rtc-ds1307: oscillator restart for ds13{37,38,39,40}

[linux-2.6/mini2440.git] / drivers / rtc / rtc-ds1307.c

/*
 * rtc-ds1307.c - RTC driver for some mostly-compatible I2C chips.
 *
 *  Copyright (C) 2005 James Chapman (ds1337 core)
 *  Copyright (C) 2006 David Brownell
 *
 * 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.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/string.h>
#include <linux/rtc.h>
#include <linux/bcd.h>



/* We can't determine type by probing, but if we expect pre-Linux code
 * to have set the chip up as a clock (turning on the oscillator and
 * setting the date and time), Linux can ignore the non-clock features.
 * That's a natural job for a factory or repair bench.
 *
 * This is currently a simple no-alarms driver.  If your board has the
 * alarm irq wired up on a ds1337 or ds1339, and you want to use that,
 * then look at the rtc-rs5c372 driver for code to steal...
 *
 * If the I2C "force" mechanism is used, we assume the chip is a ds1337.
 * (Much better would be board-specific tables of I2C devices, along with
 * the platform_data drivers would use to sort such issues out.)
 */
enum ds_type {
        unknown = 0,
        ds_1307,
        ds_1337,
        ds_1338,
        ds_1339,
        ds_1340,
        m41t00,
        // rs5c372 too?  different address...
};

static unsigned short normal_i2c[] = { 0x68, I2C_CLIENT_END };

I2C_CLIENT_INSMOD;



/* RTC registers don't differ much, except for the century flag */
#define DS1307_REG_SECS         0x00    /* 00-59 */
#       define DS1307_BIT_CH            0x80
#       define DS1340_BIT_nEOSC         0x80
#define DS1307_REG_MIN          0x01    /* 00-59 */
#define DS1307_REG_HOUR         0x02    /* 00-23, or 1-12{am,pm} */
#       define DS1340_BIT_CENTURY_EN    0x80    /* in REG_HOUR */
#       define DS1340_BIT_CENTURY       0x40    /* in REG_HOUR */
#define DS1307_REG_WDAY         0x03    /* 01-07 */
#define DS1307_REG_MDAY         0x04    /* 01-31 */
#define DS1307_REG_MONTH        0x05    /* 01-12 */
#       define DS1337_BIT_CENTURY       0x80    /* in REG_MONTH */
#define DS1307_REG_YEAR         0x06    /* 00-99 */

/* Other registers (control, status, alarms, trickle charge, NVRAM, etc)
 * start at 7, and they differ a LOT. Only control and status matter for
 * basic RTC date and time functionality; be careful using them.
 */
#define DS1307_REG_CONTROL      0x07            /* or ds1338 */
#       define DS1307_BIT_OUT           0x80
#       define DS1338_BIT_OSF           0x20
#       define DS1307_BIT_SQWE          0x10
#       define DS1307_BIT_RS1           0x02
#       define DS1307_BIT_RS0           0x01
#define DS1337_REG_CONTROL      0x0e
#       define DS1337_BIT_nEOSC         0x80
#       define DS1337_BIT_RS2           0x10
#       define DS1337_BIT_RS1           0x08
#       define DS1337_BIT_INTCN         0x04
#       define DS1337_BIT_A2IE          0x02
#       define DS1337_BIT_A1IE          0x01
#define DS1340_REG_CONTROL      0x07
#       define DS1340_BIT_OUT           0x80
#       define DS1340_BIT_FT            0x40
#       define DS1340_BIT_CALIB_SIGN    0x20
#       define DS1340_M_CALIBRATION     0x1f
#define DS1340_REG_FLAG         0x09
#       define DS1340_BIT_OSF           0x80
#define DS1337_REG_STATUS       0x0f
#       define DS1337_BIT_OSF           0x80
#       define DS1337_BIT_A2I           0x02
#       define DS1337_BIT_A1I           0x01
#define DS1339_REG_TRICKLE      0x10



struct ds1307 {
        u8                      reg_addr;
        u8                      regs[8];
        enum ds_type            type;
        struct i2c_msg          msg[2];
        struct i2c_client       *client;
        struct i2c_client       dev;
        struct rtc_device       *rtc;
};

