1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * IIO ADC driver for NXP LPC18xx ADC
4 *
5 * Copyright (C) 2016 Joachim Eastwood <manabian@gmail.com>
6 *
7 * UNSUPPORTED hardware features:
8 * - Hardware triggers
9 * - Burst mode
10 * - Interrupts
11 * - DMA
12 */
13
14 #include <linux/clk.h>
15 #include <linux/err.h>
16 #include <linux/iio/iio.h>
17 #include <linux/iio/driver.h>
18 #include <linux/io.h>
19 #include <linux/iopoll.h>
20 #include <linux/module.h>
21 #include <linux/mutex.h>
22 #include <linux/of.h>
23 #include <linux/of_device.h>
24 #include <linux/platform_device.h>
25 #include <linux/regulator/consumer.h>
26
27 /* LPC18XX ADC registers and bits */
28 #define LPC18XX_ADC_CR 0x000
29 #define LPC18XX_ADC_CR_CLKDIV_SHIFT 8
30 #define LPC18XX_ADC_CR_PDN BIT(21)
31 #define LPC18XX_ADC_CR_START_NOW (0x1 << 24)
32 #define LPC18XX_ADC_GDR 0x004
33
34 /* Data register bits */
35 #define LPC18XX_ADC_SAMPLE_SHIFT 6
36 #define LPC18XX_ADC_SAMPLE_MASK 0x3ff
37 #define LPC18XX_ADC_CONV_DONE BIT(31)
38
39 /* Clock should be 4.5 MHz or less */
40 #define LPC18XX_ADC_CLK_TARGET 4500000
41
42 struct lpc18xx_adc {
43 struct regulator *vref;
44 void __iomem *base;
45 struct device *dev;
46 struct mutex lock;
47 struct clk *clk;
48 u32 cr_reg;
49 };
50
51 #define LPC18XX_ADC_CHAN(_idx) { \
52 .type = IIO_VOLTAGE, \
53 .indexed = 1, \
54 .channel = _idx, \
55 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
56 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
57 }
58
59 static const struct iio_chan_spec lpc18xx_adc_iio_channels[] = {
60 LPC18XX_ADC_CHAN(0),
61 LPC18XX_ADC_CHAN(1),
62 LPC18XX_ADC_CHAN(2),
63 LPC18XX_ADC_CHAN(3),
64 LPC18XX_ADC_CHAN(4),
65 LPC18XX_ADC_CHAN(5),
66 LPC18XX_ADC_CHAN(6),
67 LPC18XX_ADC_CHAN(7),
68 };
69
lpc18xx_adc_read_chan(struct lpc18xx_adc * adc,unsigned int ch)70 static int lpc18xx_adc_read_chan(struct lpc18xx_adc *adc, unsigned int ch)
71 {
72 int ret;
73 u32 reg;
74
75 reg = adc->cr_reg | BIT(ch) | LPC18XX_ADC_CR_START_NOW;
76 writel(reg, adc->base + LPC18XX_ADC_CR);
77
78 ret = readl_poll_timeout(adc->base + LPC18XX_ADC_GDR, reg,
79 reg & LPC18XX_ADC_CONV_DONE, 3, 9);
80 if (ret) {
81 dev_warn(adc->dev, "adc read timed out\n");
82 return ret;
83 }
84
85 return (reg >> LPC18XX_ADC_SAMPLE_SHIFT) & LPC18XX_ADC_SAMPLE_MASK;
86 }
87
lpc18xx_adc_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)88 static int lpc18xx_adc_read_raw(struct iio_dev *indio_dev,
89 struct iio_chan_spec const *chan,
90 int *val, int *val2, long mask)
91 {
92 struct lpc18xx_adc *adc = iio_priv(indio_dev);
93
94 switch (mask) {
95 case IIO_CHAN_INFO_RAW:
96 mutex_lock(&adc->lock);
97 *val = lpc18xx_adc_read_chan(adc, chan->channel);
98 mutex_unlock(&adc->lock);
99 if (*val < 0)
100 return *val;
101
102 return IIO_VAL_INT;
103
104 case IIO_CHAN_INFO_SCALE:
105 *val = regulator_get_voltage(adc->vref) / 1000;
106 *val2 = 10;
107
108 return IIO_VAL_FRACTIONAL_LOG2;
109 }
110
111 return -EINVAL;
112 }
113
114 static const struct iio_info lpc18xx_adc_info = {
115 .read_raw = lpc18xx_adc_read_raw,
