LXR linux/drivers/hwmon/ads7828.c

   1/*
   2        ads7828.c - lm_sensors driver for ads7828 12-bit 8-channel ADC
   3        (C) 2007 EADS Astrium
   4
   5        This driver is based on the lm75 and other lm_sensors/hwmon drivers
   6
   7        Written by Steve Hardy <steve@linuxrealtime.co.uk>
   8
   9        Datasheet available at: http://focus.ti.com/lit/ds/symlink/ads7828.pdf
  10
  11        This program is free software; you can redistribute it and/or modify
  12        it under the terms of the GNU General Public License as published by
  13        the Free Software Foundation; either version 2 of the License, or
  14        (at your option) any later version.
  15
  16        This program is distributed in the hope that it will be useful,
  17        but WITHOUT ANY WARRANTY; without even the implied warranty of
  18        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.    See the
  19        GNU General Public License for more details.
  20
  21        You should have received a copy of the GNU General Public License
  22        along with this program; if not, write to the Free Software
  23        Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  24*/
  25
  26#include <linux/module.h>
  27#include <linux/init.h>
  28#include <linux/slab.h>
  29#include <linux/jiffies.h>
  30#include <linux/i2c.h>
  31#include <linux/hwmon.h>
  32#include <linux/hwmon-sysfs.h>
  33#include <linux/err.h>
  34#include <linux/mutex.h>
  35
  36/* The ADS7828 registers */
  37#define ADS7828_NCH 8 /* 8 channels of 12-bit A-D supported */
  38#define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */
  39#define ADS7828_CMD_SD_DIFF 0x00 /* Differential inputs */
  40#define ADS7828_CMD_PD0 0x0 /* Power Down between A-D conversions */
  41#define ADS7828_CMD_PD1 0x04 /* Internal ref OFF && A-D ON */
  42#define ADS7828_CMD_PD2 0x08 /* Internal ref ON && A-D OFF */
  43#define ADS7828_CMD_PD3 0x0C /* Internal ref ON && A-D ON */
  44#define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */
  45
  46/* Addresses to scan */
  47static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
  48        I2C_CLIENT_END };
  49
  50/* Insmod parameters */
  51I2C_CLIENT_INSMOD_1(ads7828);
  52
  53/* Other module parameters */
  54static int se_input = 1; /* Default is SE, 0 == diff */
  55static int int_vref = 1; /* Default is internal ref ON */
  56static int vref_mv = ADS7828_INT_VREF_MV; /* set if vref != 2.5V */
  57module_param(se_input, bool, S_IRUGO);
  58module_param(int_vref, bool, S_IRUGO);
  59module_param(vref_mv, int, S_IRUGO);
  60
  61/* Global Variables */
  62static u8 ads7828_cmd_byte; /* cmd byte without channel bits */
  63static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */
  64
  65/* Each client has this additional data */
  66struct ads7828_data {
  67        struct device *hwmon_dev;
  68        struct mutex update_lock; /* mutex protect updates */
  69        char valid; /* !=0 if following fields are valid */
  70        unsigned long last_updated; /* In jiffies */
  71        u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH 12-bit samples */
  72};
  73
  74/* Function declaration - necessary due to function dependencies */
  75static int ads7828_detect(struct i2c_client *client, int kind,
  76                          struct i2c_board_info *info);
  77static int ads7828_probe(struct i2c_client *client,
  78                         const struct i2c_device_id *id);
  79
  80/* The ADS7828 returns the 12-bit sample in two bytes,
  81        these are read as a word then byte-swapped */
  82static u16 ads7828_read_value(struct i2c_client *client, u8 reg)
  83{
  84        return swab16(i2c_smbus_read_word_data(client, reg));
  85}
  86
  87static inline u8 channel_cmd_byte(int ch)
  88{
  89        /* cmd byte C2,C1,C0 - see datasheet */
  90        u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
  91        cmd |= ads7828_cmd_byte;
  92        return cmd;
  93}
  94
  95/* Update data for the device (all 8 channels) */
  96static struct ads7828_data *ads7828_update_device(struct device *dev)
  97{
  98        struct i2c_client *client = to_i2c_client(dev);
  99        struct ads7828_data *data = i2c_get_clientdata(client);
 100
 101        mutex_lock(&data->update_lock);
 102
 103        if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
 104                        || !data->valid) {
 105                unsigned int ch;
 106                dev_dbg(&client->dev, "Starting ads7828 update\n");
 107
 108                for (ch = 0; ch < ADS7828_NCH; ch++) {
 109                        u8 cmd = channel_cmd_byte(ch);
 110                        data->adc_input[ch] = ads7828_read_value(client, cmd);
 111                }
 112                data->last_updated = jiffies;
 113                data->valid = 1;
 114        }
 115
 116        mutex_unlock(&data->update_lock);
 117
 118        return data;
 119}
 120
 121/* sysfs callback function */
 122static ssize_t show_in(struct device *dev, struct device_attribute *da,
 123        char *buf)
 124{
 125        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 126        struct ads7828_data *data = ads7828_update_device(dev);
 127        /* Print value (in mV as specified in sysfs-interface documentation) */
