/*
 * An RTC driver for Sunxi Platform of Allwinner SoC
 *
 * Copyright (c) 2013, Carlo Caione <carlo.caione@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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/delay.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/rtc.h>
#include <linux/types.h>
#include <linux/reboot.h>

#include "rtc-sunxi-v2.h"

#define DAYS_PER_YEAR    365
#define DAYS_PER_LEAP_YEAR 366

static void __iomem *global_pgregbase;
static void __iomem *global_pbase;

static struct sunxi_rtc_data_year data_year_param[] = {
	[0] = {
		.min		= 2010,
		.max		= 2073,
		.mask		= 0x3f,
		.yshift		= 16,
		.leap_shift	= 22,
	}
};

static inline int rtc_write(unsigned int reg, unsigned int val)
{
	unsigned int reg_val = 0, check = 0;

	reg_val = readl(global_pbase + SUNXI_RTC_SPI_CFG_REG);
	if ((reg_val & (1 << SUNXI_RTC_SPI_OP_BUSY)) == 1) {
		pr_err("RTC access failed(%d).(Rtc spi interface is busy.)\n",
				__LINE__);
		return -EBUSY;
	}
	reg_val  = 0;
	reg_val |= (val << SUNXI_RTC_REG_ACCESS_WRITE_VAL);
	reg_val |= (reg << SUNXI_RTC_REG_ACCESS_ADDR);
	reg_val |= (1 << SUNXI_RTC_SPI_CFG_BUSY);
	reg_val |= (1 << SUNXI_RTC_REG_ACCESS_WAY);
	writel(reg_val, global_pbase + SUNXI_RTC_SPI_CFG_REG);
	msleep(200);

	do {
		if (check++ > 10) {
			pr_err("RTC access failed(%d).(Rtc spi interface write failed.)\n",
					__LINE__);
			break;
		}
		msleep(200);
		reg_val = readl(global_pbase + SUNXI_RTC_SPI_CFG_REG);
	} while ((reg_val & (1 << SUNXI_RTC_SPI_OP_BUSY)) == 1);

	if ((reg_val & (1 << SUNXI_RTC_SPI_OP_BUSY)) == 1)
		return -EBUSY;
	else
		return 0;
}

static inline int rtc_read(unsigned int reg)
{
	unsigned int reg_val = 0, check = 0;

	reg_val = readl(global_pbase + SUNXI_RTC_SPI_CFG_REG);

	if ((reg_val & (1 << SUNXI_RTC_SPI_OP_BUSY)) == 1) {
		pr_err("RTC access failed(%d).(Rtc spi interface is busy.)\n",
				__LINE__);
		return -EBUSY;
	}

	reg_val  = 0;
	reg_val |= (reg << SUNXI_RTC_REG_ACCESS_ADDR);
	reg_val |= (0 << SUNXI_RTC_REG_ACCESS_WAY);
	reg_val |= (1 << SUNXI_RTC_SPI_CFG_BUSY);
	writel(reg_val, global_pbase + SUNXI_RTC_SPI_CFG_REG);
	msleep(200);

	do {
		if (check++ > 10) {
			pr_err("RTC access failed(%d).(Rtc spi interface read failed.)\n",
					__LINE__);
			break;
		}
		msleep(200);
		reg_val = readl(global_pbase + SUNXI_RTC_SPI_CFG_REG);
	} while ((reg_val & (1 << SUNXI_RTC_SPI_OP_BUSY)) == 1);

	if ((reg_val & (1 << SUNXI_RTC_SPI_OP_BUSY)) == 1)
		return -EBUSY;
	else
		return (reg_val & (0xFF << SUNXI_RTC_REG_ACCESS_READ_VAL));
}

static time64_t sunxi_rtc_time64_offset(unsigned int cur)
{
	struct rtc_time rtc_tm;

	rtc_tm.tm_sec = 0;
	rtc_tm.tm_min = 0;
	rtc_tm.tm_hour = 0;
	rtc_tm.tm_mon = 0;
	rtc_tm.tm_mday = 1;
	rtc_tm.tm_year = cur - 1900;

	return rtc_tm_to_time64(&rtc_tm);
}

#ifdef CONFIG_RTC_SHUTDOWN_ALARM
static int alarm_in_booting;
module_param_named(alarm_in_booting, alarm_in_booting, int, 0644);

static void sunxi_rtc_alarm_in_boot(struct sunxi_rtc_dev *rtc)
{
	unsigned int irq_en, en, int_ctrl, int_stat;

