ms5xxx kernel driver

/*
 * Driver for AMSYS MS5611 barometer sensor chips
 *
 * MS5611:
 * High Precision Pressure Sensor Module with I2C Interface
 * Datasheet: http://www.amsys-sensor.com/products/ms5611.htm
 *
 * Copyright (C) 2014 Clément Guérin <clement.guerin@ciblenetworks.fr>
 * Copyright (C) 2012-2013 Olaf Lüke <olaf@tinkerforge.com>
 *
 * 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; version 2 of the License.
 */

#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 <linux/delay.h>

/* Command definitions */
#define MS5611_CMD_RESET        0x1E
#define MS5611_CMD_D1           0x40
#define MS5611_CMD_D2           0x50
#define MS5611_CMD_ADC_READ     0x00

/* Over Sampling Ratio definitions */
#define MS561101BA_OSR_256      0x00
#define MS561101BA_OSR_512      0x02
#define MS561101BA_OSR_1024     0x04
#define MS561101BA_OSR_2048     0x06
#define MS561101BA_OSR_4096     0x08
#define MS561101BA_OSR          MS561101BA_OSR_4096

/* PROM definitions */
#define MS5611_PROM_ADDR        0xA0
#define MS5611_PROM_COUNT       8
#define MS5611_PROM_SIZE        2

enum ms5xxx_ids { ms5611 };

struct ms5xxx_data {
    struct device *hwmon_dev;
    struct mutex update_lock;
    u16 prom[MS5611_PROM_COUNT];
    u8 prom_valid;
    u32 last_adc;
};

/* Send command */
static struct ms5xxx_data *ms5xxx_cmd(struct device *dev, u8 cmd)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct ms5xxx_data *data = i2c_get_clientdata(client);

    mutex_lock(&data->update_lock);

    i2c_smbus_write_byte(client, cmd);

    mutex_unlock(&data->update_lock);

    return data;
}

/* Read calibration data */
static struct ms5xxx_data *ms5xxx_read_prom(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct ms5xxx_data *data = i2c_get_clientdata(client);
    u8 bytes[MS5611_PROM_SIZE];
    u8 i;

    mutex_lock(&data->update_lock);

    for (i = 0; i < MS5611_PROM_COUNT; i++) {
        u8 cmd = MS5611_PROM_ADDR + i * MS5611_PROM_SIZE;
        i2c_smbus_read_i2c_block_data(client, cmd, MS5611_PROM_SIZE, bytes);
        data->prom[i] = (bytes[0] << 8) | bytes[1];
    }

    mutex_unlock(&data->update_lock);

    return data;
}

/* Validate calibration data */
static struct ms5xxx_data *ms5xxx_validate_prom(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct ms5xxx_data *data = i2c_get_clientdata(client);
    u16 reminder = 0;
    u16 backup = data->prom[7];
    u8 i, k;

    data->prom[7] = 0xFF00 & data->prom[7];

    for (i = 0; i < 2 * MS5611_PROM_COUNT; i++) {
        if (i % 2 == 1) {
            reminder ^= data->prom[i >> 1] & 0x00FF;
        } else {
            reminder ^= data->prom[i >> 1] >> 8;
        }

        for (k = 8; k > 0; k--) {
            if (reminder & 0x8000) {
                reminder = (reminder << 1) ^ 0x3000;
            } else {
                reminder = reminder << 1;
            }
        }
    }

    reminder = 0x000F & (reminder >> 12);
    data->prom[7] = backup;
    data->prom_valid = (reminder == (data->prom[7] & 0x000F));

    return data;
}

/* Read sensor data */
static struct ms5xxx_data *ms5xxx_read_adc(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct ms5xxx_data *data = i2c_get_clientdata(client);
    u8 bytes[3];

    mutex_lock(&data->update_lock);

    i2c_smbus_read_i2c_block_data(client, MS5611_CMD_ADC_READ, 3, bytes);
    data->last_adc = (bytes[0] << 16) | (bytes[1] << 8) | bytes[2];

    mutex_unlock(&data->update_lock);

    return data;
}

static ssize_t show_prom(struct device *dev, struct device_attribute *da,
    char *buf)
{
    struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
    struct i2c_client *client = to_i2c_client(dev);
    struct ms5xxx_data *data = i2c_get_clientdata(client);

    return sprintf(buf, "%d\n", data->prom[attr->index]);
}

static ssize_t show_prom_valid(struct device *dev, struct device_attribute *da,
    char *buf)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct ms5xxx_data *data = i2c_get_clientdata(client);

