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 i2c_client client;
  68         struct device *hwmon_dev;
  69         struct mutex update_lock; /* mutex protect updates */
  70         char valid; /* !=0 if following fields are valid */
  71         unsigned long last_updated; /* In jiffies */
  72         u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH 12-bit samples */
  73 };
  74
  75 /* Function declaration - necessary due to function dependencies */
  76 static int ads7828_detect(struct i2c_adapter *adapter, int address, int kind);
  77
  78 /* The ADS7828 returns the 12-bit sample in two bytes,
  79         these are read as a word then byte-swapped */
  80 static u16 ads7828_read_value(struct i2c_client *client, u8 reg)
  81 {
  82         return swab16(i2c_smbus_read_word_data(client, reg));
  83 }
  84
  85 static inline u8 channel_cmd_byte(int ch)
  86 {
  87         /* cmd byte C2,C1,C0 - see datasheet */
  88         u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
  89         cmd |= ads7828_cmd_byte;
  90         return cmd;
  91 }
  92
  93 /* Update data for the device (all 8 channels) */
  94 static struct ads7828_data *ads7828_update_device(struct device *dev)
  95 {
  96         struct i2c_client *client = to_i2c_client(dev);
  97         struct ads7828_data *data = i2c_get_clientdata(client);
  98
  99         mutex_lock(&data->update_lock);
 100
 101         if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
 102                         || !data->valid) {
 103                 unsigned int ch;
 104                 dev_dbg(&client->dev, "Starting ads7828 update\n");
 105
 106                 for (ch = 0; ch < ADS7828_NCH; ch++) {
 107                         u8 cmd = channel_cmd_byte(ch);
 108                         data->adc_input[ch] = ads7828_read_value(client, cmd);
 109                 }
 110                 data->last_updated = jiffies;
 111                 data->valid = 1;
 112         }
 113
 114         mutex_unlock(&data->update_lock);
 115
 116         return data;
 117 }
 118
 119 /* sysfs callback function */
 120 static ssize_t show_in(struct device *dev, struct device_attribute *da,
 121         char *buf)
 122 {
 123         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 124         struct ads7828_data *data = ads7828_update_device(dev);
 125         /* Print value (in mV as specified in sysfs-interface documentation) */
 126         return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
 127                 ads7828_lsb_resol)/1000);
 128 }
 129
 130 #define in_reg(offset)\
 131 static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
 132         NULL, offset)
 133
 134 in_reg(0);
 135 in_reg(1);
 136 in_reg(2);
 137 in_reg(3);
 138 in_reg(4);
 139 in_reg(5);
 140 in_reg(6);
 141 in_reg(7);
 142
 143 static struct attribute *ads7828_attributes[] = {
 144         &sensor_dev_attr_in0_input.dev_attr.attr,
 145         &sensor_dev_attr_in1_input.dev_attr.attr,
 146         &sensor_dev_attr_in2_input.dev_attr.attr,
 147         &sensor_dev_attr_in3_input.dev_attr.attr,
 148         &sensor_dev_attr_in4_input.dev_attr.attr,
 149         &sensor_dev_attr_in5_input.dev_attr.attr,
 150         &sensor_dev_attr_in6_input.dev_attr.attr,
 151         &sensor_dev_attr_in7_input.dev_attr.attr,
 152         NULL
 153 };
 154
 155 static const struct attribute_group ads7828_group = {
 156         .attrs = ads7828_attributes,
 157 };
 158
 159 static int ads7828_attach_adapter(struct i2c_adapter *adapter)
 160 {
 161         if (!(adapter->class & I2C_CLASS_HWMON))
 162                 return 0;
 163         return i2c_probe(adapter, &addr_data, ads7828_detect);
 164 }
 165
 166 static int ads7828_detach_client(struct i2c_client *client)
 167 {
 168         struct ads7828_data *data = i2c_get_clientdata(client);
 169         hwmon_device_unregister(data->hwmon_dev);
 170         sysfs_remove_group(&client->dev.kobj, &ads7828_group);
 171         i2c_detach_client(client);
 172         kfree(i2c_get_clientdata(client));
 173         return 0;
 174 }
 175
 176 /* This is the driver that will be inserted */
 177 static struct i2c_driver ads7828_driver = {
 178         .driver = {
 179                 .name = "ads7828",
 180         },
 181         .attach_adapter = ads7828_attach_adapter,
 182         .detach_client = ads7828_detach_client,
 183 };
 184
 185 /* This function is called by i2c_probe */
 186 static int ads7828_detect(struct i2c_adapter *adapter, int address, int kind)
 187 {
 188         struct i2c_client *client;
 189         struct ads7828_data *data;
 190         int err = 0;
 191         const char *name = "";
 192
 193         /* Check we have a valid client */
 194         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA))
 195                 goto exit;
 196
 197         /* OK. For now, we presume we have a valid client. We now create the
 198         client structure, even though we cannot fill it completely yet.
