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lm75.c

/*
    lm75.c - Part of lm_sensors, Linux kernel modules for hardware
             monitoring
    Copyright (c) 1998, 1999  Frodo Looijaard <frodol@dds.nl>

    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.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include "lm75.h"


/* Addresses to scan */
static unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
                              0x4d, 0x4e, 0x4f, I2C_CLIENT_END };

/* Insmod parameters */
I2C_CLIENT_INSMOD_1(lm75);

/* Many LM75 constants specified below */

/* The LM75 registers */
#define LM75_REG_CONF         0x01
static const u8 LM75_REG_TEMP[3] = {
      0x00,       /* input */
      0x03,       /* max */
      0x02,       /* hyst */
};

/* Each client has this additional data */
struct lm75_data {
      struct i2c_client client;
      struct device *hwmon_dev;
      struct mutex            update_lock;
      char              valid;            /* !=0 if following fields are valid */
      unsigned long           last_updated;     /* In jiffies */
      u16               temp[3];    /* Register values,
                                       0 = input
                                       1 = max
                                       2 = hyst */
};

static int lm75_attach_adapter(struct i2c_adapter *adapter);
static int lm75_detect(struct i2c_adapter *adapter, int address, int kind);
static void lm75_init_client(struct i2c_client *client);
static int lm75_detach_client(struct i2c_client *client);
static int lm75_read_value(struct i2c_client *client, u8 reg);
static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
static struct lm75_data *lm75_update_device(struct device *dev);


/* This is the driver that will be inserted */
static struct i2c_driver lm75_driver = {
      .driver = {
            .name = "lm75",
      },
      .id         = I2C_DRIVERID_LM75,
      .attach_adapter   = lm75_attach_adapter,
      .detach_client    = lm75_detach_client,
};

static ssize_t show_temp(struct device *dev, struct device_attribute *da,
                   char *buf)
{
      struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
      struct lm75_data *data = lm75_update_device(dev);
      return sprintf(buf, "%d\n",
                   LM75_TEMP_FROM_REG(data->temp[attr->index]));
}

static ssize_t set_temp(struct device *dev, struct device_attribute *da,
                  const char *buf, size_t count)
{
      struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
      struct i2c_client *client = to_i2c_client(dev);
      struct lm75_data *data = i2c_get_clientdata(client);
      int nr = attr->index;
      long temp = simple_strtol(buf, NULL, 10);

      mutex_lock(&data->update_lock);
      data->temp[nr] = LM75_TEMP_TO_REG(temp);
      lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
      mutex_unlock(&data->update_lock);
      return count;
}

static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
                  show_temp, set_temp, 1);
static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
                  show_temp, set_temp, 2);
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);

static int lm75_attach_adapter(struct i2c_adapter *adapter)
{
      if (!(adapter->class & I2C_CLASS_HWMON))
            return 0;
      return i2c_probe(adapter, &addr_data, lm75_detect);
}

static struct attribute *lm75_attributes[] = {
      &sensor_dev_attr_temp1_input.dev_attr.attr,
      &sensor_dev_attr_temp1_max.dev_attr.attr,
      &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,

      NULL
};

static const struct attribute_group lm75_group = {
      .attrs = lm75_attributes,
};

/* This function is called by i2c_probe */
static int lm75_detect(struct i2c_adapter *adapter, int address, int kind)
{
      int i;
      struct i2c_client *new_client;
      struct lm75_data *data;
      int err = 0;
      const char *name = "";

      if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
                             I2C_FUNC_SMBUS_WORD_DATA))
            goto exit;

      /* OK. For now, we presume we have a valid client. We now create the
         client structure, even though we cannot fill it completely yet.
         But it allows us to access lm75_{read,write}_value. */
      if (!(data = kzalloc(sizeof(struct lm75_data), GFP_KERNEL))) {
            err = -ENOMEM;
            goto exit;
      }

      new_client = &data->client;
      i2c_set_clientdata(new_client, data);
      new_client->addr = address;
      new_client->adapter = adapter;
      new_client->driver = &lm75_driver;
      new_client->flags = 0;

      /* Now, we do the remaining detection. There is no identification-
         dedicated register so we have to rely on several tricks:
         unused bits, registers cycling over 8-address boundaries,
         addresses 0x04-0x07 returning the last read value.
         The cycling+unused addresses combination is not tested,
         since it would significantly slow the detection down and would
         hardly add any value. */
      if (kind < 0) {
            int cur, conf, hyst, os;