	/*
	 * when alarm irq occur at boot0~rtc_driver.probe() process in shutdown
	 * charger mode, /charger in userspace must know this irq through sysfs
	 * node 'alarm_in_booting' to reboot and startup system.
	 */

	int_ctrl = rtc_read(SUNXI_ALM0_ENABLE_REG);
	int_stat = rtc_read(SUNXI_ALM0_IRQ_STA);

	en = int_ctrl & SUNXI_ALM0_ENABLE;
	irq_en = (int_ctrl & SUNXI_ALM0_IRQ_ENABLE) >> 1;

	if (int_stat && irq_en && en)
		alarm_in_booting = 1;
}
#endif

static irqreturn_t sunxi_rtc_alarmirq(int irq, void *id)
{
	struct sunxi_rtc_dev *chip = (struct sunxi_rtc_dev *) id;
	unsigned int val;

	val = rtc_read(SUNXI_ALM0_IRQ_STA);

	if (val & (1 << SUNXI_ALM0_IRQ_PEND)) {
		val |= SUNXI_ALM0_IRQ_PEND;
		rtc_write(SUNXI_ALM0_IRQ_STA, val);

		rtc_update_irq(chip->rtc, 1, RTC_AF | RTC_IRQF);

		return IRQ_HANDLED;
	}

	return IRQ_NONE;
}

static void sunxi_rtc_setaie(int to, struct sunxi_rtc_dev *chip)
{
	unsigned int alrm_val = 0;

	if (to) {
		alrm_val = rtc_read(SUNXI_ALM0_ENABLE_REG);
		alrm_val |= SUNXI_ALM0_IRQ_ENABLE|SUNXI_ALM0_ENABLE;
	} else {
		rtc_write(SUNXI_ALM0_IRQ_STA, 1);
	}

	rtc_write(SUNXI_ALM0_ENABLE_REG, alrm_val);
}

static int sunxi_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm);

static int sunxi_rtc_getalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{
	int ret;
	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
	struct rtc_time *alrm_tm = &wkalrm->time;
	struct rtc_time hw_alrm_tm;
	unsigned int alrm_en, hw_alarm_days = 0;
	unsigned long alarm_seconds = 0, cur_seconds = 0;
	time64_t seconds = 0;

	hw_alarm_days = (rtc_read(SUNXI_ALMCFG_DH) << 8) |
			rtc_read(SUNXI_ALMCFG_DL);

	seconds = hw_alarm_days * 24 * 3600
		+ sunxi_rtc_time64_offset(chip->data_year->min);
	rtc_time64_to_tm(seconds, &hw_alrm_tm);

	hw_alrm_tm.tm_hour = rtc_read(SUNXI_ALMCFG_HH);
	hw_alrm_tm.tm_min = rtc_read(SUNXI_ALMCFG_MM);
	hw_alrm_tm.tm_sec = rtc_read(SUNXI_ALMCFG_SS);

	ret = sunxi_rtc_gettime(dev, alrm_tm);
	if (ret)
		return -EINVAL;
	rtc_time_to_tm(cur_seconds, alrm_tm);
	rtc_time_to_tm(alarm_seconds, &hw_alrm_tm);
	hw_alrm_tm.tm_mon -= 1;

	dev_dbg(dev, "alarm: %04d-%02d-%02d %02d:%02d:%02d\n",
		hw_alrm_tm.tm_year + 1900, hw_alrm_tm.tm_mon + 1,
		hw_alrm_tm.tm_mday, hw_alrm_tm.tm_hour,
		hw_alrm_tm.tm_min, hw_alrm_tm.tm_sec);

	if (cur_seconds > alarm_seconds) {
		/* alarm is disabled. */
		wkalrm->enabled = 0;
		alrm_tm->tm_mon = -1;
		alrm_tm->tm_mday = -1;
		alrm_tm->tm_year = -1;
		alrm_tm->tm_hour = -1;
		alrm_tm->tm_min = -1;
		alrm_tm->tm_sec = -1;
		return 0;
	} else
		memcpy(alrm_tm, &hw_alrm_tm, sizeof(hw_alrm_tm));

	alrm_en = rtc_read(SUNXI_ALM0_ENABLE_REG);
	if (alrm_en & SUNXI_ALM0_ENABLE)
		wkalrm->enabled = 1;

	return 0;
}

static int sunxi_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
{
	unsigned int days = 0;
	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
	time64_t seconds = 0;
	struct rtc_time rtc_days;

