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/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 aligned_s64 ts;
32 } scan;
33 /*
34 * DMA (thus cache coherency maintenance) may require the
35 * transfer buffers to live in their own cache line.
36 */
37 u16 tx_buf[4] __aligned(IIO_DMA_MINALIGN);
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 * adc084s021_adc_conversion() - 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,__be16 * data)72 static int adc084s021_adc_conversion(struct adc084s021 *adc, __be16 *data)
73 {
74 int n_words = (adc->spi_trans.len >> 1) - 1; /* Discard first word */
75 int ret, i = 0;
76
77 /* Do the transfer */
78 ret = spi_sync(adc->spi, &adc->message);
79 if (ret < 0)
80 return ret;
81
82 for (; i < n_words; i++)
83 *(data + i) = adc->rx_buf[i + 1];
84
85 return ret;
86 }
87
adc084s021_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * channel,int * val,int * val2,long mask)88 static int adc084s021_read_raw(struct iio_dev *indio_dev,
89 struct iio_chan_spec const *channel, int *val,
90 int *val2, long mask)
91 {
92 struct adc084s021 *adc = iio_priv(indio_dev);
93 int ret;
94 __be16 be_val;
95
96 switch (mask) {
97 case IIO_CHAN_INFO_RAW:
98 if (!iio_device_claim_direct(indio_dev))
99 return -EBUSY;
100
101 ret = regulator_enable(adc->reg);
102 if (ret) {
103 iio_device_release_direct(indio_dev);
104 return ret;
105 }
106
107 adc->tx_buf[0] = channel->channel << 3;
108 ret = adc084s021_adc_conversion(adc, &be_val);
109 iio_device_release_direct(indio_dev);
110 regulator_disable(adc->reg);
111 if (ret < 0)
112 return ret;
113
114 *val = be16_to_cpu(be_val);
115 *val = (*val >> channel->scan_type.shift) & 0xff;
116
117 return IIO_VAL_INT;
118 case IIO_CHAN_INFO_SCALE:
119 ret = regulator_enable(adc->reg);
120 if (ret)
121 return ret;
122
123 ret = regulator_get_voltage(adc->reg);
124 regulator_disable(adc->reg);
125 if (ret < 0)
126 return ret;
127
128 *val = ret / 1000;
129
130 return IIO_VAL_INT;
131 default:
132 return -EINVAL;
133 }
134 }
135
136 /**
137 * adc084s021_buffer_trigger_handler() - Read ADC channels and push to buffer.
138 *
139 * @irq: The interrupt number (not used).
140 * @pollfunc: Pointer to the poll func.
141 */
adc084s021_buffer_trigger_handler(int irq,void * pollfunc)142 static irqreturn_t adc084s021_buffer_trigger_handler(int irq, void *pollfunc)
143 {
144 struct iio_poll_func *pf = pollfunc;
145 struct iio_dev *indio_dev = pf->indio_dev;
146 struct adc084s021 *adc = iio_priv(indio_dev);
147
148 mutex_lock(&adc->lock);
149
150 if (adc084s021_adc_conversion(adc, adc->scan.channels) < 0)
151 dev_err(&adc->spi->dev, "Failed to read data\n");
152
153 iio_push_to_buffers_with_ts(indio_dev, &adc->scan, sizeof(adc->scan),
154 iio_get_time_ns(indio_dev));
155 mutex_unlock(&adc->lock);
156 iio_trigger_notify_done(indio_dev->trig);
157
158 return IRQ_HANDLED;
159 }
160
adc084s021_buffer_preenable(struct iio_dev * indio_dev)161 static int adc084s021_buffer_preenable(struct iio_dev *indio_dev)
162 {
163 struct adc084s021 *adc = iio_priv(indio_dev);
164 int scan_index;
165 int i = 0;
166
167 iio_for_each_active_channel(indio_dev, scan_index) {
168 const struct iio_chan_spec *channel =
169 &indio_dev->channels[scan_index];
170 adc->tx_buf[i++] = channel->channel << 3;
171 }
172 adc->spi_trans.len = 2 + (i * sizeof(__be16)); /* Trash + channels */
173
174 return regulator_enable(adc->reg);
175 }
176
adc084s021_buffer_postdisable(struct iio_dev * indio_dev)177 static int adc084s021_buffer_postdisable(struct iio_dev *indio_dev)
178 {
179 struct adc084s021 *adc = iio_priv(indio_dev);
180
181 adc->spi_trans.len = 4; /* Trash + single channel */
182
183 return regulator_disable(adc->reg);
184 }
185
186 static const struct iio_info adc084s021_info = {
187 .read_raw = adc084s021_read_raw,
188 };
189
190 static const struct iio_buffer_setup_ops adc084s021_buffer_setup_ops = {
191 .preenable = adc084s021_buffer_preenable,
192 .postdisable = adc084s021_buffer_postdisable,
193 };
194
adc084s021_probe(struct spi_device * spi)195 static int adc084s021_probe(struct spi_device *spi)
196 {
197 struct iio_dev *indio_dev;
198 struct adc084s021 *adc;
199 int ret;
200
201 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
202 if (!indio_dev)
203 return -ENOMEM;
204
205 adc = iio_priv(indio_dev);
206 adc->spi = spi;
207
208 /* Initiate the Industrial I/O device */
209 indio_dev->name = spi_get_device_id(spi)->name;
210 indio_dev->modes = INDIO_DIRECT_MODE;
211 indio_dev->info = &adc084s021_info;
212 indio_dev->channels = adc084s021_channels;
213 indio_dev->num_channels = ARRAY_SIZE(adc084s021_channels);
214
215 /* Create SPI transfer for channel reads */
216 adc->spi_trans.tx_buf = adc->tx_buf;
217 adc->spi_trans.rx_buf = adc->rx_buf;
218 adc->spi_trans.len = 4; /* Trash + single channel */
219 spi_message_init_with_transfers(&adc->message, &adc->spi_trans, 1);
220
221 adc->reg = devm_regulator_get(&spi->dev, "vref");
222 if (IS_ERR(adc->reg))
223 return PTR_ERR(adc->reg);
224
225 mutex_init(&adc->lock);
226
227 /* Setup triggered buffer with pollfunction */
228 ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
229 adc084s021_buffer_trigger_handler,
230 &adc084s021_buffer_setup_ops);
231 if (ret) {
232 dev_err(&spi->dev, "Failed to setup triggered buffer\n");
233 return ret;
234 }
235
236 return devm_iio_device_register(&spi->dev, indio_dev);
237 }
238
239 static const struct of_device_id adc084s021_of_match[] = {
240 { .compatible = "ti,adc084s021", },
241 { }
242 };
243 MODULE_DEVICE_TABLE(of, adc084s021_of_match);
244
245 static const struct spi_device_id adc084s021_id[] = {
246 { ADC084S021_DRIVER_NAME, 0 },
247 { }
248 };
249 MODULE_DEVICE_TABLE(spi, adc084s021_id);
250
251 static struct spi_driver adc084s021_driver = {
252 .driver = {
253 .name = ADC084S021_DRIVER_NAME,
254 .of_match_table = adc084s021_of_match,
255 },
256 .probe = adc084s021_probe,
257 .id_table = adc084s021_id,
258 };
259 module_spi_driver(adc084s021_driver);
260
261 MODULE_AUTHOR("Mårten Lindahl <martenli@axis.com>");
262 MODULE_DESCRIPTION("Texas Instruments ADC084S021");
263 MODULE_LICENSE("GPL v2");
264 MODULE_VERSION("1.0");
265