[PATCH v4 0/9] Add and make use of a common rs485 device tree parsing function

[PATCH v4 0/9] Add and make use of a common rs485 device tree parsing function

[Uwe Kleine-König]

Hello,

this is v4 of the series. Compared to v3 It fixes a compile error and is
rebased to a newer kernel to apply fine on Greg's tree.

Sascha Hauer (6):
  serial: Add common rs485 device tree parsing function
  serial: atmel: Use common rs485 device tree parsing function
  serial: fsl_lpuart: Use common rs485 device tree parsing function
  serial: omap-serial: Use common rs485 device tree parsing function
  serial: imx: default to half duplex rs485
  serial: imx: Use common rs485 device tree parsing function

Uwe Kleine-K?nig (3):
  serial: fsl_lpuart: clear unsupported options in .rs485_config()
  dt-bindings: serial/rs485: make rs485-rts-delay optional
  dt-bindings: serial: document rs485 bindings for various devices

 .../devicetree/bindings/serial/atmel-usart.txt     |  1 +
 .../devicetree/bindings/serial/fsl-imx-uart.txt    |  1 +
 .../devicetree/bindings/serial/fsl-lpuart.txt      |  1 +
 .../devicetree/bindings/serial/omap_serial.txt     |  1 +
 Documentation/devicetree/bindings/serial/rs485.txt |  5 +--
 drivers/tty/serial/Kconfig                         |  4 ++
 drivers/tty/serial/Makefile                        |  2 +
 drivers/tty/serial/atmel_serial.c                  | 25 +-----------
 drivers/tty/serial/fsl_lpuart.c                    | 29 ++++++++++---
 drivers/tty/serial/imx.c                           |  5 ++-
 drivers/tty/serial/of.c                            | 47 ++++++++++++++++++++++
 drivers/tty/serial/omap-serial.c                   | 13 +-----
 include/linux/serial_core.h                        | 13 ++++++
 13 files changed, 100 insertions(+), 47 deletions(-)
 create mode 100644 drivers/tty/serial/of.c

-- 
2.11.0

[PATCH v4 1/9] serial: fsl_lpuart: clear unsupported options in .rs485_config()

[Uwe Kleine-König]

The struct serial_rs485 parameter is both input and output and is
supposed to hold the actually used configuration on return. So clear
unsupported settings.

Signed-off-by: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
---
 drivers/tty/serial/fsl_lpuart.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 343de8c384b0..4becfbf35c4c 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1019,6 +1019,11 @@ static int lpuart_config_rs485(struct uart_port *port,
 		~(UARTMODEM_TXRTSPOL | UARTMODEM_TXRTSE);
 	writeb(modem, sport->port.membase + UARTMODEM);
 
+	/* clear unsupported configurations */
+	rs485->delay_rts_before_send = 0;
+	rs485->delay_rts_after_send = 0;
+	rs485->flags &= ~SER_RS485_RX_DURING_TX;
+
 	if (rs485->flags & SER_RS485_ENABLED) {
 		/* Enable auto RS-485 RTS mode */
 		modem |= UARTMODEM_TXRTSE;
-- 
2.11.0

[PATCH v4 2/9] dt-bindings: serial/rs485: make rs485-rts-delay optional

[Uwe Kleine-König]

There are a few device trees that specify one of the already optional
properties without also having the up to now required property
rs485-rts-delay. Additionally there is no technical reason to require
rs485-rts-delay and that's also what most drivers implement.

So give existing users and implementers a blessing and document
rs485-rts-delay as optional.

Signed-off-by: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
---
 Documentation/devicetree/bindings/serial/rs485.txt | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/serial/rs485.txt b/Documentation/devicetree/bindings/serial/rs485.txt
index 32b1fa1f2a5b..b8415936dfdb 100644
--- a/Documentation/devicetree/bindings/serial/rs485.txt
+++ b/Documentation/devicetree/bindings/serial/rs485.txt
@@ -5,14 +5,13 @@ the built-in half-duplex mode.
 The properties described hereafter shall be given to a half-duplex capable
 UART node.
 
