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Commit 6f2a71a3 authored by Stephen Barber's avatar Stephen Barber Committed by Alexandre Belloni
Browse files

rtc: cros-ec: add cros-ec-rtc driver. 



On platforms with a Chrome OS EC, the EC can function as a simple RTC.
Add a basic driver with this functionality.

Signed-off-by: default avatarStephen Barber <smbarber@chromium.org>
Signed-off-by: default avatarEnric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: default avatarBenson Leung <bleung@chromium.org>
Reviewed-by: default avatarBrian Norris <briannorris@chromium.org>
Tested-by: default avatarBrian Norris <briannorris@chromium.org>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent 3eff6d2c

drivers/rtc/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -1255,6 +1255,16 @@ config RTC_DRV_ZYNQMP 
	  If you say yes here you get support for the RTC controller found on

	  Xilinx Zynq Ultrascale+ MPSoC.



config RTC_DRV_CROS_EC

	tristate "Chrome OS EC RTC driver"

	depends on MFD_CROS_EC

	help

	  If you say yes here you will get support for the

	  Chrome OS Embedded Controller's RTC.



	  This driver can also be built as a module. If so, the module

	  will be called rtc-cros-ec.



comment "on-CPU RTC drivers"



config RTC_DRV_ASM9260

drivers/rtc/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ obj-$(CONFIG_RTC_DRV_BQ4802) += rtc-bq4802.o 
obj-$(CONFIG_RTC_DRV_CMOS)	+= rtc-cmos.o

obj-$(CONFIG_RTC_DRV_COH901331)	+= rtc-coh901331.o

obj-$(CONFIG_RTC_DRV_CPCAP)	+= rtc-cpcap.o

obj-$(CONFIG_RTC_DRV_CROS_EC)	+= rtc-cros-ec.o

obj-$(CONFIG_RTC_DRV_DA9052)	+= rtc-da9052.o

obj-$(CONFIG_RTC_DRV_DA9055)	+= rtc-da9055.o

obj-$(CONFIG_RTC_DRV_DA9063)	+= rtc-da9063.o

drivers/rtc/rtc-cros-ec.c

0 → 100644
+413 −0
Original line number Diff line number Diff line 
/*

 * RTC driver for Chrome OS Embedded Controller

 *

 * Copyright (c) 2017, Google, Inc

 *

 * Author: Stephen Barber <smbarber@chromium.org>

 *

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

 * under the terms and conditions of the GNU General Public License,

 * version 2, as published by the Free Software Foundation.

 *

 * This program is distributed in the hope it will be useful, 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/kernel.h>

#include <linux/mfd/cros_ec.h>

#include <linux/mfd/cros_ec_commands.h>

#include <linux/module.h>

#include <linux/platform_device.h>

#include <linux/rtc.h>

#include <linux/slab.h>



#define DRV_NAME	"cros-ec-rtc"



/**

 * struct cros_ec_rtc - Driver data for EC RTC

 *

 * @cros_ec: Pointer to EC device

 * @rtc: Pointer to RTC device

 * @notifier: Notifier info for responding to EC events

 * @saved_alarm: Alarm to restore when interrupts are reenabled

 */

struct cros_ec_rtc {

	struct cros_ec_device *cros_ec;

	struct rtc_device *rtc;

	struct notifier_block notifier;

	u32 saved_alarm;

};



static int cros_ec_rtc_get(struct cros_ec_device *cros_ec, u32 command,

			   u32 *response)

{

	int ret;

	struct {

		struct cros_ec_command msg;

		struct ec_response_rtc data;

	} __packed msg;



	memset(&msg, 0, sizeof(msg));

	msg.msg.command = command;

	msg.msg.insize = sizeof(msg.data);



	ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);

	if (ret < 0) {

		dev_err(cros_ec->dev,

			"error getting %s from EC: %d\n",

			command == EC_CMD_RTC_GET_VALUE ? "time" : "alarm",

			ret);

		return ret;

	}



	*response = msg.data.time;



	return 0;

}



static int cros_ec_rtc_set(struct cros_ec_device *cros_ec, u32 command,

			   u32 param)

{

	int ret = 0;

	struct {

		struct cros_ec_command msg;

		struct ec_response_rtc data;

	} __packed msg;



	memset(&msg, 0, sizeof(msg));

	msg.msg.command = command;

	msg.msg.outsize = sizeof(msg.data);

	msg.data.time = param;



	ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);

	if (ret < 0) {

		dev_err(cros_ec->dev, "error setting %s on EC: %d\n",

			command == EC_CMD_RTC_SET_VALUE ? "time" : "alarm",

			ret);

		return ret;

	}



	return 0;