struct chip_desc {
        char                    name[9];
        unsigned                nvram56:1;
        unsigned                alarm:1;
        enum ds_type            type;
};

static const struct chip_desc chips[] = { {
        .name           = "ds1307",
        .type           = ds_1307,
        .nvram56        = 1,
}, {
        .name           = "ds1337",
        .type           = ds_1337,
        .alarm          = 1,
}, {
        .name           = "ds1338",
        .type           = ds_1338,
        .nvram56        = 1,
}, {
        .name           = "ds1339",
        .type           = ds_1339,
        .alarm          = 1,
}, {
        .name           = "ds1340",
        .type           = ds_1340,
}, {
        .name           = "m41t00",
        .type           = m41t00,
}, };

static inline const struct chip_desc *find_chip(const char *s)
{
        unsigned i;

        for (i = 0; i < ARRAY_SIZE(chips); i++)
                if (strnicmp(s, chips[i].name, sizeof chips[i].name) == 0)
                        return &chips[i];
        return NULL;
}

static int ds1307_get_time(struct device *dev, struct rtc_time *t)
{
        struct ds1307   *ds1307 = dev_get_drvdata(dev);
        int             tmp;

        /* read the RTC date and time registers all at once */
        ds1307->msg[1].flags = I2C_M_RD;
        ds1307->msg[1].len = 7;

        tmp = i2c_transfer(to_i2c_adapter(ds1307->client->dev.parent),
                        ds1307->msg, 2);
        if (tmp != 2) {
                dev_err(dev, "%s error %d\n", "read", tmp);
                return -EIO;
        }

        dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
                        "read",
                        ds1307->regs[0], ds1307->regs[1],
                        ds1307->regs[2], ds1307->regs[3],
                        ds1307->regs[4], ds1307->regs[5],
                        ds1307->regs[6]);

        t->tm_sec = BCD2BIN(ds1307->regs[DS1307_REG_SECS] & 0x7f);
        t->tm_min = BCD2BIN(ds1307->regs[DS1307_REG_MIN] & 0x7f);
        tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
        t->tm_hour = BCD2BIN(tmp);
        t->tm_wday = BCD2BIN(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
        t->tm_mday = BCD2BIN(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
        tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
        t->tm_mon = BCD2BIN(tmp) - 1;

        /* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
        t->tm_year = BCD2BIN(ds1307->regs[DS1307_REG_YEAR]) + 100;

        dev_dbg(dev, "%s secs=%d, mins=%d, "
                "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
                "read", t->tm_sec, t->tm_min,
                t->tm_hour, t->tm_mday,
                t->tm_mon, t->tm_year, t->tm_wday);

        /* initial clock setting can be undefined */
        return rtc_valid_tm(t);
}

static int ds1307_set_time(struct device *dev, struct rtc_time *t)
{
        struct ds1307   *ds1307 = dev_get_drvdata(dev);
        int             result;
        int             tmp;
        u8              *buf = ds1307->regs;

        dev_dbg(dev, "%s secs=%d, mins=%d, "
                "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
                "write", t->tm_sec, t->tm_min,
                t->tm_hour, t->tm_mday,
                t->tm_mon, t->tm_year, t->tm_wday);

        *buf++ = 0;             /* first register addr */
        buf[DS1307_REG_SECS] = BIN2BCD(t->tm_sec);
        buf[DS1307_REG_MIN] = BIN2BCD(t->tm_min);
        buf[DS1307_REG_HOUR] = BIN2BCD(t->tm_hour);
        buf[DS1307_REG_WDAY] = BIN2BCD(t->tm_wday + 1);
        buf[DS1307_REG_MDAY] = BIN2BCD(t->tm_mday);
        buf[DS1307_REG_MONTH] = BIN2BCD(t->tm_mon + 1);

