linux/drivers/hwmon/max1111.c
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   1/*
   2 * max1111.c - +2.7V, Low-Power, Multichannel, Serial 8-bit ADCs
   3 *
   4 * Based on arch/arm/mach-pxa/corgi_ssp.c
   5 *
   6 * Copyright (C) 2004-2005 Richard Purdie
   7 *
   8 * Copyright (C) 2008 Marvell International Ltd.
   9 *      Eric Miao <eric.miao@marvell.com>
  10 *
  11 *  This program is free software; you can redistribute it and/or modify
  12 *  it under the terms of the GNU General Public License version 2 as
  13 *  publishhed by the Free Software Foundation.
  14 */
  15
  16#include <linux/module.h>
  17#include <linux/kernel.h>
  18#include <linux/init.h>
  19#include <linux/err.h>
  20#include <linux/hwmon.h>
  21#include <linux/hwmon-sysfs.h>
  22#include <linux/spi/spi.h>
  23#include <linux/slab.h>
  24
  25#define MAX1111_TX_BUF_SIZE     1
  26#define MAX1111_RX_BUF_SIZE     2
  27
  28/* MAX1111 Commands */
  29#define MAX1111_CTRL_PD0      (1u << 0)
  30#define MAX1111_CTRL_PD1      (1u << 1)
  31#define MAX1111_CTRL_SGL      (1u << 2)
  32#define MAX1111_CTRL_UNI      (1u << 3)
  33#define MAX1111_CTRL_SEL_SH   (5)       /* NOTE: bit 4 is ignored */
  34#define MAX1111_CTRL_STR      (1u << 7)
  35
  36struct max1111_data {
  37        struct spi_device       *spi;
  38        struct device           *hwmon_dev;
  39        struct spi_message      msg;
  40        struct spi_transfer     xfer[2];
  41        uint8_t tx_buf[MAX1111_TX_BUF_SIZE];
  42        uint8_t rx_buf[MAX1111_RX_BUF_SIZE];
  43        struct mutex            drvdata_lock;
  44        /* protect msg, xfer and buffers from multiple access */
  45};
  46
  47static int max1111_read(struct device *dev, int channel)
  48{
  49        struct max1111_data *data = dev_get_drvdata(dev);
  50        uint8_t v1, v2;
  51        int err;
  52
  53        /* writing to drvdata struct is not thread safe, wait on mutex */
  54        mutex_lock(&data->drvdata_lock);
  55
  56        data->tx_buf[0] = (channel << MAX1111_CTRL_SEL_SH) |
  57                MAX1111_CTRL_PD0 | MAX1111_CTRL_PD1 |
  58                MAX1111_CTRL_SGL | MAX1111_CTRL_UNI | MAX1111_CTRL_STR;
  59
  60        err = spi_sync(data->spi, &data->msg);
  61        if (err < 0) {
  62                dev_err(dev, "spi_sync failed with %d\n", err);
  63                mutex_unlock(&data->drvdata_lock);
  64                return err;
  65        }
  66
  67        v1 = data->rx_buf[0];
  68        v2 = data->rx_buf[1];
  69
  70        mutex_unlock(&data->drvdata_lock);
  71
  72        if ((v1 & 0xc0) || (v2 & 0x3f))
  73                return -EINVAL;
  74
  75        return (v1 << 2) | (v2 >> 6);
  76}
  77
  78#ifdef CONFIG_SHARPSL_PM
  79static struct max1111_data *the_max1111;
  80
  81int max1111_read_channel(int channel)
  82{
  83        return max1111_read(&the_max1111->spi->dev, channel);
  84}
  85EXPORT_SYMBOL(max1111_read_channel);
  86#endif
  87
  88/*
  89 * NOTE: SPI devices do not have a default 'name' attribute, which is
  90 * likely to be used by hwmon applications to distinguish between
  91 * different devices, explicitly add a name attribute here.