 199         But it allows us to access ads7828_read_value. */
 200         data = kzalloc(sizeof(struct ads7828_data), GFP_KERNEL);
 201         if (!data) {
 202                 err = -ENOMEM;
 203                 goto exit;
 204         }
 205
 206         client = &data->client;
 207         i2c_set_clientdata(client, data);
 208         client->addr = address;
 209         client->adapter = adapter;
 210         client->driver = &ads7828_driver;
 211
 212         /* Now, we do the remaining detection. There is no identification
 213         dedicated register so attempt to sanity check using knowledge of
 214         the chip
 215         - Read from the 8 channel addresses
 216         - Check the top 4 bits of each result are not set (12 data bits)
 217         */
 218         if (kind < 0) {
 219                 int ch;
 220                 for (ch = 0; ch < ADS7828_NCH; ch++) {
 221                         u16 in_data;
 222                         u8 cmd = channel_cmd_byte(ch);
 223                         in_data = ads7828_read_value(client, cmd);
 224                         if (in_data & 0xF000) {
 225                                 printk(KERN_DEBUG
 226                                 "%s : Doesn't look like an ads7828 device\n",
 227                                 __FUNCTION__);
 228                                 goto exit_free;
 229                         }
 230                 }
 231         }
 232
 233         /* Determine the chip type - only one kind supported! */
 234         if (kind <= 0)
 235                 kind = ads7828;
 236
 237         if (kind == ads7828)
 238                 name = "ads7828";
 239
 240         /* Fill in the remaining client fields, put it into the global list */
 241         strlcpy(client->name, name, I2C_NAME_SIZE);
 242
 243         mutex_init(&data->update_lock);
 244
 245         /* Tell the I2C layer a new client has arrived */
 246         err = i2c_attach_client(client);
 247         if (err)
 248                 goto exit_free;
 249
 250         /* Register sysfs hooks */
 251         err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
 252         if (err)
 253                 goto exit_detach;
 254
 255         data->hwmon_dev = hwmon_device_register(&client->dev);
 256         if (IS_ERR(data->hwmon_dev)) {
 257                 err = PTR_ERR(data->hwmon_dev);
 258                 goto exit_remove;
 259         }
 260
 261         return 0;
 262
 263 exit_remove:
 264         sysfs_remove_group(&client->dev.kobj, &ads7828_group);
 265 exit_detach:
 266         i2c_detach_client(client);
 267 exit_free:
 268         kfree(data);
 269 exit:
 270         return err;
 271 }
 272
 273 static int __init sensors_ads7828_init(void)
 274 {
 275         /* Initialize the command byte according to module parameters */
 276         ads7828_cmd_byte = se_input ?
 277                 ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF;
 278         ads7828_cmd_byte |= int_vref ?
 279                 ADS7828_CMD_PD3 : ADS7828_CMD_PD1;
 280
 281         /* Calculate the LSB resolution */
 282         ads7828_lsb_resol = (vref_mv*1000)/4096;
 283
 284         return i2c_add_driver(&ads7828_driver);
 285 }
 286
 287 static void __exit sensors_ads7828_exit(void)
 288 {
 289         i2c_del_driver(&ads7828_driver);
 290 }
 291
 292 MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk>");
 293 MODULE_DESCRIPTION("ADS7828 driver");
 294 MODULE_LICENSE("GPL");
 295
 296 module_init(sensors_ads7828_init);
 297 module_exit(sensors_ads7828_exit);