1 /* 2 * IIO ADC driver for NXP LPC18xx ADC 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 * - Hardware triggers 12 * - Burst mode 13 * - Interrupts 14 * - DMA 15 */ 16 17 #include <linux/clk.h> 18 #include <linux/err.h> 19 #include <linux/iio/iio.h> 20 #include <linux/iio/driver.h> 21 #include <linux/io.h> 22 #include <linux/iopoll.h> 23 #include <linux/module.h> 24 #include <linux/mutex.h> 25 #include <linux/of.h> 26 #include <linux/of_device.h> 27 #include <linux/platform_device.h> 28 #include <linux/regulator/consumer.h> 29 30 /* LPC18XX ADC registers and bits */ 31 #define LPC18XX_ADC_CR 0x000 32 #define LPC18XX_ADC_CR_CLKDIV_SHIFT 8 33 #define LPC18XX_ADC_CR_PDN BIT(21) 34 #define LPC18XX_ADC_CR_START_NOW (0x1 << 24) 35 #define LPC18XX_ADC_GDR 0x004 36 37 /* Data register bits */ 38 #define LPC18XX_ADC_SAMPLE_SHIFT 6 39 #define LPC18XX_ADC_SAMPLE_MASK 0x3ff 40 #define LPC18XX_ADC_CONV_DONE BIT(31) 41 42 /* Clock should be 4.5 MHz or less */ 43 #define LPC18XX_ADC_CLK_TARGET 4500000 44 45 struct lpc18xx_adc { 46 struct regulator *vref; 47 void __iomem *base; 48 struct device *dev; 49 struct mutex lock; 50 struct clk *clk; 51 u32 cr_reg; 52 }; 53 54 #define LPC18XX_ADC_CHAN(_idx) { \ 55 .type = IIO_VOLTAGE, \ 56 .indexed = 1, \ 57 .channel = _idx, \ 58 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 59 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 60 } 61 62 static const struct iio_chan_spec lpc18xx_adc_iio_channels[] = { 63 LPC18XX_ADC_CHAN(0), 64 LPC18XX_ADC_CHAN(1), 65 LPC18XX_ADC_CHAN(2), 66 LPC18XX_ADC_CHAN(3), 67 LPC18XX_ADC_CHAN(4), 68 LPC18XX_ADC_CHAN(5), 69 LPC18XX_ADC_CHAN(6), 70 LPC18XX_ADC_CHAN(7), 71 }; 72 73 static int lpc18xx_adc_read_chan(struct lpc18xx_adc *adc, unsigned int ch) 74 { 75 int ret; 76 u32 reg; 77 78 reg = adc->cr_reg | BIT(ch) | LPC18XX_ADC_CR_START_NOW; 79 writel(reg, adc->base + LPC18XX_ADC_CR); 80 81 ret = readl_poll_timeout(adc->base + LPC18XX_ADC_GDR, reg, 82 reg & LPC18XX_ADC_CONV_DONE, 3, 9); 83 if (ret) { 84 dev_warn(adc->dev, "adc read timed out\n"); 85 return ret; 86 } 87 88 return (reg >> LPC18XX_ADC_SAMPLE_SHIFT) & LPC18XX_ADC_SAMPLE_MASK; 89 } 90 91 static int lpc18xx_adc_read_raw(struct iio_dev *indio_dev, 92 struct iio_chan_spec const *chan, 93 int *val, int *val2, long mask) 94 { 95 struct lpc18xx_adc *adc = iio_priv(indio_dev); 96 97 switch (mask) { 98 case IIO_CHAN_INFO_RAW: 99 mutex_lock(&adc->lock); 100 *val = lpc18xx_adc_read_chan(adc, chan->channel); 101 mutex_unlock(&adc->lock); 102 if (*val < 0) 103 return *val; 104 105 return IIO_VAL_INT; 106 107 case IIO_CHAN_INFO_SCALE: 108 *val = regulator_get_voltage(adc->vref) / 1000; 109 *val2 = 10; 110 111 return IIO_VAL_FRACTIONAL_LOG2; 112 } 113 114 return -EINVAL; 115 } 116 117 static const struct iio_info lpc18xx_adc_info = { 118 .read_raw = lpc18xx_adc_read_raw, 119 }; 120 121 static int lpc18xx_adc_probe(struct platform_device *pdev) 122 { 123 struct iio_dev *indio_dev; 124 struct lpc18xx_adc *adc; 125 struct resource *res; 126 unsigned int clkdiv; 127 unsigned long rate; 128 int ret; 129 130 indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc)); 131 if (!indio_dev) 132 return -ENOMEM; 133 134 platform_set_drvdata(pdev, indio_dev); 135 adc = iio_priv(indio_dev); 136 adc->dev = &pdev->dev; 137 mutex_init(&adc->lock); 138 139 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 140 adc->base = devm_ioremap_resource(&pdev->dev, res); 141 if (IS_ERR(adc->base)) 142 return PTR_ERR(adc->base); 143 144 adc->clk = devm_clk_get(&pdev->dev, NULL); 145 if (IS_ERR(adc->clk)) { 146 dev_err(&pdev->dev, "error getting clock\n"); 147 return PTR_ERR(adc->clk); 148 } 149 150 rate = clk_get_rate(adc->clk); 151 clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET); 152 153 adc->vref = devm_regulator_get(&pdev->dev, "vref"); 154 if (IS_ERR(adc->vref)) { 155 dev_err(&pdev->dev, "error getting regulator\n"); 156 return PTR_ERR(adc->vref); 157 } 158 159 indio_dev->name = dev_name(&pdev->dev); 160 indio_dev->dev.parent = &pdev->dev; 161 indio_dev->info = &lpc18xx_adc_info; 162 indio_dev->modes = INDIO_DIRECT_MODE; 163 indio_dev->channels = lpc18xx_adc_iio_channels; 164 indio_dev->num_channels = ARRAY_SIZE(lpc18xx_adc_iio_channels); 165 166 ret = regulator_enable(adc->vref); 167 if (ret) { 168 dev_err(&pdev->dev, "unable to enable regulator\n"); 169 return ret; 170 } 171 172 ret = clk_prepare_enable(adc->clk); 173 if (ret) { 174 dev_err(&pdev->dev, "unable to enable clock\n"); 175 goto dis_reg; 176 } 177 178 adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) | 179 LPC18XX_ADC_CR_PDN; 180 writel(adc->cr_reg, adc->base + LPC18XX_ADC_CR); 181 182 ret = iio_device_register(indio_dev); 183 if (ret) { 184 dev_err(&pdev->dev, "unable to register device\n"); 185 goto dis_clk; 186 } 187 188 return 0; 189 190 dis_clk: 191 writel(0, adc->base + LPC18XX_ADC_CR); 192 clk_disable_unprepare(adc->clk); 193 dis_reg: 194 regulator_disable(adc->vref); 195 return ret; 196 } 197 198 static int lpc18xx_adc_remove(struct platform_device *pdev) 199 { 200 struct iio_dev *indio_dev = platform_get_drvdata(pdev); 201 struct lpc18xx_adc *adc = iio_priv(indio_dev); 202 203 iio_device_unregister(indio_dev); 204 205 writel(0, adc->base + LPC18XX_ADC_CR); 206 clk_disable_unprepare(adc->clk); 207 regulator_disable(adc->vref); 208 209 return 0; 210 } 211 212 static const struct of_device_id lpc18xx_adc_match[] = { 213 { .compatible = "nxp,lpc1850-adc" }, 214 { /* sentinel */ } 215 }; 216 MODULE_DEVICE_TABLE(of, lpc18xx_adc_match); 217 218 static struct platform_driver lpc18xx_adc_driver = { 219 .probe = lpc18xx_adc_probe, 220 .remove = lpc18xx_adc_remove, 221 .driver = { 222 .name = "lpc18xx-adc", 223 .of_match_table = lpc18xx_adc_match, 224 }, 225 }; 226 module_platform_driver(lpc18xx_adc_driver); 227 228 MODULE_DESCRIPTION("LPC18xx ADC driver"); 229 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>"); 230 MODULE_LICENSE("GPL v2"); 231