        /* assume 20YY not 19YY */
        tmp = t->tm_year - 100;
        buf[DS1307_REG_YEAR] = BIN2BCD(tmp);

        switch (ds1307->type) {
        case ds_1337:
        case ds_1339:
                buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
                break;
        case ds_1340:
                buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
                                | DS1340_BIT_CENTURY;
                break;
        default:
                break;
        }

        ds1307->msg[1].flags = 0;
        ds1307->msg[1].len = 8;

        dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
                "write", buf[0], buf[1], buf[2], buf[3],
                buf[4], buf[5], buf[6]);

        result = i2c_transfer(to_i2c_adapter(ds1307->client->dev.parent),
                        &ds1307->msg[1], 1);
        if (result != 1) {
                dev_err(dev, "%s error %d\n", "write", tmp);
                return -EIO;
        }
        return 0;
}

static const struct rtc_class_ops ds13xx_rtc_ops = {
        .read_time      = ds1307_get_time,
        .set_time       = ds1307_set_time,
};

static struct i2c_driver ds1307_driver;

static int __devinit
ds1307_detect(struct i2c_adapter *adapter, int address, int kind)
{
        struct ds1307           *ds1307;
        int                     err = -ENODEV;
        struct i2c_client       *client;
        int                     tmp;
        const struct chip_desc  *chip;

        if (!(ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL))) {
                err = -ENOMEM;
                goto exit;
        }

        /* REVISIT:  pending driver model conversion, set up "client"
         * ourselves, and use a hack to determine the RTC type (instead
         * of reading the client->name we're given)
         */
        client = &ds1307->dev;
        client->addr = address;
        client->adapter = adapter;
        client->driver = &ds1307_driver;

        /* HACK: "force" implies "needs ds1337-style-oscillator setup", and
         * that's the only kind of chip setup we'll know about.  Until the
         * driver model conversion, here's where to add any board-specific
         * code to say what kind of chip is present...
         */
        if (kind >= 0)
                chip = find_chip("ds1337");
        else
                chip = find_chip("ds1307");
        strlcpy(client->name, chip->name, I2C_NAME_SIZE);

        ds1307->client = client;
        i2c_set_clientdata(client, ds1307);

        ds1307->msg[0].addr = client->addr;
        ds1307->msg[0].flags = 0;
        ds1307->msg[0].len = 1;
        ds1307->msg[0].buf = &ds1307->reg_addr;

        ds1307->msg[1].addr = client->addr;
        ds1307->msg[1].flags = I2C_M_RD;
        ds1307->msg[1].len = sizeof(ds1307->regs);
        ds1307->msg[1].buf = ds1307->regs;

        ds1307->type = chip->type;

        switch (ds1307->type) {
        case ds_1337:
        case ds_1339:
                ds1307->reg_addr = DS1337_REG_CONTROL;
                ds1307->msg[1].len = 2;

                /* get registers that the "rtc" read below won't read... */
                tmp = i2c_transfer(adapter, ds1307->msg, 2);
                if (tmp != 2) {
                        pr_debug("read error %d\n", tmp);
                        err = -EIO;
                        goto exit_free;
                }

                ds1307->reg_addr = 0;
                ds1307->msg[1].len = sizeof(ds1307->regs);

                /* oscillator off?  turn it on, so clock can tick. */
                if (ds1307->regs[0] & DS1337_BIT_nEOSC)
                        i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
                                ds1307->regs[0] & ~DS1337_BIT_nEOSC);

                /* oscillator fault?  clear flag, and warn */
                if (ds1307->regs[1] & DS1337_BIT_OSF) {
                        i2c_smbus_write_byte_data(client, DS1337_REG_STATUS,
                                ds1307->regs[1] & ~DS1337_BIT_OSF);
                        dev_warn(&client->dev, "SET TIME!\n");
                }
                break;
        default:
                break;
        }

read_rtc:
        /* read RTC registers */

        tmp = i2c_transfer(adapter, ds1307->msg, 2);
        if (tmp != 2) {
                pr_debug("read error %d\n", tmp);
                err = -EIO;
                goto exit_free;
        }

