1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2017 Axis Communications AB
4 *
5 * Driver for Texas Instruments' ADC084S021 ADC chip.
6 * Datasheets can be found here:
7 * https://www.ti.com/lit/ds/symlink/adc084s021.pdf
8 */
9
10 #include <linux/err.h>
11 #include <linux/spi/spi.h>
12 #include <linux/module.h>
13 #include <linux/mod_devicetable.h>
14 #include <linux/interrupt.h>
15 #include <linux/iio/iio.h>
16 #include <linux/iio/buffer.h>
17 #include <linux/iio/triggered_buffer.h>
18 #include <linux/iio/trigger_consumer.h>
19 #include <linux/regulator/consumer.h>
20
21 #define ADC084S021_DRIVER_NAME "adc084s021"
22
23 struct adc084s021 {
24 struct spi_device *spi;
25 struct spi_message message;
26 struct spi_transfer spi_trans;
27 struct regulator *reg;
28 struct mutex lock;
29 /* Buffer used to align data */
30 struct {
31 __be16 channels[4];
32 aligned_s64 ts;
33 } scan;
34 /*
35 * DMA (thus cache coherency maintenance) may require the
36 * transfer buffers to live in their own cache line.
37 */
38 u16 tx_buf[4] __aligned(IIO_DMA_MINALIGN);
39 __be16 rx_buf[5]; /* First 16-bits are trash */
40 };
41
42 #define ADC084S021_VOLTAGE_CHANNEL(num) \
43 { \
44 .type = IIO_VOLTAGE, \
45 .channel = (num), \
46 .indexed = 1, \
47 .scan_index = (num), \
48 .scan_type = { \
49 .sign = 'u', \
50 .realbits = 8, \
51 .storagebits = 16, \
52 .shift = 4, \
53 .endianness = IIO_BE, \
54 }, \
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 adc084s021_channels[] = {
60 ADC084S021_VOLTAGE_CHANNEL(0),
61 ADC084S021_VOLTAGE_CHANNEL(1),
62 ADC084S021_VOLTAGE_CHANNEL(2),
63 ADC084S021_VOLTAGE_CHANNEL(3),
64 IIO_CHAN_SOFT_TIMESTAMP(4),
65 };
66
67 /**
68 * adc084s021_adc_conversion() - Read an ADC channel and return its value.
69 *
70 * @adc: The ADC SPI data.
71 * @data: Buffer for converted data.
72 */
adc084s021_adc_conversion(struct adc084s021 * adc,__be16 * data)73 static int adc084s021_adc_conversion(struct adc084s021 *adc, __be16 *data)
74 {
75 int n_words = (adc->spi_trans.len >> 1) - 1; /* Discard first word */
76 int ret, i = 0;
77
78 /* Do the transfer */
79 ret = spi_sync(adc->spi, &adc->message);
80 if (ret < 0)
81 return ret;
82
83 for (; i < n_words; i++)
84 *(data + i) = adc->rx_buf[i + 1];
85
86 return ret;
87 }
88
adc084s021_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * channel,int * val,int * val2,long mask)89 static int adc084s021_read_raw(struct iio_dev *indio_dev,
90 struct iio_chan_spec const *channel, int *val,
91 int *val2, long mask)
92 {
93 struct adc084s021 *adc = iio_priv(indio_dev);
94 int ret;
95 __be16 be_val;
96
97 switch (mask) {
98 case IIO_CHAN_INFO_RAW:
99 if (!iio_device_claim_direct(indio_dev))
100 return -EBUSY;
101
102 ret = regulator_enable(adc->reg);
103 if (ret) {
104 iio_device_release_direct(indio_dev);
105 return ret;
106 }
107
108 adc->tx_buf[0] = channel->channel << 3;
109 ret = adc084s021_adc_conversion(adc, &be_val);
110 iio_device_release_direct(indio_dev);
111 regulator_disable(adc->reg);
112 if (ret < 0)
113 return ret;
114
115 *val = be16_to_cpu(be_val);
116 *val = (*val >> channel->scan_type.shift) & 0xff;
117
118 return IIO_VAL_INT;
119 case IIO_CHAN_INFO_SCALE:
120 ret = regulator_enable(adc->reg);
121 if (ret)
122 return ret;
123
124 ret = regulator_get_voltage(adc->reg);
125 regulator_disable(adc->reg);
126 if (ret < 0)
127 return ret;
128
129 *val = ret / 1000;
130
131 return IIO_VAL_INT;
132 default:
133 return -EINVAL;
134 }
135 }
136
137 /**
138 * adc084s021_buffer_trigger_handler() - Read ADC channels and push to buffer.
139 *
140 * @irq: The interrupt number (not used).
141 * @pollfunc: Pointer to the poll func.
