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ds1337.c

/*
 *  linux/drivers/i2c/chips/ds1337.c
 *
 *  Copyright (C) 2005 James Chapman <jchapman@katalix.com>
 *
 *    based on linux/drivers/acorn/char/pcf8583.c
 *  Copyright (C) 2000 Russell King
 *
 * 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 Dallas Semiconductor DS1337 and DS1339 real time clock chip
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/string.h>
#include <linux/rtc.h>        /* get the user-level API */
#include <linux/bcd.h>
#include <linux/list.h>

/* Device registers */
#define DS1337_REG_HOUR       2
#define DS1337_REG_DAY        3
#define DS1337_REG_DATE       4
#define DS1337_REG_MONTH      5
#define DS1337_REG_CONTROL    14
#define DS1337_REG_STATUS     15

/* FIXME - how do we export these interface constants? */
#define DS1337_GET_DATE       0
#define DS1337_SET_DATE       1

/*
 * Functions declaration
 */
static unsigned short normal_i2c[] = { 0x68, I2C_CLIENT_END };

I2C_CLIENT_INSMOD_1(ds1337);

static int ds1337_attach_adapter(struct i2c_adapter *adapter);
static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind);
static void ds1337_init_client(struct i2c_client *client);
static int ds1337_detach_client(struct i2c_client *client);
static int ds1337_command(struct i2c_client *client, unsigned int cmd,
                    void *arg);

/*
 * Driver data (common to all clients)
 */
static struct i2c_driver ds1337_driver = {
      .driver = {
            .name = "ds1337",
      },
      .attach_adapter   = ds1337_attach_adapter,
      .detach_client    = ds1337_detach_client,
      .command    = ds1337_command,
};

/*
 * Client data (each client gets its own)
 */
struct ds1337_data {
      struct i2c_client client;
      struct list_head list;
};

/*
 * Internal variables
 */
static LIST_HEAD(ds1337_clients);

static inline int ds1337_read(struct i2c_client *client, u8 reg, u8 *value)
{
      s32 tmp = i2c_smbus_read_byte_data(client, reg);

      if (tmp < 0)
            return -EIO;

      *value = tmp;

      return 0;
}

/*
 * Chip access functions
 */
static int ds1337_get_datetime(struct i2c_client *client, struct rtc_time *dt)
{
      int result;
      u8 buf[7];
      u8 val;
      struct i2c_msg msg[2];
      u8 offs = 0;

      if (!dt) {
            dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
            return -EINVAL;
      }

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

      msg[1].addr = client->addr;
      msg[1].flags = I2C_M_RD;
      msg[1].len = sizeof(buf);
      msg[1].buf = &buf[0];

      result = i2c_transfer(client->adapter, msg, 2);

      dev_dbg(&client->dev, "%s: [%d] %02x %02x %02x %02x %02x %02x %02x\n",
            __FUNCTION__, result, buf[0], buf[1], buf[2], buf[3],
            buf[4], buf[5], buf[6]);

      if (result == 2) {
            dt->tm_sec = BCD2BIN(buf[0]);
            dt->tm_min = BCD2BIN(buf[1]);
            val = buf[2] & 0x3f;
            dt->tm_hour = BCD2BIN(val);
            dt->tm_wday = BCD2BIN(buf[3]) - 1;
            dt->tm_mday = BCD2BIN(buf[4]);
            val = buf[5] & 0x7f;
            dt->tm_mon = BCD2BIN(val) - 1;
            dt->tm_year = BCD2BIN(buf[6]);
            if (buf[5] & 0x80)
                  dt->tm_year += 100;

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

            return 0;
      }

      dev_err(&client->dev, "error reading data! %d\n", result);
      return -EIO;
}

static int ds1337_set_datetime(struct i2c_client *client, struct rtc_time *dt)
{
      int result;
      u8 buf[8];
      u8 val;
      struct i2c_msg msg[1];

      if (!dt) {
            dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
            return -EINVAL;
      }

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

      buf[0] = 0;       /* reg offset */
      buf[1] = BIN2BCD(dt->tm_sec);
      buf[2] = BIN2BCD(dt->tm_min);
      buf[3] = BIN2BCD(dt->tm_hour);
      buf[4] = BIN2BCD(dt->tm_wday + 1);
      buf[5] = BIN2BCD(dt->tm_mday);
      buf[6] = BIN2BCD(dt->tm_mon + 1);
      val = dt->tm_year;
      if (val >= 100) {
            val -= 100;
            buf[6] |= (1 << 7);
      }
      buf[7] = BIN2BCD(val);

      msg[0].addr = client->addr;
      msg[0].flags = 0;
      msg[0].len = sizeof(buf);
      msg[0].buf = &buf[0];

      result = i2c_transfer(client->adapter, msg, 1);
      if (result == 1)
            return 0;

      dev_err(&client->dev, "error writing data! %d\n", result);
      return -EIO;
}

static int ds1337_command(struct i2c_client *client, unsigned int cmd,
                    void *arg)
{
      dev_dbg(&client->dev, "%s: cmd=%d\n", __FUNCTION__, cmd);

      switch (cmd) {
      case DS1337_GET_DATE:
            return ds1337_get_datetime(client, arg);

      case DS1337_SET_DATE:
            return ds1337_set_datetime(client, arg);

      default:
            return -EINVAL;
      }
}

/*
 * Public API for access to specific device. Useful for low-level
 * RTC access from kernel code.
 */
int ds1337_do_command(int bus, int cmd, void *arg)
{
      struct list_head *walk;
      struct list_head *tmp;
      struct ds1337_data *data;

      list_for_each_safe(walk, tmp, &ds1337_clients) {
            data = list_entry(walk, struct ds1337_data, list);
            if (data->client.adapter->nr == bus)
                  return ds1337_command(&data->client, cmd, arg);
      }

      return -ENODEV;
}

static int ds1337_attach_adapter(struct i2c_adapter *adapter)
{
      return i2c_probe(adapter, &addr_data, ds1337_detect);
}

