/* drivers/rtc/rtc-v3020.c
 *
 * Copyright (C) 2006 8D Technologies inc.
 * Copyright (C) 2004 Compulab Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Driver for the V3020 RTC
 *
 * Changelog:
 *
 *  10-May-2006: Raphael Assenat <raph@8d.com>
 *                              - Converted to platform driver
 *                              - Use the generic rtc class
 *
 *  ??-???-2004: Someone at Compulab
 *                      - Initial driver creation.
 *
 */
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/types.h>
#include <linux/bcd.h>
#include <linux/rtc-v3020.h>
#include <linux/delay.h>

#include <asm/io.h>

#undef DEBUG

struct v3020 {
        void __iomem *ioaddress;
        int leftshift;
        struct rtc_device *rtc;
};

static void v3020_set_reg(struct v3020 *chip, unsigned char address,
                        unsigned char data)
{
        int i;
        unsigned char tmp;

        tmp = address;
        for (i = 0; i < 4; i++) {
                writel((tmp & 1) << chip->leftshift, chip->ioaddress);
                tmp >>= 1;
                udelay(1);
        }

        /* Commands dont have data */
        if (!V3020_IS_COMMAND(address)) {
                for (i = 0; i < 8; i++) {
                        writel((data & 1) << chip->leftshift, chip->ioaddress);
                        data >>= 1;
                        udelay(1);
                }
        }
}

static unsigned char v3020_get_reg(struct v3020 *chip, unsigned char address)
{
        unsigned int data=0;
        int i;

        for (i = 0; i < 4; i++) {
                writel((address & 1) << chip->leftshift, chip->ioaddress);
                address >>= 1;
                udelay(1);
        }

        for (i = 0; i < 8; i++) {
                data >>= 1;
                if (readl(chip->ioaddress) & (1 << chip->leftshift))
                        data |= 0x80;
                udelay(1);
        }

        return data;
}

static int v3020_read_time(struct device *dev, struct rtc_time *dt)
{
        struct v3020 *chip = dev_get_drvdata(dev);
        int tmp;

        /* Copy the current time to ram... */
        v3020_set_reg(chip, V3020_CMD_CLOCK2RAM, 0);

        /* ...and then read constant values. */
        tmp = v3020_get_reg(chip, V3020_SECONDS);
        dt->tm_sec      = BCD2BIN(tmp);
        tmp = v3020_get_reg(chip, V3020_MINUTES);
        dt->tm_min      = BCD2BIN(tmp);
        tmp = v3020_get_reg(chip, V3020_HOURS);
        dt->tm_hour     = BCD2BIN(tmp);
        tmp = v3020_get_reg(chip, V3020_MONTH_DAY);
        dt->tm_mday     = BCD2BIN(tmp);
        tmp = v3020_get_reg(chip, V3020_MONTH);
        dt->tm_mon    = BCD2BIN(tmp) - 1;
        tmp = v3020_get_reg(chip, V3020_WEEK_DAY);
        dt->tm_wday     = BCD2BIN(tmp);
        tmp = v3020_get_reg(chip, V3020_YEAR);
        dt->tm_year = BCD2BIN(tmp)+100;

#ifdef DEBUG
        printk("\n%s : Read RTC values\n",__FUNCTION__);
        printk("tm_hour: %i\n",dt->tm_hour);
        printk("tm_min : %i\n",dt->tm_min);
        printk("tm_sec : %i\n",dt->tm_sec);
        printk("tm_year: %i\n",dt->tm_year);
        printk("tm_mon : %i\n",dt->tm_mon);
        printk("tm_mday: %i\n",dt->tm_mday);
        printk("tm_wday: %i\n",dt->tm_wday);
#endif

        return 0;
}


static int v3020_set_time(struct device *dev, struct rtc_time *dt)
{
        struct v3020 *chip = dev_get_drvdata(dev);

#ifdef DEBUG
        printk("\n%s : Setting RTC values\n",__FUNCTION__);
        printk("tm_sec : %i\n",dt->tm_sec);
        printk("tm_min : %i\n",dt->tm_min);
        printk("tm_hour: %i\n",dt->tm_hour);
        printk("tm_mday: %i\n",dt->tm_mday);
        printk("tm_wday: %i\n",dt->tm_wday);
        printk("tm_year: %i\n",dt->tm_year);
#endif

