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