/*
 * 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 <linux/clk.h>
#include "rtc-sunxi-v3.h"

static const struct rtc_class_ops sunxi_rtc_ops = {
	.read_time		= NULL,
	.set_time		= NULL,
	.read_alarm		= NULL,
	.set_alarm		= NULL,
	.alarm_irq_enable	= NULL,
};

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

#if defined(CONFIG_SUNXI_BOOTUP_EXTEND) || defined(CONFIG_SUNXI_RTC_BOOTCOUNT)
static void __iomem *global_pgregbase;

static int rtc_flag_str2num(const char *rtc_str, unsigned int *rtc_flag_p)
{
	int ret = 0;
	unsigned int rtc_flag;

	if (!strcmp(rtc_str, "debug")) {
		rtc_flag = SUNXI_DEBUG_MODE_FLAG;
	} else if (!strcmp(rtc_str, "efex")) {
		rtc_flag = SUNXI_EFEX_CMD_FLAG;
	} else if (!strcmp(rtc_str, "boot-resignature")) {
		rtc_flag = SUNXI_BOOT_RESIGNATURE_FLAG;
	} else if (!strcmp(rtc_str, "recovery")
		|| !strcmp(rtc_str, "boot-recovery")) {
		rtc_flag = SUNXI_BOOT_RECOVERY_FLAG;
	} else if (!strcmp(rtc_str, "sysrecovery")) {
		rtc_flag = SUNXI_SYS_RECOVERY_FLAG;
	} else if (!strcmp(rtc_str, "bootloader")) {
		rtc_flag = SUNXI_FASTBOOT_FLAG;
	} else if (!strcmp(rtc_str, "usb-recovery")) {
		rtc_flag = SUNXI_USB_RECOVERY_FLAG;
	} else if (!strcmp(rtc_str, "uboot")) {
		rtc_flag = SUNXI_UBOOT_FLAG;
	} else {
		rtc_flag = 0;
		ret = -1;
	}

	*rtc_flag_p = rtc_flag;
	return ret;
}

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

	if (data == NULL)
		return NOTIFY_DONE;

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

	ret = rtc_flag_str2num((const char *)data, &rtc_flag);
	if (ret == -1) {
		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,
};

static ssize_t sunxi_rtc_flag_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	unsigned int rtc_flag = 0;

	rtc_flag = readl(global_pgregbase);

	return sprintf(buf, "0x%x\n", rtc_flag);
}

static ssize_t sunxi_rtc_flag_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t size)
{
	unsigned int rtc_flag = 0;
	int ret;
	char rtc_str[30] = {0};

	if (size >= 30) {
		pr_err("parameters too long\n");
		return size;
	}

	snprintf(rtc_str, size, "%s", buf);
	ret = rtc_flag_str2num(rtc_str, &rtc_flag);
	if (ret == -1)
		pr_warn("unknown arg %s", buf);
	else
		pr_info("store rtc flag 0x%x\n", rtc_flag);

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

	return size;
}

static struct device_attribute sunxi_rtc_flag_attr =
	__ATTR(flag, 0664, sunxi_rtc_flag_show, sunxi_rtc_flag_store);

#ifdef CONFIG_SUNXI_RTC_BOOTCOUNT
static void __iomem *global_bootcount;

static int rtc_bootcount_str(const char *rtc_str, unsigned int *rtc_bootcount_p)
{
	int ret = 0;
	unsigned int rtc_bootcount;

	if (!strcmp(rtc_str, "0")) {
		rtc_bootcount = 0;
	} else {
		pr_info("usage : input \"0\" to clean bootcount\n");
		return -1;
	}

	*rtc_bootcount_p = rtc_bootcount;
	return ret;
}

static ssize_t sunxi_rtc_bootcount_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	unsigned int rtc_bootcount = 0;

	rtc_bootcount = readl(global_bootcount);

	return sprintf(buf, "0x%08x\n", rtc_bootcount);
}

static ssize_t sunxi_rtc_bootcount_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t size)
{
	unsigned int rtc_bootcount = 0;
	int ret;
	char rtc_str[30] = {0};

	if (size >= 30) {
		pr_err("parameters too long\n");
		return size;
	}

	snprintf(rtc_str, size, "%s", buf);
	ret = rtc_bootcount_str(rtc_str, &rtc_bootcount);
	if (ret == -1) {
		pr_warn("unknown arg %s\n", buf);
		return -1;
	} else {
		pr_info("store rtc bootcount arg %s\n", rtc_str);
		/* write the data to reg */
		writel(rtc_bootcount, global_bootcount);
	}

	return size;
}

static struct device_attribute sunxi_rtc_bootcount_attr =
	__ATTR(bootcount, 0664, sunxi_rtc_bootcount_show, sunxi_rtc_bootcount_store);
#endif
#endif

static inline int sunxi_rtc_clk_config(struct platform_device *pdev)
{
	struct sunxi_rtc_dev *chip = platform_get_drvdata(pdev);
	void __iomem *addr = NULL;
	unsigned int  data = 0;