-Required properties:
+Optional properties:
 - rs485-rts-delay: prop-encoded-array <a b> where:
   * a is the delay between rts signal and beginning of data sent in milliseconds.
       it corresponds to the delay before sending data.
   * b is the delay between end of data sent and rts signal in milliseconds
       it corresponds to the delay after sending data and actual release of the line.
-
-Optional properties:
+  If this property is not specified, <0 0> is assumed.
 - linux,rs485-enabled-at-boot-time: empty property telling to enable the rs485
   feature at boot time. It can be disabled later with proper ioctl.
 - rs485-rx-during-tx: empty property that enables the receiving of data even
-- 
2.11.0

[PATCH v4 3/9] serial: Add common rs485 device tree parsing function

[Uwe Kleine-König]

From: Sascha Hauer <s.hauer@pengutronix.de>

Several drivers have the same device tree parsing code. Create
a common helper function for it.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
[ukl: implement default <0 0> for rts-delay, unset unspecified flags]
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
---
 drivers/tty/serial/Kconfig  |  4 ++++
 drivers/tty/serial/Makefile |  2 ++
 drivers/tty/serial/of.c     | 47 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/serial_core.h | 13 +++++++++++++
 4 files changed, 66 insertions(+)
 create mode 100644 drivers/tty/serial/of.c

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 1f096e2bb398..f7d7e4936940 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -14,6 +14,10 @@ config SERIAL_EARLYCON
 	  the console before standard serial driver is probed. The console is
 	  enabled when early_param is processed.
 
+config OF_SERIAL
+	depends on SERIAL_CORE
+	def_bool y
+
 source "drivers/tty/serial/8250/Kconfig"
 
 comment "Non-8250 serial port support"
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index fe88a75d9a59..a755faa25485 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -7,6 +7,8 @@ obj-$(CONFIG_SERIAL_CORE) += serial_core.o
 obj-$(CONFIG_SERIAL_EARLYCON) += earlycon.o
 obj-$(CONFIG_SERIAL_EARLYCON_ARM_SEMIHOST) += earlycon-arm-semihost.o
 
+obj-$(CONFIG_OF_SERIAL) += of.o
+
 # These Sparc drivers have to appear before others such as 8250
 # which share ttySx minor node space.  Otherwise console device
 # names change and other unplesantries.
diff --git a/drivers/tty/serial/of.c b/drivers/tty/serial/of.c
new file mode 100644
index 000000000000..2830c688bb5d
--- /dev/null
+++ b/drivers/tty/serial/of.c
@@ -0,0 +1,47 @@
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/of.h>
+#include <linux/serial_core.h>
+
+/**
+ * of_get_rs485_mode() - Implement parsing rs485 properties
+ * @np: uart node
+ * @rs485conf: output parameter
+ *
+ * This function implements the device tree binding described in
+ * Documentation/devicetree/bindings/serial/rs485.txt.
+ *
+ * Return: 0 on success, 1 if the node doesn't contain rs485 stuff.
+ */
+int of_get_rs485_mode(struct device_node *np, struct serial_rs485 *rs485conf)
+{
+	u32 rs485_delay[2];
+	int ret;
+
+	if (!IS_ENABLED(CONFIG_OF) || !np)
+		return 1;
+
+	ret = of_property_read_u32_array(np, "rs485-rts-delay", rs485_delay, 2);
+	if (!ret) {
+		rs485conf->delay_rts_before_send = rs485_delay[0];
+		rs485conf->delay_rts_after_send = rs485_delay[1];
+	} else {
+		rs485conf->delay_rts_before_send = 0;
+		rs485conf->delay_rts_after_send = 0;
+	}
+
+	/*
+	 * clear full-duplex and enabled flags to get to a defined state with
+	 * the two following properties.
+	 */
+	rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED);
+
+	if (of_property_read_bool(np, "rs485-rx-during-tx"))
+		rs485conf->flags |= SER_RS485_RX_DURING_TX;
+
+	if (of_property_read_bool(np, "linux,rs485-enabled-at-boot-time"))
+		rs485conf->flags |= SER_RS485_ENABLED;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_get_rs485_mode);
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 1775500294bb..3a89e8925722 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -501,4 +501,17 @@ static inline int uart_handle_break(struct uart_port *port)
 					 (cflag) & CRTSCTS || \
 					 !((cflag) & CLOCAL))
 
