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 <shardy@redhat.com>
   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 /* Module parameters */
  51 static bool se_input = 1; /* Default is SE, 0 == diff */
  52 static bool int_vref = 1; /* Default is internal ref ON */
  53 static int vref_mv = ADS7828_INT_VREF_MV; /* set if vref != 2.5V */
  54 module_param(se_input, bool, S_IRUGO);
  55 module_param(int_vref, bool, S_IRUGO);
  56 module_param(vref_mv, int, S_IRUGO);
  57
  58 /* Global Variables */
  59 static u8 ads7828_cmd_byte; /* cmd byte without channel bits */
  60 static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */
  61
  62 /* Each client has this additional data */
  63 struct ads7828_data {
  64         struct device *hwmon_dev;
  65         struct mutex update_lock; /* mutex protect updates */
  66         char valid; /* !=0 if following fields are valid */
  67         unsigned long last_updated; /* In jiffies */
  68         u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH 12-bit samples */
  69 };
  70
  71 /* Function declaration - necessary due to function dependencies */
  72 static int ads7828_detect(struct i2c_client *client,
  73                           struct i2c_board_info *info);
  74 static int ads7828_probe(struct i2c_client *client,
  75                          const struct i2c_device_id *id);
  76
  77 static inline u8 channel_cmd_byte(int ch)
  78 {
  79         /* cmd byte C2,C1,C0 - see datasheet */
  80         u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
  81         cmd |= ads7828_cmd_byte;
  82         return cmd;
  83 }
  84
  85 /* Update data for the device (all 8 channels) */
  86 static struct ads7828_data *ads7828_update_device(struct device *dev)
  87 {
  88         struct i2c_client *client = to_i2c_client(dev);
  89         struct ads7828_data *data = i2c_get_clientdata(client);
  90
  91         mutex_lock(&data->update_lock);
  92
  93         if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
  94                         || !data->valid) {
  95                 unsigned int ch;
  96                 dev_dbg(&client->dev, "Starting ads7828 update\n");
  97
  98                 for (ch = 0; ch < ADS7828_NCH; ch++) {
  99                         u8 cmd = channel_cmd_byte(ch);
 100                         data->adc_input[ch] =
 101                                 i2c_smbus_read_word_swapped(client, cmd);
 102                 }
 103                 data->last_updated = jiffies;
 104                 data->valid = 1;
 105         }
 106
 107         mutex_unlock(&data->update_lock);
 108
 109         return data;
 110 }
 111
 112 /* sysfs callback function */
 113 static ssize_t show_in(struct device *dev, struct device_attribute *da,
 114         char *buf)
 115 {
 116         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 117         struct ads7828_data *data = ads7828_update_device(dev);
 118         /* Print value (in mV as specified in sysfs-interface documentation) */
 119         return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
 120                 ads7828_lsb_resol)/1000);
 121 }
 122
 123 #define in_reg(offset)\
 124 static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
 125         NULL, offset)
 126
 127 in_reg(0);
 128 in_reg(1);
 129 in_reg(2);
 130 in_reg(3);
 131 in_reg(4);
 132 in_reg(5);
 133 in_reg(6);
 134 in_reg(7);
 135
 136 static struct attribute *ads7828_attributes[] = {
 137         &sensor_dev_attr_in0_input.dev_attr.attr,
 138         &sensor_dev_attr_in1_input.dev_attr.attr,
 139         &sensor_dev_attr_in2_input.dev_attr.attr,
 140         &sensor_dev_attr_in3_input.dev_attr.attr,
 141         &sensor_dev_attr_in4_input.dev_attr.attr,
 142         &sensor_dev_attr_in5_input.dev_attr.attr,
 143         &sensor_dev_attr_in6_input.dev_attr.attr,
 144         &sensor_dev_attr_in7_input.dev_attr.attr,
 145         NULL
 146 };
 147
 148 static const struct attribute_group ads7828_group = {
 149         .attrs = ads7828_attributes,
 150 };
 151
 152 static int ads7828_remove(struct i2c_client *client)
 153 {
