drivers/iio/dac/lpc18xx_dac.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * IIO DAC driver for NXP LPC18xx DAC
   4  *
   5  * Copyright (C) 2016 Joachim Eastwood <manabian@gmail.com>
   6  *
   7  * UNSUPPORTED hardware features:
   8  *  - Interrupts
   9  *  - DMA
  10  */
  11
  12 #include <linux/clk.h>
  13 #include <linux/err.h>
  14 #include <linux/iio/iio.h>
  15 #include <linux/iio/driver.h>
  16 #include <linux/io.h>
  17 #include <linux/iopoll.h>
  18 #include <linux/module.h>
  19 #include <linux/mod_devicetable.h>
  20 #include <linux/mutex.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/regulator/consumer.h>
  23
  24 /* LPC18XX DAC registers and bits */
  25 #define LPC18XX_DAC_CR                  0x000
  26 #define  LPC18XX_DAC_CR_VALUE_SHIFT     6
  27 #define  LPC18XX_DAC_CR_VALUE_MASK      0x3ff
  28 #define  LPC18XX_DAC_CR_BIAS            BIT(16)
  29 #define LPC18XX_DAC_CTRL                0x004
  30 #define  LPC18XX_DAC_CTRL_DMA_ENA       BIT(3)
  31
  32 struct lpc18xx_dac {
  33         struct regulator *vref;
  34         void __iomem *base;
  35         struct mutex lock;
  36         struct clk *clk;
  37 };
  38
  39 static const struct iio_chan_spec lpc18xx_dac_iio_channels[] = {
  40         {
  41                 .type = IIO_VOLTAGE,
  42                 .output = 1,
  43                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
  44                                       BIT(IIO_CHAN_INFO_SCALE),
  45         },
  46 };
  47
  48 static int lpc18xx_dac_read_raw(struct iio_dev *indio_dev,
  49                                 struct iio_chan_spec const *chan,
  50                                 int *val, int *val2, long mask)
  51 {
  52         struct lpc18xx_dac *dac = iio_priv(indio_dev);
  53         u32 reg;
  54
  55         switch (mask) {
  56         case IIO_CHAN_INFO_RAW:
  57                 reg = readl(dac->base + LPC18XX_DAC_CR);
  58                 *val = reg >> LPC18XX_DAC_CR_VALUE_SHIFT;
  59                 *val &= LPC18XX_DAC_CR_VALUE_MASK;
  60
  61                 return IIO_VAL_INT;
  62
  63         case IIO_CHAN_INFO_SCALE:
  64                 *val = regulator_get_voltage(dac->vref) / 1000;
  65                 *val2 = 10;
  66
  67                 return IIO_VAL_FRACTIONAL_LOG2;
  68         }
  69
  70         return -EINVAL;
  71 }
  72
  73 static int lpc18xx_dac_write_raw(struct iio_dev *indio_dev,
  74                                  struct iio_chan_spec const *chan,
  75                                  int val, int val2, long mask)
  76 {
  77         struct lpc18xx_dac *dac = iio_priv(indio_dev);
  78         u32 reg;
  79
  80         switch (mask) {
  81         case IIO_CHAN_INFO_RAW:
  82                 if (val < 0 || val > LPC18XX_DAC_CR_VALUE_MASK)
  83                         return -EINVAL;
  84
  85                 reg = LPC18XX_DAC_CR_BIAS;
  86                 reg |= val << LPC18XX_DAC_CR_VALUE_SHIFT;
  87
  88                 mutex_lock(&dac->lock);
  89                 writel(reg, dac->base + LPC18XX_DAC_CR);
  90                 writel(LPC18XX_DAC_CTRL_DMA_ENA, dac->base + LPC18XX_DAC_CTRL);
  91                 mutex_unlock(&dac->lock);
  92
  93                 return 0;
  94         }
  95
  96         return -EINVAL;
  97 }
  98
  99 static const struct iio_info lpc18xx_dac_info = {
 100         .read_raw = lpc18xx_dac_read_raw,
 101         .write_raw = lpc18xx_dac_write_raw,
 102 };
 103
 104 static int lpc18xx_dac_probe(struct platform_device *pdev)
 105 {
 106         struct iio_dev *indio_dev;
 107         struct lpc18xx_dac *dac;
 108         int ret;
 109
 110         indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*dac));
 111         if (!indio_dev)
 112                 return -ENOMEM;
 113
 114         platform_set_drvdata(pdev, indio_dev);
 115         dac = iio_priv(indio_dev);
 116         mutex_init(&dac->lock);
 117
 118         dac->base = devm_platform_ioremap_resource(pdev, 0);
 119         if (IS_ERR(dac->base))
 120                 return PTR_ERR(dac->base);
 121
 122         dac->clk = devm_clk_get(&pdev->dev, NULL);
 123         if (IS_ERR(dac->clk))
 124                 return dev_err_probe(&pdev->dev, PTR_ERR(dac->clk),
 125                                      "error getting clock\n");
 126
 127         dac->vref = devm_regulator_get(&pdev->dev, "vref");
 128         if (IS_ERR(dac->vref))
 129                 return dev_err_probe(&pdev->dev, PTR_ERR(dac->vref),
 130                                      "error getting regulator\n");
 131
 132         indio_dev->name = dev_name(&pdev->dev);
 133         indio_dev->info = &lpc18xx_dac_info;
 134         indio_dev->modes = INDIO_DIRECT_MODE;
 135         indio_dev->channels = lpc18xx_dac_iio_channels;
 136         indio_dev->num_channels = ARRAY_SIZE(lpc18xx_dac_iio_channels);
 137
 138         ret = regulator_enable(dac->vref);
 139         if (ret) {
 140                 dev_err(&pdev->dev, "unable to enable regulator\n");
 141                 return ret;
 142         }
 143
 144         ret = clk_prepare_enable(dac->clk);
 145         if (ret) {
 146                 dev_err(&pdev->dev, "unable to enable clock\n");
 147                 goto dis_reg;
 148         }
 149
 150         writel(0, dac->base + LPC18XX_DAC_CTRL);
 151         writel(0, dac->base + LPC18XX_DAC_CR);
 152
 153         ret = iio_device_register(indio_dev);
 154         if (ret) {
 155                 dev_err(&pdev->dev, "unable to register device\n");
 156                 goto dis_clk;
 157         }
 158
 159         return 0;
 160
 161 dis_clk:
 162         clk_disable_unprepare(dac->clk);
 163 dis_reg:
 164         regulator_disable(dac->vref);
 165         return ret;
 166 }
 167
 168 static void lpc18xx_dac_remove(struct platform_device *pdev)
 169 {
 170         struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 171         struct lpc18xx_dac *dac = iio_priv(indio_dev);
 172
 173         iio_device_unregister(indio_dev);
 174
 175         writel(0, dac->base + LPC18XX_DAC_CTRL);
 176         clk_disable_unprepare(dac->clk);
 177         regulator_disable(dac->vref);
 178 }
 179
 180 static const struct of_device_id lpc18xx_dac_match[] = {
 181         { .compatible = "nxp,lpc1850-dac" },
 182         { /* sentinel */ }
 183 };
 184 MODULE_DEVICE_TABLE(of, lpc18xx_dac_match);
 185
 186 static struct platform_driver lpc18xx_dac_driver = {
 187         .probe = lpc18xx_dac_probe,
 188         .remove = lpc18xx_dac_remove,
 189         .driver = {
 190                 .name = "lpc18xx-dac",
 191                 .of_match_table = lpc18xx_dac_match,
 192         },
 193 };
 194 module_platform_driver(lpc18xx_dac_driver);
 195
 196 MODULE_DESCRIPTION("LPC18xx DAC driver");
 197 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
 198 MODULE_LICENSE("GPL v2");