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1 | /* |
2 | * TI tlc4541 ADC Driver | |
3 | * | |
4 | * Copyright (C) 2017 Phil Reid | |
5 | * | |
6 | * Datasheets can be found here: | |
7 | * http://www.ti.com/lit/gpn/tlc3541 | |
8 | * http://www.ti.com/lit/gpn/tlc4541 | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or modify | |
11 | * it under the terms of the GNU General Public License version 2 as | |
12 | * published by the Free Software Foundation. | |
13 | * | |
14 | * The tlc4541 requires 24 clock cycles to start a transfer. | |
15 | * Conversion then takes 2.94us to complete before data is ready | |
16 | * Data is returned MSB first. | |
17 | */ | |
18 | ||
19 | #include <linux/delay.h> | |
20 | #include <linux/device.h> | |
21 | #include <linux/err.h> | |
22 | #include <linux/interrupt.h> | |
23 | #include <linux/iio/iio.h> | |
24 | #include <linux/iio/sysfs.h> | |
25 | #include <linux/iio/buffer.h> | |
26 | #include <linux/iio/trigger_consumer.h> | |
27 | #include <linux/iio/triggered_buffer.h> | |
28 | #include <linux/kernel.h> | |
29 | #include <linux/module.h> | |
30 | #include <linux/regulator/consumer.h> | |
31 | #include <linux/slab.h> | |
32 | #include <linux/spi/spi.h> | |
33 | #include <linux/sysfs.h> | |
34 | ||
35 | struct tlc4541_state { | |
36 | struct spi_device *spi; | |
37 | struct regulator *reg; | |
38 | struct spi_transfer scan_single_xfer[3]; | |
39 | struct spi_message scan_single_msg; | |
40 | ||
41 | /* | |
42 | * DMA (thus cache coherency maintenance) requires the | |
43 | * transfer buffers to live in their own cache lines. | |
44 | * 2 bytes data + 6 bytes padding + 8 bytes timestamp when | |
45 | * call iio_push_to_buffers_with_timestamp. | |
46 | */ | |
47 | __be16 rx_buf[8] ____cacheline_aligned; | |
48 | }; | |
49 | ||
50 | struct tlc4541_chip_info { | |
51 | const struct iio_chan_spec *channels; | |
52 | unsigned int num_channels; | |
53 | }; | |
54 | ||
55 | enum tlc4541_id { | |
56 | TLC3541, | |
57 | TLC4541, | |
58 | }; | |
59 | ||
60 | #define TLC4541_V_CHAN(bits, bitshift) { \ | |
61 | .type = IIO_VOLTAGE, \ | |
62 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ | |
63 | .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ | |
64 | .scan_type = { \ | |
65 | .sign = 'u', \ | |
66 | .realbits = (bits), \ | |
67 | .storagebits = 16, \ | |
68 | .shift = (bitshift), \ | |
69 | .endianness = IIO_BE, \ | |
70 | }, \ | |
71 | } | |
72 | ||
73 | #define DECLARE_TLC4541_CHANNELS(name, bits, bitshift) \ | |
74 | const struct iio_chan_spec name ## _channels[] = { \ | |
75 | TLC4541_V_CHAN(bits, bitshift), \ | |
76 | IIO_CHAN_SOFT_TIMESTAMP(1), \ | |
77 | } | |
78 | ||
79 | static DECLARE_TLC4541_CHANNELS(tlc3541, 14, 2); | |
80 | static DECLARE_TLC4541_CHANNELS(tlc4541, 16, 0); | |
81 | ||
82 | static const struct tlc4541_chip_info tlc4541_chip_info[] = { | |
83 | [TLC3541] = { | |
84 | .channels = tlc3541_channels, | |
85 | .num_channels = ARRAY_SIZE(tlc3541_channels), | |
86 | }, | |
87 | [TLC4541] = { | |
88 | .channels = tlc4541_channels, | |
89 | .num_channels = ARRAY_SIZE(tlc4541_channels), | |
90 | }, | |
91 | }; | |
92 | ||
93 | static irqreturn_t tlc4541_trigger_handler(int irq, void *p) | |
94 | { | |
95 | struct iio_poll_func *pf = p; | |
96 | struct iio_dev *indio_dev = pf->indio_dev; | |
97 | struct tlc4541_state *st = iio_priv(indio_dev); | |
98 | int ret; | |
99 | ||
100 | ret = spi_sync(st->spi, &st->scan_single_msg); | |
101 | if (ret < 0) | |
102 | goto done; | |
103 | ||
104 | iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf, | |
105 | iio_get_time_ns(indio_dev)); | |
106 | ||
107 | done: | |
108 | iio_trigger_notify_done(indio_dev->trig); | |
109 | return IRQ_HANDLED; | |
110 | } | |
111 | ||
112 | static int tlc4541_get_range(struct tlc4541_state *st) | |
113 | { | |
114 | int vref; | |
115 | ||
116 | vref = regulator_get_voltage(st->reg); | |
117 | if (vref < 0) | |
118 | return vref; | |
119 | ||
120 | vref /= 1000; | |
121 | ||
122 | return vref; | |
123 | } | |
124 | ||
125 | static int tlc4541_read_raw(struct iio_dev *indio_dev, | |
126 | struct iio_chan_spec const *chan, | |
127 | int *val, | |
128 | int *val2, | |
129 | long m) | |
130 | { | |
131 | int ret = 0; | |
132 | struct tlc4541_state *st = iio_priv(indio_dev); | |
133 | ||
134 | switch (m) { | |
135 | case IIO_CHAN_INFO_RAW: | |
