linux/drivers/iio/dac/mcp4725.c
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   1/*
   2 * mcp4725.c - Support for Microchip MCP4725
   3 *
   4 * Copyright (C) 2012 Peter Meerwald <pmeerw@pmeerw.net>
   5 *
   6 * Based on max517 by Roland Stigge <stigge@antcom.de>
   7 *
   8 * This file is subject to the terms and conditions of version 2 of
   9 * the GNU General Public License.  See the file COPYING in the main
  10 * directory of this archive for more details.
  11 *
  12 * driver for the Microchip I2C 12-bit digital-to-analog converter (DAC)
  13 * (7-bit I2C slave address 0x60, the three LSBs can be configured in
  14 * hardware)
  15 *
  16 * writing the DAC value to EEPROM is not supported
  17 */
  18
  19#include <linux/module.h>
  20#include <linux/init.h>
  21#include <linux/i2c.h>
  22#include <linux/err.h>
  23
  24#include <linux/iio/iio.h>
  25#include <linux/iio/sysfs.h>
  26
  27#include <linux/iio/dac/mcp4725.h>
  28
  29#define MCP4725_DRV_NAME "mcp4725"
  30
  31struct mcp4725_data {
  32        struct i2c_client *client;
  33        u16 vref_mv;
  34        u16 dac_value;
  35};
  36
  37#ifdef CONFIG_PM_SLEEP
  38static int mcp4725_suspend(struct device *dev)
  39{
  40        u8 outbuf[2];
  41
  42        outbuf[0] = 0x3 << 4; /* power-down bits, 500 kOhm resistor */
  43        outbuf[1] = 0;
  44
  45        return i2c_master_send(to_i2c_client(dev), outbuf, 2);
  46}
  47
  48static int mcp4725_resume(struct device *dev)
  49{
  50        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  51        struct mcp4725_data *data = iio_priv(indio_dev);
  52        u8 outbuf[2];
  53
  54        /* restore previous DAC value */
  55        outbuf[0] = (data->dac_value >> 8) & 0xf;
  56        outbuf[1] = data->dac_value & 0xff;
  57
  58        return i2c_master_send(to_i2c_client(dev), outbuf, 2);
  59}
  60
  61static SIMPLE_DEV_PM_OPS(mcp4725_pm_ops, mcp4725_suspend, mcp4725_resume);
  62#define MCP4725_PM_OPS (&mcp4725_pm_ops)
  63#else
  64#define MCP4725_PM_OPS NULL
  65#endif
  66
  67static const struct iio_chan_spec mcp4725_channel = {
  68        .type           = IIO_VOLTAGE,
  69        .indexed        = 1,
  70        .output         = 1,
  71        .channel        = 0,
  72        .info_mask      = IIO_CHAN_INFO_RAW_SEPARATE_BIT |
  73                          IIO_CHAN_INFO_SCALE_SHARED_BIT,
  74        .scan_type      = IIO_ST('u', 12, 16, 0),
  75};
  76
  77static int mcp4725_set_value(struct iio_dev *indio_dev, int val)
  78{
  79        struct mcp4725_data *data = iio_priv(indio_dev);
  80        u8 outbuf[2];
  81        int ret;
  82
  83        if (val >= (1 << 12) || val < 0)
  84                return -EINVAL;
  85
  86        outbuf[0] = (val >> 8) & 0xf;
  87        outbuf[1] = val & 0xff;
  88
  89        ret = i2c_master_send(data->client, outbuf, 2);
  90        if (ret < 0)
  91                return ret;
  92        else if (ret != 2)
  93                return -EIO;
  94        else
  95                return 0;
  96}
  97
  98static int mcp4725_read_raw(struct iio_dev *indio_dev,
  99                           struct iio_chan_spec const *chan,
 100                           int *val, int *val2, long mask)
 101{
 102        struct mcp4725_data *data = iio_priv(indio_dev);
 103        unsigned long scale_uv;
 104
 105        switch (mask) {
 106        case IIO_CHAN_INFO_RAW:
 107                *val = data->dac_value;
 108                return IIO_VAL_INT;
 109        case IIO_CHAN_INFO_SCALE:
 110                scale_uv = (data->vref_mv * 1000) >> 12;
 111                *val =  scale_uv / 1000000;
 112                *val2 = scale_uv % 1000000;
