pcf8591.c

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/*
 * Copyright (C) 2001-2004 Aurelien Jarno <[email protected]>
 * Ported to Linux 2.6 by Aurelien Jarno <[email protected]> with
 * the help of Jean Delvare <[email protected]>
 *
 * 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 pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/mutex.h>
#include <linux/err.h>
#include <linux/hwmon.h>

/* Insmod parameters */

static int input_mode;
module_param(input_mode, int, 0);
MODULE_PARM_DESC(input_mode,
    "Analog input mode:\n"
    " 0 = four single ended inputs\n"
    " 1 = three differential inputs\n"
    " 2 = single ended and differential mixed\n"
    " 3 = two differential inputs\n");

/*
 * The PCF8591 control byte
 *      7    6    5    4    3    2    1    0
 *   |  0 |AOEF|   AIP   |  0 |AINC|  AICH   |
 */

/* Analog Output Enable Flag (analog output active if 1) */
#define PCF8591_CONTROL_AOEF        0x40

/*
 * Analog Input Programming
 * 0x00 = four single ended inputs
 * 0x10 = three differential inputs
 * 0x20 = single ended and differential mixed
 * 0x30 = two differential inputs
 */
#define PCF8591_CONTROL_AIP_MASK    0x30

/* Autoincrement Flag (switch on if 1) */
#define PCF8591_CONTROL_AINC        0x04

/*
 * Channel selection
 * 0x00 = channel 0
 * 0x01 = channel 1
 * 0x02 = channel 2
 * 0x03 = channel 3
 */
#define PCF8591_CONTROL_AICH_MASK   0x03

/* Initial values */
#define PCF8591_INIT_CONTROL    ((input_mode << 4) | PCF8591_CONTROL_AOEF)
#define PCF8591_INIT_AOUT   0   /* DAC out = 0 */

/* Conversions */
#define REG_TO_SIGNED(reg)  (((reg) & 0x80) ? ((reg) - 256) : (reg))

struct pcf8591_data {
    struct device *hwmon_dev;
    struct mutex update_lock;

    u8 control;
    u8 aout;
};

static void pcf8591_init_client(struct i2c_client *client);
static int pcf8591_read_channel(struct device *dev, int channel);

/* following are the sysfs callback functions */
#define show_in_channel(channel)                    \
static ssize_t show_in##channel##_input(struct device *dev,     \
                    struct device_attribute *attr,  \
                    char *buf)          \
{                                   \
    return sprintf(buf, "%d\n", pcf8591_read_channel(dev, channel));\
}                                   \
static DEVICE_ATTR(in##channel##_input, S_IRUGO,            \
           show_in##channel##_input, NULL);

show_in_channel(0);
show_in_channel(1);
show_in_channel(2);
show_in_channel(3);

static ssize_t show_out0_ouput(struct device *dev,
                   struct device_attribute *attr, char *buf)
{
    struct pcf8591_data *data = i2c_get_clientdata(to_i2c_client(dev));
    return sprintf(buf, "%d\n", data->aout * 10);
}

static ssize_t set_out0_output(struct device *dev,
                   struct device_attribute *attr,
                   const char *buf, size_t count)
{
    unsigned long val;
    struct i2c_client *client = to_i2c_client(dev);
    struct pcf8591_data *data = i2c_get_clientdata(client);
    int err;

    err = kstrtoul(buf, 10, &val);
    if (err)
        return err;

    val /= 10;
    if (val > 255)
        return -EINVAL;

    data->aout = val;
    i2c_smbus_write_byte_data(client, data->control, data->aout);
    return count;
}

static DEVICE_ATTR(out0_output, S_IWUSR | S_IRUGO,
           show_out0_ouput, set_out0_output);

static ssize_t show_out0_enable(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    struct pcf8591_data *data = i2c_get_clientdata(to_i2c_client(dev));
    return sprintf(buf, "%u\n", !(!(data->control & PCF8591_CONTROL_AOEF)));
}

static ssize_t set_out0_enable(struct device *dev,
                   struct device_attribute *attr,
                   const char *buf, size_t count)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct pcf8591_data *data = i2c_get_clientdata(client);
    unsigned long val;
    int err;

    err = kstrtoul(buf, 10, &val);
    if (err)
        return err;

    mutex_lock(&data->update_lock);
    if (val)
        data->control |= PCF8591_CONTROL_AOEF;
    else
        data->control &= ~PCF8591_CONTROL_AOEF;
    i2c_smbus_write_byte(client, data->control);
    mutex_unlock(&data->update_lock);
    return count;
}

static DEVICE_ATTR(out0_enable, S_IWUSR | S_IRUGO,
           show_out0_enable, set_out0_enable);

static struct attribute *pcf8591_attributes[] = {
    &dev_attr_out0_enable.attr,
    &dev_attr_out0_output.attr,
    &dev_attr_in0_input.attr,
    &dev_attr_in1_input.attr,
    NULL
};

static const struct attribute_group pcf8591_attr_group = {
    .attrs = pcf8591_attributes,
};

static struct attribute *pcf8591_attributes_opt[] = {
    &dev_attr_in2_input.attr,
    &dev_attr_in3_input.attr,
    NULL
};

static const struct attribute_group pcf8591_attr_group_opt = {
    .attrs = pcf8591_attributes_opt,
};

