// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Loongson RTC driver
 *
 * Maintained out-of-tree by Huacai Chen <chenhuacai@kernel.org>.
 * Rewritten for mainline by WANG Xuerui <git@xen0n.name>.
 *                           Binbin Zhou <zhoubinbin@loongson.cn>
 */

#include <linux/bitfield.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/rtc.h>
#include <linux/acpi.h>

/* Time Of Year(TOY) counters registers */
#define TOY_TRIM_REG		0x20 /* Must be initialized to 0 */
#define TOY_WRITE0_REG		0x24 /* TOY low 32-bits value (write-only) */
#define TOY_WRITE1_REG		0x28 /* TOY high 32-bits value (write-only) */
#define TOY_READ0_REG		0x2c /* TOY low 32-bits value (read-only) */
#define TOY_READ1_REG		0x30 /* TOY high 32-bits value (read-only) */
#define TOY_MATCH0_REG		0x34 /* TOY timing interrupt 0 */
#define TOY_MATCH1_REG		0x38 /* TOY timing interrupt 1 */
#define TOY_MATCH2_REG		0x3c /* TOY timing interrupt 2 */

/* RTC counters registers */
#define RTC_CTRL_REG		0x40 /* TOY and RTC control register */
#define RTC_TRIM_REG		0x60 /* Must be initialized to 0 */
#define RTC_WRITE0_REG		0x64 /* RTC counters value (write-only) */
#define RTC_READ0_REG		0x68 /* RTC counters value (read-only) */
#define RTC_MATCH0_REG		0x6c /* RTC timing interrupt 0 */
#define RTC_MATCH1_REG		0x70 /* RTC timing interrupt 1 */
#define RTC_MATCH2_REG		0x74 /* RTC timing interrupt 2 */

/* bitmask of TOY_WRITE0_REG */
#define TOY_MON			GENMASK(31, 26)
#define TOY_DAY			GENMASK(25, 21)
#define TOY_HOUR		GENMASK(20, 16)
#define TOY_MIN			GENMASK(15, 10)
#define TOY_SEC			GENMASK(9, 4)
#define TOY_MSEC		GENMASK(3, 0)

/* bitmask of TOY_MATCH0/1/2_REG */
#define TOY_MATCH_YEAR		GENMASK(31, 26)
#define TOY_MATCH_MON		GENMASK(25, 22)
#define TOY_MATCH_DAY		GENMASK(21, 17)
#define TOY_MATCH_HOUR		GENMASK(16, 12)
#define TOY_MATCH_MIN		GENMASK(11, 6)
#define TOY_MATCH_SEC		GENMASK(5, 0)

/* bitmask of RTC_CTRL_REG */
#define RTC_ENABLE		BIT(13) /* 1: RTC counters enable */
#define TOY_ENABLE		BIT(11) /* 1: TOY counters enable */
#define OSC_ENABLE		BIT(8) /* 1: 32.768k crystal enable */
#define TOY_ENABLE_MASK		(TOY_ENABLE | OSC_ENABLE)

/* PM domain registers */
#define PM1_STS_REG		0x0c	/* Power management 1 status register */
#define RTC_STS			BIT(10)	/* RTC status */
#define PM1_EN_REG		0x10	/* Power management 1 enable register */
#define RTC_EN			BIT(10)	/* RTC event enable */

/*
 * According to the LS1C manual, RTC_CTRL and alarm-related registers are not defined.
 * Accessing the relevant registers will cause the system to hang.
 */
#define LS1C_RTC_CTRL_WORKAROUND	BIT(0)

struct loongson_rtc_config {
	u32 pm_offset;	/* Offset of PM domain, for RTC alarm wakeup */
	u32 flags;	/* Workaround bits */
};

struct loongson_rtc_priv {
	spinlock_t lock;	/* protects PM registers access */
	u32 fix_year;		/* RTC alarm year compensation value */
	struct rtc_device *rtcdev;
	struct regmap *regmap;
	void __iomem *pm_base;	/* PM domain base, for RTC alarm wakeup */
	const struct loongson_rtc_config *config;
};

