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8#include <linux/delay.h>
9#include <linux/gpio/consumer.h>
10#include <linux/iio/iio.h>
11#include <linux/module.h>
12#include <linux/regulator/consumer.h>
13#include <linux/spi/spi.h>
14
15#define MAX1241_VAL_MASK GENMASK(11, 0)
16#define MAX1241_SHUTDOWN_DELAY_USEC 4
17
18enum max1241_id {
19 max1241,
20};
21
22struct max1241 {
23 struct spi_device *spi;
24 struct mutex lock;
25 struct regulator *vdd;
26 struct regulator *vref;
27 struct gpio_desc *shutdown;
28
29 __be16 data ____cacheline_aligned;
30};
31
32static const struct iio_chan_spec max1241_channels[] = {
33 {
34 .type = IIO_VOLTAGE,
35 .indexed = 1,
36 .channel = 0,
37 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
38 BIT(IIO_CHAN_INFO_SCALE),
39 },
40};
41
42static int max1241_read(struct max1241 *adc)
43{
44 struct spi_transfer xfers[] = {
45
46
47
48
49 {
50 .len = 0,
51 .delay.value = 8,
52 .delay.unit = SPI_DELAY_UNIT_USECS,
53 },
54
55
56
57 {
58 .rx_buf = &adc->data,
59 .len = 2,
60 },
61 };
62
63 return spi_sync_transfer(adc->spi, xfers, ARRAY_SIZE(xfers));
64}
65
66static int max1241_read_raw(struct iio_dev *indio_dev,
67 struct iio_chan_spec const *chan,
68 int *val, int *val2, long mask)
69{
70 int ret, vref_uV;
71 struct max1241 *adc = iio_priv(indio_dev);
72
73 switch (mask) {
74 case IIO_CHAN_INFO_RAW:
75 mutex_lock(&adc->lock);
76
77 if (adc->shutdown) {
78 gpiod_set_value(adc->shutdown, 0);
79 udelay(MAX1241_SHUTDOWN_DELAY_USEC);
80 ret = max1241_read(adc);
81 gpiod_set_value(adc->shutdown, 1);
82 } else
83 ret = max1241_read(adc);
84
85 if (ret) {
86 mutex_unlock(&adc->lock);
87 return ret;
88 }
89
90 *val = (be16_to_cpu(adc->data) >> 3) & MAX1241_VAL_MASK;
91
92 mutex_unlock(&adc->lock);
93 return IIO_VAL_INT;
94 case IIO_CHAN_INFO_SCALE:
95 vref_uV = regulator_get_voltage(adc->vref);
96
97 if (vref_uV < 0)
98 return vref_uV;
99
100 *val = vref_uV / 1000;
101 *val2 = 12;
102
103 return IIO_VAL_FRACTIONAL_LOG2;
104 default:
105 return -EINVAL;
106 }
107}
108
109static const struct iio_info max1241_info = {
110 .read_raw = max1241_read_raw,
111};
112
113static void max1241_disable_vdd_action(void *data)
114{
115 struct max1241 *adc = data;
116 struct device *dev = &adc->spi->dev;
117 int err;
118
119 err = regulator_disable(adc->vdd);
120 if (err)
121 dev_err(dev, "could not disable vdd regulator.\n");
122}
123
124static void max1241_disable_vref_action(void *data)
125{
126 struct max1241 *adc = data;
127 struct device *dev = &adc->spi->dev;
128 int err;
129
130 err = regulator_disable(adc->vref);
131 if (err)
132 dev_err(dev, "could not disable vref regulator.\n");
133}
134
135static int max1241_probe(struct spi_device *spi)
136{
137 struct device *dev = &spi->dev;
138 struct iio_dev *indio_dev;
139 struct max1241 *adc;
140 int ret;
141
142 indio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
143 if (!indio_dev)
144 return -ENOMEM;
145
146 adc = iio_priv(indio_dev);
147 adc->spi = spi;
148 mutex_init(&adc->lock);
149
150 adc->vdd = devm_regulator_get(dev, "vdd");
151 if (IS_ERR(adc->vdd)) {
152 dev_err(dev, "failed to get vdd regulator\n");
153 return PTR_ERR(adc->vdd);
154 }
155
156 ret = regulator_enable(adc->vdd);
157 if (ret)
158 return ret;
159
160 ret = devm_add_action_or_reset(dev, max1241_disable_vdd_action, adc);
161 if (ret) {
162 dev_err(dev, "could not set up vdd regulator cleanup action\n");
163 return ret;
164 }
165
166 adc->vref = devm_regulator_get(dev, "vref");
167 if (IS_ERR(adc->vref)) {
168 dev_err(dev, "failed to get vref regulator\n");
169 return PTR_ERR(adc->vref);
170 }
171
172 ret = regulator_enable(adc->vref);
173 if (ret)
174 return ret;
175
176 ret = devm_add_action_or_reset(dev, max1241_disable_vref_action, adc);
177 if (ret) {
178 dev_err(dev, "could not set up vref regulator cleanup action\n");
179 return ret;
180 }
181
182 adc->shutdown = devm_gpiod_get_optional(dev, "shutdown",
183 GPIOD_OUT_HIGH);
184 if (IS_ERR(adc->shutdown))
185 return PTR_ERR(adc->shutdown);
186
187 if (adc->shutdown)
188 dev_dbg(dev, "shutdown pin passed, low-power mode enabled");
189 else
190 dev_dbg(dev, "no shutdown pin passed, low-power mode disabled");
191
192 indio_dev->name = spi_get_device_id(spi)->name;
193 indio_dev->info = &max1241_info;
194 indio_dev->modes = INDIO_DIRECT_MODE;
195 indio_dev->channels = max1241_channels;
196 indio_dev->num_channels = ARRAY_SIZE(max1241_channels);
197
198 return devm_iio_device_register(dev, indio_dev);
199}
200
201static const struct spi_device_id max1241_id[] = {
202 { "max1241", max1241 },
203 {}
204};
205
206static const struct of_device_id max1241_dt_ids[] = {
207 { .compatible = "maxim,max1241" },
208 {}
209};
210MODULE_DEVICE_TABLE(of, max1241_dt_ids);
211
212static struct spi_driver max1241_spi_driver = {
213 .driver = {
214 .name = "max1241",
215 .of_match_table = max1241_dt_ids,
216 },
217 .probe = max1241_probe,
218 .id_table = max1241_id,
219};
220module_spi_driver(max1241_spi_driver);
221
222MODULE_AUTHOR("Alexandru Lazar <alazar@startmail.com>");
223MODULE_DESCRIPTION("MAX1241 ADC driver");
224MODULE_LICENSE("GPL v2");
225
