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
  24 #define MAX1111_TX_BUF_SIZE     1
  25 #define MAX1111_RX_BUF_SIZE     2
  26
  27 /* MAX1111 Commands */
  28 #define MAX1111_CTRL_PD0      (1u << 0)
  29 #define MAX1111_CTRL_PD1      (1u << 1)
  30 #define MAX1111_CTRL_SGL      (1u << 2)
  31 #define MAX1111_CTRL_UNI      (1u << 3)
  32 #define MAX1111_CTRL_SEL_SH   (5)       /* NOTE: bit 4 is ignored */
  33 #define MAX1111_CTRL_STR      (1u << 7)
  34
  35 struct max1111_data {
  36         struct spi_device       *spi;
  37         struct device           *hwmon_dev;
  38         struct spi_message      msg;
  39         struct spi_transfer     xfer[2];
  40         uint8_t *tx_buf;
  41         uint8_t *rx_buf;
  42 };
  43
  44 static int max1111_read(struct device *dev, int channel)
  45 {
  46         struct max1111_data *data = dev_get_drvdata(dev);
  47         uint8_t v1, v2;
  48         int err;
  49
  50         data->tx_buf[0] = (channel << MAX1111_CTRL_SEL_SH) |
  51                 MAX1111_CTRL_PD0 | MAX1111_CTRL_PD1 |
  52                 MAX1111_CTRL_SGL | MAX1111_CTRL_UNI | MAX1111_CTRL_STR;
  53
  54         err = spi_sync(data->spi, &data->msg);
  55         if (err < 0) {
  56                 dev_err(dev, "spi_sync failed with %d\n", err);
  57                 return err;
  58         }
  59
  60         v1 = data->rx_buf[0];
  61         v2 = data->rx_buf[1];
  62
  63         if ((v1 & 0xc0) || (v2 & 0x3f))
  64                 return -EINVAL;
  65
  66         return (v1 << 2) | (v2 >> 6);
  67 }
  68
  69 #ifdef CONFIG_SHARPSL_PM
  70 static struct max1111_data *the_max1111;
  71
  72 int max1111_read_channel(int channel)
  73 {
  74         return max1111_read(&the_max1111->spi->dev, channel);
  75 }
  76 EXPORT_SYMBOL(max1111_read_channel);
  77 #endif
  78
  79 /*
  80  * NOTE: SPI devices do not have a default 'name' attribute, which is
  81  * likely to be used by hwmon applications to distinguish between
  82  * different devices, explicitly add a name attribute here.
  83  */
  84 static ssize_t show_name(struct device *dev,
  85                          struct device_attribute *attr, char *buf)
  86 {
  87         return sprintf(buf, "max1111\n");
  88 }
  89
  90 static ssize_t show_adc(struct device *dev,
  91                         struct device_attribute *attr, char *buf)
  92 {
  93         int channel = to_sensor_dev_attr(attr)->index;
  94         int ret;
  95
  96         ret = max1111_read(dev, channel);
  97         if (ret < 0)
  98                 return ret;
  99
 100         return sprintf(buf, "%d\n", ret);
 101 }
 102
 103 #define MAX1111_ADC_ATTR(_id)           \
 104         SENSOR_DEVICE_ATTR(adc##_id##_in, S_IRUGO, show_adc, NULL, _id)
 105
 106 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
 107 static MAX1111_ADC_ATTR(0);
 108 static MAX1111_ADC_ATTR(1);
 109 static MAX1111_ADC_ATTR(2);
 110 static MAX1111_ADC_ATTR(3);
 111
 112 static struct attribute *max1111_attributes[] = {
 113         &dev_attr_name.attr,
 114         &sensor_dev_attr_adc0_in.dev_attr.attr,
 115         &sensor_dev_attr_adc1_in.dev_attr.attr,
 116         &sensor_dev_attr_adc2_in.dev_attr.attr,
 117         &sensor_dev_attr_adc3_in.dev_attr.attr,
 118         NULL,
 119 };
 120
 121 static const struct attribute_group max1111_attr_group = {
 122         .attrs  = max1111_attributes,
 123 };
 124
 125 static int setup_transfer(struct max1111_data *data)
 126 {
 127         struct spi_message *m;
 128         struct spi_transfer *x;
 129
 130         data->tx_buf = kmalloc(MAX1111_TX_BUF_SIZE, GFP_KERNEL);
 131         if (!data->tx_buf)
 132                 return -ENOMEM;
 133
 134         data->rx_buf = kmalloc(MAX1111_RX_BUF_SIZE, GFP_KERNEL);
 135         if (!data->rx_buf) {
 136                 kfree(data->tx_buf);
 137                 return -ENOMEM;
 138         }
 139
 140         m = &data->msg;
 141         x = &data->xfer[0];
 142
 143         spi_message_init(m);
 144
 145         x->tx_buf = &data->tx_buf[0];
 146         x->len = 1;
 147         spi_message_add_tail(x, m);
 148
 149         x++;
 150         x->rx_buf = &data->rx_buf[0];
 151         x->len = 2;
 152         spi_message_add_tail(x, m);
 153
 154         return 0;
 155 }
 156
 157 static int __devinit max1111_probe(struct spi_device *spi)
 158 {
 159         struct max1111_data *data;
 160         int err;
 161
 162         spi->bits_per_word = 8;
 163         spi->mode = SPI_MODE_0;
 164         err = spi_setup(spi);
 165         if (err < 0)
 166                 return err;
 167
 168         data = kzalloc(sizeof(struct max1111_data), GFP_KERNEL);
 169         if (data == NULL) {
 170                 dev_err(&spi->dev, "failed to allocate memory\n");
 171                 return -ENOMEM;
 172         }
 173
 174         err = setup_transfer(data);
 175         if (err)
 176                 goto err_free_data;
 177
 178         data->spi = spi;
 179         spi_set_drvdata(spi, data);
 180
 181         err = sysfs_create_group(&spi->dev.kobj, &max1111_attr_group);
 182         if (err) {
 183                 dev_err(&spi->dev, "failed to create attribute group\n");
 184                 goto err_free_all;
 185         }
 186
 187         data->hwmon_dev = hwmon_device_register(&spi->dev);
 188         if (IS_ERR(data->hwmon_dev)) {
 189                 dev_err(&spi->dev, "failed to create hwmon device\n");
 190                 err = PTR_ERR(data->hwmon_dev);
 191                 goto err_remove;
 192         }
 193
 194 #ifdef CONFIG_SHARPSL_PM
 195         the_max1111 = data;
 196 #endif
 197         return 0;
 198
 199 err_remove:
 200         sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
 201 err_free_all:
 202         kfree(data->rx_buf);
 203         kfree(data->tx_buf);
 204 err_free_data:
 205         kfree(data);
 206         return err;
 207 }
 208
 209 static 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         kfree(data->rx_buf);
 216         kfree(data->tx_buf);
 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");