/* 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);
