// SPDX-License-Identifier: (GPL-2.0-only OR MIT)
/*
 * Copyright (C) 2024 Amlogic, Inc. All rights reserved
 * Author: Yiting Deng <yiting.deng@amlogic.com>
 */

#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/rtc.h>
#include <linux/time64.h>

/* rtc oscillator rate */
#define OSC_32K			32768
#define OSC_24M			24000000

#define RTC_CTRL		(0x0 << 2)		/* Control RTC */
#define RTC_ALRM0_EN		BIT(0)
#define RTC_OSC_SEL		BIT(8)
#define RTC_ENABLE		BIT(12)

#define RTC_COUNTER_REG		(0x1 << 2)		/* Program RTC counter initial value */

#define RTC_ALARM0_REG		(0x2 << 2)		/* Program RTC alarm0 value */

#define RTC_SEC_ADJUST_REG	(0x6 << 2)		/* Control second-based timing adjustment */
#define RTC_MATCH_COUNTER	GENMASK(18, 0)
#define RTC_SEC_ADJUST_CTRL	GENMASK(20, 19)
#define RTC_ADJ_VALID		BIT(23)

#define RTC_INT_MASK		(0x8 << 2)		/* RTC interrupt mask */
#define RTC_ALRM0_IRQ_MSK	BIT(0)

#define RTC_INT_CLR		(0x9 << 2)		/* Clear RTC interrupt */
#define RTC_ALRM0_IRQ_CLR	BIT(0)

#define RTC_OSCIN_CTRL0		(0xa << 2)		/* Control RTC clk from 24M */
#define RTC_OSCIN_CTRL1		(0xb << 2)		/* Control RTC clk from 24M */
#define RTC_OSCIN_IN_EN		BIT(31)
#define RTC_OSCIN_OUT_CFG	GENMASK(29, 28)
#define RTC_OSCIN_OUT_N0M0	GENMASK(11, 0)
#define RTC_OSCIN_OUT_N1M1	GENMASK(23, 12)

#define RTC_INT_STATUS		(0xc << 2)		/* RTC interrupt status */
#define RTC_ALRM0_IRQ_STATUS	BIT(0)

#define RTC_REAL_TIME		(0xd << 2)		/* RTC time value */

#define RTC_OSCIN_OUT_32K_N0	0x2dc
#define RTC_OSCIN_OUT_32K_N1	0x2db
#define RTC_OSCIN_OUT_32K_M0	0x1
#define RTC_OSCIN_OUT_32K_M1	0x2

#define RTC_SWALLOW_SECOND	0x2
#define RTC_INSERT_SECOND	0x3

struct aml_rtc_config {
	bool gray_stored;
};

struct aml_rtc_data {
	struct regmap *map;
	struct rtc_device *rtc_dev;
	int irq;
	struct clk *rtc_clk;
	struct clk *sys_clk;
	int rtc_enabled;
	const struct aml_rtc_config *config;
};

static inline u32 gray_to_binary(u32 gray)
{
	u32 bcd = gray;
	int size = sizeof(bcd) * 8;
	int i;

	for (i = 0; (1 << i) < size; i++)
		bcd ^= bcd >> (1 << i);

	return bcd;
}

static inline u32 binary_to_gray(u32 bcd)
{
	return bcd ^ (bcd >> 1);
}

static int aml_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	struct aml_rtc_data *rtc = dev_get_drvdata(dev);
	u32 time_sec;

	/* if RTC disabled, read time failed */
	if (!rtc->rtc_enabled)
		return -EINVAL;

	regmap_read(rtc->map, RTC_REAL_TIME, &time_sec);
	if (rtc->config->gray_stored)
		time_sec = gray_to_binary(time_sec);
	rtc_time64_to_tm(time_sec, tm);
	dev_dbg(dev, "%s: read time = %us\n", __func__, time_sec);

	return 0;
}

static int aml_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	struct aml_rtc_data *rtc = dev_get_drvdata(dev);
	u32 time_sec;

