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Commit 1e33936d authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
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media: cec-gpio: add HDMI CEC GPIO driver 



Add a simple HDMI CEC GPIO driver that sits on top of the cec-pin framework.

While I have heard of SoCs that use the GPIO pin for CEC (apparently an
early RockChip SoC used that), the main use-case of this driver is to
function as a debugging tool.

By connecting the CEC line to a GPIO pin on a Raspberry Pi 3 for example
it turns it into a CEC debugger and protocol analyzer.

With 'cec-ctl --monitor-pin' the CEC traffic can be analyzed.

But of course it can also be used with any hardware project where the
HDMI CEC line is hooked up to a pull-up gpio line.

In addition this has (optional) support for tracing HPD changes if the
HPD is connected to a GPIO.

Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent 67f2a06f

drivers/media/platform/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -553,6 +553,16 @@ config VIDEO_MESON_AO_CEC 
	  This is a driver for Amlogic Meson SoCs AO CEC interface. It uses the

	  generic CEC framework interface.

	  CEC bus is present in the HDMI connector and enables communication



config CEC_GPIO

	tristate "Generic GPIO-based CEC driver"

	depends on PREEMPT

	select CEC_CORE

	select CEC_PIN

	select GPIOLIB

	---help---

	  This is a generic GPIO-based CEC driver.

	  The CEC bus is present in the HDMI connector and enables communication

	  between compatible devices.



config VIDEO_SAMSUNG_S5P_CEC

drivers/media/platform/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -26,6 +26,8 @@ obj-$(CONFIG_VIDEO_CODA) += coda/ 


obj-$(CONFIG_VIDEO_SH_VEU)		+= sh_veu.o



obj-$(CONFIG_CEC_GPIO)			+= cec-gpio/



obj-$(CONFIG_VIDEO_MEM2MEM_DEINTERLACE)	+= m2m-deinterlace.o



obj-$(CONFIG_VIDEO_MUX)			+= video-mux.o

drivers/media/platform/cec-gpio/Makefile

0 → 100644
+1 −0
Original line number Diff line number Diff line 
obj-$(CONFIG_CEC_GPIO) += cec-gpio.o

drivers/media/platform/cec-gpio/cec-gpio.c

0 → 100644
+236 −0
Original line number Diff line number Diff line 
/*

 * Copyright 2017 Cisco Systems, Inc. and/or its affiliates. All rights reserved.

 *

 * This program is free software; you may redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; version 2 of the License.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS

 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN

 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN

 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

 * SOFTWARE.

 */



#include <linux/module.h>

#include <linux/interrupt.h>

#include <linux/delay.h>

#include <linux/platform_device.h>

#include <linux/gpio/consumer.h>

#include <media/cec-pin.h>



struct cec_gpio {

	struct cec_adapter	*adap;

	struct device		*dev;



	struct gpio_desc	*cec_gpio;

	int			cec_irq;

	bool			cec_is_low;

	bool			cec_have_irq;



	struct gpio_desc	*hpd_gpio;

	int			hpd_irq;

	bool			hpd_is_high;

	ktime_t			hpd_ts;

};



static bool cec_gpio_read(struct cec_adapter *adap)

{

	struct cec_gpio *cec = cec_get_drvdata(adap);



	if (cec->cec_is_low)

		return false;

	return gpiod_get_value(cec->cec_gpio);

}



static void cec_gpio_high(struct cec_adapter *adap)

{

	struct cec_gpio *cec = cec_get_drvdata(adap);



	if (!cec->cec_is_low)

		return;

	cec->cec_is_low = false;

	gpiod_set_value(cec->cec_gpio, 1);

}



static void cec_gpio_low(struct cec_adapter *adap)

{

	struct cec_gpio *cec = cec_get_drvdata(adap);



	if (cec->cec_is_low)

		return;

	if (WARN_ON_ONCE(cec->cec_have_irq))

		free_irq(cec->cec_irq, cec);

	cec->cec_have_irq = false;

	cec->cec_is_low = true;

	gpiod_set_value(cec->cec_gpio, 0);

}



static irqreturn_t cec_hpd_gpio_irq_handler_thread(int irq, void *priv)

{

	struct cec_gpio *cec = priv;



	cec_queue_pin_hpd_event(cec->adap, cec->hpd_is_high, cec->hpd_ts);

	return IRQ_HANDLED;

}



static irqreturn_t cec_hpd_gpio_irq_handler(int irq, void *priv)

{

	struct cec_gpio *cec = priv;



	cec->hpd_ts = ktime_get();

	cec->hpd_is_high = gpiod_get_value(cec->hpd_gpio);

	return IRQ_WAKE_THREAD;

}



static irqreturn_t cec_gpio_irq_handler(int irq, void *priv)

