drivers/staging/iio/adc/lpc32xx_adc.c

   1 /*
   2  *  lpc32xx_adc.c - Support for ADC in LPC32XX
   3  *
   4  *  3-channel, 10-bit ADC
   5  *
   6  *  Copyright (C) 2011, 2012 Roland Stigge <stigge@antcom.de>
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation; either version 2 of the License, or
  11  *  (at your option) any later version.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to the Free Software
  20  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/device.h>
  27 #include <linux/kernel.h>
  28 #include <linux/slab.h>
  29 #include <linux/io.h>
  30 #include <linux/clk.h>
  31 #include <linux/err.h>
  32 #include <linux/completion.h>
  33 #include <linux/of.h>
  34
  35 #include <linux/iio/iio.h>
  36 #include <linux/iio/sysfs.h>
  37
  38 /*
  39  * LPC32XX registers definitions
  40  */
  41 #define LPC32XX_ADC_SELECT(x)   ((x) + 0x04)
  42 #define LPC32XX_ADC_CTRL(x)     ((x) + 0x08)
  43 #define LPC32XX_ADC_VALUE(x)    ((x) + 0x48)
  44
  45 /* Bit definitions for LPC32XX_ADC_SELECT: */
  46 #define AD_REFm         0x00000200 /* constant, always write this value! */
  47 #define AD_REFp         0x00000080 /* constant, always write this value! */
  48 #define AD_IN           0x00000010 /* multiple of this is the */
  49                                    /* channel number: 0, 1, 2 */
  50 #define AD_INTERNAL     0x00000004 /* constant, always write this value! */
  51
  52 /* Bit definitions for LPC32XX_ADC_CTRL: */
  53 #define AD_STROBE       0x00000002
  54 #define AD_PDN_CTRL     0x00000004
  55
  56 /* Bit definitions for LPC32XX_ADC_VALUE: */
  57 #define ADC_VALUE_MASK  0x000003FF
  58
  59 #define MOD_NAME "lpc32xx-adc"
  60
  61 struct lpc32xx_adc_info {
  62         void __iomem *adc_base;
  63         struct clk *clk;
  64         struct completion completion;
  65
  66         u32 value;
  67 };
  68
  69 static int lpc32xx_read_raw(struct iio_dev *indio_dev,
  70                                 struct iio_chan_spec const *chan,
  71                                 int *val,
  72                                 int *val2,
  73                                 long mask)
  74 {
  75         struct lpc32xx_adc_info *info = iio_priv(indio_dev);
  76
  77         if (mask == IIO_CHAN_INFO_RAW) {
  78                 mutex_lock(&indio_dev->mlock);
  79                 clk_enable(info->clk);
  80                 /* Measurement setup */
  81                 __raw_writel(AD_INTERNAL | (chan->address) | AD_REFp | AD_REFm,
  82                         LPC32XX_ADC_SELECT(info->adc_base));
  83                 /* Trigger conversion */
  84                 __raw_writel(AD_PDN_CTRL | AD_STROBE,
  85                         LPC32XX_ADC_CTRL(info->adc_base));
  86                 wait_for_completion(&info->completion); /* set by ISR */
  87                 clk_disable(info->clk);
  88                 *val = info->value;
  89                 mutex_unlock(&indio_dev->mlock);
  90
  91                 return IIO_VAL_INT;
  92         }
  93
  94         return -EINVAL;
  95 }
  96
  97 static const struct iio_info lpc32xx_adc_iio_info = {
  98         .read_raw = &lpc32xx_read_raw,
  99         .driver_module = THIS_MODULE,
 100 };
 101
 102 #define LPC32XX_ADC_CHANNEL(_index) {                   \
 103         .type = IIO_VOLTAGE,                            \
 104         .indexed = 1,                                   \
 105         .channel = _index,                              \
 106         .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT,    \
 107         .address = AD_IN * _index,                      \
 108         .scan_index = _index,                           \
 109 }
 110
 111 static const struct iio_chan_spec lpc32xx_adc_iio_channels[] = {
 112         LPC32XX_ADC_CHANNEL(0),
 113         LPC32XX_ADC_CHANNEL(1),
 114         LPC32XX_ADC_CHANNEL(2),
 115 };
 116
 117 static irqreturn_t lpc32xx_adc_isr(int irq, void *dev_id)
 118 {
 119         struct lpc32xx_adc_info *info = (struct lpc32xx_adc_info *) dev_id;
 120
 121         /* Read value and clear irq */
 122         info->value = __raw_readl(LPC32XX_ADC_VALUE(info->adc_base)) &