	/* if RTC disabled, first enable it */
	if (!rtc->rtc_enabled) {
		regmap_write_bits(rtc->map, RTC_CTRL, RTC_ENABLE, RTC_ENABLE);
		usleep_range(100, 200);
		rtc->rtc_enabled = regmap_test_bits(rtc->map, RTC_CTRL, RTC_ENABLE);
		if (!rtc->rtc_enabled)
			return -EINVAL;
	}

	time_sec = rtc_tm_to_time64(tm);
	if (rtc->config->gray_stored)
		time_sec = binary_to_gray(time_sec);
	regmap_write(rtc->map, RTC_COUNTER_REG, time_sec);
	dev_dbg(dev, "%s: set time = %us\n", __func__, time_sec);

	return 0;
}

static int aml_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
	struct aml_rtc_data *rtc = dev_get_drvdata(dev);
	time64_t alarm_sec;

	/* if RTC disabled, set alarm failed */
	if (!rtc->rtc_enabled)
		return -EINVAL;

	regmap_update_bits(rtc->map, RTC_CTRL,
			   RTC_ALRM0_EN, RTC_ALRM0_EN);
	regmap_update_bits(rtc->map, RTC_INT_MASK,
			   RTC_ALRM0_IRQ_MSK, 0);

	alarm_sec = rtc_tm_to_time64(&alarm->time);
	if (rtc->config->gray_stored)
		alarm_sec = binary_to_gray(alarm_sec);
	regmap_write(rtc->map, RTC_ALARM0_REG, alarm_sec);

	dev_dbg(dev, "%s: alarm->enabled=%d alarm_set=%llds\n", __func__,
		alarm->enabled, alarm_sec);

	return 0;
}

static int aml_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
	struct aml_rtc_data *rtc = dev_get_drvdata(dev);
	u32 alarm_sec;
	int alarm_enable;
	int alarm_mask;

	/* if RTC disabled, read alarm failed */
	if (!rtc->rtc_enabled)
		return -EINVAL;

	regmap_read(rtc->map, RTC_ALARM0_REG, &alarm_sec);
	if (rtc->config->gray_stored)
		alarm_sec = gray_to_binary(alarm_sec);
	rtc_time64_to_tm(alarm_sec, &alarm->time);

	alarm_enable = regmap_test_bits(rtc->map, RTC_CTRL, RTC_ALRM0_EN);
	alarm_mask = regmap_test_bits(rtc->map, RTC_INT_MASK, RTC_ALRM0_IRQ_MSK);
	alarm->enabled = (alarm_enable && !alarm_mask) ? 1 : 0;
	dev_dbg(dev, "%s: alarm->enabled=%d alarm=%us\n", __func__,
		alarm->enabled, alarm_sec);

	return 0;
}

static int aml_rtc_read_offset(struct device *dev, long *offset)
{
	struct aml_rtc_data *rtc = dev_get_drvdata(dev);
	u32 reg_val;
	long val;
	int sign, match_counter, enable;

	/* if RTC disabled, read offset failed */
	if (!rtc->rtc_enabled)
		return -EINVAL;

	regmap_read(rtc->map, RTC_SEC_ADJUST_REG, &reg_val);
	enable = FIELD_GET(RTC_ADJ_VALID, reg_val);
	if (!enable) {
		val = 0;
	} else {
		sign = FIELD_GET(RTC_SEC_ADJUST_CTRL, reg_val);
		match_counter = FIELD_GET(RTC_MATCH_COUNTER, reg_val);
		val = 1000000000 / (match_counter + 1);
		if (sign == RTC_SWALLOW_SECOND)
			val = -val;
	}
	*offset = val;

	return 0;
}

static int aml_rtc_set_offset(struct device *dev, long offset)
{
	struct aml_rtc_data *rtc = dev_get_drvdata(dev);
	int sign = 0;
	int match_counter = 0;
	int enable = 0;
	u32 reg_val;

	/* if RTC disabled, set offset failed */
	if (!rtc->rtc_enabled)
		return -EINVAL;

	if (offset) {
		enable = 1;
		sign = offset < 0 ? RTC_SWALLOW_SECOND : RTC_INSERT_SECOND;
		match_counter = 1000000000 / abs(offset) - 1;
		if (match_counter < 0 || match_counter > RTC_MATCH_COUNTER)
			return -EINVAL;
	}

	reg_val = FIELD_PREP(RTC_ADJ_VALID, enable) |
		  FIELD_PREP(RTC_SEC_ADJUST_CTRL, sign) |
		  FIELD_PREP(RTC_MATCH_COUNTER, match_counter);
	regmap_write(rtc->map, RTC_SEC_ADJUST_REG, reg_val);

	return 0;
}

static int aml_rtc_alarm_enable(struct device *dev, unsigned int enabled)
{
	struct aml_rtc_data *rtc = dev_get_drvdata(dev);