/*
 * Real code
 */

static int pcf8591_probe(struct i2c_client *client,
             const struct i2c_device_id *id)
{
    struct pcf8591_data *data;
    int err;

    data = devm_kzalloc(&client->dev, sizeof(struct pcf8591_data),
                GFP_KERNEL);
    if (!data)
        return -ENOMEM;

    i2c_set_clientdata(client, data);
    mutex_init(&data->update_lock);

    /* Initialize the PCF8591 chip */
    pcf8591_init_client(client);

    /* Register sysfs hooks */
    err = sysfs_create_group(&client->dev.kobj, &pcf8591_attr_group);
    if (err)
        return err;

    /* Register input2 if not in "two differential inputs" mode */
    if (input_mode != 3) {
        err = device_create_file(&client->dev, &dev_attr_in2_input);
        if (err)
            goto exit_sysfs_remove;
    }

    /* Register input3 only in "four single ended inputs" mode */
    if (input_mode == 0) {
        err = device_create_file(&client->dev, &dev_attr_in3_input);
        if (err)
            goto exit_sysfs_remove;
    }

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

    return 0;

exit_sysfs_remove:
    sysfs_remove_group(&client->dev.kobj, &pcf8591_attr_group_opt);
    sysfs_remove_group(&client->dev.kobj, &pcf8591_attr_group);
    return err;
}

static int pcf8591_remove(struct i2c_client *client)
{
    struct pcf8591_data *data = i2c_get_clientdata(client);

    hwmon_device_unregister(data->hwmon_dev);
    sysfs_remove_group(&client->dev.kobj, &pcf8591_attr_group_opt);
    sysfs_remove_group(&client->dev.kobj, &pcf8591_attr_group);
    return 0;
}

/* Called when we have found a new PCF8591. */
static void pcf8591_init_client(struct i2c_client *client)
{
    struct pcf8591_data *data = i2c_get_clientdata(client);
    data->control = PCF8591_INIT_CONTROL;
    data->aout = PCF8591_INIT_AOUT;

    i2c_smbus_write_byte_data(client, data->control, data->aout);

    /*
     * The first byte transmitted contains the conversion code of the
     * previous read cycle. FLUSH IT!
     */
    i2c_smbus_read_byte(client);
}

static int pcf8591_read_channel(struct device *dev, int channel)
{
    u8 value;
    struct i2c_client *client = to_i2c_client(dev);
    struct pcf8591_data *data = i2c_get_clientdata(client);

    mutex_lock(&data->update_lock);

    if ((data->control & PCF8591_CONTROL_AICH_MASK) != channel) {
        data->control = (data->control & ~PCF8591_CONTROL_AICH_MASK)
                  | channel;
        i2c_smbus_write_byte(client, data->control);

        /*
         * The first byte transmitted contains the conversion code of
         * the previous read cycle. FLUSH IT!
         */
        i2c_smbus_read_byte(client);
    }
    value = i2c_smbus_read_byte(client);

    mutex_unlock(&data->update_lock);

    if ((channel == 2 && input_mode == 2) ||
        (channel != 3 && (input_mode == 1 || input_mode == 3)))
        return 10 * REG_TO_SIGNED(value);
    else
        return 10 * value;
}

static const struct i2c_device_id pcf8591_id[] = {
    { "pcf8591", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, pcf8591_id);

static struct i2c_driver pcf8591_driver = {
    .driver = {
        .name   = "pcf8591",
    },
    .probe      = pcf8591_probe,
    .remove     = pcf8591_remove,
    .id_table   = pcf8591_id,
};

static int __init pcf8591_init(void)
{
    if (input_mode < 0 || input_mode > 3) {
        pr_warn("invalid input_mode (%d)\n", input_mode);
        input_mode = 0;
    }
    return i2c_add_driver(&pcf8591_driver);
}

static void __exit pcf8591_exit(void)
{
    i2c_del_driver(&pcf8591_driver);
}

MODULE_AUTHOR("Aurelien Jarno <[email protected]>");
MODULE_DESCRIPTION("PCF8591 driver");
MODULE_LICENSE("GPL");

module_init(pcf8591_init);
module_exit(pcf8591_exit);