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
33 struct lpc18xx_dac {
34 struct regulator *vref;
35 void __iomem *base;
36 struct mutex lock;
37 struct clk *clk;
38 };
39
40 static 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
lpc18xx_dac_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)49 static 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
lpc18xx_dac_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)74 static 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
100 static const struct iio_info lpc18xx_dac_info = {
101 .read_raw = lpc18xx_dac_read_raw,
102 .write_raw = lpc18xx_dac_write_raw,
103 };
104
lpc18xx_dac_probe(struct platform_device * pdev)105 static 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 return dev_err_probe(&pdev->dev, PTR_ERR(dac->clk),
126 "error getting clock\n");
127
128 dac->vref = devm_regulator_get(&pdev->dev, "vref");
129 if (IS_ERR(dac->vref))
130 return dev_err_probe(&pdev->dev, PTR_ERR(dac->vref),
131 "error getting regulator\n");
132
133 indio_dev->name = dev_name(&pdev->dev);
134 indio_dev->info = &lpc18xx_dac_info;
135 indio_dev->modes = INDIO_DIRECT_MODE;
136 indio_dev->channels = lpc18xx_dac_iio_channels;
137 indio_dev->num_channels = ARRAY_SIZE(lpc18xx_dac_iio_channels);
138
139 ret = regulator_enable(dac->vref);
140 if (ret) {
141 dev_err(&pdev->dev, "unable to enable regulator\n");
142 return ret;
143 }
144
145 ret = clk_prepare_enable(dac->clk);
146 if (ret) {
147 dev_err(&pdev->dev, "unable to enable clock\n");
148 goto dis_reg;
149 }
150
151 writel(0, dac->base + LPC18XX_DAC_CTRL);
152 writel(0, dac->base + LPC18XX_DAC_CR);
153
154 ret = iio_device_register(indio_dev);
155 if (ret) {
156 dev_err(&pdev->dev, "unable to register device\n");
157 goto dis_clk;
158 }
159
160 return 0;
161
162 dis_clk:
163 clk_disable_unprepare(dac->clk);
164 dis_reg:
165 regulator_disable(dac->vref);
166 return ret;
167 }
168
lpc18xx_dac_remove(struct platform_device * pdev)169 static int lpc18xx_dac_remove(struct platform_device *pdev)
170 {
171 struct iio_dev *indio_dev = platform_get_drvdata(pdev);
172 struct lpc18xx_dac *dac = iio_priv(indio_dev);
173
174 iio_device_unregister(indio_dev);
175
176 writel(0, dac->base + LPC18XX_DAC_CTRL);
177 clk_disable_unprepare(dac->clk);
178 regulator_disable(dac->vref);
179
180 return 0;
181 }
182
183 static const struct of_device_id lpc18xx_dac_match[] = {
184 { .compatible = "nxp,lpc1850-dac" },
185 { /* sentinel */ }
186 };
187 MODULE_DEVICE_TABLE(of, lpc18xx_dac_match);
188
189 static struct platform_driver lpc18xx_dac_driver = {
190 .probe = lpc18xx_dac_probe,
191 .remove = lpc18xx_dac_remove,
192 .driver = {
193 .name = "lpc18xx-dac",
194 .of_match_table = lpc18xx_dac_match,
195 },
196 };
197 module_platform_driver(lpc18xx_dac_driver);
198
199 MODULE_DESCRIPTION("LPC18xx DAC driver");
200 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
201 MODULE_LICENSE("GPL v2");
202