drivers/hwmon/ads7828.c

   1 /*
   2  * ads7828.c - driver for TI ADS7828 8-channel A/D converter and compatibles
   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  * ADS7830 support, by Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>
  10  *
  11  * For further information, see the Documentation/hwmon/ads7828 file.
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2 of the License, or
  16  * (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  21  * GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with this program; if not, write to the Free Software
  25  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  26  */
  27
  28 #include <linux/err.h>
  29 #include <linux/hwmon.h>
  30 #include <linux/hwmon-sysfs.h>
  31 #include <linux/i2c.h>
  32 #include <linux/init.h>
  33 #include <linux/jiffies.h>
  34 #include <linux/module.h>
  35 #include <linux/mutex.h>
  36 #include <linux/platform_data/ads7828.h>
  37 #include <linux/slab.h>
  38
  39 /* The ADS7828 registers */
  40 #define ADS7828_NCH             8       /* 8 channels supported */
  41 #define ADS7828_CMD_SD_SE       0x80    /* Single ended inputs */
  42 #define ADS7828_CMD_PD1         0x04    /* Internal vref OFF && A/D ON */
  43 #define ADS7828_CMD_PD3         0x0C    /* Internal vref ON && A/D ON */
  44 #define ADS7828_INT_VREF_MV     2500    /* Internal vref is 2.5V, 2500mV */
  45 #define ADS7828_EXT_VREF_MV_MIN 50      /* External vref min value 0.05V */
  46 #define ADS7828_EXT_VREF_MV_MAX 5250    /* External vref max value 5.25V */
  47
  48 /* List of supported devices */
  49 enum ads7828_chips { ads7828, ads7830 };
  50
  51 /* Client specific data */
  52 struct ads7828_data {
  53         struct i2c_client *client;
  54         struct mutex update_lock;       /* Mutex protecting updates */
  55         unsigned long last_updated;     /* Last updated time (in jiffies) */
  56         u16 adc_input[ADS7828_NCH];     /* ADS7828_NCH samples */
  57         bool valid;                     /* Validity flag */
  58         bool diff_input;                /* Differential input */
  59         bool ext_vref;                  /* External voltage reference */
  60         unsigned int vref_mv;           /* voltage reference value */
  61         u8 cmd_byte;                    /* Command byte without channel bits */
  62         unsigned int lsb_resol;         /* Resolution of the ADC sample LSB */
  63         s32 (*read_channel)(const struct i2c_client *client, u8 command);
  64 };
  65
  66 /* Command byte C2,C1,C0 - see datasheet */
  67 static inline u8 ads7828_cmd_byte(u8 cmd, int ch)
  68 {
  69         return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
  70 }
  71
  72 /* Update data for the device (all 8 channels) */
  73 static struct ads7828_data *ads7828_update_device(struct device *dev)
  74 {
  75         struct ads7828_data *data = dev_get_drvdata(dev);
  76         struct i2c_client *client = data->client;
  77
  78         mutex_lock(&data->update_lock);
  79
  80         if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
  81                         || !data->valid) {
  82                 unsigned int ch;
  83                 dev_dbg(&client->dev, "Starting ads7828 update\n");
  84
  85                 for (ch = 0; ch < ADS7828_NCH; ch++) {
  86                         u8 cmd = ads7828_cmd_byte(data->cmd_byte, ch);
  87                         data->adc_input[ch] = data->read_channel(client, cmd);
  88                 }
  89                 data->last_updated = jiffies;
  90                 data->valid = true;
  91         }
  92
  93         mutex_unlock(&data->update_lock);
  94
  95         return data;
  96 }
  97
  98 /* sysfs callback function */
  99 static ssize_t ads7828_show_in(struct device *dev, struct device_attribute *da,
 100                                char *buf)
 101 {
 102         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 103         struct ads7828_data *data = ads7828_update_device(dev);
 104         unsigned int value = DIV_ROUND_CLOSEST(data->adc_input[attr->index] *
 105                                                data->lsb_resol, 1000);
 106
 107         return sprintf(buf, "%d\n", value);
 108 }
 109
 110 static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ads7828_show_in, NULL, 0);
 111 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ads7828_show_in, NULL, 1);
 112 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ads7828_show_in, NULL, 2);
 113 static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ads7828_show_in, NULL, 3);
 114 static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ads7828_show_in, NULL, 4);
 115 static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, ads7828_show_in, NULL, 5);
 116 static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, ads7828_show_in, NULL, 6);
 117 static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, ads7828_show_in, NULL, 7);
 118
 119 static struct attribute *ads7828_attrs[] = {
 120         &sensor_dev_attr_in0_input.dev_attr.attr,
 121         &sensor_dev_attr_in1_input.dev_attr.attr,
 122         &sensor_dev_attr_in2_input.dev_attr.attr,
 123         &sensor_dev_attr_in3_input.dev_attr.attr,
 124         &sensor_dev_attr_in4_input.dev_attr.attr,
 125         &sensor_dev_attr_in5_input.dev_attr.attr,
 126         &sensor_dev_attr_in6_input.dev_attr.attr,
 127         &sensor_dev_attr_in7_input.dev_attr.attr,
 128         NULL
 129 };
 130
 131 ATTRIBUTE_GROUPS(ads7828);
 132
 133 static int ads7828_probe(struct i2c_client *client,
 134                          const struct i2c_device_id *id)
 135 {
 136         struct device *dev = &client->dev;
 137         struct ads7828_platform_data *pdata = dev_get_platdata(dev);
 138         struct ads7828_data *data;
 139         struct device *hwmon_dev;
 140
 141         data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL);
 142         if (!data)
 143                 return -ENOMEM;
 144
 145         if (pdata) {
 146                 data->diff_input = pdata->diff_input;
 147                 data->ext_vref = pdata->ext_vref;
 148                 if (data->ext_vref)
 149                         data->vref_mv = pdata->vref_mv;
 150         }
 151
 152         /* Bound Vref with min/max values if it was provided */
 153         if (data->vref_mv)
 154                 data->vref_mv = clamp_val(data->vref_mv,
 155                                           ADS7828_EXT_VREF_MV_MIN,
 156                                           ADS7828_EXT_VREF_MV_MAX);
 157         else
 158                 data->vref_mv = ADS7828_INT_VREF_MV;
 159
 160         /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
 161         if (id->driver_data == ads7828) {
 162                 data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 4096);
 163                 data->read_channel = i2c_smbus_read_word_swapped;
 164         } else {
 165                 data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 256);
 166                 data->read_channel = i2c_smbus_read_byte_data;
 167         }
 168
 169         data->cmd_byte = data->ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
 170         if (!data->diff_input)
 171                 data->cmd_byte |= ADS7828_CMD_SD_SE;
 172
 173         data->client = client;
 174         mutex_init(&data->update_lock);
 175
 176         hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 177                                                            data,
 178                                                            ads7828_groups);
 179         return PTR_ERR_OR_ZERO(hwmon_dev);
 180 }
 181
 182 static const struct i2c_device_id ads7828_device_ids[] = {
 183         { "ads7828", ads7828 },
 184         { "ads7830", ads7830 },
 185         { }
 186 };
 187 MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
 188
 189 static struct i2c_driver ads7828_driver = {
 190         .driver = {
 191                 .name = "ads7828",
 192         },
 193
 194         .id_table = ads7828_device_ids,
 195         .probe = ads7828_probe,
 196 };
 197
 198 module_i2c_driver(ads7828_driver);
 199
 200 MODULE_LICENSE("GPL");
 201 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
 202 MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");