 154         struct ads7828_data *data = i2c_get_clientdata(client);
 155         hwmon_device_unregister(data->hwmon_dev);
 156         sysfs_remove_group(&client->dev.kobj, &ads7828_group);
 157         kfree(i2c_get_clientdata(client));
 158         return 0;
 159 }
 160
 161 static const struct i2c_device_id ads7828_id[] = {
 162         { "ads7828", 0 },
 163         { }
 164 };
 165 MODULE_DEVICE_TABLE(i2c, ads7828_id);
 166
 167 /* This is the driver that will be inserted */
 168 static struct i2c_driver ads7828_driver = {
 169         .class = I2C_CLASS_HWMON,
 170         .driver = {
 171                 .name = "ads7828",
 172         },
 173         .probe = ads7828_probe,
 174         .remove = ads7828_remove,
 175         .id_table = ads7828_id,
 176         .detect = ads7828_detect,
 177         .address_list = normal_i2c,
 178 };
 179
 180 /* Return 0 if detection is successful, -ENODEV otherwise */
 181 static int ads7828_detect(struct i2c_client *client,
 182                           struct i2c_board_info *info)
 183 {
 184         struct i2c_adapter *adapter = client->adapter;
 185         int ch;
 186
 187         /* Check we have a valid client */
 188         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA))
 189                 return -ENODEV;
 190
 191         /*
 192          * Now, we do the remaining detection. There is no identification
 193          * dedicated register so attempt to sanity check using knowledge of
 194          * the chip
 195          * - Read from the 8 channel addresses
 196          * - Check the top 4 bits of each result are not set (12 data bits)
 197          */
 198         for (ch = 0; ch < ADS7828_NCH; ch++) {
 199                 u16 in_data;
 200                 u8 cmd = channel_cmd_byte(ch);
 201                 in_data = i2c_smbus_read_word_swapped(client, cmd);
 202                 if (in_data & 0xF000) {
 203                         pr_debug("%s : Doesn't look like an ads7828 device\n",
 204                                  __func__);
 205                         return -ENODEV;
 206                 }
 207         }
 208
 209         strlcpy(info->type, "ads7828", I2C_NAME_SIZE);
 210
 211         return 0;
 212 }
 213
 214 static int ads7828_probe(struct i2c_client *client,
 215                          const struct i2c_device_id *id)
 216 {
 217         struct ads7828_data *data;
 218         int err;
 219
 220         data = kzalloc(sizeof(struct ads7828_data), GFP_KERNEL);
 221         if (!data) {
 222                 err = -ENOMEM;
 223                 goto exit;
 224         }
 225
 226         i2c_set_clientdata(client, data);
 227         mutex_init(&data->update_lock);
 228
 229         /* Register sysfs hooks */
 230         err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
 231         if (err)
 232                 goto exit_free;
 233
 234         data->hwmon_dev = hwmon_device_register(&client->dev);
 235         if (IS_ERR(data->hwmon_dev)) {
 236                 err = PTR_ERR(data->hwmon_dev);
 237                 goto exit_remove;
 238         }
 239
 240         return 0;
 241
 242 exit_remove:
 243         sysfs_remove_group(&client->dev.kobj, &ads7828_group);
 244 exit_free:
 245         kfree(data);
 246 exit:
 247         return err;
 248 }
 249
 250 static int __init sensors_ads7828_init(void)
 251 {
 252         /* Initialize the command byte according to module parameters */
 253         ads7828_cmd_byte = se_input ?
 254                 ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF;
 255         ads7828_cmd_byte |= int_vref ?
 256                 ADS7828_CMD_PD3 : ADS7828_CMD_PD1;
 257
 258         /* Calculate the LSB resolution */
 259         ads7828_lsb_resol = (vref_mv*1000)/4096;
 260
 261         return i2c_add_driver(&ads7828_driver);
 262 }
 263
 264 static void __exit sensors_ads7828_exit(void)
 265 {
 266         i2c_del_driver(&ads7828_driver);
 267 }
 268
 269 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
 270 MODULE_DESCRIPTION("ADS7828 driver");
 271 MODULE_LICENSE("GPL");
 272
 273 module_init(sensors_ads7828_init);
 274 module_exit(sensors_ads7828_exit);