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Commit ce59e48f authored by Uwe Kleine-König's avatar Uwe Kleine-König Committed by Greg Kroah-Hartman
Browse files

serial: mctrl_gpio: implement interrupt handling 



This allows to reduce the per-driver boiler plate considerably.

Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: default avatarNicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7d8c70d8

Documentation/serial/driver

+9 −1
Original line number Diff line number Diff line
@@ -439,11 +439,13 @@ Modem control lines via GPIO 


Some helpers are provided in order to set/get modem control lines via GPIO.



mctrl_gpio_init(dev, idx):

mctrl_gpio_init(port, idx):

	This will get the {cts,rts,...}-gpios from device tree if they are

	present and request them, set direction etc, and return an

	allocated structure. devm_* functions are used, so there's no need

	to call mctrl_gpio_free().

	As this sets up the irq handling make sure to not handle changes to the

	gpio input lines in your driver, too.



mctrl_gpio_free(dev, gpios):

	This will free the requested gpios in mctrl_gpio_init().
@@ -458,3 +460,9 @@ mctrl_gpio_set(gpios, mctrl): 


mctrl_gpio_get(gpios, mctrl):

	This will update mctrl with the gpios values.



mctrl_gpio_enable_ms(gpios):

	Enables irqs and handling of changes to the ms lines.



mctrl_gpio_disable_ms(gpios):

	Disables irqs and handling of changes to the ms lines.

drivers/tty/serial/serial_mctrl_gpio.c

+127 −2
Original line number Diff line number Diff line
@@ -12,18 +12,23 @@ 
 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 */



#include <linux/err.h>

#include <linux/device.h>

#include <linux/irq.h>

#include <linux/gpio/consumer.h>

#include <linux/termios.h>

#include <linux/serial_core.h>



#include "serial_mctrl_gpio.h"



struct mctrl_gpios {

	struct uart_port *port;

	struct gpio_desc *gpio[UART_GPIO_MAX];

	int irq[UART_GPIO_MAX];

	unsigned int mctrl_prev;

	bool mctrl_on;

};



static const struct {
@@ -112,13 +117,133 @@ struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx) 
}

EXPORT_SYMBOL_GPL(mctrl_gpio_init_noauto);



#define MCTRL_ANY_DELTA (TIOCM_RI | TIOCM_DSR | TIOCM_CD | TIOCM_CTS)

static irqreturn_t mctrl_gpio_irq_handle(int irq, void *context)

{

	struct mctrl_gpios *gpios = context;

	struct uart_port *port = gpios->port;

	u32 mctrl = gpios->mctrl_prev;

	u32 mctrl_diff;



	mctrl_gpio_get(gpios, &mctrl);



	mctrl_diff = mctrl ^ gpios->mctrl_prev;

	gpios->mctrl_prev = mctrl;



	if (mctrl_diff & MCTRL_ANY_DELTA && port->state != NULL) {

		if ((mctrl_diff & mctrl) & TIOCM_RI)

			port->icount.rng++;



		if ((mctrl_diff & mctrl) & TIOCM_DSR)

			port->icount.dsr++;



		if (mctrl_diff & TIOCM_CD)

			uart_handle_dcd_change(port, mctrl & TIOCM_CD);



		if (mctrl_diff & TIOCM_CTS)

			uart_handle_cts_change(port, mctrl & TIOCM_CTS);



		wake_up_interruptible(&port->state->port.delta_msr_wait);

	}



	return IRQ_HANDLED;

}



struct mctrl_gpios *mctrl_gpio_init(struct uart_port *port, unsigned int idx)

{

	struct mctrl_gpios *gpios;

	enum mctrl_gpio_idx i;



	gpios = mctrl_gpio_init_noauto(port->dev, idx);

	if (IS_ERR(gpios))

		return gpios;



	gpios->port = port;



	for (i = 0; i < UART_GPIO_MAX; ++i) {

		int ret;



		if (!gpios->gpio[i] || mctrl_gpios_desc[i].dir_out)

			continue;



		ret = gpiod_to_irq(gpios->gpio[i]);

		if (ret <= 0) {

			dev_err(port->dev,

				"failed to find corresponding irq for %s (idx=%d, err=%d)\n",

				mctrl_gpios_desc[i].name, idx, ret);

			return ERR_PTR(ret);