}



/* Read the current time from the EC. */

static int cros_ec_rtc_read_time(struct device *dev, struct rtc_time *tm)

{

	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);

	struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;

	int ret;

	u32 time;



	ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &time);

	if (ret) {

		dev_err(dev, "error getting time: %d\n", ret);

		return ret;

	}



	rtc_time64_to_tm(time, tm);



	return 0;

}



/* Set the current EC time. */

static int cros_ec_rtc_set_time(struct device *dev, struct rtc_time *tm)

{

	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);

	struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;

	int ret;

	time64_t time;



	time = rtc_tm_to_time64(tm);

	if (time < 0 || time > U32_MAX)

		return -EINVAL;



	ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_VALUE, (u32)time);

	if (ret < 0) {

		dev_err(dev, "error setting time: %d\n", ret);

		return ret;

	}



	return 0;

}



/* Read alarm time from RTC. */

static int cros_ec_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)

{

	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);

	struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;

	int ret;

	u32 current_time, alarm_offset;



	/*

	 * The EC host command for getting the alarm is relative (i.e. 5

	 * seconds from now) whereas rtc_wkalrm is absolute. Get the current

	 * RTC time first so we can calculate the relative time.

	 */

	ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);

	if (ret < 0) {

		dev_err(dev, "error getting time: %d\n", ret);

		return ret;

	}



	ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM, &alarm_offset);

	if (ret < 0) {

		dev_err(dev, "error getting alarm: %d\n", ret);

		return ret;

	}



	rtc_time64_to_tm(current_time + alarm_offset, &alrm->time);



	return 0;

}



/* Set the EC's RTC alarm. */

static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)

{

	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);

	struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;

	int ret;

	time64_t alarm_time;

	u32 current_time, alarm_offset;



	/*

	 * The EC host command for setting the alarm is relative

	 * (i.e. 5 seconds from now) whereas rtc_wkalrm is absolute.

	 * Get the current RTC time first so we can calculate the

	 * relative time.

	 */

	ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);

	if (ret < 0) {

		dev_err(dev, "error getting time: %d\n", ret);

		return ret;

	}



	alarm_time = rtc_tm_to_time64(&alrm->time);



	if (alarm_time < 0 || alarm_time > U32_MAX)

		return -EINVAL;



	if (!alrm->enabled) {

		/*

		 * If the alarm is being disabled, send an alarm

		 * clear command.

		 */

		alarm_offset = EC_RTC_ALARM_CLEAR;

		cros_ec_rtc->saved_alarm = (u32)alarm_time;

	} else {

		/* Don't set an alarm in the past. */

		if ((u32)alarm_time < current_time)

			alarm_offset = EC_RTC_ALARM_CLEAR;

		else

			alarm_offset = (u32)alarm_time - current_time;

	}



	ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, alarm_offset);

	if (ret < 0) {

		dev_err(dev, "error setting alarm: %d\n", ret);

		return ret;

	}



	return 0;

}



static int cros_ec_rtc_alarm_irq_enable(struct device *dev,

					unsigned int enabled)

{

	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);

	struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;

	int ret;

	u32 current_time, alarm_offset, alarm_value;



	ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);

	if (ret < 0) {

		dev_err(dev, "error getting time: %d\n", ret);

		return ret;

	}



	if (enabled) {

		/* Restore saved alarm if it's still in the future. */

		if (cros_ec_rtc->saved_alarm < current_time)

			alarm_offset = EC_RTC_ALARM_CLEAR;

		else

			alarm_offset = cros_ec_rtc->saved_alarm - current_time;



		ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,

				      alarm_offset);

		if (ret < 0) {

			dev_err(dev, "error restoring alarm: %d\n", ret);

			return ret;

		}

	} else {

		/* Disable alarm, saving the old alarm value. */

		ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM,

				      &alarm_offset);

		if (ret < 0) {

			dev_err(dev, "error saving alarm: %d\n", ret);

			return ret;

		}



		alarm_value = current_time + alarm_offset;



		/*

		 * If the current EC alarm is already past, we don't want

		 * to set an alarm when we go through the alarm irq enable

		 * path.

