xref: /openbmc/linux/drivers/iio/adc/ti-tlc4541.c (revision 62fa19bf)
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 
33 struct 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 
48 struct tlc4541_chip_info {
49 	const struct iio_chan_spec *channels;
50 	unsigned int num_channels;
51 };
52 
53 enum 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) \
72 const struct iio_chan_spec name ## _channels[] = { \
73 	TLC4541_V_CHAN(bits, bitshift), \
74 	IIO_CHAN_SOFT_TIMESTAMP(1), \
75 }
76 
77 static DECLARE_TLC4541_CHANNELS(tlc3541, 14, 2);
78 static DECLARE_TLC4541_CHANNELS(tlc4541, 16, 0);
79 
80 static 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 
tlc4541_trigger_handler(int irq,void * p)91 static 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 
105 done:
106 	iio_trigger_notify_done(indio_dev->trig);
107 	return IRQ_HANDLED;
108 }
109 
tlc4541_get_range(struct tlc4541_state * st)110 static 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 
tlc4541_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long m)123 static 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 
156 static const struct iio_info tlc4541_info = {
157 	.read_raw = &tlc4541_read_raw,
158 };
159 
tlc4541_probe(struct spi_device * spi)160 static 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 
219 error_cleanup_buffer:
220 	iio_triggered_buffer_cleanup(indio_dev);
221 error_disable_reg:
222 	regulator_disable(st->reg);
223 
224 	return ret;
225 }
226 
tlc4541_remove(struct spi_device * spi)227 static 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 
237 static const struct of_device_id tlc4541_dt_ids[] = {
238 	{ .compatible = "ti,tlc3541", },
239 	{ .compatible = "ti,tlc4541", },
240 	{}
241 };
242 MODULE_DEVICE_TABLE(of, tlc4541_dt_ids);
243 
244 static const struct spi_device_id tlc4541_id[] = {
245 	{"tlc3541", TLC3541},
246 	{"tlc4541", TLC4541},
247 	{}
248 };
249 MODULE_DEVICE_TABLE(spi, tlc4541_id);
250 
251 static 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 };
260 module_spi_driver(tlc4541_driver);
261 
262 MODULE_AUTHOR("Phil Reid <preid@electromag.com.au>");
263 MODULE_DESCRIPTION("Texas Instruments TLC4541 ADC");
264 MODULE_LICENSE("GPL v2");
265