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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * IIO ADC driver for NXP LPC18xx ADC4 *5 * Copyright (C) 2016 Joachim Eastwood <manabian@gmail.com>6 *7 * UNSUPPORTED hardware features:8 * - Hardware triggers9 * - Burst mode10 * - Interrupts11 * - DMA12 */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/mod_devicetable.h>21#include <linux/module.h>22#include <linux/mutex.h>23#include <linux/platform_device.h>24#include <linux/regulator/consumer.h>25 26/* LPC18XX ADC registers and bits */27#define LPC18XX_ADC_CR 0x00028#define LPC18XX_ADC_CR_CLKDIV_SHIFT 829#define LPC18XX_ADC_CR_PDN BIT(21)30#define LPC18XX_ADC_CR_START_NOW (0x1 << 24)31#define LPC18XX_ADC_GDR 0x00432 33/* Data register bits */34#define LPC18XX_ADC_SAMPLE_SHIFT 635#define LPC18XX_ADC_SAMPLE_MASK 0x3ff36#define LPC18XX_ADC_CONV_DONE BIT(31)37 38/* Clock should be 4.5 MHz or less */39#define LPC18XX_ADC_CLK_TARGET 450000040 41struct lpc18xx_adc {42 struct regulator *vref;43 void __iomem *base;44 struct device *dev;45 struct mutex lock;46 struct clk *clk;47 u32 cr_reg;48};49 50#define LPC18XX_ADC_CHAN(_idx) { \51 .type = IIO_VOLTAGE, \52 .indexed = 1, \53 .channel = _idx, \54 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \55 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \56}57 58static const struct iio_chan_spec lpc18xx_adc_iio_channels[] = {59 LPC18XX_ADC_CHAN(0),60 LPC18XX_ADC_CHAN(1),61 LPC18XX_ADC_CHAN(2),62 LPC18XX_ADC_CHAN(3),63 LPC18XX_ADC_CHAN(4),64 LPC18XX_ADC_CHAN(5),65 LPC18XX_ADC_CHAN(6),66 LPC18XX_ADC_CHAN(7),67};68 69static int lpc18xx_adc_read_chan(struct lpc18xx_adc *adc, unsigned int ch)70{71 int ret;72 u32 reg;73 74 reg = adc->cr_reg | BIT(ch) | LPC18XX_ADC_CR_START_NOW;75 writel(reg, adc->base + LPC18XX_ADC_CR);76 77 ret = readl_poll_timeout(adc->base + LPC18XX_ADC_GDR, reg,78 reg & LPC18XX_ADC_CONV_DONE, 3, 9);79 if (ret) {80 dev_warn(adc->dev, "adc read timed out\n");81 return ret;82 }83 84 return (reg >> LPC18XX_ADC_SAMPLE_SHIFT) & LPC18XX_ADC_SAMPLE_MASK;85}86 87static int lpc18xx_adc_read_raw(struct iio_dev *indio_dev,88 struct iio_chan_spec const *chan,89 int *val, int *val2, long mask)90{91 struct lpc18xx_adc *adc = iio_priv(indio_dev);92 93 switch (mask) {94 case IIO_CHAN_INFO_RAW:95 mutex_lock(&adc->lock);96 *val = lpc18xx_adc_read_chan(adc, chan->channel);97 mutex_unlock(&adc->lock);98 if (*val < 0)99 return *val;100 101 return IIO_VAL_INT;102 103 case IIO_CHAN_INFO_SCALE:104 *val = regulator_get_voltage(adc->vref) / 1000;105 *val2 = 10;106 107 return IIO_VAL_FRACTIONAL_LOG2;108 }109 110 return -EINVAL;111}112 113static const struct iio_info lpc18xx_adc_info = {114 .read_raw = lpc18xx_adc_read_raw,115};116 117static void lpc18xx_clear_cr_reg(void *data)118{119 struct lpc18xx_adc *adc = data;120 121 writel(0, adc->base + LPC18XX_ADC_CR);122}123 124static void lpc18xx_regulator_disable(void *vref)125{126 regulator_disable(vref);127}128 129static int lpc18xx_adc_probe(struct platform_device *pdev)130{131 struct iio_dev *indio_dev;132 struct lpc18xx_adc *adc;133 unsigned int clkdiv;134 unsigned long rate;135 int ret;136 137 indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc));138 if (!indio_dev)139 return -ENOMEM;140 141 adc = iio_priv(indio_dev);142 adc->dev = &pdev->dev;143 mutex_init(&adc->lock);144 145 adc->base = devm_platform_ioremap_resource(pdev, 0);146 if (IS_ERR(adc->base))147 return PTR_ERR(adc->base);148 149 adc->clk = devm_clk_get_enabled(&pdev->dev, NULL);150 if (IS_ERR(adc->clk))151 return dev_err_probe(&pdev->dev, PTR_ERR(adc->clk),152 "error getting clock\n");153 154 adc->vref = devm_regulator_get(&pdev->dev, "vref");155 if (IS_ERR(adc->vref))156 return dev_err_probe(&pdev->dev, PTR_ERR(adc->vref),157 "error getting regulator\n");158 159 indio_dev->name = dev_name(&pdev->dev);160 indio_dev->info = &lpc18xx_adc_info;161 indio_dev->modes = INDIO_DIRECT_MODE;162 indio_dev->channels = lpc18xx_adc_iio_channels;163 indio_dev->num_channels = ARRAY_SIZE(lpc18xx_adc_iio_channels);164 165 ret = regulator_enable(adc->vref);166 if (ret) {167 dev_err(&pdev->dev, "unable to enable regulator\n");168 return ret;169 }170 171 ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_regulator_disable, adc->vref);172 if (ret)173 return ret;174 175 rate = clk_get_rate(adc->clk);176 clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);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 = devm_add_action_or_reset(&pdev->dev, lpc18xx_clear_cr_reg, adc);183 if (ret)184 return ret;185 186 return devm_iio_device_register(&pdev->dev, indio_dev);187}188 189static const struct of_device_id lpc18xx_adc_match[] = {190 { .compatible = "nxp,lpc1850-adc" },191 { /* sentinel */ }192};193MODULE_DEVICE_TABLE(of, lpc18xx_adc_match);194 195static struct platform_driver lpc18xx_adc_driver = {196 .probe = lpc18xx_adc_probe,197 .driver = {198 .name = "lpc18xx-adc",199 .of_match_table = lpc18xx_adc_match,200 },201};202module_platform_driver(lpc18xx_adc_driver);203 204MODULE_DESCRIPTION("LPC18xx ADC driver");205MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");206MODULE_LICENSE("GPL v2");207