	/* lock rtc real time */
	rtc_write(SUNXI_RTC_TIMER_READ_CFG,
		SUNXI_RTC_TIMER_READ_LOCK_BYPASS|SUNXI_RTC_TIMER_READ_LOCK_ENABLE);

	/* read rtc time */
	rtc_tm->tm_sec  = rtc_read(SUNXI_RTC_SS_RD);
	rtc_tm->tm_min  = rtc_read(SUNXI_RTC_MM_RD);
	rtc_tm->tm_hour = rtc_read(SUNXI_RTC_HH_RD);
	days = rtc_read(SUNXI_RTC_DL_RD)|(rtc_read(SUNXI_RTC_DH_RD) << 8);
	seconds = days * 24 * 3600 +
		sunxi_rtc_time64_offset(chip->data_year->min);
	rtc_time64_to_tm(seconds, &rtc_days);
	rtc_tm->tm_year = rtc_days.tm_year;
	rtc_tm->tm_mon  = rtc_days.tm_mon - 1;
	rtc_tm->tm_mday = rtc_days.tm_mday;

	dev_dbg(dev, "Read hardware RTC time %04d-%02d-%02d %02d:%02d:%02d\n",
		rtc_tm->tm_year + 1900, rtc_tm->tm_mon + 1, rtc_tm->tm_mday,
		rtc_tm->tm_hour, rtc_tm->tm_min, rtc_tm->tm_sec);

	return rtc_valid_tm(rtc_tm);
}

static int sunxi_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{

	int ret;
	time64_t diff;
	unsigned int diff_year = 0, date = 0, year = 0;
	struct rtc_time tm_now;

	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
	struct rtc_time *alrm_tm = &wkalrm->time;

	dev_dbg(dev, "Write hardware RTC time %04d-%02d-%02d %02d:%02d:%02d\n",
		alrm_tm->tm_year + 1900, alrm_tm->tm_mon + 1, alrm_tm->tm_mday,
		alrm_tm->tm_hour, alrm_tm->tm_min, alrm_tm->tm_sec);

	ret = sunxi_rtc_gettime(dev, &tm_now);
	if (ret < 0) {
		dev_err(dev, "Error in getting time\n");
		return -EINVAL;
	}

	diff = rtc_tm_sub(alrm_tm, &tm_now);
	if (diff <= 0) {
		dev_err(dev, "Date to set in the past\n");
		return -EINVAL;
	}

	if (diff > 255 * SEC_IN_DAY) {
		dev_err(dev, "Day must be in the range 0 - 255\n");
		return -EINVAL;
	}

	alrm_tm->tm_year -= SUNXI_YEAR_OFF(chip->data_year);
	alrm_tm->tm_mon += 1;

	year = alrm_tm->tm_year + 1900;

	for (diff_year = chip->data_year->min; diff_year < year; diff_year++) {
		if (is_leap_year(diff_year))
			date += DAYS_PER_LEAP_YEAR;
		else
			date += DAYS_PER_YEAR;
	}
	date += rtc_year_days(alrm_tm->tm_mday, alrm_tm->tm_mon, year);

	sunxi_rtc_setaie(0, chip);

	rtc_write(SUNXI_ALMCFG_DL, date & 0xFF);
	rtc_write(SUNXI_ALMCFG_DH, date >> 8);
	rtc_write(SUNXI_ALMCFG_HH, alrm_tm->tm_hour);
	rtc_write(SUNXI_ALMCFG_MM, alrm_tm->tm_min);
	rtc_write(SUNXI_ALMCFG_SS, alrm_tm->tm_sec);

	sunxi_rtc_setaie(wkalrm->enabled, chip);

	return 0;
}

static int sunxi_rtc_settime(struct device *dev, struct rtc_time *rtc_tm)
{
	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
	unsigned int days = 0, year = 0, diff_year = 0;

