rtc-m48t35.c

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/*
 * Driver for the SGS-Thomson M48T35 Timekeeper RAM chip
 *
 * Copyright (C) 2000 Silicon Graphics, Inc.
 * Written by Ulf Carlsson ([email protected])
 *
 * Copyright (C) 2008 Thomas Bogendoerfer
 *
 * Based on code written by Paul Gortmaker.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 */

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

#define DRV_VERSION     "1.0"

struct m48t35_rtc {
    u8  pad[0x7ff8];    /* starts at 0x7ff8 */
    u8  control;
    u8  sec;
    u8  min;
    u8  hour;
    u8  day;
    u8  date;
    u8  month;
    u8  year;
};

#define M48T35_RTC_SET      0x80
#define M48T35_RTC_READ     0x40

struct m48t35_priv {
    struct rtc_device *rtc;
    struct m48t35_rtc __iomem *reg;
    size_t size;
    unsigned long baseaddr;
    spinlock_t lock;
};

static int m48t35_read_time(struct device *dev, struct rtc_time *tm)
{
    struct m48t35_priv *priv = dev_get_drvdata(dev);
    u8 control;

    /*
     * Only the values that we read from the RTC are set. We leave
     * tm_wday, tm_yday and tm_isdst untouched. Even though the
     * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
     * by the RTC when initially set to a non-zero value.
     */
    spin_lock_irq(&priv->lock);
    control = readb(&priv->reg->control);
    writeb(control | M48T35_RTC_READ, &priv->reg->control);
    tm->tm_sec = readb(&priv->reg->sec);
    tm->tm_min = readb(&priv->reg->min);
    tm->tm_hour = readb(&priv->reg->hour);
    tm->tm_mday = readb(&priv->reg->date);
    tm->tm_mon = readb(&priv->reg->month);
    tm->tm_year = readb(&priv->reg->year);
    writeb(control, &priv->reg->control);
    spin_unlock_irq(&priv->lock);

    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);

    /*
     * Account for differences between how the RTC uses the values
     * and how they are defined in a struct rtc_time;
     */
    tm->tm_year += 70;
    if (tm->tm_year <= 69)
        tm->tm_year += 100;

    tm->tm_mon--;
    return rtc_valid_tm(tm);
}

static int m48t35_set_time(struct device *dev, struct rtc_time *tm)
{
    struct m48t35_priv *priv = dev_get_drvdata(dev);
    unsigned char mon, day, hrs, min, sec;
    unsigned int yrs;
    u8 control;

    yrs = tm->tm_year + 1900;
    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;

    if (yrs < 1970)
        return -EINVAL;

    yrs -= 1970;
    if (yrs > 255)    /* They are unsigned */
        return -EINVAL;

    if (yrs > 169)
        return -EINVAL;

    if (yrs >= 100)
        yrs -= 100;

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

    spin_lock_irq(&priv->lock);
    control = readb(&priv->reg->control);
    writeb(control | M48T35_RTC_SET, &priv->reg->control);
    writeb(yrs, &priv->reg->year);
    writeb(mon, &priv->reg->month);
    writeb(day, &priv->reg->date);
    writeb(hrs, &priv->reg->hour);
    writeb(min, &priv->reg->min);
    writeb(sec, &priv->reg->sec);
    writeb(control, &priv->reg->control);
    spin_unlock_irq(&priv->lock);
    return 0;
}

static const struct rtc_class_ops m48t35_ops = {
    .read_time  = m48t35_read_time,
    .set_time   = m48t35_set_time,
};

static int __devinit m48t35_probe(struct platform_device *pdev)
{
    struct resource *res;
    struct m48t35_priv *priv;
    int ret = 0;

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!res)
        return -ENODEV;
    priv = kzalloc(sizeof(struct m48t35_priv), GFP_KERNEL);
    if (!priv)
        return -ENOMEM;

    priv->size = resource_size(res);
    /*
     * kludge: remove the #ifndef after ioc3 resource
     * conflicts are resolved
     */
#ifndef CONFIG_SGI_IP27
    if (!request_mem_region(res->start, priv->size, pdev->name)) {
        ret = -EBUSY;
        goto out;
    }
#endif
    priv->baseaddr = res->start;
    priv->reg = ioremap(priv->baseaddr, priv->size);
    if (!priv->reg) {
        ret = -ENOMEM;
        goto out;
    }

    spin_lock_init(&priv->lock);

    platform_set_drvdata(pdev, priv);

    priv->rtc = rtc_device_register("m48t35", &pdev->dev,
                  &m48t35_ops, THIS_MODULE);
    if (IS_ERR(priv->rtc)) {
        ret = PTR_ERR(priv->rtc);
        goto out;
    }

    return 0;

out:
    if (priv->reg)
        iounmap(priv->reg);
    if (priv->baseaddr)
        release_mem_region(priv->baseaddr, priv->size);
    kfree(priv);
    return ret;
}

static int __devexit m48t35_remove(struct platform_device *pdev)
{
    struct m48t35_priv *priv = platform_get_drvdata(pdev);

    rtc_device_unregister(priv->rtc);
    iounmap(priv->reg);
#ifndef CONFIG_SGI_IP27
    release_mem_region(priv->baseaddr, priv->size);
#endif
    kfree(priv);
    return 0;
}

static struct platform_driver m48t35_platform_driver = {
    .driver     = {
        .name   = "rtc-m48t35",
        .owner  = THIS_MODULE,
    },
    .probe      = m48t35_probe,
    .remove     = __devexit_p(m48t35_remove),
};

module_platform_driver(m48t35_platform_driver);

MODULE_AUTHOR("Thomas Bogendoerfer <[email protected]>");
MODULE_DESCRIPTION("M48T35 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);
MODULE_ALIAS("platform:rtc-m48t35");