iio/dac/lpc18xx_dac.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * IIO DAC driver for NXP LPC18xx DAC
0004  *
0005  * Copyright (C) 2016 Joachim Eastwood <manabian@gmail.com>
0006  *
0007  * UNSUPPORTED hardware features:
0008  *  - Interrupts
0009  *  - DMA
0010  */
0011
0012 #include <linux/clk.h>
0013 #include <linux/err.h>
0014 #include <linux/iio/iio.h>
0015 #include <linux/iio/driver.h>
0016 #include <linux/io.h>
0017 #include <linux/iopoll.h>
0018 #include <linux/module.h>
0019 #include <linux/mod_devicetable.h>
0020 #include <linux/mutex.h>
0021 #include <linux/platform_device.h>
0022 #include <linux/regulator/consumer.h>
0023
0024 /* LPC18XX DAC registers and bits */
0025 #define LPC18XX_DAC_CR          0x000
0026 #define  LPC18XX_DAC_CR_VALUE_SHIFT 6
0027 #define  LPC18XX_DAC_CR_VALUE_MASK  0x3ff
0028 #define  LPC18XX_DAC_CR_BIAS        BIT(16)
0029 #define LPC18XX_DAC_CTRL        0x004
0030 #define  LPC18XX_DAC_CTRL_DMA_ENA   BIT(3)
0031
0032 struct lpc18xx_dac {
0033     struct regulator *vref;
0034     void __iomem *base;
0035     struct mutex lock;
0036     struct clk *clk;
0037 };
0038
0039 static const struct iio_chan_spec lpc18xx_dac_iio_channels[] = {
0040     {
0041         .type = IIO_VOLTAGE,
0042         .output = 1,
0043         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
0044                       BIT(IIO_CHAN_INFO_SCALE),
0045     },
0046 };
0047
0048 static int lpc18xx_dac_read_raw(struct iio_dev *indio_dev,
0049                 struct iio_chan_spec const *chan,
0050                 int *val, int *val2, long mask)
0051 {
0052     struct lpc18xx_dac *dac = iio_priv(indio_dev);
0053     u32 reg;
0054
0055     switch (mask) {
0056     case IIO_CHAN_INFO_RAW:
0057         reg = readl(dac->base + LPC18XX_DAC_CR);
0058         *val = reg >> LPC18XX_DAC_CR_VALUE_SHIFT;
0059         *val &= LPC18XX_DAC_CR_VALUE_MASK;
0060
0061         return IIO_VAL_INT;
0062
0063     case IIO_CHAN_INFO_SCALE:
0064         *val = regulator_get_voltage(dac->vref) / 1000;
0065         *val2 = 10;
0066
0067         return IIO_VAL_FRACTIONAL_LOG2;
0068     }
0069
0070     return -EINVAL;
0071 }
0072
0073 static int lpc18xx_dac_write_raw(struct iio_dev *indio_dev,
0074                  struct iio_chan_spec const *chan,
0075                  int val, int val2, long mask)
0076 {
0077     struct lpc18xx_dac *dac = iio_priv(indio_dev);
0078     u32 reg;
0079
0080     switch (mask) {
0081     case IIO_CHAN_INFO_RAW:
0082         if (val < 0 || val > LPC18XX_DAC_CR_VALUE_MASK)
0083             return -EINVAL;
0084
0085         reg = LPC18XX_DAC_CR_BIAS;
0086         reg |= val << LPC18XX_DAC_CR_VALUE_SHIFT;
0087
0088         mutex_lock(&dac->lock);
0089         writel(reg, dac->base + LPC18XX_DAC_CR);
0090         writel(LPC18XX_DAC_CTRL_DMA_ENA, dac->base + LPC18XX_DAC_CTRL);
0091         mutex_unlock(&dac->lock);
0092
0093         return 0;
0094     }
0095
0096     return -EINVAL;
0097 }
0098
0099 static const struct iio_info lpc18xx_dac_info = {
0100     .read_raw = lpc18xx_dac_read_raw,
0101     .write_raw = lpc18xx_dac_write_raw,
0102 };