	/*
	 * the input rtc_tm->tm_year is the offset relative to 1900. We use
	 * the SUNXI_YEAR_OFF macro to rebase it with respect to the min year
	 * allowed by the hardware
	 */

	year = rtc_tm->tm_year + 1900;
	if (rtc_valid_tm(rtc_tm) || year < chip->data_year->min
			|| year > chip->data_year->max) {
		dev_err(dev, "rtc only supports year in range %d - %d\n",
				chip->data_year->min, chip->data_year->max);
		return -EINVAL;
	}

	rtc_tm->tm_year -= SUNXI_YEAR_OFF(chip->data_year);
	rtc_tm->tm_mon += 1;

	dev_dbg(dev, "Will set hardware RTC time %04d-%02d-%02d %02d:%02d:%02d\n",
			rtc_tm->tm_year, rtc_tm->tm_mon, rtc_tm->tm_mday,
			rtc_tm->tm_hour, rtc_tm->tm_min, rtc_tm->tm_sec);

	for (diff_year = chip->data_year->min; diff_year < year; diff_year++) {
		if (is_leap_year(diff_year))
			days += DAYS_PER_LEAP_YEAR;
		else
			days += DAYS_PER_YEAR;
	}
	days += rtc_year_days(rtc_tm->tm_mday, rtc_tm->tm_mon, year);

	/* set rtc time */
	rtc_write(SUNXI_RTC_HH_CFG, rtc_tm->tm_hour);
	rtc_write(SUNXI_RTC_MM_CFG, rtc_tm->tm_min);
	rtc_write(SUNXI_RTC_SS_CFG, rtc_tm->tm_sec);
	rtc_write(SUNXI_RTC_DH_CFG, days >> 8);
	rtc_write(SUNXI_RTC_DL_CFG, days & 0xFF);

	/* lock rtc real time */
	rtc_write(SUNXI_RTC_TIMER_READ_CFG,
			SUNXI_RTC_TIMER_READ_LOCK_BYPASS|SUNXI_RTC_TIMER_VAL_CFG_ENABLE);
	msleep(400);

	return 0;
}

static int sunxi_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);

	if (!enabled)
		sunxi_rtc_setaie(enabled, chip);

	return 0;
}

static const struct rtc_class_ops sunxi_rtc_ops = {
	.read_time		= sunxi_rtc_gettime,
	.set_time		= sunxi_rtc_settime,
	.read_alarm		= sunxi_rtc_getalarm,
	.set_alarm		= sunxi_rtc_setalarm,
	.alarm_irq_enable	= sunxi_rtc_alarm_irq_enable
};

static const struct of_device_id sunxi_rtc_dt_ids[] = {
	{.compatible = "allwinner,sunxi-rtc", .data = &data_year_param[0]},
	{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, sunxi_rtc_dt_ids);

static ssize_t sunxi_rtc_min_year_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct platform_device *pdev = container_of(dev, struct platform_device, dev);
	struct sunxi_rtc_dev *rtc_dev = platform_get_drvdata(pdev);

	return snprintf(buf, PAGE_SIZE, "%u\n", rtc_dev->data_year->min);
}
static struct device_attribute sunxi_rtc_min_year_attr =
	__ATTR(min_year, 0444, sunxi_rtc_min_year_show, NULL);

static ssize_t sunxi_rtc_max_year_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct platform_device *pdev = container_of(dev, struct platform_device, dev);
	struct sunxi_rtc_dev *rtc_dev = platform_get_drvdata(pdev);

	return snprintf(buf, PAGE_SIZE, "%u\n", rtc_dev->data_year->max);
}
static struct device_attribute sunxi_rtc_max_year_attr =
	__ATTR(max_year, 0444, sunxi_rtc_max_year_show, NULL);

#ifdef CONFIG_SUNXI_BOOTUP_EXTEND
static int sunxi_reboot_callback(struct notifier_block *this,
		unsigned long code, void *data)
{
	unsigned int rtc_flag = 0;

	if (data == NULL)
		return NOTIFY_DONE;

	pr_info("sunxi rtc reboot, arg %s\n", (char *)data);