+/*
+ * Common device tree parsing helpers
+ */
+#ifdef CONFIG_OF_SERIAL
+int of_get_rs485_mode(struct device_node *np, struct serial_rs485 *rs485conf);
+#else
+static inline int of_get_rs485_mode(struct device_node *np,
+				    struct serial_rs485 *rs485conf)
+{
+	return 1;
+}
+#endif
+
 #endif /* LINUX_SERIAL_CORE_H */
-- 
2.11.0

[PATCH v4 4/9] serial: atmel: Use common rs485 device tree parsing function

[Uwe Kleine-König]

From: Sascha Hauer <s.hauer@pengutronix.de>

We just got a common helper for parsing the rs485 specific
device tree properties. Use it and drop the open coded parser.

Note that there is a small difference between the removed and the now
used implementation: The former cleared flags to 0 if rs485-rts-delay
was given, the common helper clears SER_RS485_RX_DURING_TX and
SER_RS485_ENABLED only but always which makes more sense.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
[ukleinek: point out semantic change in commit log]
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
---
 drivers/tty/serial/atmel_serial.c | 25 +------------------------
 1 file changed, 1 insertion(+), 24 deletions(-)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 7551cab438ff..04e55f010894 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1667,29 +1667,6 @@ static void atmel_init_property(struct atmel_uart_port *atmel_port,
 	}
 }
 
-static void atmel_init_rs485(struct uart_port *port,
-				struct platform_device *pdev)
-{
-	struct device_node *np = pdev->dev.of_node;
-
-	struct serial_rs485 *rs485conf = &port->rs485;
-	u32 rs485_delay[2];
-
-	/* rs485 properties */
-	if (of_property_read_u32_array(np, "rs485-rts-delay",
-				       rs485_delay, 2) == 0) {
-		rs485conf->delay_rts_before_send = rs485_delay[0];
-		rs485conf->delay_rts_after_send = rs485_delay[1];
-		rs485conf->flags = 0;
-	}
-
-	if (of_get_property(np, "rs485-rx-during-tx", NULL))
-		rs485conf->flags |= SER_RS485_RX_DURING_TX;
-
-	if (of_get_property(np, "linux,rs485-enabled-at-boot-time", NULL))
-		rs485conf->flags |= SER_RS485_ENABLED;
-}
-
 static void atmel_set_ops(struct uart_port *port)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
@@ -2373,7 +2350,7 @@ static int atmel_init_port(struct atmel_uart_port *atmel_port,
 	atmel_init_property(atmel_port, pdev);
 	atmel_set_ops(port);
 
-	atmel_init_rs485(port, pdev);
+	of_get_rs485_mode(pdev->dev.of_node, &port->rs485);
 
 	port->iotype		= UPIO_MEM;
 	port->flags		= UPF_BOOT_AUTOCONF | UPF_IOREMAP;
-- 
2.11.0

[PATCH v4 5/9] serial: fsl_lpuart: Use common rs485 device tree parsing function

[Uwe Kleine-König]

From: Sascha Hauer <s.hauer@pengutronix.de>

We just got a common helper for parsing the rs485 specific
device tree properties. Use it and drop the open coded parser.

As a side effect this adds support for parsing rs485-rts-delay and
rs485-rx-during-tx. As the driver doesn't support this though, probing
fails if these are defined.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
---
 drivers/tty/serial/fsl_lpuart.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 4becfbf35c4c..cac81b143abe 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -2161,6 +2161,24 @@ static int lpuart_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	of_get_rs485_mode(np, &sport->port.rs485);
+
+	if (sport->port.rs485.flags & SER_RS485_RX_DURING_TX) {
+		dev_err(&pdev->dev, "driver doesn't support RX during TX\n");
+		return -ENOSYS;
+	}
+
+	if (sport->port.rs485.delay_rts_before_send ||
+	    sport->port.rs485.delay_rts_after_send) {
+		dev_err(&pdev->dev, "driver doesn't support RTS delays\n");
+		return -ENOSYS;
+	}
+
+	if (sport->port.rs485.flags & SER_RS485_ENABLED) {
+		sport->port.rs485.flags |= SER_RS485_RTS_ON_SEND;
+		writeb(UARTMODEM_TXRTSE, sport->port.membase + UARTMODEM);
+	}
+
 	sport->dma_tx_chan = dma_request_slave_channel(sport->port.dev, "tx");
 	if (!sport->dma_tx_chan)
 		dev_info(sport->port.dev, "DMA tx channel request failed, "
@@ -2171,12 +2189,6 @@ static int lpuart_probe(struct platform_device *pdev)
 		dev_info(sport->port.dev, "DMA rx channel request failed, "
 				"operating without rx DMA\n");
 