	if (enabled) {
		regmap_update_bits(rtc->map, RTC_CTRL,
				   RTC_ALRM0_EN, RTC_ALRM0_EN);
		regmap_update_bits(rtc->map, RTC_INT_MASK,
				   RTC_ALRM0_IRQ_MSK, 0);
	} else {
		regmap_update_bits(rtc->map, RTC_INT_MASK,
				   RTC_ALRM0_IRQ_MSK, RTC_ALRM0_IRQ_MSK);
		regmap_update_bits(rtc->map, RTC_CTRL,
				   RTC_ALRM0_EN, 0);
	}

	return 0;
}

static const struct rtc_class_ops aml_rtc_ops = {
	.read_time = aml_rtc_read_time,
	.set_time = aml_rtc_set_time,
	.read_alarm = aml_rtc_read_alarm,
	.set_alarm = aml_rtc_set_alarm,
	.alarm_irq_enable = aml_rtc_alarm_enable,
	.read_offset = aml_rtc_read_offset,
	.set_offset = aml_rtc_set_offset,
};

static irqreturn_t aml_rtc_handler(int irq, void *data)
{
	struct aml_rtc_data *rtc = (struct aml_rtc_data *)data;

	regmap_write(rtc->map, RTC_ALARM0_REG, 0);
	regmap_write(rtc->map, RTC_INT_CLR, RTC_ALRM0_IRQ_STATUS);

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

	return IRQ_HANDLED;
}

static void aml_rtc_init(struct aml_rtc_data *rtc)
{
	u32 reg_val = 0;

	rtc->rtc_enabled = regmap_test_bits(rtc->map, RTC_CTRL, RTC_ENABLE);
	if (!rtc->rtc_enabled) {
		if (clk_get_rate(rtc->rtc_clk) == OSC_24M) {
			/* select 24M oscillator */
			regmap_write_bits(rtc->map, RTC_CTRL, RTC_OSC_SEL, RTC_OSC_SEL);

			/*
			 * Set RTC oscillator to freq_out to freq_in/((N0*M0+N1*M1)/(M0+M1))
			 * Enable clock_in gate of oscillator 24MHz
			 * Set N0 to 733, N1 to 732
			 */
			reg_val = FIELD_PREP(RTC_OSCIN_IN_EN, 1)
				  | FIELD_PREP(RTC_OSCIN_OUT_CFG, 1)
				  | FIELD_PREP(RTC_OSCIN_OUT_N0M0, RTC_OSCIN_OUT_32K_N0)
				  | FIELD_PREP(RTC_OSCIN_OUT_N1M1, RTC_OSCIN_OUT_32K_N1);
			regmap_write_bits(rtc->map, RTC_OSCIN_CTRL0, RTC_OSCIN_IN_EN
					  | RTC_OSCIN_OUT_CFG | RTC_OSCIN_OUT_N0M0
					  | RTC_OSCIN_OUT_N1M1, reg_val);

			/* Set M0 to 2, M1 to 3, so freq_out = 32768 Hz*/
			reg_val = FIELD_PREP(RTC_OSCIN_OUT_N0M0, RTC_OSCIN_OUT_32K_M0)
				  | FIELD_PREP(RTC_OSCIN_OUT_N1M1, RTC_OSCIN_OUT_32K_M1);
			regmap_write_bits(rtc->map, RTC_OSCIN_CTRL1, RTC_OSCIN_OUT_N0M0
					  | RTC_OSCIN_OUT_N1M1, reg_val);
		} else {
			/* select 32K oscillator */
			regmap_write_bits(rtc->map, RTC_CTRL, RTC_OSC_SEL, 0);
		}
	}
	regmap_write_bits(rtc->map, RTC_INT_MASK,
			  RTC_ALRM0_IRQ_MSK, RTC_ALRM0_IRQ_MSK);
	regmap_write_bits(rtc->map, RTC_CTRL, RTC_ALRM0_EN, 0);
}

static int aml_rtc_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct aml_rtc_data *rtc;
	void __iomem *base;
	int ret = 0;

	const struct regmap_config aml_rtc_regmap_config = {
		.reg_bits = 32,
		.val_bits = 32,
		.reg_stride = 4,
		.max_register = RTC_REAL_TIME,
	};

