drivers/iio/adc/men_z188_adc.c

   1 /*
   2  * MEN 16z188 Analog to Digial Converter
   3  *
   4  * Copyright (C) 2014 MEN Mikroelektronik GmbH (www.men.de)
   5  * Author: Johannes Thumshirn <johannes.thumshirn@men.de>
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License as published by the Free
   9  * Software Foundation; version 2 of the License.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/mcb.h>
  15 #include <linux/io.h>
  16 #include <linux/iio/iio.h>
  17
  18 #define Z188_ADC_MAX_CHAN       8
  19 #define Z188_ADC_GAIN           0x0700000
  20 #define Z188_MODE_VOLTAGE       BIT(27)
  21 #define Z188_CFG_AUTO           0x1
  22 #define Z188_CTRL_REG           0x40
  23
  24 #define ADC_DATA(x) (((x) >> 2) & 0x7ffffc)
  25 #define ADC_OVR(x) ((x) & 0x1)
  26
  27 struct z188_adc {
  28         struct resource *mem;
  29         void __iomem *base;
  30 };
  31
  32 #define Z188_ADC_CHANNEL(idx) {                                 \
  33                 .type = IIO_VOLTAGE,                            \
  34                 .indexed = 1,                                   \
  35                 .channel = (idx),                               \
  36                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
  37 }
  38
  39 static const struct iio_chan_spec z188_adc_iio_channels[] = {
  40         Z188_ADC_CHANNEL(0),
  41         Z188_ADC_CHANNEL(1),
  42         Z188_ADC_CHANNEL(2),
  43         Z188_ADC_CHANNEL(3),
  44         Z188_ADC_CHANNEL(4),
  45         Z188_ADC_CHANNEL(5),
  46         Z188_ADC_CHANNEL(6),
  47         Z188_ADC_CHANNEL(7),
  48 };
  49
  50 static int z188_iio_read_raw(struct iio_dev *iio_dev,
  51                         struct iio_chan_spec const *chan,
  52                         int *val,
  53                         int *val2,
  54                         long info)
  55 {
  56         struct z188_adc *adc = iio_priv(iio_dev);
  57         int ret;
  58         u16 tmp;
  59
  60         switch (info) {
  61         case IIO_CHAN_INFO_RAW:
  62                 tmp = readw(adc->base + chan->channel * 4);
  63
  64                 if (ADC_OVR(tmp)) {
  65                         dev_info(&iio_dev->dev,
  66                                 "Oversampling error on ADC channel %d\n",
  67                                 chan->channel);
  68                         return -EIO;
  69                 }
  70                 *val = ADC_DATA(tmp);
  71                 ret = IIO_VAL_INT;
  72                 break;
  73         default:
  74                 ret = -EINVAL;
  75                 break;
  76         }
  77
  78         return ret;
  79 }
  80
  81 static struct iio_info z188_adc_info = {
  82         .read_raw = &z188_iio_read_raw,
  83         .driver_module = THIS_MODULE,
  84 };
  85
  86 static void men_z188_config_channels(void __iomem *addr)
  87 {
  88         int i;
  89         u32 cfg;
  90         u32 ctl;
  91
  92         ctl = readl(addr + Z188_CTRL_REG);
  93         ctl |= Z188_CFG_AUTO;
  94         writel(ctl, addr + Z188_CTRL_REG);
  95
  96         for (i = 0; i < Z188_ADC_MAX_CHAN; i++) {
  97                 cfg = readl(addr + i);
  98                 cfg &= ~Z188_ADC_GAIN;
  99                 cfg |= Z188_MODE_VOLTAGE;
 100                 writel(cfg, addr + i);
 101         }
 102 }
 103
 104 static int men_z188_probe(struct mcb_device *dev,
 105                         const struct mcb_device_id *id)
 106 {
 107         struct z188_adc *adc;
 108         struct iio_dev *indio_dev;
 109         struct resource *mem;
 110
 111         indio_dev = devm_iio_device_alloc(&dev->dev, sizeof(struct z188_adc));
 112         if (!indio_dev)
 113                 return -ENOMEM;
 114
 115         adc = iio_priv(indio_dev);
 116         indio_dev->name = "z188-adc";
 117         indio_dev->dev.parent = &dev->dev;
 118         indio_dev->info = &z188_adc_info;
 119         indio_dev->modes = INDIO_DIRECT_MODE;
 120         indio_dev->channels = z188_adc_iio_channels;
 121         indio_dev->num_channels = ARRAY_SIZE(z188_adc_iio_channels);
 122
 123         mem = mcb_request_mem(dev, "z188-adc");
 124         if (IS_ERR(mem))
 125                 return PTR_ERR(mem);
 126
 127         adc->base = ioremap(mem->start, resource_size(mem));
 128         if (adc->base == NULL)
 129                 goto err;
 130
 131         men_z188_config_channels(adc->base);
 132
 133         adc->mem = mem;
 134         mcb_set_drvdata(dev, indio_dev);
 135
 136         return iio_device_register(indio_dev);
 137
 138 err:
 139         mcb_release_mem(mem);
 140         return -ENXIO;
 141 }
 142
 143 static void men_z188_remove(struct mcb_device *dev)
 144 {
 145         struct iio_dev *indio_dev  = mcb_get_drvdata(dev);
 146         struct z188_adc *adc = iio_priv(indio_dev);
 147
 148         iio_device_unregister(indio_dev);
 149         iounmap(adc->base);
 150         mcb_release_mem(adc->mem);
 151 }
 152
 153 static const struct mcb_device_id men_z188_ids[] = {
 154         { .device = 0xbc },
 155         { }
 156 };
 157 MODULE_DEVICE_TABLE(mcb, men_z188_ids);
 158
 159 static struct mcb_driver men_z188_driver = {
 160         .driver = {
 161                 .name = "z188-adc",
 162                 .owner = THIS_MODULE,
 163         },
 164         .probe = men_z188_probe,
 165         .remove = men_z188_remove,
 166         .id_table = men_z188_ids,
 167 };
 168 module_mcb_driver(men_z188_driver);
 169
 170 MODULE_AUTHOR("Johannes Thumshirn <johannes.thumshirn@men.de>");
 171 MODULE_LICENSE("GPL");
 172 MODULE_DESCRIPTION("IIO ADC driver for MEN 16z188 ADC Core");
 173 MODULE_ALIAS("mcb:16z188");