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 s64 ts __aligned(8);
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 ret = iio_device_claim_direct_mode(indio_dev);
100 if (ret < 0)
101 return ret;
102
103 ret = regulator_enable(adc->reg);
104 if (ret) {
105 iio_device_release_direct_mode(indio_dev);
106 return ret;
107 }
108
109 adc->tx_buf[0] = channel->channel << 3;
110 ret = adc084s021_adc_conversion(adc, &be_val);
111 iio_device_release_direct_mode(indio_dev);
112 regulator_disable(adc->reg);
113 if (ret < 0)
114 return ret;
115
116 *val = be16_to_cpu(be_val);
117 *val = (*val >> channel->scan_type.shift) & 0xff;
118
119 return IIO_VAL_INT;
120 case IIO_CHAN_INFO_SCALE:
121 ret = regulator_enable(adc->reg);
122 if (ret)
123 return ret;
124
125 ret = regulator_get_voltage(adc->reg);
126 regulator_disable(adc->reg);
127 if (ret < 0)
128 return ret;
129
130 *val = ret / 1000;
131
132 return IIO_VAL_INT;
133 default:
134 return -EINVAL;
135 }
136 }
137
138 /**
139 * adc084s021_buffer_trigger_handler() - Read ADC channels and push to buffer.
140 *
141 * @irq: The interrupt number (not used).
142 * @pollfunc: Pointer to the poll func.
143 */
adc084s021_buffer_trigger_handler(int irq,void * pollfunc)144 static irqreturn_t adc084s021_buffer_trigger_handler(int irq, void *pollfunc)
145 {
146 struct iio_poll_func *pf = pollfunc;
147 struct iio_dev *indio_dev = pf->indio_dev;
148 struct adc084s021 *adc = iio_priv(indio_dev);
149
150 mutex_lock(&adc->lock);
151
152 if (adc084s021_adc_conversion(adc, adc->scan.channels) < 0)
153 dev_err(&adc->spi->dev, "Failed to read data\n");
154
155 iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
156 iio_get_time_ns(indio_dev));
157 mutex_unlock(&adc->lock);
158 iio_trigger_notify_done(indio_dev->trig);
159
160 return IRQ_HANDLED;
161 }
162
adc084s021_buffer_preenable(struct iio_dev * indio_dev)163 static int adc084s021_buffer_preenable(struct iio_dev *indio_dev)
164 {
165 struct adc084s021 *adc = iio_priv(indio_dev);
166 int scan_index;
167 int i = 0;
168
169 iio_for_each_active_channel(indio_dev, scan_index) {
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 .postdisable = adc084s021_buffer_postdisable,
195 };
196
adc084s021_probe(struct spi_device * spi)197 static int adc084s021_probe(struct spi_device *spi)
198 {
199 struct iio_dev *indio_dev;
200 struct adc084s021 *adc;
201 int ret;
202
203 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
204 if (!indio_dev) {
205 dev_err(&spi->dev, "Failed to allocate IIO device\n");
206 return -ENOMEM;
207 }
208
209 adc = iio_priv(indio_dev);
210 adc->spi = spi;
211
212 /* Initiate the Industrial I/O device */
213 indio_dev->name = spi_get_device_id(spi)->name;
214 indio_dev->modes = INDIO_DIRECT_MODE;
215 indio_dev->info = &adc084s021_info;
216 indio_dev->channels = adc084s021_channels;
217 indio_dev->num_channels = ARRAY_SIZE(adc084s021_channels);
218
219 /* Create SPI transfer for channel reads */
220 adc->spi_trans.tx_buf = adc->tx_buf;
221 adc->spi_trans.rx_buf = adc->rx_buf;
222 adc->spi_trans.len = 4; /* Trash + single channel */
223 spi_message_init_with_transfers(&adc->message, &adc->spi_trans, 1);
224
225 adc->reg = devm_regulator_get(&spi->dev, "vref");
226 if (IS_ERR(adc->reg))
227 return PTR_ERR(adc->reg);
228
229 mutex_init(&adc->lock);
230
231 /* Setup triggered buffer with pollfunction */
232 ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
233 adc084s021_buffer_trigger_handler,
234 &adc084s021_buffer_setup_ops);
235 if (ret) {
236 dev_err(&spi->dev, "Failed to setup triggered buffer\n");
237 return ret;
238 }
239
240 return devm_iio_device_register(&spi->dev, indio_dev);
241 }
242
243 static const struct of_device_id adc084s021_of_match[] = {
244 { .compatible = "ti,adc084s021", },
245 { }
246 };
247 MODULE_DEVICE_TABLE(of, adc084s021_of_match);
248
249 static const struct spi_device_id adc084s021_id[] = {
250 { ADC084S021_DRIVER_NAME, 0 },
251 { }
252 };
253 MODULE_DEVICE_TABLE(spi, adc084s021_id);
254
255 static struct spi_driver adc084s021_driver = {
256 .driver = {
257 .name = ADC084S021_DRIVER_NAME,
258 .of_match_table = adc084s021_of_match,
259 },
260 .probe = adc084s021_probe,
261 .id_table = adc084s021_id,
262 };
263 module_spi_driver(adc084s021_driver);
264
265 MODULE_AUTHOR("Mårten Lindahl <martenli@axis.com>");
266 MODULE_DESCRIPTION("Texas Instruments ADC084S021");
267 MODULE_LICENSE("GPL v2");
268 MODULE_VERSION("1.0");
269