static const struct loongson_rtc_config ls1b_rtc_config = {
	.pm_offset = 0,
	.flags = 0,
};

static const struct loongson_rtc_config ls1c_rtc_config = {
	.pm_offset = 0,
	.flags = LS1C_RTC_CTRL_WORKAROUND,
};

static const struct loongson_rtc_config generic_rtc_config = {
	.pm_offset = 0x100,
	.flags = 0,
};

static const struct loongson_rtc_config ls2k1000_rtc_config = {
	.pm_offset = 0x800,
	.flags = 0,
};

static const struct regmap_config loongson_rtc_regmap_config = {
	.reg_bits = 32,
	.val_bits = 32,
	.reg_stride = 4,
};

/* RTC alarm irq handler */
static irqreturn_t loongson_rtc_isr(int irq, void *id)
{
	struct loongson_rtc_priv *priv = (struct loongson_rtc_priv *)id;

	rtc_update_irq(priv->rtcdev, 1, RTC_AF | RTC_IRQF);
	return IRQ_HANDLED;
}

/* For ACPI fixed event handler */
static u32 loongson_rtc_handler(void *id)
{
	struct loongson_rtc_priv *priv = (struct loongson_rtc_priv *)id;

	spin_lock(&priv->lock);
	/* Disable RTC alarm wakeup and interrupt */
	writel(readl(priv->pm_base + PM1_EN_REG) & ~RTC_EN,
	       priv->pm_base + PM1_EN_REG);

	/* Clear RTC interrupt status */
	writel(RTC_STS, priv->pm_base + PM1_STS_REG);
	spin_unlock(&priv->lock);

	/*
	 * The TOY_MATCH0_REG should be cleared 0 here,
	 * otherwise the interrupt cannot be cleared.
	 */
	return regmap_write(priv->regmap, TOY_MATCH0_REG, 0);
}

static int loongson_rtc_set_enabled(struct device *dev)
{
	struct loongson_rtc_priv *priv = dev_get_drvdata(dev);

	if (priv->config->flags & LS1C_RTC_CTRL_WORKAROUND)
		return 0;

	/* Enable RTC TOY counters and crystal */
	return regmap_update_bits(priv->regmap, RTC_CTRL_REG, TOY_ENABLE_MASK,
				  TOY_ENABLE_MASK);
}

static bool loongson_rtc_get_enabled(struct device *dev)
{
	int ret;
	u32 ctrl_data;
	struct loongson_rtc_priv *priv = dev_get_drvdata(dev);

	if (priv->config->flags & LS1C_RTC_CTRL_WORKAROUND)
		return true;

	ret = regmap_read(priv->regmap, RTC_CTRL_REG, &ctrl_data);
	if (ret < 0)
		return false;

	return ctrl_data & TOY_ENABLE_MASK;
}

static int loongson_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	int ret;
	u32 rtc_data[2];
	struct loongson_rtc_priv *priv = dev_get_drvdata(dev);

	if (!loongson_rtc_get_enabled(dev))
		return -EINVAL;

	ret = regmap_bulk_read(priv->regmap, TOY_READ0_REG, rtc_data,
			       ARRAY_SIZE(rtc_data));
	if (ret < 0)
		return ret;

	tm->tm_sec = FIELD_GET(TOY_SEC, rtc_data[0]);
	tm->tm_min = FIELD_GET(TOY_MIN, rtc_data[0]);
	tm->tm_hour = FIELD_GET(TOY_HOUR, rtc_data[0]);
	tm->tm_mday = FIELD_GET(TOY_DAY, rtc_data[0]);
	tm->tm_mon = FIELD_GET(TOY_MON, rtc_data[0]) - 1;
	tm->tm_year = rtc_data[1];

