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 * http://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/interrupt.h>
14 #include <linux/iio/iio.h>
15 #include <linux/iio/buffer.h>
16 #include <linux/iio/triggered_buffer.h>
17 #include <linux/iio/trigger_consumer.h>
18 #include <linux/regulator/consumer.h>
19
20 #define ADC084S021_DRIVER_NAME "adc084s021"
21
22 struct adc084s021 {
23 struct spi_device *spi;
24 struct spi_message message;
25 struct spi_transfer spi_trans;
26 struct regulator *reg;
27 struct mutex lock;
28 /* Buffer used to align data */
29 struct {
30 __be16 channels[4];
31 s64 ts __aligned(8);
32 } scan;
33 /*
34 * DMA (thus cache coherency maintenance) requires the
35 * transfer buffers to live in their own cache line.
36 */
37 u16 tx_buf[4] ____cacheline_aligned;
38 __be16 rx_buf[5]; /* First 16-bits are trash */
39 };
40
41 #define ADC084S021_VOLTAGE_CHANNEL(num) \
42 { \
43 .type = IIO_VOLTAGE, \
44 .channel = (num), \
45 .indexed = 1, \
46 .scan_index = (num), \
47 .scan_type = { \
48 .sign = 'u', \
49 .realbits = 8, \
50 .storagebits = 16, \
51 .shift = 4, \
52 .endianness = IIO_BE, \
53 }, \
54 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
55 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\
56 }
57
58 static const struct iio_chan_spec adc084s021_channels[] = {
59 ADC084S021_VOLTAGE_CHANNEL(0),
60 ADC084S021_VOLTAGE_CHANNEL(1),
61 ADC084S021_VOLTAGE_CHANNEL(2),
62 ADC084S021_VOLTAGE_CHANNEL(3),
63 IIO_CHAN_SOFT_TIMESTAMP(4),
64 };
65
66 /**
67 * Read an ADC channel and return its value.
68 *
69 * @adc: The ADC SPI data.
70 * @data: Buffer for converted data.
71 */
adc084s021_adc_conversion(struct adc084s021 * adc,void * data)72 static int adc084s021_adc_conversion(struct adc084s021 *adc, void *data)
73 {
74 int n_words = (adc->spi_trans.len >> 1) - 1; /* Discard first word */
75 int ret, i = 0;
76 u16 *p = data;
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 *(p + 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
96 switch (mask) {
97 case IIO_CHAN_INFO_RAW:
98 ret = iio_device_claim_direct_mode(indio_dev);
99 if (ret < 0)
100 return ret;
101
102 ret = regulator_enable(adc->reg);
103 if (ret) {
104 iio_device_release_direct_mode(indio_dev);
105 return ret;
106 }
107
108 adc->tx_buf[0] = channel->channel << 3;
109 ret = adc084s021_adc_conversion(adc, val);
110 iio_device_release_direct_mode(indio_dev);
111 regulator_disable(adc->reg);
112 if (ret < 0)
113 return ret;
114
115 *val = be16_to_cpu(*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 * Read enabled ADC channels and push data to the 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_timestamp(indio_dev, &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 for_each_set_bit(scan_index, indio_dev->active_scan_mask,
169 indio_dev->masklength) {
170 const struct iio_chan_spec *channel =
171 &indio_dev->channels[scan_index];
172 adc->tx_buf[i++] = channel->channel << 3;
173 }
174 adc->spi_trans.len = 2 + (i * sizeof(__be16)); /* Trash + channels */
175
176 return regulator_enable(adc->reg);
177 }
178
adc084s021_buffer_postdisable(struct iio_dev * indio_dev)179 static int adc084s021_buffer_postdisable(struct iio_dev *indio_dev)
180 {
181 struct adc084s021 *adc = iio_priv(indio_dev);
182
183 adc->spi_trans.len = 4; /* Trash + single channel */
184
185 return regulator_disable(adc->reg);
186 }
187
188 static const struct iio_info adc084s021_info = {
189 .read_raw = adc084s021_read_raw,
190 };
191
192 static const struct iio_buffer_setup_ops adc084s021_buffer_setup_ops = {
193 .preenable = adc084s021_buffer_preenable,
194 .postenable = iio_triggered_buffer_postenable,
195 .predisable = iio_triggered_buffer_predisable,
196 .postdisable = adc084s021_buffer_postdisable,
197 };
198
adc084s021_probe(struct spi_device * spi)199 static int adc084s021_probe(struct spi_device *spi)
200 {
201 struct iio_dev *indio_dev;
202 struct adc084s021 *adc;
203 int ret;
204
205 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
206 if (!indio_dev) {
207 dev_err(&spi->dev, "Failed to allocate IIO device\n");
208 return -ENOMEM;
209 }
210
211 adc = iio_priv(indio_dev);
212 adc->spi = spi;
213
214 /* Connect the SPI device and the iio dev */
215 spi_set_drvdata(spi, indio_dev);
216
217 /* Initiate the Industrial I/O device */
218 indio_dev->dev.parent = &spi->dev;
219 indio_dev->dev.of_node = spi->dev.of_node;
220 indio_dev->name = spi_get_device_id(spi)->name;
221 indio_dev->modes = INDIO_DIRECT_MODE;
222 indio_dev->info = &adc084s021_info;
223 indio_dev->channels = adc084s021_channels;
224 indio_dev->num_channels = ARRAY_SIZE(adc084s021_channels);
225
226 /* Create SPI transfer for channel reads */
227 adc->spi_trans.tx_buf = adc->tx_buf;
228 adc->spi_trans.rx_buf = adc->rx_buf;
229 adc->spi_trans.len = 4; /* Trash + single channel */
230 spi_message_init_with_transfers(&adc->message, &adc->spi_trans, 1);
231
232 adc->reg = devm_regulator_get(&spi->dev, "vref");
233 if (IS_ERR(adc->reg))
234 return PTR_ERR(adc->reg);
235
236 mutex_init(&adc->lock);
237
238 /* Setup triggered buffer with pollfunction */
239 ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
240 adc084s021_buffer_trigger_handler,
241 &adc084s021_buffer_setup_ops);
242 if (ret) {
243 dev_err(&spi->dev, "Failed to setup triggered buffer\n");
244 return ret;
245 }
246
247 return devm_iio_device_register(&spi->dev, indio_dev);
248 }
249
250 static const struct of_device_id adc084s021_of_match[] = {
251 { .compatible = "ti,adc084s021", },
252 {},
253 };
254 MODULE_DEVICE_TABLE(of, adc084s021_of_match);
255
256 static const struct spi_device_id adc084s021_id[] = {
257 { ADC084S021_DRIVER_NAME, 0},
258 {}
259 };
260 MODULE_DEVICE_TABLE(spi, adc084s021_id);
261
262 static struct spi_driver adc084s021_driver = {
263 .driver = {
264 .name = ADC084S021_DRIVER_NAME,
265 .of_match_table = of_match_ptr(adc084s021_of_match),
266 },
267 .probe = adc084s021_probe,
268 .id_table = adc084s021_id,
269 };
270 module_spi_driver(adc084s021_driver);
271
272 MODULE_AUTHOR("Mårten Lindahl <martenli@axis.com>");
273 MODULE_DESCRIPTION("Texas Instruments ADC084S021");
274 MODULE_LICENSE("GPL v2");
275 MODULE_VERSION("1.0");
276