linux/drivers/hwmon/ads7828.c
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   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 */
  49enum ads7828_chips { ads7828, ads7830 };
  50
  51/* Client specific data */
  52struct ads7828_data {
  53        struct device *hwmon_dev;
  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 */
  67static 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) */
  73static struct ads7828_data *ads7828_update_device(struct device *dev)
  74{
  75        struct i2c_client *client = to_i2c_client(dev);
  76        struct ads7828_data *data = i2c_get_clientdata(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 */
  99static 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
 110static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ads7828_show_in, NULL, 0);
 111static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ads7828_show_in, NULL, 1);
 112static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ads7828_show_in, NULL, 2);
 113static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ads7828_show_in, NULL, 3);
 114static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ads7828_show_in, NULL, 4);
 115static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, ads7828_show_in, NULL, 5);
 116static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, ads7828_show_in, NULL, 6);
 117static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, ads7828_show_in, NULL, 7);
 118
 119static struct attribute *ads7828_attributes[] = {
 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
 131static const struct attribute_group ads7828_group = {
 132        .attrs = ads7828_attributes,
 133};
 134
 135static int ads7828_remove(struct i2c_client *client)
 136{
 137        struct ads7828_data *data = i2c_get_clientdata(client);
 138
 139        hwmon_device_unregister(data->hwmon_dev);
 140        sysfs_remove_group(&client->dev.kobj, &ads7828_group);
 141
 142        return 0;
 143}
 144
 145static int ads7828_probe(struct i2c_client *client,
 146                         const struct i2c_device_id *id)
 147{
 148        struct ads7828_platform_data *pdata = client->dev.platform_data;
 149        struct ads7828_data *data;
 150        int err;
 151
 152        data = devm_kzalloc(&client->dev, sizeof(struct ads7828_data),
 153                            GFP_KERNEL);
 154        if (!data)
 155                return -ENOMEM;
 156
 157        if (pdata) {
 158                data->diff_input = pdata->diff_input;
 159                data->ext_vref = pdata->ext_vref;
 160                if (data->ext_vref)
 161                        data->vref_mv = pdata->vref_mv;
 162        }
 163
 164        /* Bound Vref with min/max values if it was provided */
 165        if (data->vref_mv)
 166                data->vref_mv = clamp_val(data->vref_mv,
 167                                          ADS7828_EXT_VREF_MV_MIN,
 168                                          ADS7828_EXT_VREF_MV_MAX);
 169        else
 170                data->vref_mv = ADS7828_INT_VREF_MV;
 171
 172        /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
 173        if (id->driver_data == ads7828) {
 174                data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 4096);
 175                data->read_channel = i2c_smbus_read_word_swapped;
 176        } else {
 177                data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 256);
 178                data->read_channel = i2c_smbus_read_byte_data;
 179        }
 180
 181        data->cmd_byte = data->ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
 182        if (!data->diff_input)
 183                data->cmd_byte |= ADS7828_CMD_SD_SE;
 184
 185        i2c_set_clientdata(client, data);
 186        mutex_init(&data->update_lock);
 187
 188        err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
 189        if (err)
 190                return err;
 191
 192        data->hwmon_dev = hwmon_device_register(&client->dev);
 193        if (IS_ERR(data->hwmon_dev)) {
 194                err = PTR_ERR(data->hwmon_dev);
 195                goto error;
 196        }
 197
 198        return 0;
 199
 200error:
 201        sysfs_remove_group(&client->dev.kobj, &ads7828_group);
 202        return err;
 203}
 204
 205static const struct i2c_device_id ads7828_device_ids[] = {
 206        { "ads7828", ads7828 },
 207        { "ads7830", ads7830 },
 208        { }
 209};
 210MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
 211
 212static struct i2c_driver ads7828_driver = {
 213        .driver = {
 214                .name = "ads7828",
 215        },
 216
 217        .id_table = ads7828_device_ids,
 218        .probe = ads7828_probe,
 219        .remove = ads7828_remove,
 220};
 221
 222module_i2c_driver(ads7828_driver);
 223
 224MODULE_LICENSE("GPL");
 225MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
 226MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");
 227
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