        /* Write all the values to ram... */
        v3020_set_reg(chip, V3020_SECONDS,      BIN2BCD(dt->tm_sec));
        v3020_set_reg(chip, V3020_MINUTES,      BIN2BCD(dt->tm_min));
        v3020_set_reg(chip, V3020_HOURS,        BIN2BCD(dt->tm_hour));
        v3020_set_reg(chip, V3020_MONTH_DAY,    BIN2BCD(dt->tm_mday));
        v3020_set_reg(chip, V3020_MONTH,     BIN2BCD(dt->tm_mon + 1));
        v3020_set_reg(chip, V3020_WEEK_DAY,     BIN2BCD(dt->tm_wday));
        v3020_set_reg(chip, V3020_YEAR,         BIN2BCD(dt->tm_year % 100));

        /* ...and set the clock. */
        v3020_set_reg(chip, V3020_CMD_RAM2CLOCK, 0);

        /* Compulab used this delay here. I dont know why,
         * the datasheet does not specify a delay. */
        /*mdelay(5);*/

        return 0;
}

static const struct rtc_class_ops v3020_rtc_ops = {
        .read_time      = v3020_read_time,
        .set_time       = v3020_set_time,
};

static int rtc_probe(struct platform_device *pdev)
{
        struct v3020_platform_data *pdata = pdev->dev.platform_data;
        struct v3020 *chip;
        struct rtc_device *rtc;
        int retval = -EBUSY;
        int i;
        int temp;

        if (pdev->num_resources != 1)
                return -EBUSY;

        if (pdev->resource[0].flags != IORESOURCE_MEM)
                return -EBUSY;

        chip = kzalloc(sizeof *chip, GFP_KERNEL);
        if (!chip)
                return -ENOMEM;

        chip->leftshift = pdata->leftshift;
        chip->ioaddress = ioremap(pdev->resource[0].start, 1);
        if (chip->ioaddress == NULL)
                goto err_chip;

        /* Make sure the v3020 expects a communication cycle
         * by reading 8 times */
        for (i = 0; i < 8; i++)
                temp = readl(chip->ioaddress);

        /* Test chip by doing a write/read sequence
         * to the chip ram */
        v3020_set_reg(chip, V3020_SECONDS, 0x33);
        if(v3020_get_reg(chip, V3020_SECONDS) != 0x33) {
                retval = -ENODEV;
                goto err_io;
        }

        /* Make sure frequency measurment mode, test modes, and lock
         * are all disabled */
        v3020_set_reg(chip, V3020_STATUS_0, 0x0);

        dev_info(&pdev->dev, "Chip available at physical address 0x%llx,"
                "data connected to D%d\n",
                (unsigned long long)pdev->resource[0].start,
                chip->leftshift);

        platform_set_drvdata(pdev, chip);

        rtc = rtc_device_register("v3020",
                                &pdev->dev, &v3020_rtc_ops, THIS_MODULE);
        if (IS_ERR(rtc)) {
                retval = PTR_ERR(rtc);
                goto err_io;
        }
        chip->rtc = rtc;

        return 0;

err_io:
        iounmap(chip->ioaddress);
err_chip:
        kfree(chip);

        return retval;
}

static int rtc_remove(struct platform_device *dev)
{
        struct v3020 *chip = platform_get_drvdata(dev);
        struct rtc_device *rtc = chip->rtc;

        if (rtc)
                rtc_device_unregister(rtc);

        iounmap(chip->ioaddress);
        kfree(chip);

        return 0;
}

static struct platform_driver rtc_device_driver = {
        .probe  = rtc_probe,
        .remove = rtc_remove,
        .driver = {
                .name   = "v3020",
                .owner  = THIS_MODULE,
        },
};

static __init int v3020_init(void)
{
        return platform_driver_register(&rtc_device_driver);
}

static __exit void v3020_exit(void)
{
        platform_driver_unregister(&rtc_device_driver);
}

module_init(v3020_init);
module_exit(v3020_exit);

MODULE_DESCRIPTION("V3020 RTC");
MODULE_AUTHOR("Raphael Assenat");
MODULE_LICENSE("GPL");