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         struct mutex            drvdata_lock;
  43         /* protect msg, xfer and buffers from multiple access */
  44 };
  45
  46 static int max1111_read(struct device *dev, int channel)
  47 {
  48         struct max1111_data *data = dev_get_drvdata(dev);
  49         uint8_t v1, v2;
  50         int err;
  51
  52         /* writing to drvdata struct is not thread safe, wait on mutex */
  53         mutex_lock(&data->drvdata_lock);
  54
  55         data->tx_buf[0] = (channel << MAX1111_CTRL_SEL_SH) |
  56                 MAX1111_CTRL_PD0 | MAX1111_CTRL_PD1 |
  57                 MAX1111_CTRL_SGL | MAX1111_CTRL_UNI | MAX1111_CTRL_STR;
  58
  59         err = spi_sync(data->spi, &data->msg);
  60         if (err < 0) {
  61                 dev_err(dev, "spi_sync failed with %d\n", err);
  62                 mutex_unlock(&data->drvdata_lock);
  63                 return err;
  64         }
  65
  66         v1 = data->rx_buf[0];
  67         v2 = data->rx_buf[1];
  68
  69         mutex_unlock(&data->drvdata_lock);
  70
  71         if ((v1 & 0xc0) || (v2 & 0x3f))
  72                 return -EINVAL;
  73
  74         return (v1 << 2) | (v2 >> 6);
  75 }
  76
  77 #ifdef CONFIG_SHARPSL_PM
  78 static struct max1111_data *the_max1111;
  79
  80 int max1111_read_channel(int channel)
  81 {
  82         return max1111_read(&the_max1111->spi->dev, channel);
  83 }
  84 EXPORT_SYMBOL(max1111_read_channel);
  85 #endif
  86
  87 /*
  88  * NOTE: SPI devices do not have a default 'name' attribute, which is
  89  * likely to be used by hwmon applications to distinguish between
  90  * different devices, explicitly add a name attribute here.
  91  */
  92 static ssize_t show_name(struct device *dev,
  93                          struct device_attribute *attr, char *buf)
  94 {
  95         return sprintf(buf, "max1111\n");
  96 }
  97
  98 static ssize_t show_adc(struct device *dev,
  99                         struct device_attribute *attr, char *buf)
 100 {
 101         int channel = to_sensor_dev_attr(attr)->index;
 102         int ret;
 103
 104         ret = max1111_read(dev, channel);
 105         if (ret < 0)
 106                 return ret;
 107
 108         return sprintf(buf, "%d\n", ret);
 109 }
 110
 111 #define MAX1111_ADC_ATTR(_id)           \
 112         SENSOR_DEVICE_ATTR(adc##_id##_in, S_IRUGO, show_adc, NULL, _id)
 113
 114 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
 115 static MAX1111_ADC_ATTR(0);
 116 static MAX1111_ADC_ATTR(1);
 117 static MAX1111_ADC_ATTR(2);
 118 static MAX1111_ADC_ATTR(3);
 119
 120 static struct attribute *max1111_attributes[] = {
 121         &dev_attr_name.attr,
 122         &sensor_dev_attr_adc0_in.dev_attr.attr,
 123         &sensor_dev_attr_adc1_in.dev_attr.attr,
 124         &sensor_dev_attr_adc2_in.dev_attr.attr,
 125         &sensor_dev_attr_adc3_in.dev_attr.attr,
 126         NULL,
 127 };
 128
 129 static const struct attribute_group max1111_attr_group = {
 130         .attrs  = max1111_attributes,
 131 };
 132
 133 static int setup_transfer(struct max1111_data *data)
 134 {
 135         struct spi_message *m;
 136         struct spi_transfer *x;
 137
 138         data->tx_buf = kmalloc(MAX1111_TX_BUF_SIZE, GFP_KERNEL);
 139         if (!data->tx_buf)
 140                 return -ENOMEM;
 141
 142         data->rx_buf = kmalloc(MAX1111_RX_BUF_SIZE, GFP_KERNEL);
 143         if (!data->rx_buf) {
 144                 kfree(data->tx_buf);
 145                 return -ENOMEM;
 146         }
 147
 148         m = &data->msg;
 149         x = &data->xfer[0];
 150
 151         spi_message_init(m);
 152
 153         x->tx_buf = &data->tx_buf[0];
 154         x->len = 1;
 155         spi_message_add_tail(x, m);
 156
 157         x++;
 158         x->rx_buf = &data->rx_buf[0];
 159         x->len = 2;
 160         spi_message_add_tail(x, m);
 161
 162         return 0;
 163 }
 164
 165 static int __devinit max1111_probe(struct spi_device *spi)
 166 {
 167         struct max1111_data *data;
 168         int err;
 169
 170         spi->bits_per_word = 8;
 171         spi->mode = SPI_MODE_0;
 172         err = spi_setup(spi);
 173         if (err < 0)
 174                 return err;
 175
 176         data = kzalloc(sizeof(struct max1111_data), GFP_KERNEL);
 177         if (data == NULL) {
 178                 dev_err(&spi->dev, "failed to allocate memory\n");
 179                 return -ENOMEM;
 180         }
 181
 182         err = setup_transfer(data);
 183         if (err)
 184                 goto err_free_data;
 185
 186         mutex_init(&data->drvdata_lock);
 187
 188         data->spi = spi;
 189         spi_set_drvdata(spi, data);
 190
 191         err = sysfs_create_group(&spi->dev.kobj, &max1111_attr_group);
 192         if (err) {
 193                 dev_err(&spi->dev, "failed to create attribute group\n");
 194                 goto err_free_all;
 195         }
 196
 197         data->hwmon_dev = hwmon_device_register(&spi->dev);
 198         if (IS_ERR(data->hwmon_dev)) {
 199                 dev_err(&spi->dev, "failed to create hwmon device\n");
 200                 err = PTR_ERR(data->hwmon_dev);
 201                 goto err_remove;
 202         }
 203
 204 #ifdef CONFIG_SHARPSL_PM
 205         the_max1111 = data;
 206 #endif
 207         return 0;
 208
 209 err_remove:
 210         sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
 211 err_free_all:
 212         kfree(data->rx_buf);
 213         kfree(data->tx_buf);
 214 err_free_data:
 215         kfree(data);
 216         return err;
 217 }
 218
 219 static int __devexit max1111_remove(struct spi_device *spi)
 220 {
 221         struct max1111_data *data = spi_get_drvdata(spi);
 222
 223         hwmon_device_unregister(data->hwmon_dev);
 224         sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
 225         mutex_destroy(&data->drvdata_lock);
 226         kfree(data->rx_buf);
 227         kfree(data->tx_buf);
 228         kfree(data);
 229         return 0;
 230 }
 231
 232 static struct spi_driver max1111_driver = {
 233         .driver         = {
 234                 .name   = "max1111",
 235                 .owner  = THIS_MODULE,
 236         },
 237         .probe          = max1111_probe,
 238         .remove         = __devexit_p(max1111_remove),
 239 };
 240
 241 static int __init max1111_init(void)
 242 {
 243         return spi_register_driver(&max1111_driver);
 244 }
 245 module_init(max1111_init);
 246
 247 static void __exit max1111_exit(void)
 248 {
 249         spi_unregister_driver(&max1111_driver);
 250 }
 251 module_exit(max1111_exit);
 252
 253 MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>");
 254 MODULE_DESCRIPTION("MAX1111 ADC Driver");
 255 MODULE_LICENSE("GPL");
 256 MODULE_ALIAS("spi:max1111");