	if (!strncmp(data, "debug", sizeof("debug"))) {
		rtc_flag = SUNXI_DEBUG_MODE_FLAG;
	} else if (!strncmp(data, "efex", sizeof("efex"))) {
		rtc_flag = SUNXI_EFEX_CMD_FLAG;
	} else if (!strncmp(data, "boot-resignature",
						sizeof("boot-resignature"))) {
		rtc_flag = SUNXI_BOOT_RESIGNATURE_FLAG;
	} else if (!strncmp(data, "recovery", sizeof("recovery"))
		|| !strncmp(data, "boot-recovery", sizeof("boot-recovery"))) {
		rtc_flag = SUNXI_BOOT_RECOVERY_FLAG;
	} else if (!strncmp(data, "sysrecovery", sizeof("sysrecovery"))) {
		rtc_flag = SUNXI_SYS_RECOVERY_FLAG;
	} else if (!strncmp(data, "bootloader", sizeof("bootloader"))) {
		rtc_flag = SUNXI_FASTBOOT_FLAG;
	} else if (!strncmp(data, "usb-recovery", sizeof("usb-recovery"))) {
		rtc_flag = SUNXI_USB_RECOVERY_FLAG;
	} else {
		pr_warn("unknown reboot arg %s", (char *)data);
		return NOTIFY_DONE;
	}

	/*write the data to reg*/
	writel(rtc_flag, global_pgregbase);
	return NOTIFY_DONE;
}


static struct notifier_block sunxi_reboot_notifier = {
	.notifier_call = sunxi_reboot_callback,
};
#endif


static int sunxi_rtc_probe(struct platform_device *pdev)
{
	int ret;
	unsigned int reg_val;
	struct resource *res;
	struct sunxi_rtc_dev *chip;
	const struct of_device_id *of_id;

#ifdef CONFIG_SUNXI_BOOTUP_EXTEND
	unsigned int gpr_offset = 0, gpr_len = 0, gpr_num = 0;
#endif
	global_pgregbase = NULL;

	of_id = of_match_device(sunxi_rtc_dt_ids, &pdev->dev);
	if (!of_id) {
		dev_err(&pdev->dev, "Unable to setup RTC data\n");
		return -ENODEV;
	}

	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
	if (!chip)
		return -ENOMEM;

	platform_set_drvdata(pdev, chip);
	chip->dev = &pdev->dev;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	chip->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(chip->base))
		return PTR_ERR(chip->base);
	global_pbase = chip->base;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
	chip->prcm_base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(chip->base))
		return PTR_ERR(chip->base);

	/* Enable the clock/module so that we can access the registers */
	pm_runtime_enable(&pdev->dev);
	pm_runtime_get_sync(&pdev->dev);

	chip->data_year = (struct sunxi_rtc_data_year *) of_id->data;

	/* set prcm. enable rtc apb bus clk.*/
	reg_val = readl(chip->prcm_base + SUNXI_RTC_BGR_REG);
	reg_val |= SUNXI_RTC_GATING_ENABLE;
	writel(reg_val, chip->prcm_base + SUNXI_RTC_BGR_REG);

	/* set rtc spi clk.*/
	reg_val = readl(chip->base + SUNXI_SPI_CLK_CFG_REG);
	reg_val &= ~(0x1f << SUNXI_RTC_SPI_CLK_DIV);
	reg_val |= (0x13 << SUNXI_RTC_SPI_CLK_DIV);
	reg_val |= SUNXI_RTC_SPI_CLK_ENABLE;
	writel(reg_val, chip->base + SUNXI_SPI_CLK_CFG_REG);


#ifdef CONFIG_RTC_SHUTDOWN_ALARM
	sunxi_rtc_alarm_in_boot(chip);
#else
	/* disable alarm, not generate irq pending, wakeup output */
	rtc_write(SUNXI_ALM0_ENABLE_REG, 0);

	/* clear alarm  irq pending */
	rtc_write(SUNXI_ALM0_IRQ_STA, 0);
#endif
	/*
	 * select RTC clock source(external 32k),disable auto switch func.
	 */
	reg_val = rtc_read(SUNXI_LOSC_CTRL);
	reg_val |= (1 << SUNXI_RTC_CLK_SRC);
	reg_val |= SUNXI_EXT_LOSC_ENABLE;
	reg_val &= ~SUNXI_LOSC_AUTO_SWT_PEND_ENABLE;
	reg_val &= ~SUNXI_LOSC_AUTO_SWT_ENABLE;
	reg_val &= ~SUNXI_RC16M_OUT_ENABLE;
	rtc_write(SUNXI_LOSC_CTRL, reg_val);

	device_init_wakeup(&pdev->dev, 1);