116 };
117
lpc18xx_adc_probe(struct platform_device * pdev)118 static int lpc18xx_adc_probe(struct platform_device *pdev)
119 {
120 struct iio_dev *indio_dev;
121 struct lpc18xx_adc *adc;
122 unsigned int clkdiv;
123 unsigned long rate;
124 int ret;
125
126 indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc));
127 if (!indio_dev)
128 return -ENOMEM;
129
130 platform_set_drvdata(pdev, indio_dev);
131 adc = iio_priv(indio_dev);
132 adc->dev = &pdev->dev;
133 mutex_init(&adc->lock);
134
135 adc->base = devm_platform_ioremap_resource(pdev, 0);
136 if (IS_ERR(adc->base))
137 return PTR_ERR(adc->base);
138
139 adc->clk = devm_clk_get(&pdev->dev, NULL);
140 if (IS_ERR(adc->clk)) {
141 dev_err(&pdev->dev, "error getting clock\n");
142 return PTR_ERR(adc->clk);
143 }
144
145 rate = clk_get_rate(adc->clk);
146 clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);
147
148 adc->vref = devm_regulator_get(&pdev->dev, "vref");
149 if (IS_ERR(adc->vref)) {
150 dev_err(&pdev->dev, "error getting regulator\n");
151 return PTR_ERR(adc->vref);
152 }
153
154 indio_dev->name = dev_name(&pdev->dev);
155 indio_dev->info = &lpc18xx_adc_info;
156 indio_dev->modes = INDIO_DIRECT_MODE;
157 indio_dev->channels = lpc18xx_adc_iio_channels;
158 indio_dev->num_channels = ARRAY_SIZE(lpc18xx_adc_iio_channels);
159
160 ret = regulator_enable(adc->vref);
161 if (ret) {
162 dev_err(&pdev->dev, "unable to enable regulator\n");
163 return ret;
164 }
165
166 ret = clk_prepare_enable(adc->clk);
167 if (ret) {
168 dev_err(&pdev->dev, "unable to enable clock\n");
169 goto dis_reg;
170 }
171
172 adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) |
173 LPC18XX_ADC_CR_PDN;
174 writel(adc->cr_reg, adc->base + LPC18XX_ADC_CR);
175
176 ret = iio_device_register(indio_dev);
177 if (ret) {
178 dev_err(&pdev->dev, "unable to register device\n");
179 goto dis_clk;
180 }
181
182 return 0;
183
184 dis_clk:
185 writel(0, adc->base + LPC18XX_ADC_CR);
186 clk_disable_unprepare(adc->clk);
187 dis_reg:
188 regulator_disable(adc->vref);
189 return ret;
190 }
191
lpc18xx_adc_remove(struct platform_device * pdev)192 static int lpc18xx_adc_remove(struct platform_device *pdev)
193 {
194 struct iio_dev *indio_dev = platform_get_drvdata(pdev);
195 struct lpc18xx_adc *adc = iio_priv(indio_dev);
196
197 iio_device_unregister(indio_dev);
198
199 writel(0, adc->base + LPC18XX_ADC_CR);
200 clk_disable_unprepare(adc->clk);
201 regulator_disable(adc->vref);
202
203 return 0;
204 }
205
206 static const struct of_device_id lpc18xx_adc_match[] = {
207 { .compatible = "nxp,lpc1850-adc" },
208 { /* sentinel */ }
209 };
210 MODULE_DEVICE_TABLE(of, lpc18xx_adc_match);
211
212 static struct platform_driver lpc18xx_adc_driver = {
213 .probe = lpc18xx_adc_probe,
214 .remove = lpc18xx_adc_remove,
215 .driver = {
216 .name = "lpc18xx-adc",
217 .of_match_table = lpc18xx_adc_match,
218 },
219 };
220 module_platform_driver(lpc18xx_adc_driver);
221
222 MODULE_DESCRIPTION("LPC18xx ADC driver");
223 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
224 MODULE_LICENSE("GPL v2");
225