-	if (of_property_read_bool(np, "linux,rs485-enabled-at-boot-time")) {
-		sport->port.rs485.flags |= SER_RS485_ENABLED;
-		sport->port.rs485.flags |= SER_RS485_RTS_ON_SEND;
-		writeb(UARTMODEM_TXRTSE, sport->port.membase + UARTMODEM);
-	}
-
 	return 0;
 }
 
-- 
2.11.0

[PATCH v4 6/9] serial: omap-serial: Use common rs485 device tree parsing function

[Uwe Kleine-König]

From: Sascha Hauer <s.hauer@pengutronix.de>

We just got a common helper for parsing the rs485 specific
device tree properties. Use it and drop the open coded parser.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
---
 drivers/tty/serial/omap-serial.c | 13 +------------
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 1ea05ac57aa7..6d22097e6dd0 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1607,7 +1607,6 @@ static int serial_omap_probe_rs485(struct uart_omap_port *up,
 				   struct device_node *np)
 {
 	struct serial_rs485 *rs485conf = &up->port.rs485;
-	u32 rs485_delay[2];
 	enum of_gpio_flags flags;
 	int ret;
 
@@ -1638,17 +1637,7 @@ static int serial_omap_probe_rs485(struct uart_omap_port *up,
 		up->rts_gpio = -EINVAL;
 	}
 
-	if (of_property_read_u32_array(np, "rs485-rts-delay",
-				    rs485_delay, 2) == 0) {
-		rs485conf->delay_rts_before_send = rs485_delay[0];
-		rs485conf->delay_rts_after_send = rs485_delay[1];
-	}
-
-	if (of_property_read_bool(np, "rs485-rx-during-tx"))
-		rs485conf->flags |= SER_RS485_RX_DURING_TX;
-
-	if (of_property_read_bool(np, "linux,rs485-enabled-at-boot-time"))
-		rs485conf->flags |= SER_RS485_ENABLED;
+	of_get_rs485_mode(np, rs485conf);
 
 	return 0;
 }
-- 
2.11.0

[PATCH v4 7/9] serial: imx: default to half duplex rs485

[Uwe Kleine-König]

From: Sascha Hauer <s.hauer@pengutronix.de>

The i.MX driver defaulted to full duplex rs485 which is rather
unusual and doesn't match the default implemented in other drivers.

So change the default to half duplex.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
---
 drivers/tty/serial/imx.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 80934e7bd67f..bb5cd8ff7d86 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -2120,8 +2120,7 @@ static int serial_imx_probe(struct platform_device *pdev)
 	sport->port.fifosize = 32;
 	sport->port.ops = &imx_pops;
 	sport->port.rs485_config = imx_rs485_config;
-	sport->port.rs485.flags =
-		SER_RS485_RTS_ON_SEND | SER_RS485_RX_DURING_TX;
+	sport->port.rs485.flags = SER_RS485_RTS_ON_SEND;
 	sport->port.flags = UPF_BOOT_AUTOCONF;
 	init_timer(&sport->timer);
 	sport->timer.function = imx_timeout;
-- 
2.11.0

[PATCH v4 8/9] serial: imx: Use common rs485 device tree parsing function

[Uwe Kleine-König]