136 | ret = iio_device_claim_direct_mode(indio_dev); | |
137 | if (ret) | |
138 | return ret; | |
139 | ret = spi_sync(st->spi, &st->scan_single_msg); | |
140 | iio_device_release_direct_mode(indio_dev); | |
141 | if (ret < 0) | |
142 | return ret; | |
143 | *val = be16_to_cpu(st->rx_buf[0]); | |
144 | *val = *val >> chan->scan_type.shift; | |
145 | *val &= GENMASK(chan->scan_type.realbits - 1, 0); | |
146 | return IIO_VAL_INT; | |
147 | case IIO_CHAN_INFO_SCALE: | |
148 | ret = tlc4541_get_range(st); | |
149 | if (ret < 0) | |
150 | return ret; | |
151 | *val = ret; | |
152 | *val2 = chan->scan_type.realbits; | |
153 | return IIO_VAL_FRACTIONAL_LOG2; | |
154 | } | |
155 | return -EINVAL; | |
156 | } | |
157 | ||
158 | static const struct iio_info tlc4541_info = { | |
159 | .read_raw = &tlc4541_read_raw, | |
160 | .driver_module = THIS_MODULE, | |
161 | }; | |
162 | ||
163 | static int tlc4541_probe(struct spi_device *spi) | |
164 | { | |
165 | struct tlc4541_state *st; | |
166 | struct iio_dev *indio_dev; | |
167 | const struct tlc4541_chip_info *info; | |
168 | int ret; | |
169 | int8_t device_init = 0; | |
170 | ||
171 | indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st)); | |
172 | if (indio_dev == NULL) | |
173 | return -ENOMEM; | |
174 | ||
175 | st = iio_priv(indio_dev); | |
176 | ||
177 | spi_set_drvdata(spi, indio_dev); | |
178 | ||
179 | st->spi = spi; | |
180 | ||
181 | info = &tlc4541_chip_info[spi_get_device_id(spi)->driver_data]; | |
182 | ||
183 | indio_dev->name = spi_get_device_id(spi)->name; | |
184 | indio_dev->dev.parent = &spi->dev; | |
185 | indio_dev->modes = INDIO_DIRECT_MODE; | |
186 | indio_dev->channels = info->channels; | |
187 | indio_dev->num_channels = info->num_channels; | |
188 | indio_dev->info = &tlc4541_info; | |
189 | ||
190 | /* perform reset */ | |
191 | spi_write(spi, &device_init, 1); | |
192 | ||
193 | /* Setup default message */ | |
194 | st->scan_single_xfer[0].rx_buf = &st->rx_buf[0]; | |
195 | st->scan_single_xfer[0].len = 3; | |
196 | st->scan_single_xfer[1].delay_usecs = 3; | |
197 | st->scan_single_xfer[2].rx_buf = &st->rx_buf[0]; | |
198 | st->scan_single_xfer[2].len = 2; | |
199 | ||
200 | spi_message_init_with_transfers(&st->scan_single_msg, | |
201 | st->scan_single_xfer, 3); | |
202 | ||
203 | st->reg = devm_regulator_get(&spi->dev, "vref"); | |
204 | if (IS_ERR(st->reg)) | |
205 | return PTR_ERR(st->reg); | |
206 | ||
207 | ret = regulator_enable(st->reg); | |
208 | if (ret) | |
209 | return ret; | |
210 | ||
211 | ret = iio_triggered_buffer_setup(indio_dev, NULL, | |
212 | &tlc4541_trigger_handler, NULL); | |
213 | if (ret) | |
214 | goto error_disable_reg; | |
215 | ||
216 | ret = iio_device_register(indio_dev); | |
217 | if (ret) | |
218 | goto error_cleanup_buffer; | |
219 | ||
220 | return 0; | |
221 | ||
222 | error_cleanup_buffer: | |
223 | iio_triggered_buffer_cleanup(indio_dev); | |
224 | error_disable_reg: | |
225 | regulator_disable(st->reg); | |
226 | ||
227 | return ret; | |
228 | } | |
229 | ||
230 | static int tlc4541_remove(struct spi_device *spi) | |
231 | { | |
232 | struct iio_dev *indio_dev = spi_get_drvdata(spi); | |
233 | struct tlc4541_state *st = iio_priv(indio_dev); | |
234 | ||
235 | iio_device_unregister(indio_dev); | |
236 | iio_triggered_buffer_cleanup(indio_dev); | |
237 | regulator_disable(st->reg); | |
238 | ||
239 | return 0; | |
240 | } | |
241 | ||
242 | #ifdef CONFIG_OF | |
243 | static const struct of_device_id tlc4541_dt_ids[] = { | |
244 | { .compatible = "ti,tlc3541", }, | |
245 | { .compatible = "ti,tlc4541", }, | |
246 | {} | |
247 | }; | |
248 | MODULE_DEVICE_TABLE(of, tlc4541_dt_ids); | |
249 | #endif | |
250 | ||
251 | static const struct spi_device_id tlc4541_id[] = { | |
252 | {"tlc3541", TLC3541}, | |
253 | {"tlc4541", TLC4541}, | |
254 | {} | |
255 | }; | |
256 | MODULE_DEVICE_TABLE(spi, tlc4541_id); | |
257 | ||
258 | static struct spi_driver tlc4541_driver = { | |
259 | .driver = { | |
260 | .name = "tlc4541", | |
261 | .of_match_table = of_match_ptr(tlc4541_dt_ids), | |
262 | }, | |
263 | .probe = tlc4541_probe, | |
264 | .remove = tlc4541_remove, | |
265 | .id_table = tlc4541_id, | |
266 | }; | |
267 | module_spi_driver(tlc4541_driver); | |
268 | ||
269 | MODULE_AUTHOR("Phil Reid <preid@electromag.com.au>"); | |
270 | MODULE_DESCRIPTION("Texas Instruments TLC4541 ADC"); | |
271 | MODULE_LICENSE("GPL v2"); |