drivers/hwmon/ads7828.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * ads7828.c - driver for TI ADS7828 8-channel A/D converter and compatibles
   4  * (C) 2007 EADS Astrium
   5  *
   6  * This driver is based on the lm75 and other lm_sensors/hwmon drivers
   7  *
   8  * Written by Steve Hardy <shardy@redhat.com>
   9  *
  10  * ADS7830 support, by Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>
  11  *
  12  * For further information, see the Documentation/hwmon/ads7828.rst file.
  13  */
  14
  15 #include <linux/err.h>
  16 #include <linux/hwmon.h>
  17 #include <linux/hwmon-sysfs.h>
  18 #include <linux/i2c.h>
  19 #include <linux/init.h>
  20 #include <linux/module.h>
  21 #include <linux/of.h>
  22 #include <linux/platform_data/ads7828.h>
  23 #include <linux/regmap.h>
  24 #include <linux/slab.h>
  25 #include <linux/regulator/consumer.h>
  26
  27 /* The ADS7828 registers */
  28 #define ADS7828_CMD_SD_SE       0x80    /* Single ended inputs */
  29 #define ADS7828_CMD_PD1         0x04    /* Internal vref OFF && A/D ON */
  30 #define ADS7828_CMD_PD3         0x0C    /* Internal vref ON && A/D ON */
  31 #define ADS7828_INT_VREF_MV     2500    /* Internal vref is 2.5V, 2500mV */
  32 #define ADS7828_EXT_VREF_MV_MIN 50      /* External vref min value 0.05V */
  33 #define ADS7828_EXT_VREF_MV_MAX 5250    /* External vref max value 5.25V */
  34
  35 /* List of supported devices */
  36 enum ads7828_chips { ads7828, ads7830 };
  37
  38 /* Client specific data */
  39 struct ads7828_data {
  40         struct regmap *regmap;
  41         u8 cmd_byte;                    /* Command byte without channel bits */
  42         unsigned int lsb_resol;         /* Resolution of the ADC sample LSB */
  43 };
  44
  45 /* Command byte C2,C1,C0 - see datasheet */
  46 static inline u8 ads7828_cmd_byte(u8 cmd, int ch)
  47 {
  48         return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
  49 }
  50
  51 /* sysfs callback function */
  52 static ssize_t ads7828_in_show(struct device *dev,
  53                                struct device_attribute *da, char *buf)
  54 {
  55         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  56         struct ads7828_data *data = dev_get_drvdata(dev);
  57         u8 cmd = ads7828_cmd_byte(data->cmd_byte, attr->index);
  58         unsigned int regval;
  59         int err;
  60
  61         err = regmap_read(data->regmap, cmd, &regval);
  62         if (err < 0)
  63                 return err;
  64
  65         return sprintf(buf, "%d\n",
  66                        DIV_ROUND_CLOSEST(regval * data->lsb_resol, 1000));
  67 }
  68
  69 static SENSOR_DEVICE_ATTR_RO(in0_input, ads7828_in, 0);
  70 static SENSOR_DEVICE_ATTR_RO(in1_input, ads7828_in, 1);
  71 static SENSOR_DEVICE_ATTR_RO(in2_input, ads7828_in, 2);
  72 static SENSOR_DEVICE_ATTR_RO(in3_input, ads7828_in, 3);
  73 static SENSOR_DEVICE_ATTR_RO(in4_input, ads7828_in, 4);
  74 static SENSOR_DEVICE_ATTR_RO(in5_input, ads7828_in, 5);
  75 static SENSOR_DEVICE_ATTR_RO(in6_input, ads7828_in, 6);
  76 static SENSOR_DEVICE_ATTR_RO(in7_input, ads7828_in, 7);
  77
  78 static struct attribute *ads7828_attrs[] = {
  79         &sensor_dev_attr_in0_input.dev_attr.attr,
  80         &sensor_dev_attr_in1_input.dev_attr.attr,
  81         &sensor_dev_attr_in2_input.dev_attr.attr,
  82         &sensor_dev_attr_in3_input.dev_attr.attr,
  83         &sensor_dev_attr_in4_input.dev_attr.attr,
  84         &sensor_dev_attr_in5_input.dev_attr.attr,
  85         &sensor_dev_attr_in6_input.dev_attr.attr,
  86         &sensor_dev_attr_in7_input.dev_attr.attr,
  87         NULL
  88 };
  89
  90 ATTRIBUTE_GROUPS(ads7828);
  91
  92 static const struct regmap_config ads2828_regmap_config = {
  93         .reg_bits = 8,
  94         .val_bits = 16,
  95 };
  96
  97 static const struct regmap_config ads2830_regmap_config = {
  98         .reg_bits = 8,
  99         .val_bits = 8,
 100 };
 101
 102 static int ads7828_probe(struct i2c_client *client)
 103 {
 104         struct device *dev = &client->dev;
 105         struct ads7828_platform_data *pdata = dev_get_platdata(dev);
 106         struct ads7828_data *data;
 107         struct device *hwmon_dev;
 108         unsigned int vref_mv = ADS7828_INT_VREF_MV;