From: Sascha Hauer <s.hauer@pengutronix.de>

This adds support for the rs485 specific properties defined in
Documentation/devicetree/bindings/serial/rs485.txt.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
---
 drivers/tty/serial/imx.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index bb5cd8ff7d86..88957f31d8ed 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -2059,6 +2059,8 @@ static int serial_imx_probe_dt(struct imx_port *sport,
 	if (of_get_property(np, "rts-gpios", NULL))
 		sport->have_rtsgpio = 1;
 
+	of_get_rs485_mode(np, &sport->port.rs485);
+
 	return 0;
 }
 #else
-- 
2.11.0

[PATCH v4 9/9] dt-bindings: serial: document rs485 bindings for various devices

[Uwe Kleine-König]

Atmel USART, Freescale UARTs and OMAP UART all support the rs485 binding
described in rs485.txt, this commit just makes that explicit.

Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
---
 Documentation/devicetree/bindings/serial/atmel-usart.txt  | 1 +
 Documentation/devicetree/bindings/serial/fsl-imx-uart.txt | 1 +
 Documentation/devicetree/bindings/serial/fsl-lpuart.txt   | 1 +
 Documentation/devicetree/bindings/serial/omap_serial.txt  | 1 +
 4 files changed, 4 insertions(+)

diff --git a/Documentation/devicetree/bindings/serial/atmel-usart.txt b/Documentation/devicetree/bindings/serial/atmel-usart.txt
index e6e6142e33ac..7c0d6b2f53e4 100644
--- a/Documentation/devicetree/bindings/serial/atmel-usart.txt
+++ b/Documentation/devicetree/bindings/serial/atmel-usart.txt
@@ -24,6 +24,7 @@ Optional properties:
 	- dma-names: "rx" for RX channel, "tx" for TX channel.
 - atmel,fifo-size: maximum number of data the RX and TX FIFOs can store for FIFO
   capable USARTs.
+- rs485-rts-delay, rs485-rx-during-tx, linux,rs485-enabled-at-boot-time: see rs485.txt
 
 <chip> compatible description:
 - at91rm9200:  legacy USART support
diff --git a/Documentation/devicetree/bindings/serial/fsl-imx-uart.txt b/Documentation/devicetree/bindings/serial/fsl-imx-uart.txt
index 574c3a2c77d5..860a9559839a 100644
--- a/Documentation/devicetree/bindings/serial/fsl-imx-uart.txt
+++ b/Documentation/devicetree/bindings/serial/fsl-imx-uart.txt
@@ -9,6 +9,7 @@ Optional properties:
 - fsl,irda-mode : Indicate the uart supports irda mode
 - fsl,dte-mode : Indicate the uart works in DTE mode. The uart works
                   in DCE mode by default.
+- rs485-rts-delay, rs485-rx-during-tx, linux,rs485-enabled-at-boot-time: see rs485.txt
 
 Please check Documentation/devicetree/bindings/serial/serial.txt
 for the complete list of generic properties.
diff --git a/Documentation/devicetree/bindings/serial/fsl-lpuart.txt b/Documentation/devicetree/bindings/serial/fsl-lpuart.txt
index a1252a047f78..59567b51cf09 100644
--- a/Documentation/devicetree/bindings/serial/fsl-lpuart.txt
+++ b/Documentation/devicetree/bindings/serial/fsl-lpuart.txt
@@ -16,6 +16,7 @@ Required properties:
 Optional properties:
 - dmas: A list of two dma specifiers, one for each entry in dma-names.
 - dma-names: should contain "tx" and "rx".
+- rs485-rts-delay, rs485-rx-during-tx, linux,rs485-enabled-at-boot-time: see rs485.txt
 
 Note: Optional properties for DMA support. Write them both or both not.
 
diff --git a/Documentation/devicetree/bindings/serial/omap_serial.txt b/Documentation/devicetree/bindings/serial/omap_serial.txt
index 7a71b5de77d6..43eac675f21f 100644
--- a/Documentation/devicetree/bindings/serial/omap_serial.txt
+++ b/Documentation/devicetree/bindings/serial/omap_serial.txt
@@ -19,6 +19,7 @@ Optional properties:
 - dmas : DMA specifier, consisting of a phandle to the DMA controller
          node and a DMA channel number.
 - dma-names : "rx" for receive channel, "tx" for transmit channel.
+- rs485-rts-delay, rs485-rx-during-tx, linux,rs485-enabled-at-boot-time: see rs485.txt
 
