1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * ad2s1200.c simple support for the ADI Resolver to Digital Converters:
4  * AD2S1200/1205
5  *
6  * Copyright (c) 2018-2018 David Veenstra <davidjulianveenstra@gmail.com>
7  * Copyright (c) 2010-2010 Analog Devices Inc.
8  */
9 
10 #include <linux/bitops.h>
11 #include <linux/delay.h>
12 #include <linux/device.h>
13 #include <linux/gpio/consumer.h>
14 #include <linux/module.h>
15 #include <linux/mod_devicetable.h>
16 #include <linux/mutex.h>
17 #include <linux/spi/spi.h>
18 #include <linux/sysfs.h>
19 #include <linux/types.h>
20 
21 #include <linux/iio/iio.h>
22 #include <linux/iio/sysfs.h>
23 
24 #define DRV_NAME "ad2s1200"
25 
26 /* input clock on serial interface */
27 #define AD2S1200_HZ	8192000
28 /* clock period in nano second */
29 #define AD2S1200_TSCLK	(1000000000 / AD2S1200_HZ)
30 
31 /**
32  * struct ad2s1200_state - driver instance specific data.
33  * @lock:	protects both the GPIO pins and the rx buffer.
34  * @sdev:	spi device.
35  * @sample:	GPIO pin SAMPLE.
36  * @rdvel:	GPIO pin RDVEL.
37  * @rx:		buffer for spi transfers.
38  */
39 struct ad2s1200_state {
40 	struct mutex lock;
41 	struct spi_device *sdev;
42 	struct gpio_desc *sample;
43 	struct gpio_desc *rdvel;
44 	__be16 rx ____cacheline_aligned;
45 };
46 
ad2s1200_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long m)47 static int ad2s1200_read_raw(struct iio_dev *indio_dev,
48 			     struct iio_chan_spec const *chan,
49 			     int *val,
50 			     int *val2,
51 			     long m)
52 {
53 	struct ad2s1200_state *st = iio_priv(indio_dev);
54 	int ret;
55 
56 	switch (m) {
57 	case IIO_CHAN_INFO_SCALE:
58 		switch (chan->type) {
59 		case IIO_ANGL:
60 			/* 2 * Pi / (2^12 - 1) ~= 0.001534355 */
61 			*val = 0;
62 			*val2 = 1534355;
63 			return IIO_VAL_INT_PLUS_NANO;
64 		case IIO_ANGL_VEL:
65 			/* 2 * Pi ~= 6.283185 */
66 			*val = 6;
67 			*val2 = 283185;
68 			return IIO_VAL_INT_PLUS_MICRO;
69 		default:
70 			return -EINVAL;
71 		}
72 		break;
73 	case IIO_CHAN_INFO_RAW:
74 		mutex_lock(&st->lock);
75 		gpiod_set_value(st->sample, 0);
76 
77 		/* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
78 		udelay(1);
79 		gpiod_set_value(st->sample, 1);
80 		gpiod_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
81 
82 		ret = spi_read(st->sdev, &st->rx, 2);
83 		if (ret < 0) {
84 			mutex_unlock(&st->lock);
85 			return ret;
86 		}
87 
88 		switch (chan->type) {
89 		case IIO_ANGL:
90 			*val = be16_to_cpup(&st->rx) >> 4;
91 			break;
92 		case IIO_ANGL_VEL:
93 			*val = sign_extend32(be16_to_cpup(&st->rx) >> 4, 11);
94 			break;
95 		default:
96 			mutex_unlock(&st->lock);
97 			return -EINVAL;
98 		}
99 
100 		/* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
101 		udelay(1);
102 		mutex_unlock(&st->lock);
103 
104 		return IIO_VAL_INT;
105 	default:
106 		break;
107 	}
108 
109 	return -EINVAL;
110 }
111 
112 static const struct iio_chan_spec ad2s1200_channels[] = {
113 	{
114 		.type = IIO_ANGL,
115 		.indexed = 1,
116 		.channel = 0,
117 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
118 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
119 	}, {
120 		.type = IIO_ANGL_VEL,
121 		.indexed = 1,
122 		.channel = 0,
123 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
124 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
125 	}
126 };
127 
128 static const struct iio_info ad2s1200_info = {
129 	.read_raw = ad2s1200_read_raw,
130 };
131 
ad2s1200_probe(struct spi_device * spi)132 static int ad2s1200_probe(struct spi_device *spi)
133 {
134 	struct ad2s1200_state *st;
135 	struct iio_dev *indio_dev;
136 	int ret;
137 
138 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
139 	if (!indio_dev)
140 		return -ENOMEM;
141 
142 	spi_set_drvdata(spi, indio_dev);
143 	st = iio_priv(indio_dev);
144 	mutex_init(&st->lock);
145 	st->sdev = spi;
146 
147 	st->sample = devm_gpiod_get(&spi->dev, "adi,sample", GPIOD_OUT_LOW);
148 	if (IS_ERR(st->sample)) {
149 		dev_err(&spi->dev, "Failed to claim SAMPLE gpio: err=%ld\n",
150 			PTR_ERR(st->sample));
151 		return PTR_ERR(st->sample);
152 	}
153 
154 	st->rdvel = devm_gpiod_get(&spi->dev, "adi,rdvel", GPIOD_OUT_LOW);
155 	if (IS_ERR(st->rdvel)) {
156 		dev_err(&spi->dev, "Failed to claim RDVEL gpio: err=%ld\n",
157 			PTR_ERR(st->rdvel));
158 		return PTR_ERR(st->rdvel);
159 	}
160 
161 	indio_dev->info = &ad2s1200_info;
162 	indio_dev->modes = INDIO_DIRECT_MODE;
163 	indio_dev->channels = ad2s1200_channels;
164 	indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
165 	indio_dev->name = spi_get_device_id(spi)->name;
166 
167 	spi->max_speed_hz = AD2S1200_HZ;
168 	spi->mode = SPI_MODE_3;
169 	ret = spi_setup(spi);
170 
171 	if (ret < 0) {
172 		dev_err(&spi->dev, "spi_setup failed!\n");
173 		return ret;
174 	}
175 
176 	return devm_iio_device_register(&spi->dev, indio_dev);
177 }
178 
179 static const struct of_device_id ad2s1200_of_match[] = {
180 	{ .compatible = "adi,ad2s1200", },
181 	{ .compatible = "adi,ad2s1205", },
182 	{ }
183 };
184 MODULE_DEVICE_TABLE(of, ad2s1200_of_match);
185 
186 static const struct spi_device_id ad2s1200_id[] = {
187 	{ "ad2s1200" },
188 	{ "ad2s1205" },
189 	{}
190 };
191 MODULE_DEVICE_TABLE(spi, ad2s1200_id);
192 
193 static struct spi_driver ad2s1200_driver = {
194 	.driver = {
195 		.name = DRV_NAME,
196 		.of_match_table = ad2s1200_of_match,
197 	},
198 	.probe = ad2s1200_probe,
199 	.id_table = ad2s1200_id,
200 };
201 module_spi_driver(ad2s1200_driver);
202 
203 MODULE_AUTHOR("David Veenstra <davidjulianveenstra@gmail.com>");
204 MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
205 MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
206 MODULE_LICENSE("GPL v2");
207