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/*
    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.
*/

/* #define DEBUG 1 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/i2c-sensor.h>


/* Addresses to scan */
static unsigned short normal_i2c[] = { I2C_CLIENT_END };
static unsigned short normal_i2c_range[] = { 0x48, 0x4f, I2C_CLIENT_END };
static unsigned int normal_isa[] = { I2C_CLIENT_ISA_END };
static unsigned int normal_isa_range[] = { I2C_CLIENT_ISA_END };

/* Insmod parameters */
SENSORS_INSMOD_1(lm75);

/* Many LM75 constants specified below */

/* The LM75 registers */
#define LM75_REG_TEMP           0x00
#define LM75_REG_CONF           0x01
#define LM75_REG_TEMP_HYST      0x02
#define LM75_REG_TEMP_OS        0x03

/* Conversions. Rounding and limit checking is only done on the TO_REG
   variants. Note that you should be a bit careful with which arguments
   these macros are called: arguments may be evaluated more than once.
   Fixing this is just not worth it. */
#define TEMP_FROM_REG(val)      ((((val & 0x7fff) >> 7) * 5) | ((val & 0x8000)?-256:0))
#define TEMP_TO_REG(val)        (SENSORS_LIMIT((val<0?(0x200+((val)/5))<<7:(((val) + 2) / 5) << 7),0,0xffff))

/* Initial values */
#define LM75_INIT_TEMP_OS       600
#define LM75_INIT_TEMP_HYST     500

/* Each client has this additional data */
struct lm75_data {
        struct semaphore        update_lock;
        char                    valid;          /* !=0 if following fields are valid */
        unsigned long           last_updated;   /* In jiffies */
        u16                     temp_input;     /* Register values */
        u16                     temp_max;
        u16                     temp_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 void lm75_update_client(struct i2c_client *client);


/* This is the driver that will be inserted */
static struct i2c_driver lm75_driver = {
        .owner          = THIS_MODULE,
        .name           = "lm75",
        .id             = I2C_DRIVERID_LM75,
        .flags          = I2C_DF_NOTIFY,
        .attach_adapter = lm75_attach_adapter,
        .detach_client  = lm75_detach_client,
};

static int lm75_id = 0;

#define show(value)     \
static ssize_t show_##value(struct device *dev, char *buf)      \
{                                                               \
        struct i2c_client *client = to_i2c_client(dev);         \
        struct lm75_data *data = i2c_get_clientdata(client);    \
        int temp;                                               \
                                                                \
        lm75_update_client(client);                             \
        temp = TEMP_FROM_REG(data->value);                      \
        return sprintf(buf, "%d\n", temp * 100);                \
}
show(temp_max);
show(temp_hyst);
show(temp_input);

#define set(value, reg) \
static ssize_t set_##value(struct device *dev, const char *buf, size_t count)   \
{                                                               \
        struct i2c_client *client = to_i2c_client(dev);         \
        struct lm75_data *data = i2c_get_clientdata(client);    \
        int temp = simple_strtoul(buf, NULL, 10) / 100;         \
                                                                \
        data->value = TEMP_TO_REG(temp);                        \
        lm75_write_value(client, reg, data->value);             \
        return count;                                           \
}
set(temp_max, LM75_REG_TEMP_OS);
set(temp_hyst, LM75_REG_TEMP_HYST);

static DEVICE_ATTR(temp_max, S_IWUSR | S_IRUGO, show_temp_max, set_temp_max);
static DEVICE_ATTR(temp_min, S_IWUSR | S_IRUGO, show_temp_hyst, set_temp_hyst);
static DEVICE_ATTR(temp_input, S_IRUGO, show_temp_input, NULL);

static int lm75_attach_adapter(struct i2c_adapter *adapter)
{
        if (!(adapter->class & I2C_ADAP_CLASS_SMBUS))
                return 0;
        return i2c_detect(adapter, &addr_data, lm75_detect);
}

/* This function is called by i2c_detect */
static int lm75_detect(struct i2c_adapter *adapter, int address, int kind)
{
        int i, cur, conf, hyst, os;
        struct i2c_client *new_client;
        struct lm75_data *data;
        int err = 0;
        const char *name;

        /* Make sure we aren't probing the ISA bus!! This is just a safety check
           at this moment; i2c_detect really won't call us. */
#ifdef DEBUG
        if (i2c_is_isa_adapter(adapter)) {
                dev_dbg(&adapter->dev,
                        "lm75_detect called for an ISA bus adapter?!?\n");
                goto exit;
        }
#endif

        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 (!(new_client = kmalloc(sizeof(struct i2c_client) +
                                   sizeof(struct lm75_data),
                                   GFP_KERNEL))) {
                err = -ENOMEM;
                goto exit;
        }
        memset(new_client, 0x00, sizeof(struct i2c_client) +
                                 sizeof(struct lm75_data));

        data = (struct lm75_data *) (new_client + 1);
        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. It is lousy. */
        if (kind < 0) {
                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);
                os = i2c_smbus_read_word_data(new_client, 3);
                for (i = 0; i <= 0x1f; i++)
                        if ((i2c_smbus_read_byte_data(new_client, i * 8 + 1) != conf) ||
                            (i2c_smbus_read_word_data(new_client, i * 8 + 2) != hyst) ||
                            (i2c_smbus_read_word_data(new_client, i * 8 + 3) != os))
                                goto exit_free;
        }

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

        if (kind == lm75) {
                name = "lm75";
        } else {
                dev_dbg(&adapter->dev, "Internal error: unknown kind (%d)?!?",
                        kind);
                goto exit_free;
        }

        /* Fill in the remaining client fields and put it into the global list */
        strlcpy(new_client->name, name, I2C_NAME_SIZE);

        new_client->id = lm75_id++;
        data->valid = 0;
        init_MUTEX(&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 */
        device_create_file(&new_client->dev, &dev_attr_temp_max);
        device_create_file(&new_client->dev, &dev_attr_temp_min);
        device_create_file(&new_client->dev, &dev_attr_temp_input);

        return 0;

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

static int lm75_detach_client(struct i2c_client *client)
{
        i2c_detach_client(client);
        kfree(client);
        return 0;
}

static u16 swap_bytes(u16 val)
{
        return (val >> 8) | (val << 8);
}

/* 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 swap_bytes(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,
                                                 swap_bytes(value));
}

static void lm75_init_client(struct i2c_client *client)
{
        /* Initialize the LM75 chip */
        lm75_write_value(client, LM75_REG_TEMP_OS,
                         TEMP_TO_REG(LM75_INIT_TEMP_OS));
        lm75_write_value(client, LM75_REG_TEMP_HYST,
                         TEMP_TO_REG(LM75_INIT_TEMP_HYST));
        lm75_write_value(client, LM75_REG_CONF, 0);
}

static void lm75_update_client(struct i2c_client *client)
{
        struct lm75_data *data = i2c_get_clientdata(client);

        down(&data->update_lock);

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

                data->temp_input = lm75_read_value(client, LM75_REG_TEMP);
                data->temp_max = lm75_read_value(client, LM75_REG_TEMP_OS);
                data->temp_hyst = lm75_read_value(client, LM75_REG_TEMP_HYST);
                data->last_updated = jiffies;
                data->valid = 1;
        }

        up(&data->update_lock);
}

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);