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/*

    lm77.c - Part of lm_sensors, Linux kernel modules for hardware

             monitoring

    Copyright (c) 2004  Andras BALI <drewie@freemail.hu>

    Heavily based on lm75.c by Frodo Looijaard <frodol@dds.nl>.  The LM77

    is a temperature sensor and thermal window comparator with 0.5 deg

    resolution made by National Semiconductor.  Complete datasheet can be

    obtained at their site:

       http://www.national.com/pf/LM/LM77.html

    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/err.h>

#include <linux/mutex.h>

/* Addresses to scan */

static unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, I2C_CLIENT_END };

/* Insmod parameters */

I2C_CLIENT_INSMOD_1(lm77);

/* The LM77 registers */

#define LM77_REG_TEMP           0x00

#define LM77_REG_CONF           0x01

#define LM77_REG_TEMP_HYST      0x02

#define LM77_REG_TEMP_CRIT      0x03

#define LM77_REG_TEMP_MIN       0x04

#define LM77_REG_TEMP_MAX       0x05

/* Each client has this additional data */

struct lm77_data {

        struct i2c_client       client;

        struct device           *hwmon_dev;

        struct mutex            update_lock;

        char                    valid;

        unsigned long           last_updated;   /* In jiffies */

        int                     temp_input;     /* Temperatures */

        int                     temp_crit;

        int                     temp_min;

        int                     temp_max;

        int                     temp_hyst;

        u8                      alarms;

};

static int lm77_attach_adapter(struct i2c_adapter *adapter);

static int lm77_detect(struct i2c_adapter *adapter, int address, int kind);

static void lm77_init_client(struct i2c_client *client);

static int lm77_detach_client(struct i2c_client *client);

static u16 lm77_read_value(struct i2c_client *client, u8 reg);

static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value);

static struct lm77_data *lm77_update_device(struct device *dev);

/* This is the driver that will be inserted */

static struct i2c_driver lm77_driver = {

        .driver = {

                .name   = "lm77",

        },

        .attach_adapter = lm77_attach_adapter,

        .detach_client  = lm77_detach_client,

};

/* straight from the datasheet */

#define LM77_TEMP_MIN (-55000)

#define LM77_TEMP_MAX 125000

/* In the temperature registers, the low 3 bits are not part of the

   temperature values; they are the status bits. */

static inline s16 LM77_TEMP_TO_REG(int temp)

{

        int ntemp = SENSORS_LIMIT(temp, LM77_TEMP_MIN, LM77_TEMP_MAX);

        return (ntemp / 500) * 8;

}

static inline int LM77_TEMP_FROM_REG(s16 reg)

{

        return (reg / 8) * 500;

}

/* sysfs stuff */

/* read routines for temperature limits */

#define show(value)     \

static ssize_t show_##value(struct device *dev, struct device_attribute *attr, char *buf)       \

{                                                               \

        struct lm77_data *data = lm77_update_device(dev);       \

        return sprintf(buf, "%d\n", data->value);               \

}

show(temp_input);

show(temp_crit);

show(temp_min);

show(temp_max);

show(alarms);

/* read routines for hysteresis values */

static ssize_t show_temp_crit_hyst(struct device *dev, struct device_attribute *attr, char *buf)

{

        struct lm77_data *data = lm77_update_device(dev);

        return sprintf(buf, "%d\n", data->temp_crit - data->temp_hyst);

}

static ssize_t show_temp_min_hyst(struct device *dev, struct device_attribute *attr, char *buf)

{

        struct lm77_data *data = lm77_update_device(dev);

        return sprintf(buf, "%d\n", data->temp_min + data->temp_hyst);

}

static ssize_t show_temp_max_hyst(struct device *dev, struct device_attribute *attr, char *buf)

{

        struct lm77_data *data = lm77_update_device(dev);

        return sprintf(buf, "%d\n", data->temp_max - data->temp_hyst);

}

/* write routines */

#define set(value, reg) \

static ssize_t set_##value(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)    \

{                                                                               \

        struct i2c_client *client = to_i2c_client(dev);                         \

        struct lm77_data *data = i2c_get_clientdata(client);                    \

        long val = simple_strtol(buf, NULL, 10);                                \

                                                                                \

        mutex_lock(&data->update_lock);                                         \

        data->value = val;                              \

        lm77_write_value(client, reg, LM77_TEMP_TO_REG(data->value));           \

        mutex_unlock(&data->update_lock);                                       \

        return count;                                                           \

}

set(temp_min, LM77_REG_TEMP_MIN);

set(temp_max, LM77_REG_TEMP_MAX);

