xref: /openbmc/linux/drivers/iio/adc/ti-tlc4541.c (revision 7f877908)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * TI tlc4541 ADC Driver
4  *
5  * Copyright (C) 2017 Phil Reid
6  *
7  * Datasheets can be found here:
8  * http://www.ti.com/lit/gpn/tlc3541
9  * http://www.ti.com/lit/gpn/tlc4541
10  *
11  * The tlc4541 requires 24 clock cycles to start a transfer.
12  * Conversion then takes 2.94us to complete before data is ready
13  * Data is returned MSB first.
14  */
15 
16 #include <linux/delay.h>
17 #include <linux/device.h>
18 #include <linux/err.h>
19 #include <linux/interrupt.h>
20 #include <linux/iio/iio.h>
21 #include <linux/iio/sysfs.h>
22 #include <linux/iio/buffer.h>
23 #include <linux/iio/trigger_consumer.h>
24 #include <linux/iio/triggered_buffer.h>
25 #include <linux/kernel.h>
26 #include <linux/module.h>
27 #include <linux/regulator/consumer.h>
28 #include <linux/slab.h>
29 #include <linux/spi/spi.h>
30 #include <linux/sysfs.h>
31 
32 struct tlc4541_state {
33 	struct spi_device               *spi;
34 	struct regulator                *reg;
35 	struct spi_transfer             scan_single_xfer[3];
36 	struct spi_message              scan_single_msg;
37 
38 	/*
39 	 * DMA (thus cache coherency maintenance) requires the
40 	 * transfer buffers to live in their own cache lines.
41 	 * 2 bytes data + 6 bytes padding + 8 bytes timestamp when
42 	 * call iio_push_to_buffers_with_timestamp.
43 	 */
44 	__be16                          rx_buf[8] ____cacheline_aligned;
45 };
46 
47 struct tlc4541_chip_info {
48 	const struct iio_chan_spec *channels;
49 	unsigned int num_channels;
50 };
51 
52 enum tlc4541_id {
53 	TLC3541,
54 	TLC4541,
55 };
56 
57 #define TLC4541_V_CHAN(bits, bitshift) {                              \
58 		.type = IIO_VOLTAGE,                                  \
59 		.info_mask_separate       = BIT(IIO_CHAN_INFO_RAW),   \
60 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
61 		.scan_type = {                                        \
62 			.sign = 'u',                                  \
63 			.realbits = (bits),                           \
64 			.storagebits = 16,                            \
65 			.shift = (bitshift),                          \
66 			.endianness = IIO_BE,                         \
67 		},                                                    \
68 	}
69 
70 #define DECLARE_TLC4541_CHANNELS(name, bits, bitshift) \
71 const struct iio_chan_spec name ## _channels[] = { \
72 	TLC4541_V_CHAN(bits, bitshift), \
73 	IIO_CHAN_SOFT_TIMESTAMP(1), \
74 }
75 
76 static DECLARE_TLC4541_CHANNELS(tlc3541, 14, 2);
77 static DECLARE_TLC4541_CHANNELS(tlc4541, 16, 0);
78 
79 static const struct tlc4541_chip_info tlc4541_chip_info[] = {
80 	[TLC3541] = {
81 		.channels = tlc3541_channels,
82 		.num_channels = ARRAY_SIZE(tlc3541_channels),
83 	},
84 	[TLC4541] = {
85 		.channels = tlc4541_channels,
86 		.num_channels = ARRAY_SIZE(tlc4541_channels),
87 	},
88 };
89 
90 static irqreturn_t tlc4541_trigger_handler(int irq, void *p)
91 {
92 	struct iio_poll_func *pf = p;
93 	struct iio_dev *indio_dev = pf->indio_dev;
94 	struct tlc4541_state *st = iio_priv(indio_dev);
95 	int ret;
96 
97 	ret = spi_sync(st->spi, &st->scan_single_msg);
98 	if (ret < 0)
99 		goto done;
100 
101 	iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
102 					   iio_get_time_ns(indio_dev));
103 
104 done:
105 	iio_trigger_notify_done(indio_dev->trig);
106 	return IRQ_HANDLED;
107 }
108 
109 static int tlc4541_get_range(struct tlc4541_state *st)
110 {
111 	int vref;
112 
113 	vref = regulator_get_voltage(st->reg);
114 	if (vref < 0)
115 		return vref;
116 
117 	vref /= 1000;
118 
119 	return vref;
120 }
121 
122 static int tlc4541_read_raw(struct iio_dev *indio_dev,
123 			    struct iio_chan_spec const *chan,
124 			    int *val,
125 			    int *val2,
126 			    long m)
127 {
128 	int ret = 0;