		}

		gpios->irq[i] = ret;



		/* irqs should only be enabled in .enable_ms */

		irq_set_status_flags(gpios->irq[i], IRQ_NOAUTOEN);



		ret = devm_request_irq(port->dev, gpios->irq[i],

				       mctrl_gpio_irq_handle,

				       IRQ_TYPE_EDGE_BOTH, dev_name(port->dev),

				       gpios);

		if (ret) {

			/* alternatively implement polling */

			dev_err(port->dev,

				"failed to request irq for %s (idx=%d, err=%d)\n",

				mctrl_gpios_desc[i].name, idx, ret);

			return ERR_PTR(ret);

		}

	}



	return gpios;

}



void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)

{

	enum mctrl_gpio_idx i;



	for (i = 0; i < UART_GPIO_MAX; i++)

	for (i = 0; i < UART_GPIO_MAX; i++) {

		if (gpios->irq[i])

			devm_free_irq(gpios->port->dev, gpios->irq[i], gpios);



		if (gpios->gpio[i])

			devm_gpiod_put(dev, gpios->gpio[i]);

	}

	devm_kfree(dev, gpios);

}

EXPORT_SYMBOL_GPL(mctrl_gpio_free);



void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)

{

	enum mctrl_gpio_idx i;



	/* .enable_ms may be called multiple times */

	if (gpios->mctrl_on)

		return;



	gpios->mctrl_on = true;



	/* get initial status of modem lines GPIOs */

	mctrl_gpio_get(gpios, &gpios->mctrl_prev);



	for (i = 0; i < UART_GPIO_MAX; ++i) {

		if (!gpios->irq[i])

			continue;



		enable_irq(gpios->irq[i]);

	}

}

EXPORT_SYMBOL_GPL(mctrl_gpio_enable_ms);



void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)

{

	enum mctrl_gpio_idx i;



	if (!gpios->mctrl_on)

		return;



	gpios->mctrl_on = false;



	for (i = 0; i < UART_GPIO_MAX; ++i) {

		if (!gpios->irq[i])

			continue;



		disable_irq(gpios->irq[i]);

	}

}

drivers/tty/serial/serial_mctrl_gpio.h

+35 −0
Original line number Diff line number Diff line
@@ -22,6 +22,8 @@ 
#include <linux/device.h>

#include <linux/gpio/consumer.h>



struct uart_port;



enum mctrl_gpio_idx {

	UART_GPIO_CTS,

	UART_GPIO_DSR,
@@ -59,6 +61,15 @@ unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl); 
struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,

				      enum mctrl_gpio_idx gidx);



/*

 * Request and set direction of modem control lines GPIOs and sets up irq

 * handling.

 * devm_* functions are used, so there's no need to call mctrl_gpio_free().

 * Returns a pointer to the allocated mctrl structure if ok, -ENOMEM on

 * allocation error.

 */

struct mctrl_gpios *mctrl_gpio_init(struct uart_port *port, unsigned int idx);



/*

 * Request and set direction of modem control lines GPIOs.

 * devm_* functions are used, so there's no need to call mctrl_gpio_free().
@@ -75,6 +86,16 @@ struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, 
 */

void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios);



/*

 * Enable gpio interrupts to report status line changes.

 */

void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios);



/*

 * Disable gpio interrupts to report status line changes.

 */

void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios);



#else /* GPIOLIB */



static inline
@@ -95,6 +116,12 @@ struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios, 
	return ERR_PTR(-ENOSYS);

}



static inline

struct mctrl_gpios *mctrl_gpio_init(struct uart_port *port, unsigned int idx)

{

	return ERR_PTR(-ENOSYS);

}



static inline

struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx)

{
@@ -106,6 +133,14 @@ void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios) 
{

}



void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)

{

}



void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)

{

}



#endif /* GPIOLIB */



#endif