/*
 * The following function does more than just detection. If detection
 * succeeds, it also registers the new chip.
 */
static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind)
{
      struct i2c_client *new_client;
      struct ds1337_data *data;
      int err = 0;
      const char *name = "";

      if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
                             I2C_FUNC_I2C))
            goto exit;

      if (!(data = kzalloc(sizeof(struct ds1337_data), GFP_KERNEL))) {
            err = -ENOMEM;
            goto exit;
      }
      INIT_LIST_HEAD(&data->list);

      /* The common I2C client data is placed right before the
       * DS1337-specific data. 
       */
      new_client = &data->client;
      i2c_set_clientdata(new_client, data);
      new_client->addr = address;
      new_client->adapter = adapter;
      new_client->driver = &ds1337_driver;
      new_client->flags = 0;

      /*
       * Now we do the remaining detection. A negative kind means that
       * the driver was loaded with no force parameter (default), so we
       * must both detect and identify the chip. A zero kind means that
       * the driver was loaded with the force parameter, the detection
       * step shall be skipped. A positive kind means that the driver
       * was loaded with the force parameter and a given kind of chip is
       * requested, so both the detection and the identification steps
       * are skipped.
       *
       * For detection, we read registers that are most likely to cause
       * detection failure, i.e. those that have more bits with fixed
       * or reserved values.
       */

      /* Default to an DS1337 if forced */
      if (kind == 0)
            kind = ds1337;

      if (kind < 0) {         /* detection and identification */
            u8 data;

            /* Check that status register bits 6-2 are zero */
            if ((ds1337_read(new_client, DS1337_REG_STATUS, &data) < 0) ||
                (data & 0x7c))
                  goto exit_free;

            /* Check for a valid day register value */
            if ((ds1337_read(new_client, DS1337_REG_DAY, &data) < 0) ||
                (data == 0) || (data & 0xf8))
                  goto exit_free;

            /* Check for a valid date register value */
            if ((ds1337_read(new_client, DS1337_REG_DATE, &data) < 0) ||
                (data == 0) || (data & 0xc0) || ((data & 0x0f) > 9) ||
                (data >= 0x32))
                  goto exit_free;

            /* Check for a valid month register value */
            if ((ds1337_read(new_client, DS1337_REG_MONTH, &data) < 0) ||
                (data == 0) || (data & 0x60) || ((data & 0x0f) > 9) ||
                ((data >= 0x13) && (data <= 0x19)))
                  goto exit_free;

            /* Check that control register bits 6-5 are zero */
            if ((ds1337_read(new_client, DS1337_REG_CONTROL, &data) < 0) ||
                (data & 0x60))
                  goto exit_free;

            kind = ds1337;
      }

      if (kind == ds1337)
            name = "ds1337";

      /* We can fill in the remaining client fields */
      strlcpy(new_client->name, name, I2C_NAME_SIZE);

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

      /* Initialize the DS1337 chip */
      ds1337_init_client(new_client);

      /* Add client to local list */
      list_add(&data->list, &ds1337_clients);

      return 0;

exit_free:
      kfree(data);
exit:
      return err;
}

static void ds1337_init_client(struct i2c_client *client)
{
      u8 status, control;

      /* On some boards, the RTC isn't configured by boot firmware.
       * Handle that case by starting/configuring the RTC now.
       */
      status = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
      control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);

      if ((status & 0x80) || (control & 0x80)) {
            /* RTC not running */
            u8 buf[1+16];     /* First byte is interpreted as address */
            struct i2c_msg msg[1];

            dev_dbg(&client->dev, "%s: RTC not running!\n", __FUNCTION__);

            /* Initialize all, including STATUS and CONTROL to zero */
            memset(buf, 0, sizeof(buf));

            /* Write valid values in the date/time registers */
            buf[1+DS1337_REG_DAY] = 1;
            buf[1+DS1337_REG_DATE] = 1;
            buf[1+DS1337_REG_MONTH] = 1;

            msg[0].addr = client->addr;
            msg[0].flags = 0;
            msg[0].len = sizeof(buf);
            msg[0].buf = &buf[0];

            i2c_transfer(client->adapter, msg, 1);
      } else {
            /* Running: ensure that device is set in 24-hour mode */
            s32 val;

            val = i2c_smbus_read_byte_data(client, DS1337_REG_HOUR);
            if ((val >= 0) && (val & (1 << 6)))
                  i2c_smbus_write_byte_data(client, DS1337_REG_HOUR,
                                      val & 0x3f);
      }
}

static int ds1337_detach_client(struct i2c_client *client)
{
      int err;
      struct ds1337_data *data = i2c_get_clientdata(client);

      if ((err = i2c_detach_client(client)))
            return err;

      list_del(&data->list);
      kfree(data);
      return 0;
}

static int __init ds1337_init(void)
{
      return i2c_add_driver(&ds1337_driver);
}

static void __exit ds1337_exit(void)
{
      i2c_del_driver(&ds1337_driver);
}

MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
MODULE_DESCRIPTION("DS1337 RTC driver");
MODULE_LICENSE("GPL");

EXPORT_SYMBOL_GPL(ds1337_do_command);

module_init(ds1337_init);
module_exit(ds1337_exit);

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