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

static ssize_t show_raw_pres(struct device *dev, struct device_attribute *da,
    char *buf)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct ms5xxx_data *data = i2c_get_clientdata(client);

    ms5xxx_cmd(dev, MS5611_CMD_D1 | MS561101BA_OSR);
    msleep(10);
    ms5xxx_read_adc(dev);

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

static ssize_t show_raw_temp(struct device *dev, struct device_attribute *da,
    char *buf)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct ms5xxx_data *data = i2c_get_clientdata(client);
    s32 dt, temp;

    ms5xxx_cmd(dev, MS5611_CMD_D2 | MS561101BA_OSR);
    msleep(10);
    ms5xxx_read_adc(dev);

    dt = (s32)data->last_adc - ((s32)data->prom[5] << 8);
    temp = 2000 + (((s64)dt * (s64)data->prom[6]) >> 23);

    return sprintf(buf, "%d\n", temp);
}

static SENSOR_DEVICE_ATTR(prom0, S_IRUGO, show_prom, NULL, 0);
static SENSOR_DEVICE_ATTR(prom1, S_IRUGO, show_prom, NULL, 1);
static SENSOR_DEVICE_ATTR(prom2, S_IRUGO, show_prom, NULL, 2);
static SENSOR_DEVICE_ATTR(prom3, S_IRUGO, show_prom, NULL, 3);
static SENSOR_DEVICE_ATTR(prom4, S_IRUGO, show_prom, NULL, 4);
static SENSOR_DEVICE_ATTR(prom5, S_IRUGO, show_prom, NULL, 5);
static SENSOR_DEVICE_ATTR(prom6, S_IRUGO, show_prom, NULL, 6);
static SENSOR_DEVICE_ATTR(prom7, S_IRUGO, show_prom, NULL, 7);
static SENSOR_DEVICE_ATTR(prom_valid, S_IRUGO, show_prom_valid, NULL, 0);
static SENSOR_DEVICE_ATTR(raw_pres, S_IRUGO, show_raw_pres, NULL, 0);
static SENSOR_DEVICE_ATTR(temp, S_IRUGO, show_raw_temp, NULL, 0);

static struct attribute *ms5xxx_attributes[] = {
    &sensor_dev_attr_prom0.dev_attr.attr,
    &sensor_dev_attr_prom1.dev_attr.attr,
    &sensor_dev_attr_prom2.dev_attr.attr,
    &sensor_dev_attr_prom3.dev_attr.attr,
    &sensor_dev_attr_prom4.dev_attr.attr,
    &sensor_dev_attr_prom5.dev_attr.attr,
    &sensor_dev_attr_prom6.dev_attr.attr,
    &sensor_dev_attr_prom7.dev_attr.attr,
    &sensor_dev_attr_prom_valid.dev_attr.attr,
    &sensor_dev_attr_raw_pres.dev_attr.attr,
    &sensor_dev_attr_temp.dev_attr.attr,
    NULL
};

static const struct attribute_group ms5xxx_group = {
    .attrs = ms5xxx_attributes,
};


static int ms5xxx_probe(struct i2c_client *client,
            const struct i2c_device_id *id)
{
    struct ms5xxx_data *data;
    int err;

    data = kzalloc(sizeof(struct ms5xxx_data), GFP_KERNEL);
    if (!data) {
        err = -ENOMEM;
        goto exit;
    }

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

    /* Register sysfs hooks */
    err = sysfs_create_group(&client->dev.kobj, &ms5xxx_group);
    if (err)
        goto exit_free;

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

    ms5xxx_cmd(&client->dev, MS5611_CMD_RESET);
    msleep(5);
    ms5xxx_read_prom(&client->dev);
    ms5xxx_validate_prom(&client->dev);

    return 0;

exit_remove:
    sysfs_remove_group(&client->dev.kobj, &ms5xxx_group);
exit_free:
    kfree(data);
exit:
    return err;
}

static const struct i2c_device_id ms5xxx_id[] = {
    { "ms5611", ms5611 },
    { }
};
MODULE_DEVICE_TABLE(i2c, ms5xxx_id);

static struct i2c_driver ms5xxx_driver = {
    .driver = {
        .name   = "ms5xxx",
    },
    .probe      = ms5xxx_probe,
    .id_table   = ms5xxx_id,
};

module_i2c_driver(ms5xxx_driver);

MODULE_AUTHOR("Clément Guérin <clement.guerin@ciblenetworks.fr>");
MODULE_DESCRIPTION("ms5xxx driver");
MODULE_LICENSE("GPL");