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"); 211