 Example:
 
-- 
2.11.0

[PATCH v4 3/9] serial: Add common rs485 device tree parsing function

[Greg KH]

On Tue, Jul 18, 2017 at 12:59:42PM +0200, Uwe Kleine-K?nig wrote:
> From: Sascha Hauer <s.hauer@pengutronix.de>
> 
> Several drivers have the same device tree parsing code. Create
> a common helper function for it.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> [ukl: implement default <0 0> for rts-delay, unset unspecified flags]
> Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
> Signed-off-by: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
> ---
>  drivers/tty/serial/Kconfig  |  4 ++++
>  drivers/tty/serial/Makefile |  2 ++
>  drivers/tty/serial/of.c     | 47 +++++++++++++++++++++++++++++++++++++++++++++

Why is this a separate file, with a Kconfig option that is always
enabled?  Why not just add the single function to the serial core?

> +/**
> + * of_get_rs485_mode() - Implement parsing rs485 properties
> + * @np: uart node
> + * @rs485conf: output parameter
> + *
> + * This function implements the device tree binding described in
> + * Documentation/devicetree/bindings/serial/rs485.txt.
> + *
> + * Return: 0 on success, 1 if the node doesn't contain rs485 stuff.

1 is not an error code :(

Return a proper error please.


> + */
> +int of_get_rs485_mode(struct device_node *np, struct serial_rs485 *rs485conf)
> +{
> +	u32 rs485_delay[2];
> +	int ret;
> +
> +	if (!IS_ENABLED(CONFIG_OF) || !np)
> +		return 1;
> +
> +	ret = of_property_read_u32_array(np, "rs485-rts-delay", rs485_delay, 2);
> +	if (!ret) {
> +		rs485conf->delay_rts_before_send = rs485_delay[0];
> +		rs485conf->delay_rts_after_send = rs485_delay[1];
> +	} else {
> +		rs485conf->delay_rts_before_send = 0;
> +		rs485conf->delay_rts_after_send = 0;
> +	}
> +
> +	/*
> +	 * clear full-duplex and enabled flags to get to a defined state with
> +	 * the two following properties.
> +	 */
> +	rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED);
> +
> +	if (of_property_read_bool(np, "rs485-rx-during-tx"))
> +		rs485conf->flags |= SER_RS485_RX_DURING_TX;
> +
> +	if (of_property_read_bool(np, "linux,rs485-enabled-at-boot-time"))
> +		rs485conf->flags |= SER_RS485_ENABLED;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(of_get_rs485_mode);
> diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
> index 1775500294bb..3a89e8925722 100644
> --- a/include/linux/serial_core.h
> +++ b/include/linux/serial_core.h
> @@ -501,4 +501,17 @@ static inline int uart_handle_break(struct uart_port *port)
>  					 (cflag) & CRTSCTS || \
>  					 !((cflag) & CLOCAL))
>  
> +/*
> + * Common device tree parsing helpers
> + */
> +#ifdef CONFIG_OF_SERIAL
> +int of_get_rs485_mode(struct device_node *np, struct serial_rs485 *rs485conf);
> +#else
> +static inline int of_get_rs485_mode(struct device_node *np,
> +				    struct serial_rs485 *rs485conf)
> +{
> +	return 1;

Again, a real error.

And why not have a "generic" firmware function for this that defaults to
the of_ for that platform type if present?  What's the odds that acpi
will need/want this soon anyway?

thanks,

greg k-h

[PATCH v4 4/9] serial: atmel: Use common rs485 device tree parsing function

[Greg KH]