0103
0104 static int lpc18xx_dac_probe(struct platform_device *pdev)
0105 {
0106     struct iio_dev *indio_dev;
0107     struct lpc18xx_dac *dac;
0108     int ret;
0109
0110     indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*dac));
0111     if (!indio_dev)
0112         return -ENOMEM;
0113
0114     platform_set_drvdata(pdev, indio_dev);
0115     dac = iio_priv(indio_dev);
0116     mutex_init(&dac->lock);
0117
0118     dac->base = devm_platform_ioremap_resource(pdev, 0);
0119     if (IS_ERR(dac->base))
0120         return PTR_ERR(dac->base);
0121
0122     dac->clk = devm_clk_get(&pdev->dev, NULL);
0123     if (IS_ERR(dac->clk))
0124         return dev_err_probe(&pdev->dev, PTR_ERR(dac->clk),
0125                      "error getting clock\n");
0126
0127     dac->vref = devm_regulator_get(&pdev->dev, "vref");
0128     if (IS_ERR(dac->vref))
0129         return dev_err_probe(&pdev->dev, PTR_ERR(dac->vref),
0130                      "error getting regulator\n");
0131
0132     indio_dev->name = dev_name(&pdev->dev);
0133     indio_dev->info = &lpc18xx_dac_info;
0134     indio_dev->modes = INDIO_DIRECT_MODE;
0135     indio_dev->channels = lpc18xx_dac_iio_channels;
0136     indio_dev->num_channels = ARRAY_SIZE(lpc18xx_dac_iio_channels);
0137
0138     ret = regulator_enable(dac->vref);
0139     if (ret) {
0140         dev_err(&pdev->dev, "unable to enable regulator\n");
0141         return ret;
0142     }
0143
0144     ret = clk_prepare_enable(dac->clk);
0145     if (ret) {
0146         dev_err(&pdev->dev, "unable to enable clock\n");
0147         goto dis_reg;
0148     }
0149
0150     writel(0, dac->base + LPC18XX_DAC_CTRL);
0151     writel(0, dac->base + LPC18XX_DAC_CR);
0152
0153     ret = iio_device_register(indio_dev);
0154     if (ret) {
0155         dev_err(&pdev->dev, "unable to register device\n");
0156         goto dis_clk;
0157     }
0158
0159     return 0;
0160
0161 dis_clk:
0162     clk_disable_unprepare(dac->clk);
0163 dis_reg:
0164     regulator_disable(dac->vref);
0165     return ret;
0166 }
0167
0168 static int lpc18xx_dac_remove(struct platform_device *pdev)
0169 {
0170     struct iio_dev *indio_dev = platform_get_drvdata(pdev);
0171     struct lpc18xx_dac *dac = iio_priv(indio_dev);
0172
0173     iio_device_unregister(indio_dev);
0174
0175     writel(0, dac->base + LPC18XX_DAC_CTRL);
0176     clk_disable_unprepare(dac->clk);
0177     regulator_disable(dac->vref);
0178
0179     return 0;
0180 }
0181
0182 static const struct of_device_id lpc18xx_dac_match[] = {
0183     { .compatible = "nxp,lpc1850-dac" },
0184     { /* sentinel */ }
0185 };
0186 MODULE_DEVICE_TABLE(of, lpc18xx_dac_match);
0187
0188 static struct platform_driver lpc18xx_dac_driver = {
0189     .probe  = lpc18xx_dac_probe,
0190     .remove = lpc18xx_dac_remove,
0191     .driver = {
0192         .name = "lpc18xx-dac",
0193         .of_match_table = lpc18xx_dac_match,
0194     },
0195 };
0196 module_platform_driver(lpc18xx_dac_driver);
0197
0198 MODULE_DESCRIPTION("LPC18xx DAC driver");
0199 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
0200 MODULE_LICENSE("GPL v2");