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Commit 7c573d7e authored by Janusz Uzycki's avatar Janusz Uzycki Committed by Greg Kroah-Hartman
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serial: mxs-auart: use mctrl_gpio helpers for handling modem signals 



Dedicated CTS and RTS pins are unusable together with a lot of other
peripherals because they share the same line. Pinctrl is limited.

Moreover, the AUART controller doesn't handle DTR/DSR/DCD/RI signals,
so we have to control them via GPIO.

This patch permits to use GPIOs to control the CTS/RTS/DTR/DSR/DCD/RI
signals.

Signed-off-by: default avatarJanusz Uzycki <j.uzycki@elproma.com.pl>
Reviewed-by: default avatarRichard Genoud <richard.genoud@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 42b4eba0

Documentation/devicetree/bindings/serial/fsl-mxs-auart.txt

+9 −1
Original line number Diff line number Diff line
@@ -11,8 +11,13 @@ Required properties: 
- dma-names: "rx" for RX channel, "tx" for TX channel.



Optional properties:

- fsl,uart-has-rtscts : Indicate the UART has RTS and CTS lines,

- fsl,uart-has-rtscts : Indicate the UART has RTS and CTS lines

  for hardware flow control,

	it also means you enable the DMA support for this UART.

- {rts,cts,dtr,dsr,rng,dcd}-gpios: specify a GPIO for RTS/CTS/DTR/DSR/RI/DCD

  line respectively. It will use specified PIO instead of the peripheral

  function pin for the USART feature.

  If unsure, don't specify this property.



Example:

auart0: serial@8006a000 {
@@ -21,6 +26,9 @@ auart0: serial@8006a000 { 
	interrupts = <112>;

	dmas = <&dma_apbx 8>, <&dma_apbx 9>;

	dma-names = "rx", "tx";

	cts-gpios = <&gpio1 15 GPIO_ACTIVE_LOW>;

	dsr-gpios = <&gpio1 16 GPIO_ACTIVE_LOW>;

	dcd-gpios = <&gpio1 17 GPIO_ACTIVE_LOW>;

};



Note: Each auart port should have an alias correctly numbered in "aliases"

drivers/tty/serial/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -1408,6 +1408,7 @@ config SERIAL_MXS_AUART 
	depends on ARCH_MXS

	tristate "MXS AUART support"

	select SERIAL_CORE

	select SERIAL_MCTRL_GPIO if GPIOLIB

	help

	  This driver supports the MXS Application UART (AUART) port.

drivers/tty/serial/mxs-auart.c

+45 −5
Original line number Diff line number Diff line
@@ -42,6 +42,9 @@ 


#include <asm/cacheflush.h>



#include <linux/err.h>

#include "serial_mctrl_gpio.h"



#define MXS_AUART_PORTS 5

#define MXS_AUART_FIFO_SIZE		16
@@ -158,6 +161,8 @@ struct mxs_auart_port { 
	struct scatterlist rx_sgl;

	struct dma_chan	*rx_dma_chan;

	void *rx_dma_buf;



	struct mctrl_gpios	*gpios;

};



static struct platform_device_id mxs_auart_devtype[] = {
@@ -405,6 +410,8 @@ static void mxs_auart_release_port(struct uart_port *u) 


static void mxs_auart_set_mctrl(struct uart_port *u, unsigned mctrl)

{

	struct mxs_auart_port *s = to_auart_port(u);



	u32 ctrl = readl(u->membase + AUART_CTRL2);



	ctrl &= ~(AUART_CTRL2_RTSEN | AUART_CTRL2_RTS);
@@ -416,17 +423,20 @@ static void mxs_auart_set_mctrl(struct uart_port *u, unsigned mctrl) 
	}



	writel(ctrl, u->membase + AUART_CTRL2);



	mctrl_gpio_set(s->gpios, mctrl);

}



static u32 mxs_auart_get_mctrl(struct uart_port *u)

{

	struct mxs_auart_port *s = to_auart_port(u);

	u32 stat = readl(u->membase + AUART_STAT);

	u32 mctrl = 0;



	if (stat & AUART_STAT_CTS)

		mctrl |= TIOCM_CTS;



	return mctrl;

	return mctrl_gpio_get(s->gpios, &mctrl);

}



static int mxs_auart_dma_prep_rx(struct mxs_auart_port *s);
@@ -554,6 +564,10 @@ static int mxs_auart_dma_init(struct mxs_auart_port *s) 


}



#define RTS_AT_AUART()	IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(s->gpios,	\

							UART_GPIO_RTS))

#define CTS_AT_AUART()	IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(s->gpios,	\

							UART_GPIO_CTS))

static void mxs_auart_settermios(struct uart_port *u,

				 struct ktermios *termios,

				 struct ktermios *old)
@@ -630,6 +644,7 @@ static void mxs_auart_settermios(struct uart_port *u, 
		ctrl |= AUART_LINECTRL_STP2;



	/* figure out the hardware flow control settings */

	ctrl2 &= ~(AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN);

	if (cflag & CRTSCTS) {

		/*

		 * The DMA has a bug(see errata:2836) in mx23.
@@ -644,9 +659,11 @@ static void mxs_auart_settermios(struct uart_port *u, 
				ctrl2 |= AUART_CTRL2_TXDMAE | AUART_CTRL2_RXDMAE

				       | AUART_CTRL2_DMAONERR;

		}

		ctrl2 |= AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN;

	} else {

		ctrl2 &= ~(AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN);

		/* Even if RTS is GPIO line RTSEN can be enabled because

		 * the pinctrl configuration decides about RTS pin function */

		ctrl2 |= AUART_CTRL2_RTSEN;

		if (CTS_AT_AUART())

			ctrl2 |= AUART_CTRL2_CTSEN;

	}



	/* set baud rate */
@@ -690,7 +707,9 @@ static irqreturn_t mxs_auart_irq_handle(int irq, void *context) 
			s->port.membase + AUART_INTR_CLR);



	if (istat & AUART_INTR_CTSMIS) {

		uart_handle_cts_change(&s->port, stat & AUART_STAT_CTS);

		if (CTS_AT_AUART())

			uart_handle_cts_change(&s->port,

					stat & AUART_STAT_CTS);

		writel(AUART_INTR_CTSMIS,

				s->port.membase + AUART_INTR_CLR);

		istat &= ~AUART_INTR_CTSMIS;
@@ -1014,6 +1033,23 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s, 
	return 0;

}



static bool mxs_auart_init_gpios(struct mxs_auart_port *s, struct device *dev)

{

	s->gpios = mctrl_gpio_init(dev, 0);

	if (IS_ERR_OR_NULL(s->gpios))

		return false;



	/* Block (enabled before) DMA option if RTS or CTS is GPIO line */

	if (!RTS_AT_AUART() || !CTS_AT_AUART()) {

		if (test_bit(MXS_AUART_RTSCTS, &s->flags))

			dev_warn(dev,

				 "DMA and flow control via gpio may cause some problems. DMA disabled!\n");

		clear_bit(MXS_AUART_RTSCTS, &s->flags);

	}



	return true;

}



static int mxs_auart_probe(struct platform_device *pdev)

{

	const struct of_device_id *of_id =
@@ -1069,6 +1105,10 @@ static int mxs_auart_probe(struct platform_device *pdev) 


	platform_set_drvdata(pdev, s);



	if (!mxs_auart_init_gpios(s, &pdev->dev))

		dev_err(&pdev->dev,

			"Failed to initialize GPIOs. The serial port may not work as expected\n");



	auart_port[s->port.line] = s;



	mxs_auart_reset(&s->port);