129 	struct tlc4541_state *st = iio_priv(indio_dev);
130 
131 	switch (m) {
132 	case IIO_CHAN_INFO_RAW:
133 		ret = iio_device_claim_direct_mode(indio_dev);
134 		if (ret)
135 			return ret;
136 		ret = spi_sync(st->spi, &st->scan_single_msg);
137 		iio_device_release_direct_mode(indio_dev);
138 		if (ret < 0)
139 			return ret;
140 		*val = be16_to_cpu(st->rx_buf[0]);
141 		*val = *val >> chan->scan_type.shift;
142 		*val &= GENMASK(chan->scan_type.realbits - 1, 0);
143 		return IIO_VAL_INT;
144 	case IIO_CHAN_INFO_SCALE:
145 		ret = tlc4541_get_range(st);
146 		if (ret < 0)
147 			return ret;
148 		*val = ret;
149 		*val2 = chan->scan_type.realbits;
150 		return IIO_VAL_FRACTIONAL_LOG2;
151 	}
152 	return -EINVAL;
153 }
154 
155 static const struct iio_info tlc4541_info = {
156 	.read_raw = &tlc4541_read_raw,
157 };
158 
159 static int tlc4541_probe(struct spi_device *spi)
160 {
161 	struct tlc4541_state *st;
162 	struct iio_dev *indio_dev;
163 	const struct tlc4541_chip_info *info;
164 	int ret;
165 	int8_t device_init = 0;
166 
167 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
168 	if (indio_dev == NULL)
169 		return -ENOMEM;
170 
171 	st = iio_priv(indio_dev);
172 
173 	spi_set_drvdata(spi, indio_dev);
174 
175 	st->spi = spi;
176 
177 	info = &tlc4541_chip_info[spi_get_device_id(spi)->driver_data];
178 
179 	indio_dev->name = spi_get_device_id(spi)->name;
180 	indio_dev->dev.parent = &spi->dev;
181 	indio_dev->modes = INDIO_DIRECT_MODE;
182 	indio_dev->channels = info->channels;
183 	indio_dev->num_channels = info->num_channels;
184 	indio_dev->info = &tlc4541_info;
185 
186 	/* perform reset */
187 	spi_write(spi, &device_init, 1);
188 
189 	/* Setup default message */
190 	st->scan_single_xfer[0].rx_buf = &st->rx_buf[0];
191 	st->scan_single_xfer[0].len = 3;
192 	st->scan_single_xfer[1].delay_usecs = 3;
193 	st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
194 	st->scan_single_xfer[2].len = 2;
195 
196 	spi_message_init_with_transfers(&st->scan_single_msg,
197 					st->scan_single_xfer, 3);
198 
199 	st->reg = devm_regulator_get(&spi->dev, "vref");
200 	if (IS_ERR(st->reg))
201 		return PTR_ERR(st->reg);
202 
203 	ret = regulator_enable(st->reg);
204 	if (ret)
205 		return ret;
206 
207 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
208 			&tlc4541_trigger_handler, NULL);
209 	if (ret)
210 		goto error_disable_reg;
211 
212 	ret = iio_device_register(indio_dev);
213 	if (ret)
214 		goto error_cleanup_buffer;
215 
216 	return 0;
217 
218 error_cleanup_buffer:
219 	iio_triggered_buffer_cleanup(indio_dev);
220 error_disable_reg:
221 	regulator_disable(st->reg);
222 
223 	return ret;
224 }
225 
226 static int tlc4541_remove(struct spi_device *spi)
227 {
228 	struct iio_dev *indio_dev = spi_get_drvdata(spi);
229 	struct tlc4541_state *st = iio_priv(indio_dev);
230 
231 	iio_device_unregister(indio_dev);
232 	iio_triggered_buffer_cleanup(indio_dev);
233 	regulator_disable(st->reg);
234 
235 	return 0;
236 }
237 
238 #ifdef CONFIG_OF
239 static const struct of_device_id tlc4541_dt_ids[] = {
240 	{ .compatible = "ti,tlc3541", },
241 	{ .compatible = "ti,tlc4541", },
242 	{}
243 };
244 MODULE_DEVICE_TABLE(of, tlc4541_dt_ids);
245 #endif
246 
247 static const struct spi_device_id tlc4541_id[] = {
248 	{"tlc3541", TLC3541},
249 	{"tlc4541", TLC4541},
250 	{}
251 };
252 MODULE_DEVICE_TABLE(spi, tlc4541_id);
253 
254 static struct spi_driver tlc4541_driver = {
255 	.driver = {
256 		.name   = "tlc4541",
257 		.of_match_table = of_match_ptr(tlc4541_dt_ids),
258 	},
259 	.probe          = tlc4541_probe,
260 	.remove         = tlc4541_remove,
261 	.id_table       = tlc4541_id,
262 };
263 module_spi_driver(tlc4541_driver);
264 
265 MODULE_AUTHOR("Phil Reid <preid@electromag.com.au>");
266 MODULE_DESCRIPTION("Texas Instruments TLC4541 ADC");
267 MODULE_LICENSE("GPL v2");
268