On Tue, Jul 18, 2017 at 12:59:43PM +0200, Uwe Kleine-K?nig wrote:
> From: Sascha Hauer <s.hauer@pengutronix.de>
> 
> We just got a common helper for parsing the rs485 specific
> device tree properties. Use it and drop the open coded parser.
> 
> Note that there is a small difference between the removed and the now
> used implementation: The former cleared flags to 0 if rs485-rts-delay
> was given, the common helper clears SER_RS485_RX_DURING_TX and
> SER_RS485_ENABLED only but always which makes more sense.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> [ukleinek: point out semantic change in commit log]
> Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
> Acked-by: Richard Genoud <richard.genoud@gmail.com>
> Signed-off-by: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
> ---
>  drivers/tty/serial/atmel_serial.c | 25 +------------------------
>  1 file changed, 1 insertion(+), 24 deletions(-)
> 
> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
> index 7551cab438ff..04e55f010894 100644
> --- a/drivers/tty/serial/atmel_serial.c
> +++ b/drivers/tty/serial/atmel_serial.c
> @@ -1667,29 +1667,6 @@ static void atmel_init_property(struct atmel_uart_port *atmel_port,
>  	}
>  }
>  
> -static void atmel_init_rs485(struct uart_port *port,
> -				struct platform_device *pdev)
> -{
> -	struct device_node *np = pdev->dev.of_node;
> -
> -	struct serial_rs485 *rs485conf = &port->rs485;
> -	u32 rs485_delay[2];
> -
> -	/* rs485 properties */
> -	if (of_property_read_u32_array(np, "rs485-rts-delay",
> -				       rs485_delay, 2) == 0) {
> -		rs485conf->delay_rts_before_send = rs485_delay[0];
> -		rs485conf->delay_rts_after_send = rs485_delay[1];
> -		rs485conf->flags = 0;
> -	}
> -
> -	if (of_get_property(np, "rs485-rx-during-tx", NULL))
> -		rs485conf->flags |= SER_RS485_RX_DURING_TX;
> -
> -	if (of_get_property(np, "linux,rs485-enabled-at-boot-time", NULL))
> -		rs485conf->flags |= SER_RS485_ENABLED;
> -}
> -
>  static void atmel_set_ops(struct uart_port *port)
>  {
>  	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> @@ -2373,7 +2350,7 @@ static int atmel_init_port(struct atmel_uart_port *atmel_port,
>  	atmel_init_property(atmel_port, pdev);
>  	atmel_set_ops(port);
>  
> -	atmel_init_rs485(port, pdev);
> +	of_get_rs485_mode(pdev->dev.of_node, &port->rs485);

No error checking?

[PATCH v4 5/9] serial: fsl_lpuart: Use common rs485 device tree parsing function

[Greg KH]

On Tue, Jul 18, 2017 at 12:59:44PM +0200, Uwe Kleine-K?nig wrote:
> From: Sascha Hauer <s.hauer@pengutronix.de>
> 
> We just got a common helper for parsing the rs485 specific
> device tree properties. Use it and drop the open coded parser.
> 
> As a side effect this adds support for parsing rs485-rts-delay and
> rs485-rx-during-tx. As the driver doesn't support this though, probing
> fails if these are defined.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> Signed-off-by: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
> ---
>  drivers/tty/serial/fsl_lpuart.c | 24 ++++++++++++++++++------
>  1 file changed, 18 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
> index 4becfbf35c4c..cac81b143abe 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -2161,6 +2161,24 @@ static int lpuart_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> +	of_get_rs485_mode(np, &sport->port.rs485);

error checking?

Elsewhere in this series as well.

Also, why did you not cc: me on this series so I am sure to see it?

thanks,

greg k-h

[PATCH v4 3/9] serial: Add common rs485 device tree parsing function

[Uwe Kleine-König]

On Sun, Jul 30, 2017 at 07:49:47AM -0700, Greg KH wrote:
> On Tue, Jul 18, 2017 at 12:59:42PM +0200, Uwe Kleine-K?nig wrote:
> > From: Sascha Hauer <s.hauer@pengutronix.de>
> > 
> > Several drivers have the same device tree parsing code. Create
> > a common helper function for it.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > [ukl: implement default <0 0> for rts-delay, unset unspecified flags]
> > Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
> > Signed-off-by: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
> > ---
> >  drivers/tty/serial/Kconfig  |  4 ++++
> >  drivers/tty/serial/Makefile |  2 ++
> >  drivers/tty/serial/of.c     | 47 +++++++++++++++++++++++++++++++++++++++++++++
> 
> Why is this a separate file, with a Kconfig option that is always
> enabled?  Why not just add the single function to the serial core?

