// 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/mod_devicetable.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;
};

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 rtc_device *rtc;
        int err;

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

        ep93xx_rtc->mmio_base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(ep93xx_rtc->mmio_base))
                return PTR_ERR(ep93xx_rtc->mmio_base);

        platform_set_drvdata(pdev, ep93xx_rtc);

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

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

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

        return devm_rtc_register_device(rtc);
}

static const struct of_device_id ep93xx_rtc_of_ids[] = {
        { .compatible = "cirrus,ep9301-rtc" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, ep93xx_rtc_of_ids);

static struct platform_driver ep93xx_rtc_driver = {
        .driver         = {
                .name   = "ep93xx-rtc",
                .of_match_table = ep93xx_rtc_of_ids,
        },
        .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");