * Max time with active RTS before/after data is sent.
+ */
+#define RS485_MAX_RTS_DELAY 100 /* msecs */
+
static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
struct ktermios *old_termios);
static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
@@ -1296,8 +1301,36 @@ 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)) {
+ dev_warn_ratelimited(port->dev,
+ "%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n",
+ port->name, port->line);
+ rs485.flags |= SER_RS485_RTS_ON_SEND;
+ rs485.flags &= ~SER_RS485_RTS_AFTER_SEND;
+ }
+
+ if (rs485.delay_rts_before_send > RS485_MAX_RTS_DELAY) {
+ rs485.delay_rts_before_send = RS485_MAX_RTS_DELAY;
+ dev_warn_ratelimited(port->dev,
+ "%s (%d): RTS delay before sending clamped to %u ms\n",
+ port->name, port->line, rs485.delay_rts_before_send);
+ }
+
+ if (rs485.delay_rts_after_send > RS485_MAX_RTS_DELAY) {
+ rs485.delay_rts_after_send = RS485_MAX_RTS_DELAY;
+ dev_warn_ratelimited(port->dev,
+ "%s (%d): RTS delay after sending clamped to %u ms\n",
+ port->name, port->line, rs485.delay_rts_after_send);
+ }
+ /* 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;
base-commit: 3123109284176b1532874591f7c81f3837bbdc17
--
2.35.1
On Sun, Apr 10, 2022 at 12:46:33PM +0200, Lino Sanfilippo wrote:
> This patch series is an attempt to simplify rs485 implementation in drivers
> by moving the following tasks out of the drivers into the serial core:
>
> - ensure sane RTS settings: in case of an invalid configuration (both RTS
> after send and RTS on send set or both unset) enable RTS on send and
> disable RTS after send
[...]
> Redundant code has been removed from the following drivers for now:
>
> - atmel
> - fsl_lpuart
> - amba
> - imx
> - max310x
> - omap-serial
> - sc16is7xx
> - stm32-usart
It looks like there's more of this cruft left at least in
serial8250_em485_config()...
Thanks,
Lukas