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