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 */
  47 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
  48         I2C_CLIENT_END };
  49
  50 /* Insmod parameters */
  51 I2C_CLIENT_INSMOD_1(ads7828);
  52
  53 /* Other module parameters */
  54 static int se_input = 1; /* Default is SE, 0 == diff */
  55 static int int_vref = 1; /* Default is internal ref ON */
  56 static int vref_mv = ADS7828_INT_VREF_MV; /* set if vref != 2.5V */
  57 module_param(se_input, bool, S_IRUGO);
  58 module_param(int_vref, bool, S_IRUGO);
  59 module_param(vref_mv, int, S_IRUGO);
  60
  61 /* Global Variables */
  62 static u8 ads7828_cmd_byte; /* cmd byte without channel bits */
  63 static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */
  64
  65 /* Each client has this additional data */
  66 struct 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 */
  75 static int ads7828_detect(struct i2c_client *client, int kind,
  76                           struct i2c_board_info *info);
  77 static 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 */
  82 static u16 ads7828_read_value(struct i2c_client *client, u8 reg)
  83 {
  84         return swab16(i2c_smbus_read_word_data(client, reg));
  85 }
  86
  87 static 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) */
  96 static 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 */
 122 static 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)\
 133 static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
 134         NULL, offset)
 135
 136 in_reg(0);
 137 in_reg(1);
 138 in_reg(2);
 139 in_reg(3);
 140 in_reg(4);
 141 in_reg(5);
 142 in_reg(6);
 143 in_reg(7);
 144
 145 static 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
 157 static const struct attribute_group ads7828_group = {
 158         .attrs = ads7828_attributes,
 159 };
 160
 161 static 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
 170 static const struct i2c_device_id ads7828_id[] = {
 171         { "ads7828", ads7828 },
 172         { }
 173 };
 174 MODULE_DEVICE_TABLE(i2c, ads7828_id);
 175
 176 /* This is the driver that will be inserted */
 177 static 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 */
 190 static 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
 224 static 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
 252 exit_remove:
 253         sysfs_remove_group(&client->dev.kobj, &ads7828_group);
 254 exit_free:
 255         kfree(data);
 256 exit:
 257         return err;
 258 }
 259
 260 static 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
 274 static void __exit sensors_ads7828_exit(void)
 275 {
 276         i2c_del_driver(&ads7828_driver);
 277 }
 278
 279 MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk>");
 280 MODULE_DESCRIPTION("ADS7828 driver");
 281 MODULE_LICENSE("GPL");
 282
 283 module_init(sensors_ads7828_init);
 284 module_exit(sensors_ads7828_exit);