 113                return IIO_VAL_INT_PLUS_MICRO;
 114        }
 115        return -EINVAL;
 116}
 117
 118static int mcp4725_write_raw(struct iio_dev *indio_dev,
 119                               struct iio_chan_spec const *chan,
 120                               int val, int val2, long mask)
 121{
 122        struct mcp4725_data *data = iio_priv(indio_dev);
 123        int ret;
 124
 125        switch (mask) {
 126        case IIO_CHAN_INFO_RAW:
 127                ret = mcp4725_set_value(indio_dev, val);
 128                data->dac_value = val;
 129                break;
 130        default:
 131                ret = -EINVAL;
 132                break;
 133        }
 134
 135        return ret;
 136}
 137
 138static const struct iio_info mcp4725_info = {
 139        .read_raw = mcp4725_read_raw,
 140        .write_raw = mcp4725_write_raw,
 141        .driver_module = THIS_MODULE,
 142};
 143
 144static int __devinit mcp4725_probe(struct i2c_client *client,
 145                        const struct i2c_device_id *id)
 146{
 147        struct mcp4725_data *data;
 148        struct iio_dev *indio_dev;
 149        struct mcp4725_platform_data *platform_data = client->dev.platform_data;
 150        u8 inbuf[3];
 151        int err;
 152
 153        if (!platform_data || !platform_data->vref_mv) {
 154                dev_err(&client->dev, "invalid platform data");
 155                err = -EINVAL;
 156                goto exit;
 157        }
 158
 159        indio_dev = iio_device_alloc(sizeof(*data));
 160        if (indio_dev == NULL) {
 161                err = -ENOMEM;
 162                goto exit;
 163        }
 164        data = iio_priv(indio_dev);
 165        i2c_set_clientdata(client, indio_dev);
 166        data->client = client;
 167
 168        indio_dev->dev.parent = &client->dev;
 169        indio_dev->info = &mcp4725_info;
 170        indio_dev->channels = &mcp4725_channel;
 171        indio_dev->num_channels = 1;
 172        indio_dev->modes = INDIO_DIRECT_MODE;
 173
 174        data->vref_mv = platform_data->vref_mv;
 175
 176        /* read current DAC value */
 177        err = i2c_master_recv(client, inbuf, 3);
 178        if (err < 0) {
 179                dev_err(&client->dev, "failed to read DAC value");
 180                goto exit_free_device;
 181        }
 182        data->dac_value = (inbuf[1] << 4) | (inbuf[2] >> 4);
 183
 184        err = iio_device_register(indio_dev);
 185        if (err)
 186                goto exit_free_device;
 187
 188        dev_info(&client->dev, "MCP4725 DAC registered\n");
 189
 190        return 0;
 191
 192exit_free_device:
 193        iio_device_free(indio_dev);
 194exit:
 195        return err;
 196}
 197
 198static int __devexit mcp4725_remove(struct i2c_client *client)
 199{
 200        struct iio_dev *indio_dev = i2c_get_clientdata(client);
 201
 202        iio_device_unregister(indio_dev);
 203        iio_device_free(indio_dev);
 204
 205        return 0;
 206}
 207
 208static const struct i2c_device_id mcp4725_id[] = {
 209        { "mcp4725", 0 },
 210        { }
 211};
 212MODULE_DEVICE_TABLE(i2c, mcp4725_id);
 213
 214static struct i2c_driver mcp4725_driver = {
 215        .driver = {
 216                .name   = MCP4725_DRV_NAME,
 217                .pm     = MCP4725_PM_OPS,
 218        },
 219        .probe          = mcp4725_probe,
 220        .remove         = __devexit_p(mcp4725_remove),
 221        .id_table       = mcp4725_id,
 222};
 223module_i2c_driver(mcp4725_driver);
 224
 225MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
 226MODULE_DESCRIPTION("MCP4725 12-bit DAC");
 227MODULE_LICENSE("GPL");
 228