		 */

		if (alarm_value < current_time)

			cros_ec_rtc->saved_alarm = EC_RTC_ALARM_CLEAR;

		else

			cros_ec_rtc->saved_alarm = alarm_value;



		alarm_offset = EC_RTC_ALARM_CLEAR;

		ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,

				      alarm_offset);

		if (ret < 0) {

			dev_err(dev, "error disabling alarm: %d\n", ret);

			return ret;

		}

	}



	return 0;

}



static int cros_ec_rtc_event(struct notifier_block *nb,

			     unsigned long queued_during_suspend,

			     void *_notify)

{

	struct cros_ec_rtc *cros_ec_rtc;

	struct rtc_device *rtc;

	struct cros_ec_device *cros_ec;

	u32 host_event;



	cros_ec_rtc = container_of(nb, struct cros_ec_rtc, notifier);

	rtc = cros_ec_rtc->rtc;

	cros_ec = cros_ec_rtc->cros_ec;



	host_event = cros_ec_get_host_event(cros_ec);

	if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_RTC)) {

		rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);

		return NOTIFY_OK;

	} else {

		return NOTIFY_DONE;

	}

}



static const struct rtc_class_ops cros_ec_rtc_ops = {

	.read_time = cros_ec_rtc_read_time,

	.set_time = cros_ec_rtc_set_time,

	.read_alarm = cros_ec_rtc_read_alarm,

	.set_alarm = cros_ec_rtc_set_alarm,

	.alarm_irq_enable = cros_ec_rtc_alarm_irq_enable,

};



#ifdef CONFIG_PM_SLEEP

static int cros_ec_rtc_suspend(struct device *dev)

{

	struct platform_device *pdev = to_platform_device(dev);

	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);



	if (device_may_wakeup(dev))

		enable_irq_wake(cros_ec_rtc->cros_ec->irq);



	return 0;

}



static int cros_ec_rtc_resume(struct device *dev)

{

	struct platform_device *pdev = to_platform_device(dev);

	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);



	if (device_may_wakeup(dev))

		disable_irq_wake(cros_ec_rtc->cros_ec->irq);



	return 0;

}

#endif



static SIMPLE_DEV_PM_OPS(cros_ec_rtc_pm_ops, cros_ec_rtc_suspend,

			 cros_ec_rtc_resume);



static int cros_ec_rtc_probe(struct platform_device *pdev)

{

	struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);

	struct cros_ec_device *cros_ec = ec_dev->ec_dev;

	struct cros_ec_rtc *cros_ec_rtc;

	struct rtc_time tm;

	int ret;



	cros_ec_rtc = devm_kzalloc(&pdev->dev, sizeof(*cros_ec_rtc),

				   GFP_KERNEL);

	if (!cros_ec_rtc)

		return -ENOMEM;



	platform_set_drvdata(pdev, cros_ec_rtc);

	cros_ec_rtc->cros_ec = cros_ec;



	/* Get initial time */

	ret = cros_ec_rtc_read_time(&pdev->dev, &tm);

	if (ret) {

		dev_err(&pdev->dev, "failed to read RTC time\n");

		return ret;

	}



	ret = device_init_wakeup(&pdev->dev, 1);

	if (ret) {

		dev_err(&pdev->dev, "failed to initialize wakeup\n");

		return ret;

	}



	cros_ec_rtc->rtc = devm_rtc_device_register(&pdev->dev, DRV_NAME,

						    &cros_ec_rtc_ops,

						    THIS_MODULE);

	if (IS_ERR(cros_ec_rtc->rtc)) {

		ret = PTR_ERR(cros_ec_rtc->rtc);

		dev_err(&pdev->dev, "failed to register rtc device\n");

		return ret;

	}



	/* Get RTC events from the EC. */

	cros_ec_rtc->notifier.notifier_call = cros_ec_rtc_event;

	ret = blocking_notifier_chain_register(&cros_ec->event_notifier,

					       &cros_ec_rtc->notifier);

	if (ret) {

		dev_err(&pdev->dev, "failed to register notifier\n");

		return ret;

	}



	return 0;

}



static int cros_ec_rtc_remove(struct platform_device *pdev)

{

	struct cros_ec_rtc *cros_ec_rtc = platform_get_drvdata(pdev);

	struct device *dev = &pdev->dev;

	int ret;



	ret = blocking_notifier_chain_unregister(

				&cros_ec_rtc->cros_ec->event_notifier,

				&cros_ec_rtc->notifier);

	if (ret) {

		dev_err(dev, "failed to unregister notifier\n");

		return ret;

	}



	return 0;

}



static struct platform_driver cros_ec_rtc_driver = {

	.probe = cros_ec_rtc_probe,

	.remove = cros_ec_rtc_remove,

	.driver = {

		.name = DRV_NAME,

		.pm = &cros_ec_rtc_pm_ops,

	},

};



module_platform_driver(cros_ec_rtc_driver);



MODULE_DESCRIPTION("RTC driver for Chrome OS ECs");

MODULE_AUTHOR("Stephen Barber <smbarber@chromium.org>");

MODULE_LICENSE("GPL");

MODULE_ALIAS("platform:" DRV_NAME);