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"); 199