Probably just a matter of taste. If you prefer I can put it into
drivers/tty/serial/serial_core.c
 
> > +/**
> > + * of_get_rs485_mode() - Implement parsing rs485 properties
> > + * @np: uart node
> > + * @rs485conf: output parameter
> > + *
> > + * This function implements the device tree binding described in
> > + * Documentation/devicetree/bindings/serial/rs485.txt.
> > + *
> > + * Return: 0 on success, 1 if the node doesn't contain rs485 stuff.
> 
> 1 is not an error code :(
> 
> Return a proper error please.

Well, it's not an error. These properties are optional and if I return
(say) -ENOENT in this case, a caller looks as follows:

	ret = of_get_rs485_mode(...);
	if (ret == -ENOENT) {
		/*
		 * hmm, does this mean there are no rs485 properties, or
		 * is this a different error that I should propagate
		 * because there is a problem with the device tree?
		 * I'm optimistic and assume the former.
		 * As of_get_rs485_mode already did everything
		 * necessary, there is no need to do anything else.
		 */
	} else if (ret < 0) {
		return ret;
	}

With the semantic I chose it is just:

	ret = of_get_rs485_mode(...);
	if (ret < 0)
		return ret;

without any guessing.

> > + */
> > +int of_get_rs485_mode(struct device_node *np, struct serial_rs485 *rs485conf)
> > +{
> > +	u32 rs485_delay[2];
> > +	int ret;
> > +
> > +	if (!IS_ENABLED(CONFIG_OF) || !np)
> > +		return 1;
> > +
> > +	ret = of_property_read_u32_array(np, "rs485-rts-delay", rs485_delay, 2);
> > +	if (!ret) {
> > +		rs485conf->delay_rts_before_send = rs485_delay[0];
> > +		rs485conf->delay_rts_after_send = rs485_delay[1];
> > +	} else {
> > +		rs485conf->delay_rts_before_send = 0;
> > +		rs485conf->delay_rts_after_send = 0;
> > +	}
> > +
> > +	/*
> > +	 * clear full-duplex and enabled flags to get to a defined state with
> > +	 * the two following properties.
> > +	 */
> > +	rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED);
> > +
> > +	if (of_property_read_bool(np, "rs485-rx-during-tx"))
> > +		rs485conf->flags |= SER_RS485_RX_DURING_TX;
> > +
> > +	if (of_property_read_bool(np, "linux,rs485-enabled-at-boot-time"))
> > +		rs485conf->flags |= SER_RS485_ENABLED;
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(of_get_rs485_mode);
> > diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
> > index 1775500294bb..3a89e8925722 100644
> > --- a/include/linux/serial_core.h
> > +++ b/include/linux/serial_core.h
> > @@ -501,4 +501,17 @@ static inline int uart_handle_break(struct uart_port *port)
> >  					 (cflag) & CRTSCTS || \
> >  					 !((cflag) & CLOCAL))
> >  
> > +/*
> > + * Common device tree parsing helpers
> > + */
> > +#ifdef CONFIG_OF_SERIAL
> > +int of_get_rs485_mode(struct device_node *np, struct serial_rs485 *rs485conf);
> > +#else
> > +static inline int of_get_rs485_mode(struct device_node *np,
> > +				    struct serial_rs485 *rs485conf)
> > +{
> > +	return 1;
> 
> Again, a real error.

OK, I could agree to return -ENOSYS here. I predict I get complaints
about this though and people will do:

	ret = of_get_rs485_mode(...);
	if (ret == -ENOSYS) {
		/* ignore */
	} else if (ret < 0) {
		return ret;
	}

which one might consider troublesome or even wrong. (See the same
discussions about 22c403676dbbb7c6f186099527af7f065498ef45 where I
wanted to keep -ENOSYS.)
 
> And why not have a "generic" firmware function for this that defaults to
> the of_ for that platform type if present?  What's the odds that acpi
> will need/want this soon anyway?

I don't know about ACPI and all systems I care about are using dt. So
I'd suggest we stick to dt and switch to "generic" if and when the need
arises?

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-K?nig            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |