drivers/iio/dac/lpc18xx_dac.c

   1 /*
   2  * IIO DAC driver for NXP LPC18xx DAC
   3  *
   4  * Copyright (C) 2016 Joachim Eastwood <manabian@gmail.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * UNSUPPORTED hardware features:
  11  *  - Interrupts
  12  *  - DMA
  13  */
  14
  15 #include <linux/clk.h>
  16 #include <linux/err.h>
  17 #include <linux/iio/iio.h>
  18 #include <linux/iio/driver.h>
  19 #include <linux/io.h>
  20 #include <linux/iopoll.h>
  21 #include <linux/module.h>
  22 #include <linux/mutex.h>
  23 #include <linux/of.h>
  24 #include <linux/of_device.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/regulator/consumer.h>
  27
  28 /* LPC18XX DAC registers and bits */
  29 #define LPC18XX_DAC_CR                  0x000
  30 #define  LPC18XX_DAC_CR_VALUE_SHIFT     6
  31 #define  LPC18XX_DAC_CR_VALUE_MASK      0x3ff
  32 #define  LPC18XX_DAC_CR_BIAS            BIT(16)
  33 #define LPC18XX_DAC_CTRL                0x004
  34 #define  LPC18XX_DAC_CTRL_DMA_ENA       BIT(3)
  35
  36 struct lpc18xx_dac {
  37         struct regulator *vref;
  38         void __iomem *base;
  39         struct mutex lock;
  40         struct clk *clk;
  41 };
  42
  43 static const struct iio_chan_spec lpc18xx_dac_iio_channels[] = {
  44         {
  45                 .type = IIO_VOLTAGE,
  46                 .output = 1,
  47                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
  48                                       BIT(IIO_CHAN_INFO_SCALE),
  49         },
  50 };
  51
  52 static int lpc18xx_dac_read_raw(struct iio_dev *indio_dev,
  53                                 struct iio_chan_spec const *chan,
  54                                 int *val, int *val2, long mask)
  55 {
  56         struct lpc18xx_dac *dac = iio_priv(indio_dev);
  57         u32 reg;
  58
  59         switch (mask) {
  60         case IIO_CHAN_INFO_RAW:
  61                 reg = readl(dac->base + LPC18XX_DAC_CR);
  62                 *val = reg >> LPC18XX_DAC_CR_VALUE_SHIFT;
  63                 *val &= LPC18XX_DAC_CR_VALUE_MASK;
  64
  65                 return IIO_VAL_INT;
  66
  67         case IIO_CHAN_INFO_SCALE:
  68                 *val = regulator_get_voltage(dac->vref) / 1000;
  69                 *val2 = 10;
  70
  71                 return IIO_VAL_FRACTIONAL_LOG2;
  72         }
  73
  74         return -EINVAL;
  75 }
  76
  77 static int lpc18xx_dac_write_raw(struct iio_dev *indio_dev,
  78                                  struct iio_chan_spec const *chan,
  79                                  int val, int val2, long mask)
  80 {
  81         struct lpc18xx_dac *dac = iio_priv(indio_dev);
  82         u32 reg;
  83
  84         switch (mask) {
  85         case IIO_CHAN_INFO_RAW:
  86                 if (val < 0 || val > LPC18XX_DAC_CR_VALUE_MASK)
  87                         return -EINVAL;
  88
  89                 reg = LPC18XX_DAC_CR_BIAS;
  90                 reg |= val << LPC18XX_DAC_CR_VALUE_SHIFT;
  91
  92                 mutex_lock(&dac->lock);
  93                 writel(reg, dac->base + LPC18XX_DAC_CR);
  94                 writel(LPC18XX_DAC_CTRL_DMA_ENA, dac->base + LPC18XX_DAC_CTRL);
  95                 mutex_unlock(&dac->lock);
  96
  97                 return 0;
  98         }
  99
 100         return -EINVAL;
 101 }
 102
 103 static const struct iio_info lpc18xx_dac_info = {
 104         .read_raw = lpc18xx_dac_read_raw,
 105         .write_raw = lpc18xx_dac_write_raw,
 106         .driver_module = THIS_MODULE,
 107 };
 108
