linux/drivers/hwmon/adcxx.c
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   1/*
   2 * adcxx.c
   3 *
   4 * The adcxx4s is an AD converter family from National Semiconductor (NS).
   5 *
   6 * Copyright (c) 2008 Marc Pignat <marc.pignat@hevs.ch>
   7 *
   8 * The adcxx4s communicates with a host processor via an SPI/Microwire Bus
   9 * interface. This driver supports the whole family of devices with name
  10 * ADC<bb><c>S<sss>, where
  11 * * bb is the resolution in number of bits (8, 10, 12)
  12 * * c is the number of channels (1, 2, 4, 8)
  13 * * sss is the maximum conversion speed (021 for 200 kSPS, 051 for 500 kSPS
  14 *   and 101 for 1 MSPS)
  15 *
  16 * Complete datasheets are available at National's website here:
  17 * http://www.national.com/ds/DC/ADC<bb><c>S<sss>.pdf
  18 *
  19 * Handling of 8, 10 and 12 bits converters are the same, the
  20 * unavailable bits are 0 :)
  21 *
  22 * This program is free software; you can redistribute it and/or modify
  23 * it under the terms of the GNU General Public License as published by
  24 * the Free Software Foundation; either version 2 of the License, or
  25 * (at your option) any later version.
  26 *
  27 * This program is distributed in the hope that it will be useful,
  28 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  29 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  30 * GNU General Public License for more details.
  31 *
  32 * You should have received a copy of the GNU General Public License
  33 * along with this program; if not, write to the Free Software
  34 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  35 */
  36
  37#include <linux/init.h>
  38#include <linux/module.h>
  39#include <linux/kernel.h>
  40#include <linux/slab.h>
  41#include <linux/device.h>
  42#include <linux/err.h>
  43#include <linux/sysfs.h>
  44#include <linux/hwmon.h>
  45#include <linux/hwmon-sysfs.h>
  46#include <linux/mutex.h>
  47#include <linux/mod_devicetable.h>
  48#include <linux/spi/spi.h>
  49
  50#define DRVNAME         "adcxx"
  51
  52struct adcxx {
  53        struct device *hwmon_dev;
  54        struct mutex lock;
  55        u32 channels;
  56        u32 reference; /* in millivolts */
  57};
  58
  59/* sysfs hook function */
  60static ssize_t adcxx_read(struct device *dev,
  61                struct device_attribute *devattr, char *buf)
  62{
  63        struct spi_device *spi = to_spi_device(dev);
  64        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
  65        struct adcxx *adc = spi_get_drvdata(spi);
  66        u8 tx_buf[2];
  67        u8 rx_buf[2];
  68        int status;
  69        u32 value;
  70
  71        if (mutex_lock_interruptible(&adc->lock))
  72                return -ERESTARTSYS;
  73
  74        if (adc->channels == 1) {
  75                status = spi_read(spi, rx_buf, sizeof(rx_buf));
  76        } else {
  77                tx_buf[0] = attr->index << 3; /* other bits are don't care */
  78                status = spi_write_then_read(spi, tx_buf, sizeof(tx_buf),
  79                                                rx_buf, sizeof(rx_buf));
  80        }
  81        if (status < 0) {
  82                dev_warn(dev, "SPI synch. transfer failed with status %d\n",
  83                                status);
  84                goto out;
  85        }
  86
  87        value = (rx_buf[0] << 8) + rx_buf[1];
  88        dev_dbg(dev, "raw value = 0x%x\n", value);
  89
  90        value = value * adc->reference >> 12;
  91        status = sprintf(buf, "%d\n", value);
  92out:
  93        mutex_unlock(&adc->lock);
  94        return status;
  95}
  96
  97static ssize_t adcxx_show_min(struct device *dev,
  98                struct device_attribute *devattr, char *buf)
  99{
 100        /* The minimum reference is 0 for this chip family */
 101        return sprintf(buf, "0\n");
 102}
 103
 104static ssize_t adcxx_show_max(struct device *dev,
 105                struct device_attribute *devattr, char *buf)
 106{
 107        struct spi_device *spi = to_spi_device(dev);
 108        struct adcxx *adc = spi_get_drvdata(spi);
 109        u32 reference;
 110
 111        if (mutex_lock_interruptible(&adc->lock))
 112                return -ERESTARTSYS;
 113
 114        reference = adc->reference;
 115
 116        mutex_unlock(&adc->lock);
 117
 118        return sprintf(buf, "%d\n", reference);
 119}
 120
 121static ssize_t adcxx_set_max(struct device *dev,
 122        struct device_attribute *devattr, const char *buf, size_t count)
 123{