 109         unsigned int vref_uv;
 110         bool diff_input = false;
 111         bool ext_vref = false;
 112         unsigned int regval;
 113         enum ads7828_chips chip;
 114         struct regulator *reg;
 115
 116         data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL);
 117         if (!data)
 118                 return -ENOMEM;
 119
 120         if (pdata) {
 121                 diff_input = pdata->diff_input;
 122                 ext_vref = pdata->ext_vref;
 123                 if (ext_vref && pdata->vref_mv)
 124                         vref_mv = pdata->vref_mv;
 125         } else if (dev->of_node) {
 126                 diff_input = of_property_read_bool(dev->of_node,
 127                                                    "ti,differential-input");
 128                 reg = devm_regulator_get_optional(dev, "vref");
 129                 if (!IS_ERR(reg)) {
 130                         vref_uv = regulator_get_voltage(reg);
 131                         vref_mv = DIV_ROUND_CLOSEST(vref_uv, 1000);
 132                         if (vref_mv < ADS7828_EXT_VREF_MV_MIN ||
 133                             vref_mv > ADS7828_EXT_VREF_MV_MAX)
 134                                 return -EINVAL;
 135                         ext_vref = true;
 136                 }
 137         }
 138
 139         chip = (uintptr_t)i2c_get_match_data(client);
 140
 141         /* Bound Vref with min/max values */
 142         vref_mv = clamp_val(vref_mv, ADS7828_EXT_VREF_MV_MIN,
 143                             ADS7828_EXT_VREF_MV_MAX);
 144
 145         /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
 146         if (chip == ads7828) {
 147                 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 4096);
 148                 data->regmap = devm_regmap_init_i2c(client,
 149                                                     &ads2828_regmap_config);
 150         } else {
 151                 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 256);
 152                 data->regmap = devm_regmap_init_i2c(client,
 153                                                     &ads2830_regmap_config);
 154         }
 155
 156         if (IS_ERR(data->regmap))
 157                 return PTR_ERR(data->regmap);
 158
 159         data->cmd_byte = ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
 160         if (!diff_input)
 161                 data->cmd_byte |= ADS7828_CMD_SD_SE;
 162
 163         /*
 164          * Datasheet specifies internal reference voltage is disabled by
 165          * default. The internal reference voltage needs to be enabled and
 166          * voltage needs to settle before getting valid ADC data. So perform a
 167          * dummy read to enable the internal reference voltage.
 168          */
 169         if (!ext_vref)
 170                 regmap_read(data->regmap, data->cmd_byte, &regval);
 171
 172         hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 173                                                            data,
 174                                                            ads7828_groups);
 175         return PTR_ERR_OR_ZERO(hwmon_dev);
 176 }
 177
 178 static const struct i2c_device_id ads7828_device_ids[] = {
 179         { "ads7828", ads7828 },
 180         { "ads7830", ads7830 },
 181         { }
 182 };
 183 MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
 184
 185 static const struct of_device_id __maybe_unused ads7828_of_match[] = {
 186         {
 187                 .compatible = "ti,ads7828",
 188                 .data = (void *)ads7828
 189         },
 190         {
 191                 .compatible = "ti,ads7830",
 192                 .data = (void *)ads7830
 193         },
 194         { },
 195 };
 196 MODULE_DEVICE_TABLE(of, ads7828_of_match);
 197
 198 static struct i2c_driver ads7828_driver = {
 199         .driver = {
 200                 .name = "ads7828",
 201                 .of_match_table = of_match_ptr(ads7828_of_match),
 202         },
 203
 204         .id_table = ads7828_device_ids,
 205         .probe = ads7828_probe,
 206 };
 207
 208 module_i2c_driver(ads7828_driver);
 209
 210 MODULE_LICENSE("GPL");
 211 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
 212 MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");