 109 static int lpc18xx_dac_probe(struct platform_device *pdev)
 110 {
 111         struct iio_dev *indio_dev;
 112         struct lpc18xx_dac *dac;
 113         struct resource *res;
 114         int ret;
 115
 116         indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*dac));
 117         if (!indio_dev)
 118                 return -ENOMEM;
 119
 120         platform_set_drvdata(pdev, indio_dev);
 121         dac = iio_priv(indio_dev);
 122         mutex_init(&dac->lock);
 123
 124         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 125         dac->base = devm_ioremap_resource(&pdev->dev, res);
 126         if (IS_ERR(dac->base))
 127                 return PTR_ERR(dac->base);
 128
 129         dac->clk = devm_clk_get(&pdev->dev, NULL);
 130         if (IS_ERR(dac->clk)) {
 131                 dev_err(&pdev->dev, "error getting clock\n");
 132                 return PTR_ERR(dac->clk);
 133         }
 134
 135         dac->vref = devm_regulator_get(&pdev->dev, "vref");
 136         if (IS_ERR(dac->vref)) {
 137                 dev_err(&pdev->dev, "error getting regulator\n");
 138                 return PTR_ERR(dac->vref);
 139         }
 140
 141         indio_dev->name = dev_name(&pdev->dev);
 142         indio_dev->dev.parent = &pdev->dev;
 143         indio_dev->info = &lpc18xx_dac_info;
 144         indio_dev->modes = INDIO_DIRECT_MODE;
 145         indio_dev->channels = lpc18xx_dac_iio_channels;
 146         indio_dev->num_channels = ARRAY_SIZE(lpc18xx_dac_iio_channels);
 147
 148         ret = regulator_enable(dac->vref);
 149         if (ret) {
 150                 dev_err(&pdev->dev, "unable to enable regulator\n");
 151                 return ret;
 152         }
 153
 154         ret = clk_prepare_enable(dac->clk);
 155         if (ret) {
 156                 dev_err(&pdev->dev, "unable to enable clock\n");
 157                 goto dis_reg;
 158         }
 159
 160         writel(0, dac->base + LPC18XX_DAC_CTRL);
 161         writel(0, dac->base + LPC18XX_DAC_CR);
 162
 163         ret = iio_device_register(indio_dev);
 164         if (ret) {
 165                 dev_err(&pdev->dev, "unable to register device\n");
 166                 goto dis_clk;
 167         }
 168
 169         return 0;
 170
 171 dis_clk:
 172         clk_disable_unprepare(dac->clk);
 173 dis_reg:
 174         regulator_disable(dac->vref);
 175         return ret;
 176 }
 177
 178 static int lpc18xx_dac_remove(struct platform_device *pdev)
 179 {
 180         struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 181         struct lpc18xx_dac *dac = iio_priv(indio_dev);
 182
 183         iio_device_unregister(indio_dev);
 184
 185         writel(0, dac->base + LPC18XX_DAC_CTRL);
 186         clk_disable_unprepare(dac->clk);
 187         regulator_disable(dac->vref);
 188
 189         return 0;
 190 }
 191
 192 static const struct of_device_id lpc18xx_dac_match[] = {
 193         { .compatible = "nxp,lpc1850-dac" },
 194         { /* sentinel */ }
 195 };
 196 MODULE_DEVICE_TABLE(of, lpc18xx_dac_match);
 197
 198 static struct platform_driver lpc18xx_dac_driver = {
 199         .probe  = lpc18xx_dac_probe,
 200         .remove = lpc18xx_dac_remove,
 201         .driver = {
 202                 .name = "lpc18xx-dac",
 203                 .of_match_table = lpc18xx_dac_match,
 204         },
 205 };
 206 module_platform_driver(lpc18xx_dac_driver);
 207
 208 MODULE_DESCRIPTION("LPC18xx DAC driver");
 209 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
 210 MODULE_LICENSE("GPL v2");