{

	struct cec_gpio *cec = priv;



	cec_pin_changed(cec->adap, gpiod_get_value(cec->cec_gpio));

	return IRQ_HANDLED;

}



static bool cec_gpio_enable_irq(struct cec_adapter *adap)

{

	struct cec_gpio *cec = cec_get_drvdata(adap);



	if (cec->cec_have_irq)

		return true;



	if (request_irq(cec->cec_irq, cec_gpio_irq_handler,

			IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,

			adap->name, cec))

		return false;

	cec->cec_have_irq = true;

	return true;

}



static void cec_gpio_disable_irq(struct cec_adapter *adap)

{

	struct cec_gpio *cec = cec_get_drvdata(adap);



	if (cec->cec_have_irq)

		free_irq(cec->cec_irq, cec);

	cec->cec_have_irq = false;

}



static void cec_gpio_status(struct cec_adapter *adap, struct seq_file *file)

{

	struct cec_gpio *cec = cec_get_drvdata(adap);



	seq_printf(file, "mode: %s\n", cec->cec_is_low ? "low-drive" : "read");

	if (cec->cec_have_irq)

		seq_printf(file, "using irq: %d\n", cec->cec_irq);

	if (cec->hpd_gpio)

		seq_printf(file, "hpd: %s\n",

			   cec->hpd_is_high ? "high" : "low");

}



static int cec_gpio_read_hpd(struct cec_adapter *adap)

{

	struct cec_gpio *cec = cec_get_drvdata(adap);



	if (!cec->hpd_gpio)

		return -ENOTTY;

	return gpiod_get_value(cec->hpd_gpio);

}



static void cec_gpio_free(struct cec_adapter *adap)

{

	cec_gpio_disable_irq(adap);

}



static const struct cec_pin_ops cec_gpio_pin_ops = {

	.read = cec_gpio_read,

	.low = cec_gpio_low,

	.high = cec_gpio_high,

	.enable_irq = cec_gpio_enable_irq,

	.disable_irq = cec_gpio_disable_irq,

	.status = cec_gpio_status,

	.free = cec_gpio_free,

	.read_hpd = cec_gpio_read_hpd,

};



static int cec_gpio_probe(struct platform_device *pdev)

{

	struct device *dev = &pdev->dev;

	struct cec_gpio *cec;

	int ret;



	cec = devm_kzalloc(dev, sizeof(*cec), GFP_KERNEL);

	if (!cec)

		return -ENOMEM;



	cec->dev = dev;



	cec->cec_gpio = devm_gpiod_get(dev, "cec", GPIOD_IN);

	if (IS_ERR(cec->cec_gpio))

		return PTR_ERR(cec->cec_gpio);

	cec->cec_irq = gpiod_to_irq(cec->cec_gpio);



	cec->hpd_gpio = devm_gpiod_get_optional(dev, "hpd", GPIOD_IN);

	if (IS_ERR(cec->hpd_gpio))

		return PTR_ERR(cec->hpd_gpio);



	cec->adap = cec_pin_allocate_adapter(&cec_gpio_pin_ops,

		cec, pdev->name, CEC_CAP_DEFAULTS | CEC_CAP_PHYS_ADDR |

				 CEC_CAP_MONITOR_ALL | CEC_CAP_MONITOR_PIN);

	if (IS_ERR(cec->adap))

		return PTR_ERR(cec->adap);



	if (cec->hpd_gpio) {

		cec->hpd_irq = gpiod_to_irq(cec->hpd_gpio);

		ret = devm_request_threaded_irq(dev, cec->hpd_irq,

			cec_hpd_gpio_irq_handler,

			cec_hpd_gpio_irq_handler_thread,

			IRQF_ONESHOT |

			IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,

			"hpd-gpio", cec);

		if (ret)

			return ret;

	}



	ret = cec_register_adapter(cec->adap, &pdev->dev);

	if (ret) {

		cec_delete_adapter(cec->adap);

		return ret;

	}



	platform_set_drvdata(pdev, cec);

	return 0;

}



static int cec_gpio_remove(struct platform_device *pdev)

{

	struct cec_gpio *cec = platform_get_drvdata(pdev);



	cec_unregister_adapter(cec->adap);

	return 0;

}



static const struct of_device_id cec_gpio_match[] = {

	{

		.compatible	= "cec-gpio",

	},

	{},

};

MODULE_DEVICE_TABLE(of, cec_gpio_match);



static struct platform_driver cec_gpio_pdrv = {

	.probe	= cec_gpio_probe,

	.remove = cec_gpio_remove,

	.driver = {

		.name		= "cec-gpio",

		.of_match_table	= cec_gpio_match,

	},

};



module_platform_driver(cec_gpio_pdrv);



MODULE_AUTHOR("Hans Verkuil <hans.verkuil@cisco.com>");

MODULE_LICENSE("GPL v2");

MODULE_DESCRIPTION("CEC GPIO driver");