	/* Prepare for RTC alarm year compensation value. */
	priv->fix_year = tm->tm_year / 64 * 64;
	return 0;
}

static int loongson_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	int ret;
	u32 rtc_data[2];
	struct loongson_rtc_priv *priv = dev_get_drvdata(dev);

	rtc_data[0] = FIELD_PREP(TOY_SEC, tm->tm_sec)
		    | FIELD_PREP(TOY_MIN, tm->tm_min)
		    | FIELD_PREP(TOY_HOUR, tm->tm_hour)
		    | FIELD_PREP(TOY_DAY, tm->tm_mday)
		    | FIELD_PREP(TOY_MON, tm->tm_mon + 1);
	rtc_data[1] = tm->tm_year;

	ret = regmap_bulk_write(priv->regmap, TOY_WRITE0_REG, rtc_data,
				ARRAY_SIZE(rtc_data));
	if (ret < 0)
		return ret;

	return loongson_rtc_set_enabled(dev);
}

static int loongson_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	int ret;
	u32 alarm_data;
	struct loongson_rtc_priv *priv = dev_get_drvdata(dev);

	ret = regmap_read(priv->regmap, TOY_MATCH0_REG, &alarm_data);
	if (ret < 0)
		return ret;

	alrm->time.tm_sec = FIELD_GET(TOY_MATCH_SEC, alarm_data);
	alrm->time.tm_min = FIELD_GET(TOY_MATCH_MIN, alarm_data);
	alrm->time.tm_hour = FIELD_GET(TOY_MATCH_HOUR, alarm_data);
	alrm->time.tm_mday = FIELD_GET(TOY_MATCH_DAY, alarm_data);
	alrm->time.tm_mon = FIELD_GET(TOY_MATCH_MON, alarm_data) - 1;
	/*
	 * This is a hardware bug: the year field of SYS_TOYMATCH is only 6 bits,
	 * making it impossible to save year values larger than 64.
	 *
	 * SYS_TOYMATCH is used to match the alarm time value and determine if
	 * an alarm is triggered, so we must keep the lower 6 bits of the year
	 * value constant during the value conversion.
	 *
	 * In summary, we need to manually add 64(or a multiple of 64) to the
	 * year value to avoid the invalid alarm prompt at startup.
	 */
	alrm->time.tm_year = FIELD_GET(TOY_MATCH_YEAR, alarm_data) + priv->fix_year;

	alrm->enabled = !!(readl(priv->pm_base + PM1_EN_REG) & RTC_EN);
	return 0;
}

static int loongson_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
	u32 val;
	struct loongson_rtc_priv *priv = dev_get_drvdata(dev);

	spin_lock(&priv->lock);
	val = readl(priv->pm_base + PM1_EN_REG);
	/* Enable RTC alarm wakeup */
	writel(enabled ? val | RTC_EN : val & ~RTC_EN,
	       priv->pm_base + PM1_EN_REG);
	spin_unlock(&priv->lock);

	return 0;
}

static int loongson_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	int ret;
	u32 alarm_data;
	struct loongson_rtc_priv *priv = dev_get_drvdata(dev);

	alarm_data = FIELD_PREP(TOY_MATCH_SEC, alrm->time.tm_sec)
		   | FIELD_PREP(TOY_MATCH_MIN, alrm->time.tm_min)
		   | FIELD_PREP(TOY_MATCH_HOUR, alrm->time.tm_hour)
		   | FIELD_PREP(TOY_MATCH_DAY, alrm->time.tm_mday)
		   | FIELD_PREP(TOY_MATCH_MON, alrm->time.tm_mon + 1)
		   | FIELD_PREP(TOY_MATCH_YEAR, alrm->time.tm_year - priv->fix_year);

	ret = regmap_write(priv->regmap, TOY_MATCH0_REG, alarm_data);
	if (ret < 0)
		return ret;

	return loongson_rtc_alarm_irq_enable(dev, alrm->enabled);
}

static const struct rtc_class_ops loongson_rtc_ops = {
	.read_time = loongson_rtc_read_time,
	.set_time = loongson_rtc_set_time,
	.read_alarm = loongson_rtc_read_alarm,
	.set_alarm = loongson_rtc_set_alarm,
	.alarm_irq_enable = loongson_rtc_alarm_irq_enable,
};

static int loongson_rtc_probe(struct platform_device *pdev)
{
	int ret, alarm_irq;
	void __iomem *regs;
	struct loongson_rtc_priv *priv;
	struct device *dev = &pdev->dev;