	chip->rtc = devm_rtc_device_register(&pdev->dev, "sunxi-rtc",
			&sunxi_rtc_ops, THIS_MODULE);
	if (IS_ERR(chip->rtc)) {
		dev_err(&pdev->dev, "unable to register device\n");
		goto fail;
	}

	chip->irq = platform_get_irq(pdev, 0);
	if (chip->irq < 0) {
		dev_err(&pdev->dev, "No IRQ resource\n");
		goto fail;
	}
	ret = devm_request_irq(&pdev->dev, chip->irq, sunxi_rtc_alarmirq,
			0, dev_name(&pdev->dev), chip);
	if (ret) {
		dev_err(&pdev->dev, "Could not request IRQ\n");
		goto fail;
	}

	dev_info(&pdev->dev, "RTC enabled\n");

	device_create_file(&pdev->dev, &sunxi_rtc_min_year_attr);
	device_create_file(&pdev->dev, &sunxi_rtc_max_year_attr);

#ifdef CONFIG_SUNXI_BOOTUP_EXTEND
	ret = of_property_read_u32(pdev->dev.of_node,
			"gpr_offset", &gpr_offset);
	if (ret) {
		dev_err(&pdev->dev, "Could not get Gpr offset\n");
		goto fail_3;
	}

	ret = of_property_read_u32(pdev->dev.of_node,
			"gpr_len", &gpr_len);
	if (ret) {
		dev_err(&pdev->dev, "Could not get Gpr len\n");
		goto fail_3;
	}

	ret = of_property_read_u32(pdev->dev.of_node,
			"gpr_cur_pos", &gpr_num);
	if (ret) {
		dev_err(&pdev->dev, "Could not get Gpr reboot cur pos");
		goto fail_3;
	} else {

		if (gpr_num >= gpr_len) {
			dev_err(&pdev->dev,
					"gpr_cur_pos is out of range!\n");
			goto fail_3;
		}
		/*
		 * This notification function is for monitoring reboot command
		 * when the system has been started, the reboot parameter is
		 * stored in the RTC General Purpose register.
		 *
		 * gpr_offset:  General Purpose register's offset
		 * gpr_len: The number of General Purpose registers
		 * gpr_cur_pos: which to store the parameter in
		 * General Purpose register
		 */
		ret = register_reboot_notifier(&sunxi_reboot_notifier);
		if (ret) {
			dev_err(&pdev->dev,
				"register reboot notifier error %d\n", ret);
			goto fail_3;
		}
		global_pgregbase = chip->base + gpr_offset + 0x4 * gpr_num;
	}

	return 0;

fail_3:
	device_remove_file(&pdev->dev, &sunxi_rtc_min_year_attr);
	device_remove_file(&pdev->dev, &sunxi_rtc_max_year_attr);
	devm_free_irq(&pdev->dev, chip->irq, chip);
#else
	return 0;
#endif

fail:
	pm_runtime_put_sync(&pdev->dev);
	pm_runtime_disable(&pdev->dev);
	return -EIO;
}

static int sunxi_rtc_remove(struct platform_device *pdev)
{
	struct sunxi_rtc_dev *chip = platform_get_drvdata(pdev);
#ifdef CONFIG_SUNXI_BOOTUP_EXTEND
	unregister_reboot_notifier(&sunxi_reboot_notifier);
#endif
	device_remove_file(&pdev->dev, &sunxi_rtc_min_year_attr);
	device_remove_file(&pdev->dev, &sunxi_rtc_max_year_attr);

	devm_rtc_device_unregister(chip->dev, chip->rtc);

	/* Disable the clock/module */
	pm_runtime_put_sync(&pdev->dev);
	pm_runtime_disable(&pdev->dev);

	return 0;
}

static void sunxi_rtc_shutdown(struct platform_device *pdev)
{
}

static struct platform_driver sunxi_rtc_driver = {
	.probe		= sunxi_rtc_probe,
	.remove		= sunxi_rtc_remove,
	.shutdown   = sunxi_rtc_shutdown,
	.driver		= {
		.name		= "sunxi-rtc",
		.of_match_table = sunxi_rtc_dt_ids,
	},
};

module_platform_driver(sunxi_rtc_driver);

MODULE_DESCRIPTION("sunxi RTC driver V2");
MODULE_AUTHOR("Carlo Caione <carlo.caione@gmail.com>");
MODULE_LICENSE("GPL");