 123                                 ADC_VALUE_MASK;
 124         complete(&info->completion);
 125
 126         return IRQ_HANDLED;
 127 }
 128
 129 static int lpc32xx_adc_probe(struct platform_device *pdev)
 130 {
 131         struct lpc32xx_adc_info *info = NULL;
 132         struct resource *res;
 133         int retval = -ENODEV;
 134         struct iio_dev *iodev = NULL;
 135         int irq;
 136
 137         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 138         if (!res) {
 139                 dev_err(&pdev->dev, "failed to get platform I/O memory\n");
 140                 retval = -EBUSY;
 141                 goto errout1;
 142         }
 143
 144         iodev = iio_device_alloc(sizeof(struct lpc32xx_adc_info));
 145         if (!iodev) {
 146                 dev_err(&pdev->dev, "failed allocating iio device\n");
 147                 retval = -ENOMEM;
 148                 goto errout1;
 149         }
 150
 151         info = iio_priv(iodev);
 152
 153         info->adc_base = ioremap(res->start, resource_size(res));
 154         if (!info->adc_base) {
 155                 dev_err(&pdev->dev, "failed mapping memory\n");
 156                 retval = -EBUSY;
 157                 goto errout2;
 158         }
 159
 160         info->clk = clk_get(&pdev->dev, NULL);
 161         if (IS_ERR(info->clk)) {
 162                 dev_err(&pdev->dev, "failed getting clock\n");
 163                 goto errout3;
 164         }
 165
 166         irq = platform_get_irq(pdev, 0);
 167         if ((irq < 0) || (irq >= NR_IRQS)) {
 168                 dev_err(&pdev->dev, "failed getting interrupt resource\n");
 169                 retval = -EINVAL;
 170                 goto errout4;
 171         }
 172
 173         retval = request_irq(irq, lpc32xx_adc_isr, 0, MOD_NAME, info);
 174         if (retval < 0) {
 175                 dev_err(&pdev->dev, "failed requesting interrupt\n");
 176                 goto errout4;
 177         }
 178
 179         platform_set_drvdata(pdev, iodev);
 180
 181         init_completion(&info->completion);
 182
 183         iodev->name = MOD_NAME;
 184         iodev->dev.parent = &pdev->dev;
 185         iodev->info = &lpc32xx_adc_iio_info;
 186         iodev->modes = INDIO_DIRECT_MODE;
 187         iodev->channels = lpc32xx_adc_iio_channels;
 188         iodev->num_channels = ARRAY_SIZE(lpc32xx_adc_iio_channels);
 189
 190         retval = iio_device_register(iodev);
 191         if (retval)
 192                 goto errout5;
 193
 194         dev_info(&pdev->dev, "LPC32XX ADC driver loaded, IRQ %d\n", irq);
 195
 196         return 0;
 197
 198 errout5:
 199         free_irq(irq, info);
 200 errout4:
 201         clk_put(info->clk);
 202 errout3:
 203         iounmap(info->adc_base);
 204 errout2:
 205         iio_device_free(iodev);
 206 errout1:
 207         return retval;
 208 }
 209
 210 static int lpc32xx_adc_remove(struct platform_device *pdev)
 211 {
 212         struct iio_dev *iodev = platform_get_drvdata(pdev);
 213         struct lpc32xx_adc_info *info = iio_priv(iodev);
 214         int irq = platform_get_irq(pdev, 0);
 215
 216         iio_device_unregister(iodev);
 217         free_irq(irq, info);
 218         platform_set_drvdata(pdev, NULL);
 219         clk_put(info->clk);
 220         iounmap(info->adc_base);
 221         iio_device_free(iodev);
 222
 223         return 0;
 224 }
 225
 226 #ifdef CONFIG_OF
 227 static const struct of_device_id lpc32xx_adc_match[] = {
 228         { .compatible = "nxp,lpc3220-adc" },
 229         {},
 230 };
 231 MODULE_DEVICE_TABLE(of, lpc32xx_adc_match);
 232 #endif
 233
 234 static struct platform_driver lpc32xx_adc_driver = {
 235         .probe          = lpc32xx_adc_probe,
 236         .remove         = lpc32xx_adc_remove,
 237         .driver         = {
 238                 .name   = MOD_NAME,
 239                 .owner  = THIS_MODULE,
 240                 .of_match_table = of_match_ptr(lpc32xx_adc_match),
 241         },
 242 };
 243
 244 module_platform_driver(lpc32xx_adc_driver);
 245
 246 MODULE_AUTHOR("Roland Stigge <stigge@antcom.de>");
 247 MODULE_DESCRIPTION("LPC32XX ADC driver");
 248 MODULE_LICENSE("GPL");