/* hysteresis is stored as a relative value on the chip, so it has to be

   converted first */

static ssize_t set_temp_crit_hyst(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)

{

        struct i2c_client *client = to_i2c_client(dev);

        struct lm77_data *data = i2c_get_clientdata(client);

        unsigned long val = simple_strtoul(buf, NULL, 10);

        mutex_lock(&data->update_lock);

        data->temp_hyst = data->temp_crit - val;

        lm77_write_value(client, LM77_REG_TEMP_HYST,

                         LM77_TEMP_TO_REG(data->temp_hyst));

        mutex_unlock(&data->update_lock);

        return count;

}

/* preserve hysteresis when setting T_crit */

static ssize_t set_temp_crit(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)

{

        struct i2c_client *client = to_i2c_client(dev);

        struct lm77_data *data = i2c_get_clientdata(client);

        long val = simple_strtoul(buf, NULL, 10);

        int oldcrithyst;

        mutex_lock(&data->update_lock);

        oldcrithyst = data->temp_crit - data->temp_hyst;

        data->temp_crit = val;

        data->temp_hyst = data->temp_crit - oldcrithyst;

        lm77_write_value(client, LM77_REG_TEMP_CRIT,

                         LM77_TEMP_TO_REG(data->temp_crit));

        lm77_write_value(client, LM77_REG_TEMP_HYST,

                         LM77_TEMP_TO_REG(data->temp_hyst));

        mutex_unlock(&data->update_lock);

        return count;

}

static DEVICE_ATTR(temp1_input, S_IRUGO,

                   show_temp_input, NULL);

static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO,

                   show_temp_crit, set_temp_crit);

static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO,

                   show_temp_min, set_temp_min);

static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,

                   show_temp_max, set_temp_max);

static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO,

                   show_temp_crit_hyst, set_temp_crit_hyst);

static DEVICE_ATTR(temp1_min_hyst, S_IRUGO,

                   show_temp_min_hyst, NULL);

static DEVICE_ATTR(temp1_max_hyst, S_IRUGO,

                   show_temp_max_hyst, NULL);

static DEVICE_ATTR(alarms, S_IRUGO,

                   show_alarms, NULL);

static int lm77_attach_adapter(struct i2c_adapter *adapter)

{

        if (!(adapter->class & I2C_CLASS_HWMON))

                return 0;

        return i2c_probe(adapter, &addr_data, lm77_detect);

}

static struct attribute *lm77_attributes[] = {

        &dev_attr_temp1_input.attr,

        &dev_attr_temp1_crit.attr,

        &dev_attr_temp1_min.attr,

        &dev_attr_temp1_max.attr,

        &dev_attr_temp1_crit_hyst.attr,

        &dev_attr_temp1_min_hyst.attr,

        &dev_attr_temp1_max_hyst.attr,

        &dev_attr_alarms.attr,

        NULL

};

static const struct attribute_group lm77_group = {

        .attrs = lm77_attributes,

};

/* This function is called by i2c_probe */

static int lm77_detect(struct i2c_adapter *adapter, int address, int kind)

{

        struct i2c_client *new_client;

        struct lm77_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 lm77_{read,write}_value. */

        if (!(data = kzalloc(sizeof(struct lm77_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 = &lm77_driver;

        new_client->flags = 0;

        /* Here comes the remaining detection.  Since the LM77 has no

           register dedicated to identification, we have to rely on the

           following tricks:

           1. the high 4 bits represent the sign and thus they should

              always be the same

           2. the high 3 bits are unused in the configuration register

           3. addresses 0x06 and 0x07 return the last read value

           4. registers cycling over 8-address boundaries

           Word-sized registers are high-byte first. */

        if (kind < 0) {

                int i, cur, conf, hyst, crit, min, max;

                /* addresses cycling */

                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);

                crit = i2c_smbus_read_word_data(new_client, 3);

                min = i2c_smbus_read_word_data(new_client, 4);

                max = i2c_smbus_read_word_data(new_client, 5);

                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) != crit

                            || i2c_smbus_read_word_data(new_client, i + 4) != min

                            || i2c_smbus_read_word_data(new_client, i + 5) != max)

                                goto exit_free;

