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/of_device.h>
  35 #include <linux/platform_data/ads7828.h>
  36 #include <linux/regmap.h>
  37 #include <linux/slab.h>
  38 #include <linux/regulator/consumer.h>
  39
  40 /* The ADS7828 registers */
  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 regmap *regmap;
  54         u8 cmd_byte;                    /* Command byte without channel bits */
  55         unsigned int lsb_resol;         /* Resolution of the ADC sample LSB */
  56 };
  57
  58 /* Command byte C2,C1,C0 - see datasheet */
  59 static inline u8 ads7828_cmd_byte(u8 cmd, int ch)
  60 {
  61         return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
  62 }
  63
  64 /* sysfs callback function */
  65 static ssize_t ads7828_show_in(struct device *dev, struct device_attribute *da,
  66                                char *buf)
  67 {
  68         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  69         struct ads7828_data *data = dev_get_drvdata(dev);
  70         u8 cmd = ads7828_cmd_byte(data->cmd_byte, attr->index);
  71         unsigned int regval;
  72         int err;
  73
  74         err = regmap_read(data->regmap, cmd, &regval);
  75         if (err < 0)
  76                 return err;
  77
  78         return sprintf(buf, "%d\n",
  79                        DIV_ROUND_CLOSEST(regval * data->lsb_resol, 1000));
  80 }
  81
  82 static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ads7828_show_in, NULL, 0);
  83 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ads7828_show_in, NULL, 1);
  84 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ads7828_show_in, NULL, 2);
  85 static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ads7828_show_in, NULL, 3);
  86 static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ads7828_show_in, NULL, 4);
  87 static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, ads7828_show_in, NULL, 5);
  88 static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, ads7828_show_in, NULL, 6);
  89 static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, ads7828_show_in, NULL, 7);
  90
  91 static struct attribute *ads7828_attrs[] = {
  92         &sensor_dev_attr_in0_input.dev_attr.attr,
  93         &sensor_dev_attr_in1_input.dev_attr.attr,
  94         &sensor_dev_attr_in2_input.dev_attr.attr,
  95         &sensor_dev_attr_in3_input.dev_attr.attr,
  96         &sensor_dev_attr_in4_input.dev_attr.attr,
  97         &sensor_dev_attr_in5_input.dev_attr.attr,
  98         &sensor_dev_attr_in6_input.dev_attr.attr,
  99         &sensor_dev_attr_in7_input.dev_attr.attr,
 100         NULL
 101 };
 102
 103 ATTRIBUTE_GROUPS(ads7828);
 104
 105 static const struct regmap_config ads2828_regmap_config = {
 106         .reg_bits = 8,
 107         .val_bits = 16,
 108 };
 109
 110 static const struct regmap_config ads2830_regmap_config = {
 111         .reg_bits = 8,
 112         .val_bits = 8,
 113 };
 114
 115 static int ads7828_probe(struct i2c_client *client,
 116                          const struct i2c_device_id *id)
 117 {
 118         struct device *dev = &client->dev;
 119         struct ads7828_platform_data *pdata = dev_get_platdata(dev);
 120         struct ads7828_data *data;
 121         struct device *hwmon_dev;
 122         unsigned int vref_mv = ADS7828_INT_VREF_MV;
 123         unsigned int vref_uv;
 124         bool diff_input = false;
 125         bool ext_vref = false;
 126         unsigned int regval;
 127         enum ads7828_chips chip;
 128         struct regulator *reg;
 129
 130         data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL);
 131         if (!data)
 132                 return -ENOMEM;
 133
 134         if (pdata) {
 135                 diff_input = pdata->diff_input;
 136                 ext_vref = pdata->ext_vref;
 137                 if (ext_vref && pdata->vref_mv)
 138                         vref_mv = pdata->vref_mv;
 139         } else if (dev->of_node) {
 140                 diff_input = of_property_read_bool(dev->of_node,
 141                                                    "ti,differential-input");
 142                 reg = devm_regulator_get_optional(dev, "vref");
 143                 if (!IS_ERR(reg)) {
 144                         vref_uv = regulator_get_voltage(reg);
 145                         vref_mv = DIV_ROUND_CLOSEST(vref_uv, 1000);
 146                         if (vref_mv < ADS7828_EXT_VREF_MV_MIN ||
 147                             vref_mv > ADS7828_EXT_VREF_MV_MAX)
 148                                 return -EINVAL;
 149                         ext_vref = true;
 150                 }
 151         }
 152
 153         if (client->dev.of_node)
 154                 chip = (enum ads7828_chips)
 155                         of_device_get_match_data(&client->dev);
 156         else
 157                 chip = id->driver_data;
 158
 159         /* Bound Vref with min/max values */
 160         vref_mv = clamp_val(vref_mv, ADS7828_EXT_VREF_MV_MIN,
 161                             ADS7828_EXT_VREF_MV_MAX);
 162
 163         /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
 164         if (chip == ads7828) {
 165                 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 4096);
 166                 data->regmap = devm_regmap_init_i2c(client,
 167                                                     &ads2828_regmap_config);
 168         } else {
 169                 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 256);
 170                 data->regmap = devm_regmap_init_i2c(client,
 171                                                     &ads2830_regmap_config);
 172         }
 173
 174         if (IS_ERR(data->regmap))
 175                 return PTR_ERR(data->regmap);
 176
 177         data->cmd_byte = ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
 178         if (!diff_input)
 179                 data->cmd_byte |= ADS7828_CMD_SD_SE;
 180
 181         /*
 182          * Datasheet specifies internal reference voltage is disabled by
 183          * default. The internal reference voltage needs to be enabled and
 184          * voltage needs to settle before getting valid ADC data. So perform a
 185          * dummy read to enable the internal reference voltage.
 186          */
 187         if (!ext_vref)
 188                 regmap_read(data->regmap, data->cmd_byte, &regval);
 189
 190         hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 191                                                            data,
 192                                                            ads7828_groups);
 193         return PTR_ERR_OR_ZERO(hwmon_dev);
 194 }
 195
 196 static const struct i2c_device_id ads7828_device_ids[] = {
 197         { "ads7828", ads7828 },
 198         { "ads7830", ads7830 },
 199         { }
 200 };
 201 MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
 202
 203 static const struct of_device_id ads7828_of_match[] = {
 204         {
 205                 .compatible = "ti,ads7828",
 206                 .data = (void *)ads7828
 207         },
 208         {
 209                 .compatible = "ti,ads7830",
 210                 .data = (void *)ads7830
 211         },
 212         { },
 213 };
 214 MODULE_DEVICE_TABLE(of, ads7828_of_match);
 215
 216 static struct i2c_driver ads7828_driver = {
 217         .driver = {
 218                 .name = "ads7828",
 219                 .of_match_table = of_match_ptr(ads7828_of_match),
 220         },
 221
 222         .id_table = ads7828_device_ids,
 223         .probe = ads7828_probe,
 224 };
 225
 226 module_i2c_driver(ads7828_driver);
 227
 228 MODULE_LICENSE("GPL");
 229 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
 230 MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");