        /* minimal sanity checking; some chips (like DS1340) don't
         * specify the extra bits as must-be-zero, but there are
         * still a few values that are clearly out-of-range.
         */
        tmp = ds1307->regs[DS1307_REG_SECS];
        switch (ds1307->type) {
        case ds_1340:
                /* FIXME read register with DS1340_BIT_OSF, use that to
                 * trigger the "set time" warning (*after* restarting the
                 * oscillator!) instead of this weaker ds1307/m41t00 test.
                 */
        case ds_1307:
        case m41t00:
                /* clock halted?  turn it on, so clock can tick. */
                if (tmp & DS1307_BIT_CH) {
                        i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
                        dev_warn(&client->dev, "SET TIME!\n");
                        goto read_rtc;
                }
                break;
        case ds_1338:
                /* clock halted?  turn it on, so clock can tick. */
                if (tmp & DS1307_BIT_CH)
                        i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);

                /* oscillator fault?  clear flag, and warn */
                if (ds1307->regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
                        i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL,
                                        ds1307->regs[DS1337_REG_CONTROL]
                                        & ~DS1338_BIT_OSF);
                        dev_warn(&client->dev, "SET TIME!\n");
                        goto read_rtc;
                }
                break;
        default:
                break;
        }

        tmp = ds1307->regs[DS1307_REG_SECS];
        tmp = BCD2BIN(tmp & 0x7f);
        if (tmp > 60)
                goto exit_free;
        tmp = BCD2BIN(ds1307->regs[DS1307_REG_MIN] & 0x7f);
        if (tmp > 60)
                goto exit_free;

        tmp = BCD2BIN(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
        if (tmp == 0 || tmp > 31)
                goto exit_free;

        tmp = BCD2BIN(ds1307->regs[DS1307_REG_MONTH] & 0x1f);
        if (tmp == 0 || tmp > 12)
                goto exit_free;

        /* force into in 24 hour mode (most chips) or
         * disable century bit (ds1340)
         *
         * REVISIT forcing 24 hour mode can prevent multi-master
         * configs from sharing this RTC ... don't do this.
         * The clock needs to be reset after changing it, too...
         */
        tmp = ds1307->regs[DS1307_REG_HOUR];
        if (tmp & (1 << 6)) {
                if (tmp & (1 << 5))
                        tmp = BCD2BIN(tmp & 0x1f) + 12;
                else
                        tmp = BCD2BIN(tmp);
                i2c_smbus_write_byte_data(client,
                                DS1307_REG_HOUR,
                                BIN2BCD(tmp));
        }

        /* Tell the I2C layer a new client has arrived */
        if ((err = i2c_attach_client(client)))
                goto exit_free;

        ds1307->rtc = rtc_device_register(client->name, &client->dev,
                                &ds13xx_rtc_ops, THIS_MODULE);
        if (IS_ERR(ds1307->rtc)) {
                err = PTR_ERR(ds1307->rtc);
                dev_err(&client->dev,
                        "unable to register the class device\n");
                goto exit_detach;
        }

        return 0;

exit_detach:
        i2c_detach_client(client);
exit_free:
        kfree(ds1307);
exit:
        return err;
}

static int __devinit
ds1307_attach_adapter(struct i2c_adapter *adapter)
{
        if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
                return 0;
        return i2c_probe(adapter, &addr_data, ds1307_detect);
}

static int __devexit ds1307_detach_client(struct i2c_client *client)
{
        int             err;
        struct ds1307   *ds1307 = i2c_get_clientdata(client);

        rtc_device_unregister(ds1307->rtc);
        if ((err = i2c_detach_client(client)))
                return err;
        kfree(ds1307);
        return 0;
}

static struct i2c_driver ds1307_driver = {
        .driver = {
                .name   = "ds1307",
                .owner  = THIS_MODULE,
        },
        .attach_adapter = ds1307_attach_adapter,
        .detach_client  = __devexit_p(ds1307_detach_client),
};

static int __init ds1307_init(void)
{
        return i2c_add_driver(&ds1307_driver);
}
module_init(ds1307_init);

static void __exit ds1307_exit(void)
{
        i2c_del_driver(&ds1307_driver);
}
module_exit(ds1307_exit);

MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
MODULE_LICENSE("GPL");