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

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

	priv->regmap = devm_regmap_init_mmio(dev, regs,
					     &loongson_rtc_regmap_config);
	if (IS_ERR(priv->regmap))
		return dev_err_probe(dev, PTR_ERR(priv->regmap),
				     "devm_regmap_init_mmio failed\n");

	priv->config = device_get_match_data(dev);
	spin_lock_init(&priv->lock);
	platform_set_drvdata(pdev, priv);

	priv->rtcdev = devm_rtc_allocate_device(dev);
	if (IS_ERR(priv->rtcdev))
		return dev_err_probe(dev, PTR_ERR(priv->rtcdev),
				     "devm_rtc_allocate_device failed\n");

	/* Get RTC alarm irq */
	alarm_irq = platform_get_irq(pdev, 0);
	if (alarm_irq > 0) {
		ret = devm_request_irq(dev, alarm_irq, loongson_rtc_isr,
				       0, "loongson-alarm", priv);
		if (ret < 0)
			return dev_err_probe(dev, ret, "Unable to request irq %d\n",
					     alarm_irq);

		priv->pm_base = regs - priv->config->pm_offset;
		device_init_wakeup(dev, 1);

		if (has_acpi_companion(dev))
			acpi_install_fixed_event_handler(ACPI_EVENT_RTC,
							 loongson_rtc_handler, priv);
	} else {
		/* Loongson-1C RTC does not support alarm */
		clear_bit(RTC_FEATURE_ALARM, priv->rtcdev->features);
	}

	/* Loongson RTC does not support UIE */
	clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, priv->rtcdev->features);
	priv->rtcdev->ops = &loongson_rtc_ops;
	priv->rtcdev->range_min = RTC_TIMESTAMP_BEGIN_2000;
	priv->rtcdev->range_max = RTC_TIMESTAMP_END_2099;

	return devm_rtc_register_device(priv->rtcdev);
}

static void loongson_rtc_remove(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct loongson_rtc_priv *priv = dev_get_drvdata(dev);

	if (!test_bit(RTC_FEATURE_ALARM, priv->rtcdev->features))
		return;

	if (has_acpi_companion(dev))
		acpi_remove_fixed_event_handler(ACPI_EVENT_RTC,
						loongson_rtc_handler);

	device_init_wakeup(dev, 0);
	loongson_rtc_alarm_irq_enable(dev, 0);
}

static const struct of_device_id loongson_rtc_of_match[] = {
	{ .compatible = "loongson,ls1b-rtc", .data = &ls1b_rtc_config },
	{ .compatible = "loongson,ls1c-rtc", .data = &ls1c_rtc_config },
	{ .compatible = "loongson,ls7a-rtc", .data = &generic_rtc_config },
	{ .compatible = "loongson,ls2k1000-rtc", .data = &ls2k1000_rtc_config },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, loongson_rtc_of_match);

static const struct acpi_device_id loongson_rtc_acpi_match[] = {
	{ "LOON0001", .driver_data = (kernel_ulong_t)&generic_rtc_config },
	{ }
};
MODULE_DEVICE_TABLE(acpi, loongson_rtc_acpi_match);

static struct platform_driver loongson_rtc_driver = {
	.probe		= loongson_rtc_probe,
	.remove_new	= loongson_rtc_remove,
	.driver		= {
		.name	= "loongson-rtc",
		.of_match_table = loongson_rtc_of_match,
		.acpi_match_table = loongson_rtc_acpi_match,
	},
};
module_platform_driver(loongson_rtc_driver);

MODULE_DESCRIPTION("Loongson RTC driver");
MODULE_AUTHOR("Binbin Zhou <zhoubinbin@loongson.cn>");
MODULE_AUTHOR("WANG Xuerui <git@xen0n.name>");
MODULE_AUTHOR("Huacai Chen <chenhuacai@kernel.org>");
MODULE_LICENSE("GPL");