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/module.h>
21 #include <linux/mutex.h>
23 #include <linux/of_device.h>
24 #include <linux/platform_device.h>
25 #include <linux/regulator/consumer.h>
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
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)
39 /* Clock should be 4.5 MHz or less */
40 #define LPC18XX_ADC_CLK_TARGET 4500000
43 struct regulator *vref;
51 #define LPC18XX_ADC_CHAN(_idx) { \
52 .type = IIO_VOLTAGE, \
55 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
56 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
59 static const struct iio_chan_spec lpc18xx_adc_iio_channels[] = {
70 static int lpc18xx_adc_read_chan(struct lpc18xx_adc *adc, unsigned int ch)
75 reg = adc->cr_reg | BIT(ch) | LPC18XX_ADC_CR_START_NOW;
76 writel(reg, adc->base + LPC18XX_ADC_CR);
78 ret = readl_poll_timeout(adc->base + LPC18XX_ADC_GDR, reg,
79 reg & LPC18XX_ADC_CONV_DONE, 3, 9);
81 dev_warn(adc->dev, "adc read timed out\n");
85 return (reg >> LPC18XX_ADC_SAMPLE_SHIFT) & LPC18XX_ADC_SAMPLE_MASK;
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)
92 struct lpc18xx_adc *adc = iio_priv(indio_dev);
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);
104 case IIO_CHAN_INFO_SCALE:
105 *val = regulator_get_voltage(adc->vref) / 1000;
108 return IIO_VAL_FRACTIONAL_LOG2;
114 static const struct iio_info lpc18xx_adc_info = {
115 .read_raw = lpc18xx_adc_read_raw,
118 static void lpc18xx_clear_cr_reg(void *data)
120 struct lpc18xx_adc *adc = data;
122 writel(0, adc->base + LPC18XX_ADC_CR);
125 static void lpc18xx_clk_disable(void *clk)
127 clk_disable_unprepare(clk);
130 static void lpc18xx_regulator_disable(void *vref)
132 regulator_disable(vref);
135 static int lpc18xx_adc_probe(struct platform_device *pdev)
137 struct iio_dev *indio_dev;
138 struct lpc18xx_adc *adc;
143 indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc));
147 adc = iio_priv(indio_dev);
148 adc->dev = &pdev->dev;
149 mutex_init(&adc->lock);
151 adc->base = devm_platform_ioremap_resource(pdev, 0);
152 if (IS_ERR(adc->base))
153 return PTR_ERR(adc->base);
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");
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");
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);
171 ret = regulator_enable(adc->vref);
173 dev_err(&pdev->dev, "unable to enable regulator\n");
177 ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_regulator_disable, adc->vref);
181 ret = clk_prepare_enable(adc->clk);
183 dev_err(&pdev->dev, "unable to enable clock\n");
187 ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_clk_disable,
192 rate = clk_get_rate(adc->clk);
193 clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);
195 adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) |
197 writel(adc->cr_reg, adc->base + LPC18XX_ADC_CR);
199 ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_clear_cr_reg, adc);
203 return devm_iio_device_register(&pdev->dev, indio_dev);
206 static const struct of_device_id lpc18xx_adc_match[] = {
207 { .compatible = "nxp,lpc1850-adc" },
210 MODULE_DEVICE_TABLE(of, lpc18xx_adc_match);
212 static struct platform_driver lpc18xx_adc_driver = {
213 .probe = lpc18xx_adc_probe,
215 .name = "lpc18xx-adc",
216 .of_match_table = lpc18xx_adc_match,
219 module_platform_driver(lpc18xx_adc_driver);
221 MODULE_DESCRIPTION("LPC18xx ADC driver");
222 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
223 MODULE_LICENSE("GPL v2");