1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * IIO ADC driver for NXP LPC18xx ADC 4 * 5 * Copyright (C) 2016 Joachim Eastwood <manabian@gmail.com> 6 * 7 * UNSUPPORTED hardware features: 8 * - Hardware triggers 9 * - Burst mode 10 * - Interrupts 11 * - DMA 12 */ 13 14 #include <linux/clk.h> 15 #include <linux/err.h> 16 #include <linux/iio/iio.h> 17 #include <linux/iio/driver.h> 18 #include <linux/io.h> 19 #include <linux/iopoll.h> 20 #include <linux/module.h> 21 #include <linux/mutex.h> 22 #include <linux/of.h> 23 #include <linux/of_device.h> 24 #include <linux/platform_device.h> 25 #include <linux/regulator/consumer.h> 26 27 /* LPC18XX ADC registers and bits */ 28 #define LPC18XX_ADC_CR 0x000 29 #define LPC18XX_ADC_CR_CLKDIV_SHIFT 8 30 #define LPC18XX_ADC_CR_PDN BIT(21) 31 #define LPC18XX_ADC_CR_START_NOW (0x1 << 24) 32 #define LPC18XX_ADC_GDR 0x004 33 34 /* Data register bits */ 35 #define LPC18XX_ADC_SAMPLE_SHIFT 6 36 #define LPC18XX_ADC_SAMPLE_MASK 0x3ff 37 #define LPC18XX_ADC_CONV_DONE BIT(31) 38 39 /* Clock should be 4.5 MHz or less */ 40 #define LPC18XX_ADC_CLK_TARGET 4500000 41 42 struct lpc18xx_adc { 43 struct regulator *vref; 44 void __iomem *base; 45 struct device *dev; 46 struct mutex lock; 47 struct clk *clk; 48 u32 cr_reg; 49 }; 50 51 #define LPC18XX_ADC_CHAN(_idx) { \ 52 .type = IIO_VOLTAGE, \ 53 .indexed = 1, \ 54 .channel = _idx, \ 55 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 56 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 57 } 58 59 static const struct iio_chan_spec lpc18xx_adc_iio_channels[] = { 60 LPC18XX_ADC_CHAN(0), 61 LPC18XX_ADC_CHAN(1), 62 LPC18XX_ADC_CHAN(2), 63 LPC18XX_ADC_CHAN(3), 64 LPC18XX_ADC_CHAN(4), 65 LPC18XX_ADC_CHAN(5), 66 LPC18XX_ADC_CHAN(6), 67 LPC18XX_ADC_CHAN(7), 68 }; 69 70 static int lpc18xx_adc_read_chan(struct lpc18xx_adc *adc, unsigned int ch) 71 { 72 int ret; 73 u32 reg; 74 75 reg = adc->cr_reg | BIT(ch) | LPC18XX_ADC_CR_START_NOW; 76 writel(reg, adc->base + LPC18XX_ADC_CR); 77 78 ret = readl_poll_timeout(adc->base + LPC18XX_ADC_GDR, reg, 79 reg & LPC18XX_ADC_CONV_DONE, 3, 9); 80 if (ret) { 81 dev_warn(adc->dev, "adc read timed out\n"); 82 return ret; 83 } 84 85 return (reg >> LPC18XX_ADC_SAMPLE_SHIFT) & LPC18XX_ADC_SAMPLE_MASK; 86 } 87 88 static int lpc18xx_adc_read_raw(struct iio_dev *indio_dev, 89 struct iio_chan_spec const *chan, 90 int *val, int *val2, long mask) 91 { 92 struct lpc18xx_adc *adc = iio_priv(indio_dev); 93 94 switch (mask) { 95 case IIO_CHAN_INFO_RAW: 96 mutex_lock(&adc->lock); 97 *val = lpc18xx_adc_read_chan(adc, chan->channel); 98 mutex_unlock(&adc->lock); 99 if (*val < 0) 100 return *val; 101 102 return IIO_VAL_INT; 103 104 case IIO_CHAN_INFO_SCALE: 105 *val = regulator_get_voltage(adc->vref) / 1000; 106 *val2 = 10; 107 108 return IIO_VAL_FRACTIONAL_LOG2; 109 } 110 111 return -EINVAL; 112 } 113 114 static const struct iio_info lpc18xx_adc_info = { 115 .read_raw = lpc18xx_adc_read_raw, 116 }; 117 118 