lpc18xx_dac.c

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