 124        struct spi_device *spi = to_spi_device(dev);
 125        struct adcxx *adc = spi_get_drvdata(spi);
 126        unsigned long value;
 127
 128        if (kstrtoul(buf, 10, &value))
 129                return -EINVAL;
 130
 131        if (mutex_lock_interruptible(&adc->lock))
 132                return -ERESTARTSYS;
 133
 134        adc->reference = value;
 135
 136        mutex_unlock(&adc->lock);
 137
 138        return count;
 139}
 140
 141static ssize_t adcxx_show_name(struct device *dev, struct device_attribute
 142                              *devattr, char *buf)
 143{
 144        struct spi_device *spi = to_spi_device(dev);
 145        struct adcxx *adc = spi_get_drvdata(spi);
 146
 147        return sprintf(buf, "adcxx%ds\n", adc->channels);
 148}
 149
 150static struct sensor_device_attribute ad_input[] = {
 151        SENSOR_ATTR(name, S_IRUGO, adcxx_show_name, NULL, 0),
 152        SENSOR_ATTR(in_min, S_IRUGO, adcxx_show_min, NULL, 0),
 153        SENSOR_ATTR(in_max, S_IWUSR | S_IRUGO, adcxx_show_max,
 154                                        adcxx_set_max, 0),
 155        SENSOR_ATTR(in0_input, S_IRUGO, adcxx_read, NULL, 0),
 156        SENSOR_ATTR(in1_input, S_IRUGO, adcxx_read, NULL, 1),
 157        SENSOR_ATTR(in2_input, S_IRUGO, adcxx_read, NULL, 2),
 158        SENSOR_ATTR(in3_input, S_IRUGO, adcxx_read, NULL, 3),
 159        SENSOR_ATTR(in4_input, S_IRUGO, adcxx_read, NULL, 4),
 160        SENSOR_ATTR(in5_input, S_IRUGO, adcxx_read, NULL, 5),
 161        SENSOR_ATTR(in6_input, S_IRUGO, adcxx_read, NULL, 6),
 162        SENSOR_ATTR(in7_input, S_IRUGO, adcxx_read, NULL, 7),
 163};
 164
 165/*----------------------------------------------------------------------*/
 166
 167static int __devinit adcxx_probe(struct spi_device *spi)
 168{
 169        int channels = spi_get_device_id(spi)->driver_data;
 170        struct adcxx *adc;
 171        int status;
 172        int i;
 173
 174        adc = kzalloc(sizeof *adc, GFP_KERNEL);
 175        if (!adc)
 176                return -ENOMEM;
 177
 178        /* set a default value for the reference */
 179        adc->reference = 3300;
 180        adc->channels = channels;
 181        mutex_init(&adc->lock);
 182
 183        mutex_lock(&adc->lock);
 184
 185        spi_set_drvdata(spi, adc);
 186
 187        for (i = 0; i < 3 + adc->channels; i++) {
 188                status = device_create_file(&spi->dev, &ad_input[i].dev_attr);
 189                if (status) {
 190                        dev_err(&spi->dev, "device_create_file failed.\n");
 191                        goto out_err;
 192                }
 193        }
 194
 195        adc->hwmon_dev = hwmon_device_register(&spi->dev);
 196        if (IS_ERR(adc->hwmon_dev)) {
 197                dev_err(&spi->dev, "hwmon_device_register failed.\n");
 198                status = PTR_ERR(adc->hwmon_dev);
 199                goto out_err;
 200        }
 201
 202        mutex_unlock(&adc->lock);
 203        return 0;
 204
 205out_err:
 206        for (i--; i >= 0; i--)
 207                device_remove_file(&spi->dev, &ad_input[i].dev_attr);
 208
 209        spi_set_drvdata(spi, NULL);
 210        mutex_unlock(&adc->lock);
 211        kfree(adc);
 212        return status;
 213}
 214
 215static int __devexit adcxx_remove(struct spi_device *spi)
 216{
 217        struct adcxx *adc = spi_get_drvdata(spi);
 218        int i;
 219
 220        mutex_lock(&adc->lock);
 221        hwmon_device_unregister(adc->hwmon_dev);
 222        for (i = 0; i < 3 + adc->channels; i++)
 223                device_remove_file(&spi->dev, &ad_input[i].dev_attr);
 224
 225        spi_set_drvdata(spi, NULL);
 226        mutex_unlock(&adc->lock);
 227        kfree(adc);
 228
 229        return 0;
 230}
 231
 232static const struct spi_device_id adcxx_ids[] = {
 233        { "adcxx1s", 1 },
 234        { "adcxx2s", 2 },
 235        { "adcxx4s", 4 },
 236        { "adcxx8s", 8 },
 237        { },
 238};
 239MODULE_DEVICE_TABLE(spi, adcxx_ids);
 240
 241static struct spi_driver adcxx_driver = {
 242        .driver = {
 243                .name   = "adcxx",
 244                .owner  = THIS_MODULE,
 245        },
 246        .id_table = adcxx_ids,
 247        .probe  = adcxx_probe,
 248        .remove = __devexit_p(adcxx_remove),
 249};
 250
 251module_spi_driver(adcxx_driver);
 252
 253MODULE_AUTHOR("Marc Pignat");
 254MODULE_DESCRIPTION("National Semiconductor adcxx8sxxx Linux driver");
 255MODULE_LICENSE("GPL");
 256
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