 128        return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
 129                ads7828_lsb_resol)/1000);
 130}
 131
 132#define in_reg(offset)\
 133static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
 134        NULL, offset)
 135
 136in_reg(0);
 137in_reg(1);
 138in_reg(2);
 139in_reg(3);
 140in_reg(4);
 141in_reg(5);
 142in_reg(6);
 143in_reg(7);
 144
 145static struct attribute *ads7828_attributes[] = {
 146        &sensor_dev_attr_in0_input.dev_attr.attr,
 147        &sensor_dev_attr_in1_input.dev_attr.attr,
 148        &sensor_dev_attr_in2_input.dev_attr.attr,
 149        &sensor_dev_attr_in3_input.dev_attr.attr,
 150        &sensor_dev_attr_in4_input.dev_attr.attr,
 151        &sensor_dev_attr_in5_input.dev_attr.attr,
 152        &sensor_dev_attr_in6_input.dev_attr.attr,
 153        &sensor_dev_attr_in7_input.dev_attr.attr,
 154        NULL
 155};
 156
 157static const struct attribute_group ads7828_group = {
 158        .attrs = ads7828_attributes,
 159};
 160
 161static int ads7828_remove(struct i2c_client *client)
 162{
 163        struct ads7828_data *data = i2c_get_clientdata(client);
 164        hwmon_device_unregister(data->hwmon_dev);
 165        sysfs_remove_group(&client->dev.kobj, &ads7828_group);
 166        kfree(i2c_get_clientdata(client));
 167        return 0;
 168}
 169
 170static const struct i2c_device_id ads7828_id[] = {
 171        { "ads7828", ads7828 },
 172        { }
 173};
 174MODULE_DEVICE_TABLE(i2c, ads7828_id);
 175
 176/* This is the driver that will be inserted */
 177static struct i2c_driver ads7828_driver = {
 178        .class = I2C_CLASS_HWMON,
 179        .driver = {
 180                .name = "ads7828",
 181        },
 182        .probe = ads7828_probe,
 183        .remove = ads7828_remove,
 184        .id_table = ads7828_id,
 185        .detect = ads7828_detect,
 186        .address_data = &addr_data,
 187};
 188
 189/* Return 0 if detection is successful, -ENODEV otherwise */
 190static int ads7828_detect(struct i2c_client *client, int kind,
 191                          struct i2c_board_info *info)
 192{
 193        struct i2c_adapter *adapter = client->adapter;
 194
 195        /* Check we have a valid client */
 196        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA))
 197                return -ENODEV;
 198
 199        /* Now, we do the remaining detection. There is no identification
 200        dedicated register so attempt to sanity check using knowledge of
 201        the chip
 202        - Read from the 8 channel addresses
 203        - Check the top 4 bits of each result are not set (12 data bits)
 204        */
 205        if (kind < 0) {
 206                int ch;
 207                for (ch = 0; ch < ADS7828_NCH; ch++) {
 208                        u16 in_data;
 209                        u8 cmd = channel_cmd_byte(ch);
 210                        in_data = ads7828_read_value(client, cmd);
 211                        if (in_data & 0xF000) {
 212                                printk(KERN_DEBUG
 213                                "%s : Doesn't look like an ads7828 device\n",
 214                                __func__);
 215                                return -ENODEV;
 216                        }
 217                }
 218        }
 219        strlcpy(info->type, "ads7828", I2C_NAME_SIZE);
 220
 221        return 0;
 222}
 223
 224static int ads7828_probe(struct i2c_client *client,
 225                         const struct i2c_device_id *id)
 226{
 227        struct ads7828_data *data;
 228        int err;
 229
 230        data = kzalloc(sizeof(struct ads7828_data), GFP_KERNEL);
 231        if (!data) {
 232                err = -ENOMEM;
 233                goto exit;
 234        }
 235
 236        i2c_set_clientdata(client, data);
 237        mutex_init(&data->update_lock);
 238
 239        /* Register sysfs hooks */
 240        err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
 241        if (err)
 242                goto exit_free;
 243
 244        data->hwmon_dev = hwmon_device_register(&client->dev);
 245        if (IS_ERR(data->hwmon_dev)) {
 246                err = PTR_ERR(data->hwmon_dev);
 247                goto exit_remove;
 248        }
 249
 250        return 0;
 251
 252exit_remove:
 253        sysfs_remove_group(&client->dev.kobj, &ads7828_group);
 254exit_free:
 255        kfree(data);
 256exit:
 257        return err;
 258}
 259
 260static int __init sensors_ads7828_init(void)
 261{
 262        /* Initialize the command byte according to module parameters */
 263        ads7828_cmd_byte = se_input ?
 264                ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF;
 265        ads7828_cmd_byte |= int_vref ?
 266                ADS7828_CMD_PD3 : ADS7828_CMD_PD1;
 267
 268        /* Calculate the LSB resolution */
 269        ads7828_lsb_resol = (vref_mv*1000)/4096;
 270
 271        return i2c_add_driver(&ads7828_driver);
 272}
 273
 274static void __exit sensors_ads7828_exit(void)
 275{
 276        i2c_del_driver(&ads7828_driver);
 277}
 278
 279MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk>");
 280MODULE_DESCRIPTION("ADS7828 driver");
 281MODULE_LICENSE("GPL");
 282
 283module_init(sensors_ads7828_init);
 284module_exit(sensors_ads7828_exit);
 285