xref: /openbmc/linux/drivers/iio/dac/lpc18xx_dac.c (revision 09a74ea7)
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 
32 struct lpc18xx_dac {
33 	struct regulator *vref;
34 	void __iomem *base;
35 	struct mutex lock;
36 	struct clk *clk;
37 };
38 
39 static 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 
lpc18xx_dac_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)48 static 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 
lpc18xx_dac_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)73 static 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 
99 static const struct iio_info lpc18xx_dac_info = {
100 	.read_raw = lpc18xx_dac_read_raw,
101 	.write_raw = lpc18xx_dac_write_raw,
102 };
103 
lpc18xx_dac_probe(struct platform_device * pdev)104 static 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 
161 dis_clk:
162 	clk_disable_unprepare(dac->clk);
163 dis_reg:
164 	regulator_disable(dac->vref);
165 	return ret;
166 }
167 
lpc18xx_dac_remove(struct platform_device * pdev)168 static int 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 	return 0;
180 }
181 
182 static const struct of_device_id lpc18xx_dac_match[] = {
183 	{ .compatible = "nxp,lpc1850-dac" },
184 	{ /* sentinel */ }
185 };
186 MODULE_DEVICE_TABLE(of, lpc18xx_dac_match);
187 
188 static struct platform_driver lpc18xx_dac_driver = {
189 	.probe	= lpc18xx_dac_probe,
190 	.remove	= lpc18xx_dac_remove,
191 	.driver	= {
192 		.name = "lpc18xx-dac",
193 		.of_match_table = lpc18xx_dac_match,
194 	},
195 };
196 module_platform_driver(lpc18xx_dac_driver);
197 
198 MODULE_DESCRIPTION("LPC18xx DAC driver");
199 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
200 MODULE_LICENSE("GPL v2");
201