// SPDX-License-Identifier: GPL-2.0
/*
 * A driver for the RTC embedded in the Cirrus Logic EP93XX processors
 * Copyright (c) 2006 Tower Technologies
 *
 * Author: Alessandro Zummo <a.zummo@towertech.it>
 */

#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/gfp.h>

#define EP93XX_RTC_DATA			0x000
#define EP93XX_RTC_MATCH		0x004
#define EP93XX_RTC_STATUS		0x008
#define  EP93XX_RTC_STATUS_INTR		 BIT(0)
#define EP93XX_RTC_LOAD			0x00C
#define EP93XX_RTC_CONTROL		0x010
#define  EP93XX_RTC_CONTROL_MIE		 BIT(0)
#define EP93XX_RTC_SWCOMP		0x108
#define  EP93XX_RTC_SWCOMP_DEL_MASK	 0x001f0000
#define  EP93XX_RTC_SWCOMP_DEL_SHIFT	 16
#define  EP93XX_RTC_SWCOMP_INT_MASK	 0x0000ffff
#define  EP93XX_RTC_SWCOMP_INT_SHIFT	 0

struct ep93xx_rtc {
	void __iomem	*mmio_base;
	struct rtc_device *rtc;
};

static int ep93xx_rtc_get_swcomp(struct device *dev, unsigned short *preload,
				 unsigned short *delete)
{
	struct ep93xx_rtc *ep93xx_rtc = dev_get_drvdata(dev);
	unsigned long comp;

	comp = readl(ep93xx_rtc->mmio_base + EP93XX_RTC_SWCOMP);

	if (preload)
		*preload = (comp & EP93XX_RTC_SWCOMP_INT_MASK)
				>> EP93XX_RTC_SWCOMP_INT_SHIFT;

	if (delete)
		*delete = (comp & EP93XX_RTC_SWCOMP_DEL_MASK)
				>> EP93XX_RTC_SWCOMP_DEL_SHIFT;

	return 0;
}

static int ep93xx_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	struct ep93xx_rtc *ep93xx_rtc = dev_get_drvdata(dev);
	unsigned long time;

	time = readl(ep93xx_rtc->mmio_base + EP93XX_RTC_DATA);

	rtc_time64_to_tm(time, tm);
	return 0;
}

static int ep93xx_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	struct ep93xx_rtc *ep93xx_rtc = dev_get_drvdata(dev);
	unsigned long secs = rtc_tm_to_time64(tm);

	writel(secs + 1, ep93xx_rtc->mmio_base + EP93XX_RTC_LOAD);
	return 0;
}

static int ep93xx_rtc_proc(struct device *dev, struct seq_file *seq)
{
	unsigned short preload, delete;

	ep93xx_rtc_get_swcomp(dev, &preload, &delete);

	seq_printf(seq, "preload\t\t: %d\n", preload);
	seq_printf(seq, "delete\t\t: %d\n", delete);

	return 0;
}

static const struct rtc_class_ops ep93xx_rtc_ops = {
	.read_time	= ep93xx_rtc_read_time,
	.set_time	= ep93xx_rtc_set_time,
	.proc		= ep93xx_rtc_proc,
};

static ssize_t comp_preload_show(struct device *dev,
				 struct device_attribute *attr, char *buf)
{
	unsigned short preload;

	ep93xx_rtc_get_swcomp(dev->parent, &preload, NULL);

	return sprintf(buf, "%d\n", preload);
}
static DEVICE_ATTR_RO(comp_preload);

static ssize_t comp_delete_show(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	unsigned short delete;

	ep93xx_rtc_get_swcomp(dev->parent, NULL, &delete);

	return sprintf(buf, "%d\n", delete);
}
static DEVICE_ATTR_RO(comp_delete);

static struct attribute *ep93xx_rtc_attrs[] = {
	&dev_attr_comp_preload.attr,
	&dev_attr_comp_delete.attr,
	NULL
};

static const struct attribute_group ep93xx_rtc_sysfs_files = {
	.attrs	= ep93xx_rtc_attrs,
};

static int ep93xx_rtc_probe(struct platform_device *pdev)
{
	struct ep93xx_rtc *ep93xx_rtc;
	struct resource *res;
	int err;

	ep93xx_rtc = devm_kzalloc(&pdev->dev, sizeof(*ep93xx_rtc), GFP_KERNEL);
	if (!ep93xx_rtc)
		return -ENOMEM;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	ep93xx_rtc->mmio_base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(ep93xx_rtc->mmio_base))
		return PTR_ERR(ep93xx_rtc->mmio_base);

	platform_set_drvdata(pdev, ep93xx_rtc);

	ep93xx_rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
	if (IS_ERR(ep93xx_rtc->rtc))
		return PTR_ERR(ep93xx_rtc->rtc);

	ep93xx_rtc->rtc->ops = &ep93xx_rtc_ops;
	ep93xx_rtc->rtc->range_max = U32_MAX;

	err = rtc_add_group(ep93xx_rtc->rtc, &ep93xx_rtc_sysfs_files);
	if (err)
		return err;

	return rtc_register_device(ep93xx_rtc->rtc);
}

static struct platform_driver ep93xx_rtc_driver = {
	.driver		= {
		.name	= "ep93xx-rtc",
	},
	.probe		= ep93xx_rtc_probe,
};

module_platform_driver(ep93xx_rtc_driver);

MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
MODULE_DESCRIPTION("EP93XX RTC driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ep93xx-rtc");