drivers/hwmon/max1111.c

   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
  36 struct 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
  47 static 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
  79 static struct max1111_data *the_max1111;
  80
  81 int max1111_read_channel(int channel)
  82 {
  83         return max1111_read(&the_max1111->spi->dev, channel);
  84 }
  85 EXPORT_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  */
  93 static ssize_t show_name(struct device *dev,
  94                          struct device_attribute *attr, char *buf)
  95 {
  96         return sprintf(buf, "max1111\n");
  97 }
  98
  99 static 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         /* assume the reference voltage to be 2.048V, with an 8-bit sample,
 110          * the LSB weight is 8mV
 111          */
 112         return sprintf(buf, "%d\n", ret * 8);
 113 }
 114
 115 #define MAX1111_ADC_ATTR(_id)           \
 116         SENSOR_DEVICE_ATTR(in##_id##_input, S_IRUGO, show_adc, NULL, _id)
 117
 118 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
 119 static MAX1111_ADC_ATTR(0);
 120 static MAX1111_ADC_ATTR(1);
 121 static MAX1111_ADC_ATTR(2);
 122 static MAX1111_ADC_ATTR(3);
 123
 124 static struct attribute *max1111_attributes[] = {
 125         &dev_attr_name.attr,
 126         &sensor_dev_attr_in0_input.dev_attr.attr,
 127         &sensor_dev_attr_in1_input.dev_attr.attr,
 128         &sensor_dev_attr_in2_input.dev_attr.attr,
 129         &sensor_dev_attr_in3_input.dev_attr.attr,
 130         NULL,
 131 };
 132
 133 static const struct attribute_group max1111_attr_group = {
 134         .attrs  = max1111_attributes,
 135 };
 136
 137 static int __devinit setup_transfer(struct max1111_data *data)
 138 {
 139         struct spi_message *m;
 140         struct spi_transfer *x;
 141
 142         m = &data->msg;
 143         x = &data->xfer[0];
 144
 145         spi_message_init(m);
 146
 147         x->tx_buf = &data->tx_buf[0];
 148         x->len = MAX1111_TX_BUF_SIZE;
 149         spi_message_add_tail(x, m);
 150
 151         x++;
 152         x->rx_buf = &data->rx_buf[0];
 153         x->len = MAX1111_RX_BUF_SIZE;
 154         spi_message_add_tail(x, m);
 155
 156         return 0;
 157 }
 158
 159 static int __devinit max1111_probe(struct spi_device *spi)
 160 {
 161         struct max1111_data *data;
 162         int err;
 163
 164         spi->bits_per_word = 8;
 165         spi->mode = SPI_MODE_0;
 166         err = spi_setup(spi);
 167         if (err < 0)
 168                 return err;
 169
 170         data = kzalloc(sizeof(struct max1111_data), GFP_KERNEL);
 171         if (data == NULL) {
 172                 dev_err(&spi->dev, "failed to allocate memory\n");
 173                 return -ENOMEM;
 174         }
 175
 176         err = setup_transfer(data);
 177         if (err)
 178                 goto err_free_data;
 179
 180         mutex_init(&data->drvdata_lock);
 181
 182         data->spi = spi;
 183         spi_set_drvdata(spi, data);
 184
 185         err = sysfs_create_group(&spi->dev.kobj, &max1111_attr_group);
 186         if (err) {
 187                 dev_err(&spi->dev, "failed to create attribute group\n");
 188                 goto err_free_data;
 189         }
 190
 191         data->hwmon_dev = hwmon_device_register(&spi->dev);
 192         if (IS_ERR(data->hwmon_dev)) {
 193                 dev_err(&spi->dev, "failed to create hwmon device\n");
 194                 err = PTR_ERR(data->hwmon_dev);
 195                 goto err_remove;
 196         }
 197
 198 #ifdef CONFIG_SHARPSL_PM
 199         the_max1111 = data;
 200 #endif
 201         return 0;
 202
 203 err_remove:
 204         sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
 205 err_free_data:
 206         kfree(data);
 207         return err;
 208 }
 209
 210 static int __devexit max1111_remove(struct spi_device *spi)
 211 {
 212         struct max1111_data *data = spi_get_drvdata(spi);
 213
 214         hwmon_device_unregister(data->hwmon_dev);
 215         sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
 216         mutex_destroy(&data->drvdata_lock);
 217         kfree(data);
 218         return 0;
 219 }
 220
 221 static struct spi_driver max1111_driver = {
 222         .driver         = {
 223                 .name   = "max1111",
 224                 .owner  = THIS_MODULE,
 225         },
 226         .probe          = max1111_probe,
 227         .remove         = __devexit_p(max1111_remove),
 228 };
 229
 230 static int __init max1111_init(void)
 231 {
 232         return spi_register_driver(&max1111_driver);
 233 }
 234 module_init(max1111_init);
 235
 236 static void __exit max1111_exit(void)
 237 {
 238         spi_unregister_driver(&max1111_driver);
 239 }
 240 module_exit(max1111_exit);
 241
 242 MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>");
 243 MODULE_DESCRIPTION("MAX1111 ADC Driver");
 244 MODULE_LICENSE("GPL");
 245 MODULE_ALIAS("spi:max1111");