msm: mcu_time_sync: add mcu time sync for apq8009

MCU time sync driver is used for communicating with customer board, it using GPIO to trigger customer board. At the same time, to record currenct cpu time.

Required properties:

 - compatible        : Should be "qcom,mcu-time-sync".

 - qcom,mcu-link-gpio : the conenct gpio.

Example:

	qcom,mcu_time_sync {

		compatible = "qcom,mcu-time-sync";

		qcom,mcu-link-gpio = <&msm_gpio 90 1>;

	};

	  ultrasound data paths between

	  HW and services, calculating input events

	  upon the ultrasound data.

config MSM_MCU_TIME_SYNC

       tristate "MCU time sync with apq8009"

       depends on SYSFS

       help

         Say Y here if you want to get mcu and apq8009 data transfer

         with gpio.

obj-y		+= qdsp6v2/

obj-$(CONFIG_MSM_MCU_TIME_SYNC) += mcu_time_sync.o

/*

 * Copyright (c) 2017, The Linux Foundation. All rights reserved.

 *

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

 * it under the terms of the GNU General Public License version 2 and

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

 *

 * This program is distributed in the hope that 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/module.h>

#include <linux/io.h>

#include <linux/init.h>

#include <linux/slab.h>

#include <linux/err.h>

#include <linux/delay.h>

#include <linux/sysfs.h>

#include <linux/gpio.h>

#include <linux/of.h>

#include <linux/of_device.h>

#include <linux/of_address.h>

#include <linux/of_gpio.h>

#include <linux/time.h>

#define S2US (1000*1000)

struct mcu_time {

	struct device *dev;

	unsigned gpio;

	long long time_us;

};

static ssize_t mcu_time_show(struct device *dev,

		struct device_attribute *attr, char *buf)

{

	struct mcu_time *time = dev_get_drvdata(dev);

	return snprintf(buf, PAGE_SIZE, "%lld\n", time->time_us);

}

static DEVICE_ATTR_RO(mcu_time);

static int mcu_time_sync_probe(struct platform_device *pdev)

{

	int ret;

	struct mcu_time *mcu_time;

	struct timeval current_time;

	mcu_time = devm_kzalloc(&pdev->dev, sizeof(struct mcu_time),

			GFP_KERNEL);

	if (!mcu_time)

		return -ENOMEM;

	platform_set_drvdata(pdev, mcu_time);

	mcu_time->dev = &pdev->dev;

	mcu_time->gpio = of_get_named_gpio(pdev->dev.of_node,

			"qcom,mcu-link-gpio", 0);

	if (!gpio_is_valid(mcu_time->gpio)) {

		dev_err(&pdev->dev, "Invalid gpio number.\n");

		return -EIO;

	}

	ret = devm_gpio_request(&pdev->dev, mcu_time->gpio, "mcu_gpio");

	if (ret) {

		dev_err(&pdev->dev, "gpio request %d failed\n", mcu_time->gpio);

		return ret;

	}

	ret = gpio_direction_output(mcu_time->gpio, 0);

	if (ret) {

		dev_err(&pdev->dev, "Failed to set gpio direction output: %d\n",

			mcu_time->gpio);

		return ret;

	}

	do_gettimeofday(&current_time);

	mcu_time->time_us = current_time.tv_sec * S2US + current_time.tv_usec;

	device_create_file(&pdev->dev, &dev_attr_mcu_time);

	return 0;

}

static int mcu_time_sync_remove(struct platform_device *pdev)

{

	device_remove_file(&pdev->dev, &dev_attr_mcu_time);

	return 0;

}

static struct of_device_id mcu_time_sync_match_table[] =  {

	{.compatible = "qcom,mcu-time-sync"},

	{},

};

static struct platform_driver mcu_time_sync_driver = {

	.probe = mcu_time_sync_probe,

	.remove = mcu_time_sync_remove,

	.driver = {

		.name = "mcu-time-sync",

		.owner = THIS_MODULE,

		.of_match_table = mcu_time_sync_match_table,

	},

};

module_platform_driver(mcu_time_sync_driver);

MODULE_DESCRIPTION("MCU time sync driver");

MODULE_LICENSE("GPL v2");