1 // SPDX-License-Identifier: GPL-2.0-only
3 * IIO ADC driver for NXP LPC18xx ADC
5 * Copyright (C) 2016 Joachim Eastwood <manabian@gmail.com>
7 * UNSUPPORTED hardware features:
14 #include <linux/clk.h>
15 #include <linux/err.h>
16 #include <linux/iio/iio.h>
17 #include <linux/iio/driver.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>
26 /* LPC18XX ADC registers and bits */
27 #define LPC18XX_ADC_CR 0x000
28 #define LPC18XX_ADC_CR_CLKDIV_SHIFT 8
29 #define LPC18XX_ADC_CR_PDN BIT(21)
30 #define LPC18XX_ADC_CR_START_NOW (0x1 << 24)
31 #define LPC18XX_ADC_GDR 0x004
33 /* Data register bits */
34 #define LPC18XX_ADC_SAMPLE_SHIFT 6
35 #define LPC18XX_ADC_SAMPLE_MASK 0x3ff
36 #define LPC18XX_ADC_CONV_DONE BIT(31)
38 /* Clock should be 4.5 MHz or less */
39 #define LPC18XX_ADC_CLK_TARGET 4500000
42 struct regulator *vref;
50 #define LPC18XX_ADC_CHAN(_idx) { \
51 .type = IIO_VOLTAGE, \
54 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
55 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
58 static const struct iio_chan_spec lpc18xx_adc_iio_channels[] = {
69 static int lpc18xx_adc_read_chan(struct lpc18xx_adc *adc, unsigned int ch)
74 reg = adc->cr_reg | BIT(ch) | LPC18XX_ADC_CR_START_NOW;
75 writel(reg, adc->base + LPC18XX_ADC_CR);
77 ret = readl_poll_timeout(adc->base + LPC18XX_ADC_GDR, reg,
78 reg & LPC18XX_ADC_CONV_DONE, 3, 9);
80 dev_warn(adc->dev, "adc read timed out\n");
84 return (reg >> LPC18XX_ADC_SAMPLE_SHIFT) & LPC18XX_ADC_SAMPLE_MASK;
87 static int lpc18xx_adc_read_raw(struct iio_dev *indio_dev,
88 struct iio_chan_spec const *chan,
89 int *val, int *val2, long mask)
91 struct lpc18xx_adc *adc = iio_priv(indio_dev);
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);
103 case IIO_CHAN_INFO_SCALE:
104 *val = regulator_get_voltage(adc->vref) / 1000;
107 return IIO_VAL_FRACTIONAL_LOG2;
113 static const struct iio_info lpc18xx_adc_info = {
114 .read_raw = lpc18xx_adc_read_raw,
117 static void lpc18xx_clear_cr_reg(void *data)
119 struct lpc18xx_adc *adc = data;
121 writel(0, adc->base + LPC18XX_ADC_CR);
124 static void lpc18xx_clk_disable(void *clk)
126 clk_disable_unprepare(clk);
129 static void lpc18xx_regulator_disable(void *vref)
131 regulator_disable(vref);
134 static int lpc18xx_adc_probe(struct platform_device *pdev)
136 struct iio_dev *indio_dev;
137 struct lpc18xx_adc *adc;
142 indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc));
146 adc = iio_priv(indio_dev);
147 adc->dev = &pdev->dev;
148 mutex_init(&adc->lock);
150 adc->base = devm_platform_ioremap_resource(pdev, 0);
151 if (IS_ERR(adc->base))
152 return PTR_ERR(adc->base);
154 adc->clk = devm_clk_get(&pdev->dev, NULL);
155 if (IS_ERR(adc->clk))
156 return dev_err_probe(&pdev->dev, PTR_ERR(adc->clk),
157 "error getting clock\n");
159 adc->vref = devm_regulator_get(&pdev->dev, "vref");
160 if (IS_ERR(adc->vref))
161 return dev_err_probe(&pdev->dev, PTR_ERR(adc->vref),
162 "error getting regulator\n");
164 indio_dev->name = dev_name(&pdev->dev);
165 indio_dev->info = &lpc18xx_adc_info;
166 indio_dev->modes = INDIO_DIRECT_MODE;
167 indio_dev->channels = lpc18xx_adc_iio_channels;
168 indio_dev->num_channels = ARRAY_SIZE(lpc18xx_adc_iio_channels);
170 ret = regulator_enable(adc->vref);
172 dev_err(&pdev->dev, "unable to enable regulator\n");
176 ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_regulator_disable, adc->vref);
180 ret = clk_prepare_enable(adc->clk);
182 dev_err(&pdev->dev, "unable to enable clock\n");
186 ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_clk_disable,
191 rate = clk_get_rate(adc->clk);
192 clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);
194 adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) |
196 writel(adc->cr_reg, adc->base + LPC18XX_ADC_CR);
198 ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_clear_cr_reg, adc);
202 return devm_iio_device_register(&pdev->dev, indio_dev);
205 static const struct of_device_id lpc18xx_adc_match[] = {
206 { .compatible = "nxp,lpc1850-adc" },
209 MODULE_DEVICE_TABLE(of, lpc18xx_adc_match);
211 static struct platform_driver lpc18xx_adc_driver = {
212 .probe = lpc18xx_adc_probe,
214 .name = "lpc18xx-adc",
215 .of_match_table = lpc18xx_adc_match,
218 module_platform_driver(lpc18xx_adc_driver);
220 MODULE_DESCRIPTION("LPC18xx ADC driver");
221 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
222 MODULE_LICENSE("GPL v2");