LXR linux/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 */
  49enum ads7828_chips { ads7828, ads7830 };
  50
  51/* Client specific data */
  52struct 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 */
  59static 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 */
  65static 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
  82static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ads7828_show_in, NULL, 0);
  83static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ads7828_show_in, NULL, 1);
  84static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ads7828_show_in, NULL, 2);
  85static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ads7828_show_in, NULL, 3);
  86static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ads7828_show_in, NULL, 4);
  87static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, ads7828_show_in, NULL, 5);
  88static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, ads7828_show_in, NULL, 6);
  89static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, ads7828_show_in, NULL, 7);
  90
  91static 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
 103ATTRIBUTE_GROUPS(ads7828);
 104
 105static const struct regmap_config ads2828_regmap_config = {
 106        .reg_bits = 8,
 107        .val_bits = 16,
 108};
 109
 110static const struct regmap_config ads2830_regmap_config = {
 111        .reg_bits = 8,
 112        .val_bits = 8,
 113};
 114
 115static 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
 196static const struct i2c_device_id ads7828_device_ids[] = {
 197        { "ads7828", ads7828 },
 198        { "ads7830", ads7830 },
 199        { }
 200};
 201MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
 202
 203static 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};
 214MODULE_DEVICE_TABLE(of, ads7828_of_match);
 215
 216static 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
 226module_i2c_driver(ads7828_driver);
 227
 228MODULE_LICENSE("GPL");
 229MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
 230MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");
 231