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/module.h>
  34 #include <linux/platform_data/ads7828.h>
  35 #include <linux/regmap.h>
  36 #include <linux/slab.h>
  37
  38 /* The ADS7828 registers */
  39 #define ADS7828_CMD_SD_SE       0x80    /* Single ended inputs */
  40 #define ADS7828_CMD_PD1         0x04    /* Internal vref OFF && A/D ON */
  41 #define ADS7828_CMD_PD3         0x0C    /* Internal vref ON && A/D ON */
  42 #define ADS7828_INT_VREF_MV     2500    /* Internal vref is 2.5V, 2500mV */
  43 #define ADS7828_EXT_VREF_MV_MIN 50      /* External vref min value 0.05V */
  44 #define ADS7828_EXT_VREF_MV_MAX 5250    /* External vref max value 5.25V */
  45
  46 /* List of supported devices */
  47 enum ads7828_chips { ads7828, ads7830 };
  48
  49 /* Client specific data */
  50 struct ads7828_data {
  51         struct regmap *regmap;
  52         u8 cmd_byte;                    /* Command byte without channel bits */
  53         unsigned int lsb_resol;         /* Resolution of the ADC sample LSB */
  54 };
  55
  56 /* Command byte C2,C1,C0 - see datasheet */
  57 static inline u8 ads7828_cmd_byte(u8 cmd, int ch)
  58 {
  59         return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
  60 }
  61
  62 /* sysfs callback function */
  63 static ssize_t ads7828_show_in(struct device *dev, struct device_attribute *da,
  64                                char *buf)
  65 {
  66         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  67         struct ads7828_data *data = dev_get_drvdata(dev);
  68         u8 cmd = ads7828_cmd_byte(data->cmd_byte, attr->index);
  69         unsigned int regval;
  70         int err;
  71
  72         err = regmap_read(data->regmap, cmd, &regval);
  73         if (err < 0)
  74                 return err;
  75
  76         return sprintf(buf, "%d\n",
  77                        DIV_ROUND_CLOSEST(regval * data->lsb_resol, 1000));
  78 }
  79
  80 static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ads7828_show_in, NULL, 0);
  81 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ads7828_show_in, NULL, 1);
  82 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ads7828_show_in, NULL, 2);
  83 static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ads7828_show_in, NULL, 3);
  84 static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ads7828_show_in, NULL, 4);
  85 static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, ads7828_show_in, NULL, 5);
  86 static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, ads7828_show_in, NULL, 6);
  87 static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, ads7828_show_in, NULL, 7);
  88
  89 static struct attribute *ads7828_attrs[] = {
  90         &sensor_dev_attr_in0_input.dev_attr.attr,
  91         &sensor_dev_attr_in1_input.dev_attr.attr,
  92         &sensor_dev_attr_in2_input.dev_attr.attr,
  93         &sensor_dev_attr_in3_input.dev_attr.attr,
  94         &sensor_dev_attr_in4_input.dev_attr.attr,
  95         &sensor_dev_attr_in5_input.dev_attr.attr,
  96         &sensor_dev_attr_in6_input.dev_attr.attr,
  97         &sensor_dev_attr_in7_input.dev_attr.attr,
  98         NULL
  99 };
 100
 101 ATTRIBUTE_GROUPS(ads7828);
 102
 103 static const struct regmap_config ads2828_regmap_config = {
 104         .reg_bits = 8,
 105         .val_bits = 16,
 106 };
 107
 108 static const struct regmap_config ads2830_regmap_config = {
 109         .reg_bits = 8,
 110         .val_bits = 8,
 111 };
 112
 113 static int ads7828_probe(struct i2c_client *client,
 114                          const struct i2c_device_id *id)
 115 {
 116         struct device *dev = &client->dev;
 117         struct ads7828_platform_data *pdata = dev_get_platdata(dev);
 118         struct ads7828_data *data;
 119         struct device *hwmon_dev;
 120         unsigned int vref_mv = ADS7828_INT_VREF_MV;
 121         bool diff_input = false;
 122         bool ext_vref = false;
 123         unsigned int regval;
 124
 125         data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL);
 126         if (!data)
 127                 return -ENOMEM;
 128
 129         if (pdata) {
 130                 diff_input = pdata->diff_input;
 131                 ext_vref = pdata->ext_vref;
 132                 if (ext_vref && pdata->vref_mv)
 133                         vref_mv = pdata->vref_mv;
 134         }
 135
 136         /* Bound Vref with min/max values */
 137         vref_mv = clamp_val(vref_mv, ADS7828_EXT_VREF_MV_MIN,
 138                             ADS7828_EXT_VREF_MV_MAX);
 139
 140         /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
 141         if (id->driver_data == ads7828) {
 142                 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 4096);
 143                 data->regmap = devm_regmap_init_i2c(client,
 144                                                     &ads2828_regmap_config);
 145         } else {
 146                 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 256);
 147                 data->regmap = devm_regmap_init_i2c(client,
 148                                                     &ads2830_regmap_config);
 149         }
 150
 151         if (IS_ERR(data->regmap))
 152                 return PTR_ERR(data->regmap);
 153
 154         data->cmd_byte = ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
 155         if (!diff_input)
 156                 data->cmd_byte |= ADS7828_CMD_SD_SE;
 157
 158         /*
 159          * Datasheet specifies internal reference voltage is disabled by
 160          * default. The internal reference voltage needs to be enabled and
 161          * voltage needs to settle before getting valid ADC data. So perform a
 162          * dummy read to enable the internal reference voltage.
 163          */
 164         if (!ext_vref)
 165                 regmap_read(data->regmap, data->cmd_byte, &regval);
 166
 167         hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 168                                                            data,
 169                                                            ads7828_groups);
 170         return PTR_ERR_OR_ZERO(hwmon_dev);
 171 }
 172
 173 static const struct i2c_device_id ads7828_device_ids[] = {
 174         { "ads7828", ads7828 },
 175         { "ads7830", ads7830 },
 176         { }
 177 };
 178 MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
 179
 180 static struct i2c_driver ads7828_driver = {
 181         .driver = {
 182                 .name = "ads7828",
 183         },
 184
 185         .id_table = ads7828_device_ids,
 186         .probe = ads7828_probe,
 187 };
 188
 189 module_i2c_driver(ads7828_driver);
 190
 191 MODULE_LICENSE("GPL");
 192 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
 193 MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");