	rtc = devm_kzalloc(dev, sizeof(*rtc), GFP_KERNEL);
	if (!rtc)
		return -ENOMEM;

	rtc->config = of_device_get_match_data(dev);
	if (!rtc->config)
		return -ENODEV;

	base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(base))
		return dev_err_probe(dev, PTR_ERR(base), "resource ioremap failed\n");

	rtc->map = devm_regmap_init_mmio(dev, base, &aml_rtc_regmap_config);
	if (IS_ERR(rtc->map))
		return dev_err_probe(dev, PTR_ERR(rtc->map), "regmap init failed\n");

	rtc->irq = platform_get_irq(pdev, 0);
	if (rtc->irq < 0)
		return rtc->irq;

	rtc->rtc_clk = devm_clk_get(dev, "osc");
	if (IS_ERR(rtc->rtc_clk))
		return dev_err_probe(dev, PTR_ERR(rtc->rtc_clk),
				     "failed to find rtc clock\n");
	if (clk_get_rate(rtc->rtc_clk) != OSC_32K && clk_get_rate(rtc->rtc_clk) != OSC_24M)
		return dev_err_probe(dev, -EINVAL, "Invalid clock configuration\n");

	rtc->sys_clk = devm_clk_get_enabled(dev, "sys");
	if (IS_ERR(rtc->sys_clk))
		return dev_err_probe(dev, PTR_ERR(rtc->sys_clk),
				     "failed to get_enable rtc sys clk\n");
	aml_rtc_init(rtc);

	device_init_wakeup(dev, true);
	platform_set_drvdata(pdev, rtc);

	rtc->rtc_dev = devm_rtc_allocate_device(dev);
	if (IS_ERR(rtc->rtc_dev)) {
		ret = PTR_ERR(rtc->rtc_dev);
		goto err_clk;
	}

	ret = devm_request_irq(dev, rtc->irq, aml_rtc_handler,
			       IRQF_ONESHOT, "aml-rtc alarm", rtc);
	if (ret) {
		dev_err_probe(dev, ret, "IRQ%d request failed, ret = %d\n",
			      rtc->irq, ret);
		goto err_clk;
	}

	rtc->rtc_dev->ops = &aml_rtc_ops;
	rtc->rtc_dev->range_min = 0;
	rtc->rtc_dev->range_max = U32_MAX;

	ret = devm_rtc_register_device(rtc->rtc_dev);
	if (ret) {
		dev_err_probe(&pdev->dev, ret, "Failed to register RTC device: %d\n", ret);
		goto err_clk;
	}

	return 0;
err_clk:
	device_init_wakeup(dev, false);

	return ret;
}

#ifdef CONFIG_PM_SLEEP
static int aml_rtc_suspend(struct device *dev)
{
	struct aml_rtc_data *rtc = dev_get_drvdata(dev);

	if (device_may_wakeup(dev))
		enable_irq_wake(rtc->irq);

	return 0;
}

static int aml_rtc_resume(struct device *dev)
{
	struct aml_rtc_data *rtc = dev_get_drvdata(dev);

	if (device_may_wakeup(dev))
		disable_irq_wake(rtc->irq);

	return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(aml_rtc_pm_ops,
			 aml_rtc_suspend, aml_rtc_resume);

static void aml_rtc_remove(struct platform_device *pdev)
{
	device_init_wakeup(&pdev->dev, false);
}

static const struct aml_rtc_config a5_rtc_config = {
};

static const struct aml_rtc_config a4_rtc_config = {
	.gray_stored = true,
};

static const struct of_device_id aml_rtc_device_id[] = {
	{
		.compatible = "amlogic,a4-rtc",
		.data = &a4_rtc_config,
	},
	{
		.compatible = "amlogic,a5-rtc",
		.data = &a5_rtc_config,
	},
	{ }
};
MODULE_DEVICE_TABLE(of, aml_rtc_device_id);

static struct platform_driver aml_rtc_driver = {
	.probe = aml_rtc_probe,
	.remove = aml_rtc_remove,
	.driver = {
		.name = "aml-rtc",
		.pm = &aml_rtc_pm_ops,
		.of_match_table = aml_rtc_device_id,
	},
};

module_platform_driver(aml_rtc_driver);
MODULE_DESCRIPTION("Amlogic RTC driver");
MODULE_AUTHOR("Yiting Deng <yiting.deng@amlogic.com>");
MODULE_LICENSE("GPL");