            /* Unused addresses */
            cur = i2c_smbus_read_word_data(new_client, 0);
            conf = i2c_smbus_read_byte_data(new_client, 1);
            hyst = i2c_smbus_read_word_data(new_client, 2);
            if (i2c_smbus_read_word_data(new_client, 4) != hyst
             || i2c_smbus_read_word_data(new_client, 5) != hyst
             || i2c_smbus_read_word_data(new_client, 6) != hyst
             || i2c_smbus_read_word_data(new_client, 7) != hyst)
                  goto exit_free;
            os = i2c_smbus_read_word_data(new_client, 3);
            if (i2c_smbus_read_word_data(new_client, 4) != os
             || i2c_smbus_read_word_data(new_client, 5) != os
             || i2c_smbus_read_word_data(new_client, 6) != os
             || i2c_smbus_read_word_data(new_client, 7) != os)
                  goto exit_free;

            /* Unused bits */
            if (conf & 0xe0)
                  goto exit_free;

            /* Addresses cycling */
            for (i = 8; i < 0xff; i += 8)
                  if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
                   || i2c_smbus_read_word_data(new_client, i + 2) != hyst
                   || i2c_smbus_read_word_data(new_client, i + 3) != os)
                        goto exit_free;
      }

      /* Determine the chip type - only one kind supported! */
      if (kind <= 0)
            kind = lm75;

      if (kind == lm75) {
            name = "lm75";
      }

      /* Fill in the remaining client fields and put it into the global list */
      strlcpy(new_client->name, name, I2C_NAME_SIZE);
      data->valid = 0;
      mutex_init(&data->update_lock);

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

      /* Initialize the LM75 chip */
      lm75_init_client(new_client);
      
      /* Register sysfs hooks */
      if ((err = sysfs_create_group(&new_client->dev.kobj, &lm75_group)))
            goto exit_detach;

      data->hwmon_dev = hwmon_device_register(&new_client->dev);
      if (IS_ERR(data->hwmon_dev)) {
            err = PTR_ERR(data->hwmon_dev);
            goto exit_remove;
      }

      return 0;

exit_remove:
      sysfs_remove_group(&new_client->dev.kobj, &lm75_group);
exit_detach:
      i2c_detach_client(new_client);
exit_free:
      kfree(data);
exit:
      return err;
}

static int lm75_detach_client(struct i2c_client *client)
{
      struct lm75_data *data = i2c_get_clientdata(client);
      hwmon_device_unregister(data->hwmon_dev);
      sysfs_remove_group(&client->dev.kobj, &lm75_group);
      i2c_detach_client(client);
      kfree(data);
      return 0;
}

/* All registers are word-sized, except for the configuration register.
   LM75 uses a high-byte first convention, which is exactly opposite to
   the usual practice. */
static int lm75_read_value(struct i2c_client *client, u8 reg)
{
      if (reg == LM75_REG_CONF)
            return i2c_smbus_read_byte_data(client, reg);
      else
            return swab16(i2c_smbus_read_word_data(client, reg));
}

/* All registers are word-sized, except for the configuration register.
   LM75 uses a high-byte first convention, which is exactly opposite to
   the usual practice. */
static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
{
      if (reg == LM75_REG_CONF)
            return i2c_smbus_write_byte_data(client, reg, value);
      else
            return i2c_smbus_write_word_data(client, reg, swab16(value));
}

static void lm75_init_client(struct i2c_client *client)
{
      int reg;

      /* Enable if in shutdown mode */
      reg = lm75_read_value(client, LM75_REG_CONF);
      if (reg >= 0 && (reg & 0x01))
            lm75_write_value(client, LM75_REG_CONF, reg & 0xfe);
}

static struct lm75_data *lm75_update_device(struct device *dev)
{
      struct i2c_client *client = to_i2c_client(dev);
      struct lm75_data *data = i2c_get_clientdata(client);

      mutex_lock(&data->update_lock);

      if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
          || !data->valid) {
            int i;
            dev_dbg(&client->dev, "Starting lm75 update\n");

            for (i = 0; i < ARRAY_SIZE(data->temp); i++)
                  data->temp[i] = lm75_read_value(client,
                                          LM75_REG_TEMP[i]);
            data->last_updated = jiffies;
            data->valid = 1;
      }

      mutex_unlock(&data->update_lock);

      return data;
}

static int __init sensors_lm75_init(void)
{
      return i2c_add_driver(&lm75_driver);
}

static void __exit sensors_lm75_exit(void)
{
      i2c_del_driver(&lm75_driver);
}

MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
MODULE_DESCRIPTION("LM75 driver");
MODULE_LICENSE("GPL");

module_init(sensors_lm75_init);
module_exit(sensors_lm75_exit);

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