	//Use internal 24MHz-divided clock
	addr = chip->base + SUNXI_LOSC_CTRL_REG;
	data = readl(addr);
	data &= ~BIT(14);
	writel(data, addr);

	data = readl(addr);
	data |= (BIT(1) | LOSC_CTRL_KEY_FIELD_MAGIC);
	writel(data, addr);

	data = readl(addr);
	data |= (BIT(0) | LOSC_CTRL_KEY_FIELD_MAGIC);
	writel(data, addr);

	//Enable LOSC output gating
	addr = chip->base + SUNXI_LOSC_OUT_GATING_REG;
	data = readl(addr);
	data |= BIT(0);
	writel(data, addr);

	return 0;
}

static int sunxi_rtc_probe(struct platform_device *pdev)
{
	struct sunxi_rtc_dev *chip;
	struct resource *res;
	const struct of_device_id *of_id;
	struct clk *clk = NULL;
	int clk_is_out = 0;
	int ret = 0;

#if defined(CONFIG_SUNXI_BOOTUP_EXTEND) || defined(CONFIG_SUNXI_RTC_BOOTCOUNT)
	u32 gpr_offset = 0;
	u32 gpr_len = 0;
#ifdef CONFIG_SUNXI_BOOTUP_EXTEND
	u32 gpr_cur_pos = 0;
	global_pgregbase = NULL;
#endif
#ifdef CONFIG_SUNXI_RTC_BOOTCOUNT
	u32 gpr_bootcount_pos = 0;
	global_bootcount = NULL;
#endif
#endif

	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);

	/* 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;


	//Write CCU registers, to enable internal 24MHz-calibrated clock
	clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(clk)) {
		ret = PTR_ERR(clk);
		goto fail1;
	}
	ret = clk_prepare_enable(clk);
	if (ret)
		goto fail1;

	of_property_read_u32(pdev->dev.of_node,
					"clk32k_out", &clk_is_out);

	if (clk_is_out) {
		//After writing CCU registers, write RTC clock registers
		sunxi_rtc_clk_config(pdev);
	}

	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 fail2;
	}

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

#if defined(CONFIG_SUNXI_BOOTUP_EXTEND) || defined(CONFIG_SUNXI_RTC_BOOTCOUNT)
	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 fail2;
	}

	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 fail2;
	}

#ifdef CONFIG_SUNXI_BOOTUP_EXTEND
	ret = of_property_read_u32(pdev->dev.of_node,
					"gpr_cur_pos", &gpr_cur_pos);
	if (ret) {
		dev_err(&pdev->dev, "Could not get Gpr reboot cur pos");
		goto fail2;
	}

	if (gpr_cur_pos >= gpr_len) {
		dev_err(&pdev->dev,
			"gpr_cur_pos is out of range!\n");
		goto fail2;
	}

	global_pgregbase = chip->base + gpr_offset + 0x4 * gpr_cur_pos;

	/*
	  * 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 fail2;
	}

	/*
	  * Export sunxi rtc flag to sysfs:
	  * To support "reboot efex" with RTC, we need to store a flag
	  * in RTC before reboot. Android's reboot can pass parameters to
	  * kernel but busybox's reboot can not do that.
	  * Here we export rtc flag to sysfs, so the flowing command can
	  * be used as an alternative of "reboot efex":
	  * echo "efex" > "/sys/devices/platform/soc/rtc/flag"; reboot
	*/
	ret = device_create_file(&pdev->dev, &sunxi_rtc_flag_attr);
	if (ret) {
		dev_err(&pdev->dev, "device_create_file failed\n");
		goto fail2;
	}
#endif

#ifdef CONFIG_SUNXI_RTC_BOOTCOUNT
	ret = of_property_read_u32(pdev->dev.of_node,
			"gpr_bootcount_pos", &gpr_bootcount_pos);
	if (ret) {
		dev_err(&pdev->dev, "Could not get Gpr bootcount");
		goto fail2;
	}

	if (gpr_bootcount_pos >= gpr_len) {
		dev_err(&pdev->dev,
			"gpr_bootcount_pos is out of range!\n");
		goto fail2;
	}

	global_bootcount = chip->base + gpr_offset + 0x4 * gpr_bootcount_pos;

	ret = device_create_file(&pdev->dev, &sunxi_rtc_bootcount_attr);
	if (ret) {
		dev_err(&pdev->dev, "device_create_file failed\n");
		goto fail2;
	}
#endif
#endif  //CONFIG_SUNXI_BOOTUP_EXTEND
	return 0;

fail2:
	clk_disable_unprepare(clk);
fail1:
	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

	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)
{
	return;
}

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");
MODULE_AUTHOR("Carlo Caione <carlo.caione@gmail.com>");
MODULE_LICENSE("GPL");