  92 */
  93static ssize_t show_name(struct device *dev,
  94                         struct device_attribute *attr, char *buf)
  95{
  96        return sprintf(buf, "max1111\n");
  97}
  98
  99static ssize_t show_adc(struct device *dev,
 100                        struct device_attribute *attr, char *buf)
 101{
 102        int channel = to_sensor_dev_attr(attr)->index;
 103        int ret;
 104
 105        ret = max1111_read(dev, channel);
 106        if (ret < 0)
 107                return ret;
 108
 109        /*
 110         * assume the reference voltage to be 2.048V, with an 8-bit sample,
 111         * the LSB weight is 8mV
 112         */
 113        return sprintf(buf, "%d\n", ret * 8);
 114}
 115
 116#define MAX1111_ADC_ATTR(_id)           \
 117        SENSOR_DEVICE_ATTR(in##_id##_input, S_IRUGO, show_adc, NULL, _id)
 118
 119static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
 120static MAX1111_ADC_ATTR(0);
 121static MAX1111_ADC_ATTR(1);
 122static MAX1111_ADC_ATTR(2);
 123static MAX1111_ADC_ATTR(3);
 124
 125static struct attribute *max1111_attributes[] = {
 126        &dev_attr_name.attr,
 127        &sensor_dev_attr_in0_input.dev_attr.attr,
 128        &sensor_dev_attr_in1_input.dev_attr.attr,
 129        &sensor_dev_attr_in2_input.dev_attr.attr,
 130        &sensor_dev_attr_in3_input.dev_attr.attr,
 131        NULL,
 132};
 133
 134static const struct attribute_group max1111_attr_group = {
 135        .attrs  = max1111_attributes,
 136};
 137
 138static int __devinit setup_transfer(struct max1111_data *data)
 139{
 140        struct spi_message *m;
 141        struct spi_transfer *x;
 142
 143        m = &data->msg;
 144        x = &data->xfer[0];
 145
 146        spi_message_init(m);
 147
 148        x->tx_buf = &data->tx_buf[0];
 149        x->len = MAX1111_TX_BUF_SIZE;
 150        spi_message_add_tail(x, m);
 151
 152        x++;
 153        x->rx_buf = &data->rx_buf[0];
 154        x->len = MAX1111_RX_BUF_SIZE;
 155        spi_message_add_tail(x, m);
 156
 157        return 0;
 158}
 159
 160static int __devinit max1111_probe(struct spi_device *spi)
 161{
 162        struct max1111_data *data;
 163        int err;
 164
 165        spi->bits_per_word = 8;
 166        spi->mode = SPI_MODE_0;
 167        err = spi_setup(spi);
 168        if (err < 0)
 169                return err;
 170
 171        data = devm_kzalloc(&spi->dev, sizeof(struct max1111_data), GFP_KERNEL);
 172        if (data == NULL) {
 173                dev_err(&spi->dev, "failed to allocate memory\n");
 174                return -ENOMEM;
 175        }
 176
 177        err = setup_transfer(data);
 178        if (err)
 179                return err;
 180
 181        mutex_init(&data->drvdata_lock);
 182
 183        data->spi = spi;
 184        spi_set_drvdata(spi, data);
 185
 186        err = sysfs_create_group(&spi->dev.kobj, &max1111_attr_group);
 187        if (err) {
 188                dev_err(&spi->dev, "failed to create attribute group\n");
 189                return err;
 190        }
 191
 192        data->hwmon_dev = hwmon_device_register(&spi->dev);
 193        if (IS_ERR(data->hwmon_dev)) {
 194                dev_err(&spi->dev, "failed to create hwmon device\n");
 195                err = PTR_ERR(data->hwmon_dev);
 196                goto err_remove;
 197        }
 198
 199#ifdef CONFIG_SHARPSL_PM
 200        the_max1111 = data;
 201#endif
 202        return 0;
 203
 204err_remove:
 205        sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
 206        return err;
 207}
 208
 209static int __devexit max1111_remove(struct spi_device *spi)
 210{
 211        struct max1111_data *data = spi_get_drvdata(spi);
 212
 213        hwmon_device_unregister(data->hwmon_dev);
 214        sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
 215        mutex_destroy(&data->drvdata_lock);
 216        return 0;
 217}
 218
 219static struct spi_driver max1111_driver = {
 220        .driver         = {
 221                .name   = "max1111",
 222                .owner  = THIS_MODULE,
 223        },
 224        .probe          = max1111_probe,
 225        .remove         = __devexit_p(max1111_remove),
 226};
 227
 228module_spi_driver(max1111_driver);
 229
 230MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>");
 231MODULE_DESCRIPTION("MAX1111 ADC Driver");
 232MODULE_LICENSE("GPL");
 233MODULE_ALIAS("spi:max1111");
 234
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