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