// SPDX-License-Identifier: GPL-2.0-only
/* rtc-bq4802.c: TI BQ4802 RTC driver.
 *
 * Copyright (C) 2008 David S. Miller <davem@davemloft.net>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/slab.h>

MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
MODULE_DESCRIPTION("TI BQ4802 RTC driver");
MODULE_LICENSE("GPL");

struct bq4802 {
        void __iomem            *regs;
        unsigned long           ioport;
        struct rtc_device       *rtc;
        spinlock_t              lock;
        struct resource         *r;
        u8 (*read)(struct bq4802 *, int);
        void (*write)(struct bq4802 *, int, u8);
};

static u8 bq4802_read_io(struct bq4802 *p, int off)
{
        return inb(p->ioport + off);
}

static void bq4802_write_io(struct bq4802 *p, int off, u8 val)
{
        outb(val, p->ioport + off);
}

static u8 bq4802_read_mem(struct bq4802 *p, int off)
{
        return readb(p->regs + off);
}

static void bq4802_write_mem(struct bq4802 *p, int off, u8 val)
{
        writeb(val, p->regs + off);
}

static int bq4802_read_time(struct device *dev, struct rtc_time *tm)
{
        struct bq4802 *p = dev_get_drvdata(dev);
        unsigned long flags;
        unsigned int century;
        u8 val;

        spin_lock_irqsave(&p->lock, flags);

        val = p->read(p, 0x0e);
        p->write(p, 0xe, val | 0x08);

        tm->tm_sec = p->read(p, 0x00);
        tm->tm_min = p->read(p, 0x02);
        tm->tm_hour = p->read(p, 0x04);
        tm->tm_mday = p->read(p, 0x06);
        tm->tm_mon = p->read(p, 0x09);
        tm->tm_year = p->read(p, 0x0a);
        tm->tm_wday = p->read(p, 0x08);
        century = p->read(p, 0x0f);

        p->write(p, 0x0e, val);

        spin_unlock_irqrestore(&p->lock, flags);

        tm->tm_sec = bcd2bin(tm->tm_sec);
        tm->tm_min = bcd2bin(tm->tm_min);
        tm->tm_hour = bcd2bin(tm->tm_hour);
        tm->tm_mday = bcd2bin(tm->tm_mday);
        tm->tm_mon = bcd2bin(tm->tm_mon);
        tm->tm_year = bcd2bin(tm->tm_year);
        tm->tm_wday = bcd2bin(tm->tm_wday);
        century = bcd2bin(century);

        tm->tm_year += (century * 100);
        tm->tm_year -= 1900;

        tm->tm_mon--;

        return 0;
}

static int bq4802_set_time(struct device *dev, struct rtc_time *tm)
{
        struct bq4802 *p = dev_get_drvdata(dev);
        u8 sec, min, hrs, day, mon, yrs, century, val;
        unsigned long flags;
        unsigned int year;

        year = tm->tm_year + 1900;
        century = year / 100;
        yrs = year % 100;

        mon = tm->tm_mon + 1;   /* tm_mon starts at zero */
        day = tm->tm_mday;
        hrs = tm->tm_hour;
        min = tm->tm_min;
        sec = tm->tm_sec;

        sec = bin2bcd(sec);
        min = bin2bcd(min);
        hrs = bin2bcd(hrs);
        day = bin2bcd(day);
        mon = bin2bcd(mon);
        yrs = bin2bcd(yrs);
        century = bin2bcd(century);

        spin_lock_irqsave(&p->lock, flags);

        val = p->read(p, 0x0e);
        p->write(p, 0x0e, val | 0x08);

        p->write(p, 0x00, sec);
        p->write(p, 0x02, min);
        p->write(p, 0x04, hrs);
        p->write(p, 0x06, day);
        p->write(p, 0x09, mon);
        p->write(p, 0x0a, yrs);
        p->write(p, 0x0f, century);

        p->write(p, 0x0e, val);

        spin_unlock_irqrestore(&p->lock, flags);

        return 0;
}

static const struct rtc_class_ops bq4802_ops = {
        .read_time      = bq4802_read_time,
        .set_time       = bq4802_set_time,
};

static int bq4802_probe(struct platform_device *pdev)
{
        struct bq4802 *p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
        int err = -ENOMEM;

        if (!p)
                goto out;

        spin_lock_init(&p->lock);

        p->r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!p->r) {
                p->r = platform_get_resource(pdev, IORESOURCE_IO, 0);
                err = -EINVAL;
                if (!p->r)
                        goto out;
        }
        if (p->r->flags & IORESOURCE_IO) {
                p->ioport = p->r->start;
                p->read = bq4802_read_io;
                p->write = bq4802_write_io;
        } else if (p->r->flags & IORESOURCE_MEM) {
                p->regs = devm_ioremap(&pdev->dev, p->r->start,
                                        resource_size(p->r));
                if (!p->regs){
                        err = -ENOMEM;
                        goto out;
                }
                p->read = bq4802_read_mem;
                p->write = bq4802_write_mem;
        } else {
                err = -EINVAL;
                goto out;
        }

        platform_set_drvdata(pdev, p);

        p->rtc = devm_rtc_device_register(&pdev->dev, "bq4802",
                                        &bq4802_ops, THIS_MODULE);
        if (IS_ERR(p->rtc)) {
                err = PTR_ERR(p->rtc);
                goto out;
        }

        err = 0;
out:
        return err;

}

/* work with hotplug and coldplug */
MODULE_ALIAS("platform:rtc-bq4802");

static struct platform_driver bq4802_driver = {
        .driver         = {
                .name   = "rtc-bq4802",
        },
        .probe          = bq4802_probe,
};

module_platform_driver(bq4802_driver);