142 */
adc084s021_buffer_trigger_handler(int irq,void * pollfunc)143 static irqreturn_t adc084s021_buffer_trigger_handler(int irq, void *pollfunc)
144 {
145 struct iio_poll_func *pf = pollfunc;
146 struct iio_dev *indio_dev = pf->indio_dev;
147 struct adc084s021 *adc = iio_priv(indio_dev);
148
149 mutex_lock(&adc->lock);
150
151 if (adc084s021_adc_conversion(adc, adc->scan.channels) < 0)
152 dev_err(&adc->spi->dev, "Failed to read data\n");
153
154 iio_push_to_buffers_with_ts(indio_dev, &adc->scan, sizeof(adc->scan),
155 iio_get_time_ns(indio_dev));
156 mutex_unlock(&adc->lock);
157 iio_trigger_notify_done(indio_dev->trig);
158
159 return IRQ_HANDLED;
160 }
161
adc084s021_buffer_preenable(struct iio_dev * indio_dev)162 static int adc084s021_buffer_preenable(struct iio_dev *indio_dev)
163 {
164 struct adc084s021 *adc = iio_priv(indio_dev);
165 int scan_index;
166 int i = 0;
167
168 iio_for_each_active_channel(indio_dev, scan_index) {
169 const struct iio_chan_spec *channel =
170 &indio_dev->channels[scan_index];
171 adc->tx_buf[i++] = channel->channel << 3;
172 }
173 adc->spi_trans.len = 2 + (i * sizeof(__be16)); /* Trash + channels */
174
175 return regulator_enable(adc->reg);
176 }
177
adc084s021_buffer_postdisable(struct iio_dev * indio_dev)178 static int adc084s021_buffer_postdisable(struct iio_dev *indio_dev)
179 {
180 struct adc084s021 *adc = iio_priv(indio_dev);
181
182 adc->spi_trans.len = 4; /* Trash + single channel */
183
184 return regulator_disable(adc->reg);
185 }
186
187 static const struct iio_info adc084s021_info = {
188 .read_raw = adc084s021_read_raw,
189 };
190
191 static const struct iio_buffer_setup_ops adc084s021_buffer_setup_ops = {
192 .preenable = adc084s021_buffer_preenable,
193 .postdisable = adc084s021_buffer_postdisable,
194 };
195
adc084s021_probe(struct spi_device * spi)196 static int adc084s021_probe(struct spi_device *spi)
197 {
198 struct iio_dev *indio_dev;
199 struct adc084s021 *adc;
200 int ret;
201
202 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
203 if (!indio_dev) {
204 dev_err(&spi->dev, "Failed to allocate IIO device\n");
205 return -ENOMEM;
206 }
207
208 adc = iio_priv(indio_dev);
209 adc->spi = spi;
210
211 /* Initiate the Industrial I/O device */
212 indio_dev->name = spi_get_device_id(spi)->name;
213 indio_dev->modes = INDIO_DIRECT_MODE;
214 indio_dev->info = &adc084s021_info;
215 indio_dev->channels = adc084s021_channels;
216 indio_dev->num_channels = ARRAY_SIZE(adc084s021_channels);
217
218 /* Create SPI transfer for channel reads */
219 adc->spi_trans.tx_buf = adc->tx_buf;
220 adc->spi_trans.rx_buf = adc->rx_buf;
221 adc->spi_trans.len = 4; /* Trash + single channel */
222 spi_message_init_with_transfers(&adc->message, &adc->spi_trans, 1);
223
224 adc->reg = devm_regulator_get(&spi->dev, "vref");
225 if (IS_ERR(adc->reg))
226 return PTR_ERR(adc->reg);
227
228 mutex_init(&adc->lock);
229
230 /* Setup triggered buffer with pollfunction */
231 ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
232 adc084s021_buffer_trigger_handler,
233 &adc084s021_buffer_setup_ops);
234 if (ret) {
235 dev_err(&spi->dev, "Failed to setup triggered buffer\n");
236 return ret;
237 }
238
239 return devm_iio_device_register(&spi->dev, indio_dev);
240 }
241
242 static const struct of_device_id adc084s021_of_match[] = {
243 { .compatible = "ti,adc084s021", },
244 { }
245 };
246 MODULE_DEVICE_TABLE(of, adc084s021_of_match);
247
248 static const struct spi_device_id adc084s021_id[] = {
249 { ADC084S021_DRIVER_NAME, 0 },
250 { }
251 };
252 MODULE_DEVICE_TABLE(spi, adc084s021_id);
253
254 static struct spi_driver adc084s021_driver = {
255 .driver = {
256 .name = ADC084S021_DRIVER_NAME,
257 .of_match_table = adc084s021_of_match,
258 },
259 .probe = adc084s021_probe,
260 .id_table = adc084s021_id,
261 };
262 module_spi_driver(adc084s021_driver);
263
264 MODULE_AUTHOR("Mårten Lindahl <martenli@axis.com>");
265 MODULE_DESCRIPTION("Texas Instruments ADC084S021");
266 MODULE_LICENSE("GPL v2");
267 MODULE_VERSION("1.0");
268