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;
  42         uint8_t *rx_buf;
  43 };
  44
  45 static int max1111_read(struct device *dev, int channel)
  46 {
  47         struct max1111_data *data = dev_get_drvdata(dev);
  48         uint8_t v1, v2;
  49         int err;
  50
  51         data->tx_buf[0] = (channel << MAX1111_CTRL_SEL_SH) |
  52                 MAX1111_CTRL_PD0 | MAX1111_CTRL_PD1 |
  53                 MAX1111_CTRL_SGL | MAX1111_CTRL_UNI | MAX1111_CTRL_STR;
  54
  55         err = spi_sync(data->spi, &data->msg);
  56         if (err < 0) {
  57                 dev_err(dev, "spi_sync failed with %d\n", err);
  58                 return err;
  59         }
  60
  61         v1 = data->rx_buf[0];
  62         v2 = data->rx_buf[1];
  63
  64         if ((v1 & 0xc0) || (v2 & 0x3f))
  65                 return -EINVAL;
  66
  67         return (v1 << 2) | (v2 >> 6);
  68 }
  69
  70 #ifdef CONFIG_SHARPSL_PM
  71 static struct max1111_data *the_max1111;
  72
  73 int max1111_read_channel(int channel)
  74 {
  75         return max1111_read(&the_max1111->spi->dev, channel);
  76 }
  77 EXPORT_SYMBOL(max1111_read_channel);
  78 #endif
  79
  80 /*
  81  * NOTE: SPI devices do not have a default 'name' attribute, which is
  82  * likely to be used by hwmon applications to distinguish between
  83  * different devices, explicitly add a name attribute here.
  84  */
  85 static ssize_t show_name(struct device *dev,
  86                          struct device_attribute *attr, char *buf)
  87 {
  88         return sprintf(buf, "max1111\n");
  89 }
  90
  91 static ssize_t show_adc(struct device *dev,
  92                         struct device_attribute *attr, char *buf)
  93 {
  94         int channel = to_sensor_dev_attr(attr)->index;
  95         int ret;
  96
  97         ret = max1111_read(dev, channel);
  98         if (ret < 0)
  99                 return ret;
 100
 101         return sprintf(buf, "%d\n", ret);
 102 }
 103
 104 #define MAX1111_ADC_ATTR(_id)           \
 105         SENSOR_DEVICE_ATTR(adc##_id##_in, S_IRUGO, show_adc, NULL, _id)
 106
 107 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
 108 static MAX1111_ADC_ATTR(0);
 109 static MAX1111_ADC_ATTR(1);
 110 static MAX1111_ADC_ATTR(2);
 111 static MAX1111_ADC_ATTR(3);
 112
 113 static struct attribute *max1111_attributes[] = {
 114         &dev_attr_name.attr,
 115         &sensor_dev_attr_adc0_in.dev_attr.attr,
 116         &sensor_dev_attr_adc1_in.dev_attr.attr,
 117         &sensor_dev_attr_adc2_in.dev_attr.attr,
 118         &sensor_dev_attr_adc3_in.dev_attr.attr,
 119         NULL,
 120 };
 121
 122 static const struct attribute_group max1111_attr_group = {
 123         .attrs  = max1111_attributes,
 124 };
 125
 126 static int setup_transfer(struct max1111_data *data)
 127 {
 128         struct spi_message *m;
 129         struct spi_transfer *x;
 130
 131         data->tx_buf = kmalloc(MAX1111_TX_BUF_SIZE, GFP_KERNEL);
 132         if (!data->tx_buf)
 133                 return -ENOMEM;
 134
 135         data->rx_buf = kmalloc(MAX1111_RX_BUF_SIZE, GFP_KERNEL);
 136         if (!data->rx_buf) {
 137                 kfree(data->tx_buf);
 138                 return -ENOMEM;
 139         }
 140
 141         m = &data->msg;
 142         x = &data->xfer[0];
 143
 144         spi_message_init(m);
 145
 146         x->tx_buf = &data->tx_buf[0];
 147         x->len = 1;
 148         spi_message_add_tail(x, m);
 149
 150         x++;
 151         x->rx_buf = &data->rx_buf[0];
 152         x->len = 2;
 153         spi_message_add_tail(x, m);
 154
 155         return 0;
 156 }
 157
 158 static int __devinit max1111_probe(struct spi_device *spi)
 159 {
 160         struct max1111_data *data;
 161         int err;
 162
 163         spi->bits_per_word = 8;
 164         spi->mode = SPI_MODE_0;
 165         err = spi_setup(spi);
 166         if (err < 0)
 167                 return err;
 168
 169         data = kzalloc(sizeof(struct max1111_data), GFP_KERNEL);
 170         if (data == NULL) {
 171                 dev_err(&spi->dev, "failed to allocate memory\n");
 172                 return -ENOMEM;
 173         }
 174
 175         err = setup_transfer(data);
 176         if (err)
 177                 goto err_free_data;
 178
 179         data->spi = spi;
 180         spi_set_drvdata(spi, data);
 181
 182         err = sysfs_create_group(&spi->dev.kobj, &max1111_attr_group);
 183         if (err) {
 184                 dev_err(&spi->dev, "failed to create attribute group\n");
 185                 goto err_free_all;
 186         }
 187
 188         data->hwmon_dev = hwmon_device_register(&spi->dev);
 189         if (IS_ERR(data->hwmon_dev)) {
 190                 dev_err(&spi->dev, "failed to create hwmon device\n");
 191                 err = PTR_ERR(data->hwmon_dev);
 192                 goto err_remove;
 193         }
 194
 195 #ifdef CONFIG_SHARPSL_PM
 196         the_max1111 = data;
 197 #endif
 198         return 0;
 199
 200 err_remove:
 201         sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
 202 err_free_all:
 203         kfree(data->rx_buf);
 204         kfree(data->tx_buf);
 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         kfree(data->rx_buf);
 217         kfree(data->tx_buf);
 218         kfree(data);
 219         return 0;
 220 }
 221
 222 static struct spi_driver max1111_driver = {
 223         .driver         = {
 224                 .name   = "max1111",
 225                 .owner  = THIS_MODULE,
 226         },
 227         .probe          = max1111_probe,
 228         .remove         = __devexit_p(max1111_remove),
 229 };
 230
 231 static int __init max1111_init(void)
 232 {
 233         return spi_register_driver(&max1111_driver);
 234 }
 235 module_init(max1111_init);
 236
 237 static void __exit max1111_exit(void)
 238 {
 239         spi_unregister_driver(&max1111_driver);
 240 }
 241 module_exit(max1111_exit);
 242
 243 MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>");
 244 MODULE_DESCRIPTION("MAX1111 ADC Driver");
 245 MODULE_LICENSE("GPL");
 246 MODULE_ALIAS("spi:max1111");