1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * IIO DAC driver for NXP LPC18xx DAC
4 *
5 * Copyright (C) 2016 Joachim Eastwood <manabian@gmail.com>
6 *
7 * UNSUPPORTED hardware features:
8 *  - Interrupts
9 *  - DMA
10 */
11
12#include <linux/clk.h>
13#include <linux/err.h>
14#include <linux/iio/iio.h>
15#include <linux/iio/driver.h>
16#include <linux/io.h>
17#include <linux/iopoll.h>
18#include <linux/module.h>
19#include <linux/mutex.h>
20#include <linux/of.h>
21#include <linux/of_device.h>
22#include <linux/platform_device.h>
23#include <linux/regulator/consumer.h>
24
25/* LPC18XX DAC registers and bits */
26#define LPC18XX_DAC_CR			0x000
27#define  LPC18XX_DAC_CR_VALUE_SHIFT	6
28#define  LPC18XX_DAC_CR_VALUE_MASK	0x3ff
29#define  LPC18XX_DAC_CR_BIAS		BIT(16)
30#define LPC18XX_DAC_CTRL		0x004
31#define  LPC18XX_DAC_CTRL_DMA_ENA	BIT(3)
32
33struct lpc18xx_dac {
34	struct regulator *vref;
35	void __iomem *base;
36	struct mutex lock;
37	struct clk *clk;
38};
39
40static const struct iio_chan_spec lpc18xx_dac_iio_channels[] = {
41	{
42		.type = IIO_VOLTAGE,
43		.output = 1,
44		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
45				      BIT(IIO_CHAN_INFO_SCALE),
46	},
47};
48
49static int lpc18xx_dac_read_raw(struct iio_dev *indio_dev,
50				struct iio_chan_spec const *chan,
51				int *val, int *val2, long mask)
52{
53	struct lpc18xx_dac *dac = iio_priv(indio_dev);
54	u32 reg;
55
56	switch (mask) {
57	case IIO_CHAN_INFO_RAW:
58		reg = readl(dac->base + LPC18XX_DAC_CR);
59		*val = reg >> LPC18XX_DAC_CR_VALUE_SHIFT;
60		*val &= LPC18XX_DAC_CR_VALUE_MASK;
61
62		return IIO_VAL_INT;
63
64	case IIO_CHAN_INFO_SCALE:
65		*val = regulator_get_voltage(dac->vref) / 1000;
66		*val2 = 10;
67
68		return IIO_VAL_FRACTIONAL_LOG2;
69	}
70
71	return -EINVAL;
72}
73
74static int lpc18xx_dac_write_raw(struct iio_dev *indio_dev,
75				 struct iio_chan_spec const *chan,
76				 int val, int val2, long mask)
77{
78	struct lpc18xx_dac *dac = iio_priv(indio_dev);
79	u32 reg;
80
81	switch (mask) {
82	case IIO_CHAN_INFO_RAW:
83		if (val < 0 || val > LPC18XX_DAC_CR_VALUE_MASK)
84			return -EINVAL;
85
86		reg = LPC18XX_DAC_CR_BIAS;
87		reg |= val << LPC18XX_DAC_CR_VALUE_SHIFT;
88
89		mutex_lock(&dac->lock);
90		writel(reg, dac->base + LPC18XX_DAC_CR);
91		writel(LPC18XX_DAC_CTRL_DMA_ENA, dac->base + LPC18XX_DAC_CTRL);
92		mutex_unlock(&dac->lock);
93
94		return 0;
95	}
96
97	return -EINVAL;
98}
99
100static const struct iio_info lpc18xx_dac_info = {
101	.read_raw = lpc18xx_dac_read_raw,
102	.write_raw = lpc18xx_dac_write_raw,
103};
104
105static int lpc18xx_dac_probe(struct platform_device *pdev)
106{
107	struct iio_dev *indio_dev;
108	struct lpc18xx_dac *dac;
109	int ret;
110
111	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*dac));
112	if (!indio_dev)
113		return -ENOMEM;
114
115	platform_set_drvdata(pdev, indio_dev);
116	dac = iio_priv(indio_dev);
117	mutex_init(&dac->lock);
118
119	dac->base = devm_platform_ioremap_resource(pdev, 0);
120	if (IS_ERR(dac->base))
121		return PTR_ERR(dac->base);
122
123	dac->clk = devm_clk_get(&pdev->dev, NULL);
124	if (IS_ERR(dac->clk)) {
125		dev_err(&pdev->dev, "error getting clock\n");
126		return PTR_ERR(dac->clk);
127	}
128
129	dac->vref = devm_regulator_get(&pdev->dev, "vref");
130	if (IS_ERR(dac->vref)) {
131		dev_err(&pdev->dev, "error getting regulator\n");
132		return PTR_ERR(dac->vref);
133	}
134
135	indio_dev->name = dev_name(&pdev->dev);
136	indio_dev->info = &lpc18xx_dac_info;
137	indio_dev->modes = INDIO_DIRECT_MODE;
138	indio_dev->channels = lpc18xx_dac_iio_channels;
139	indio_dev->num_channels = ARRAY_SIZE(lpc18xx_dac_iio_channels);
140
141	ret = regulator_enable(dac->vref);
142	if (ret) {
143		dev_err(&pdev->dev, "unable to enable regulator\n");
144		return ret;
145	}
146
147	ret = clk_prepare_enable(dac->clk);
148	if (ret) {
149		dev_err(&pdev->dev, "unable to enable clock\n");
150		goto dis_reg;
151	}
152
153	writel(0, dac->base + LPC18XX_DAC_CTRL);
154	writel(0, dac->base + LPC18XX_DAC_CR);
155
156	ret = iio_device_register(indio_dev);
157	if (ret) {
158		dev_err(&pdev->dev, "unable to register device\n");
159		goto dis_clk;
160	}
161
162	return 0;
163
164dis_clk:
165	clk_disable_unprepare(dac->clk);
166dis_reg:
167	regulator_disable(dac->vref);
168	return ret;
169}
170
171static int lpc18xx_dac_remove(struct platform_device *pdev)
172{
173	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
174	struct lpc18xx_dac *dac = iio_priv(indio_dev);
175
176	iio_device_unregister(indio_dev);
177
178	writel(0, dac->base + LPC18XX_DAC_CTRL);
179	clk_disable_unprepare(dac->clk);
180	regulator_disable(dac->vref);
181
182	return 0;
183}
184
185static const struct of_device_id lpc18xx_dac_match[] = {
186	{ .compatible = "nxp,lpc1850-dac" },
187	{ /* sentinel */ }
188};
189MODULE_DEVICE_TABLE(of, lpc18xx_dac_match);
190
191static struct platform_driver lpc18xx_dac_driver = {
192	.probe	= lpc18xx_dac_probe,
193	.remove	= lpc18xx_dac_remove,
194	.driver	= {
195		.name = "lpc18xx-dac",
196		.of_match_table = lpc18xx_dac_match,
197	},
198};
199module_platform_driver(lpc18xx_dac_driver);
200
201MODULE_DESCRIPTION("LPC18xx DAC driver");
202MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
203MODULE_LICENSE("GPL v2");
204