                /* sign bits */

                if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0)

                    || ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0)

                    || ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0)

                    || ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0)

                    || ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0))

                        goto exit_free;

                /* unused bits */

                if (conf & 0xe0)

                        goto exit_free;

                /* 0x06 and 0x07 return the last read value */

                cur = i2c_smbus_read_word_data(new_client, 0);

                if (i2c_smbus_read_word_data(new_client, 6) != cur

                    || i2c_smbus_read_word_data(new_client, 7) != cur)

                        goto exit_free;

                hyst = i2c_smbus_read_word_data(new_client, 2);

                if (i2c_smbus_read_word_data(new_client, 6) != hyst

                    || i2c_smbus_read_word_data(new_client, 7) != hyst)

                        goto exit_free;

                min = i2c_smbus_read_word_data(new_client, 4);

                if (i2c_smbus_read_word_data(new_client, 6) != min

                    || i2c_smbus_read_word_data(new_client, 7) != min)

                        goto exit_free;

        }

        /* Determine the chip type - only one kind supported! */

        if (kind <= 0)

                kind = lm77;

        if (kind == lm77) {

                name = "lm77";

        }

        /* 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 LM77 chip */

        lm77_init_client(new_client);

        /* Register sysfs hooks */

        if ((err = sysfs_create_group(&new_client->dev.kobj, &lm77_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, &lm77_group);

exit_detach:

        i2c_detach_client(new_client);

exit_free:

        kfree(data);

exit:

        return err;

}

static int lm77_detach_client(struct i2c_client *client)

{

        struct lm77_data *data = i2c_get_clientdata(client);

        hwmon_device_unregister(data->hwmon_dev);

        sysfs_remove_group(&client->dev.kobj, &lm77_group);

        i2c_detach_client(client);

        kfree(data);

        return 0;

}

/* All registers are word-sized, except for the configuration register.

   The LM77 uses the high-byte first convention. */

static u16 lm77_read_value(struct i2c_client *client, u8 reg)

{

        if (reg == LM77_REG_CONF)

                return i2c_smbus_read_byte_data(client, reg);

        else

                return swab16(i2c_smbus_read_word_data(client, reg));

}

static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value)

{

        if (reg == LM77_REG_CONF)

                return i2c_smbus_write_byte_data(client, reg, value);

        else

                return i2c_smbus_write_word_data(client, reg, swab16(value));

}

static void lm77_init_client(struct i2c_client *client)

{

        /* Initialize the LM77 chip - turn off shutdown mode */

        int conf = lm77_read_value(client, LM77_REG_CONF);

        if (conf & 1)

                lm77_write_value(client, LM77_REG_CONF, conf & 0xfe);

}

static struct lm77_data *lm77_update_device(struct device *dev)

{

        struct i2c_client *client = to_i2c_client(dev);

        struct lm77_data *data = i2c_get_clientdata(client);

        mutex_lock(&data->update_lock);

        if (time_after(jiffies, data->last_updated + HZ + HZ / 2)

            || !data->valid) {

                dev_dbg(&client->dev, "Starting lm77 update\n");

                data->temp_input =

                        LM77_TEMP_FROM_REG(lm77_read_value(client,

                                                           LM77_REG_TEMP));

                data->temp_hyst =

                        LM77_TEMP_FROM_REG(lm77_read_value(client,

                                                           LM77_REG_TEMP_HYST));

                data->temp_crit =

                        LM77_TEMP_FROM_REG(lm77_read_value(client,

                                                           LM77_REG_TEMP_CRIT));

                data->temp_min =

                        LM77_TEMP_FROM_REG(lm77_read_value(client,

                                                           LM77_REG_TEMP_MIN));

                data->temp_max =

                        LM77_TEMP_FROM_REG(lm77_read_value(client,

                                                           LM77_REG_TEMP_MAX));

                data->alarms =

                        lm77_read_value(client, LM77_REG_TEMP) & 0x0007;

                data->last_updated = jiffies;

                data->valid = 1;

        }

        mutex_unlock(&data->update_lock);

        return data;

}

static int __init sensors_lm77_init(void)

{

        return i2c_add_driver(&lm77_driver);

}

static void __exit sensors_lm77_exit(void)

{

        i2c_del_driver(&lm77_driver);

}

MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>");

MODULE_DESCRIPTION("LM77 driver");

MODULE_LICENSE("GPL");

module_init(sensors_lm77_init);

module_exit(sensors_lm77_exit);