static void lpc18xx_clear_cr_reg(void *data) 119 { 120 struct lpc18xx_adc *adc = data; 121 122 writel(0, adc->base + LPC18XX_ADC_CR); 123 } 124 125 static void lpc18xx_clk_disable(void *clk) 126 { 127 clk_disable_unprepare(clk); 128 } 129 130 static void lpc18xx_regulator_disable(void *vref) 131 { 132 regulator_disable(vref); 133 } 134 135 static int lpc18xx_adc_probe(struct platform_device *pdev) 136 { 137 struct iio_dev *indio_dev; 138 struct lpc18xx_adc *adc; 139 unsigned int clkdiv; 140 unsigned long rate; 141 int ret; 142 143 indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc)); 144 if (!indio_dev) 145 return -ENOMEM; 146 147 adc = iio_priv(indio_dev); 148 adc->dev = &pdev->dev; 149 mutex_init(&adc->lock); 150 151 adc->base = devm_platform_ioremap_resource(pdev, 0); 152 if (IS_ERR(adc->base)) 153 return PTR_ERR(adc->base); 154 155 adc->clk = devm_clk_get(&pdev->dev, NULL); 156 if (IS_ERR(adc->clk)) 157 return dev_err_probe(&pdev->dev, PTR_ERR(adc->clk), 158 "error getting clock\n"); 159 160 adc->vref = devm_regulator_get(&pdev->dev, "vref"); 161 if (IS_ERR(adc->vref)) 162 return dev_err_probe(&pdev->dev, PTR_ERR(adc->vref), 163 "error getting regulator\n"); 164 165 indio_dev->name = dev_name(&pdev->dev); 166 indio_dev->info = &lpc18xx_adc_info; 167 indio_dev->modes = INDIO_DIRECT_MODE; 168 indio_dev->channels = lpc18xx_adc_iio_channels; 169 indio_dev->num_channels = ARRAY_SIZE(lpc18xx_adc_iio_channels); 170 171 ret = regulator_enable(adc->vref); 172 if (ret) { 173 dev_err(&pdev->dev, "unable to enable regulator\n"); 174 return ret; 175 } 176 177 ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_regulator_disable, adc->vref); 178 if (ret) 179 return ret; 180 181 ret = clk_prepare_enable(adc->clk); 182 if (ret) { 183 dev_err(&pdev->dev, "unable to enable clock\n"); 184 return ret; 185 } 186 187 ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_clk_disable, 188 adc->clk); 189 if (ret) 190 return ret; 191 192 rate = clk_get_rate(adc->clk); 193 clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET); 194 195 adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) | 196 LPC18XX_ADC_CR_PDN; 197 writel(adc->cr_reg, adc->base + LPC18XX_ADC_CR); 198 199 ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_clear_cr_reg, adc); 200 if (ret) 201 return ret; 202 203 return devm_iio_device_register(&pdev->dev, indio_dev); 204 } 205 206 static const struct of_device_id lpc18xx_adc_match[] = { 207 { .compatible = "nxp,lpc1850-adc" }, 208 { /* sentinel */ } 209 }; 210 MODULE_DEVICE_TABLE(of, lpc18xx_adc_match); 211 212 static struct platform_driver lpc18xx_adc_driver = { 213 .probe = lpc18xx_adc_probe, 214 .driver = { 215 .name = "lpc18xx-adc", 216 .of_match_table = lpc18xx_adc_match, 217 }, 218 }; 219 module_platform_driver(lpc18xx_adc_driver); 220 221 MODULE_DESCRIPTION("LPC18xx ADC driver"); 222 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>"); 223 MODULE_LICENSE("GPL v2"); 224