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/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			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
32
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)
37
38/* Clock should be 4.5 MHz or less */
39#define LPC18XX_ADC_CLK_TARGET		4500000
40
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