1 /*
2 * ad2s1200.c simple support for the ADI Resolver to Digital Converters:
3 * AD2S1200/1205
4 *
5 * Copyright (c) 2010-2010 Analog Devices Inc.
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 */
12 #include <linux/types.h>
13 #include <linux/mutex.h>
14 #include <linux/device.h>
15 #include <linux/spi/spi.h>
16 #include <linux/slab.h>
17 #include <linux/sysfs.h>
18 #include <linux/delay.h>
19 #include <linux/gpio.h>
20 #include <linux/module.h>
21 #include <linux/bitops.h>
22
23 #include <linux/iio/iio.h>
24 #include <linux/iio/sysfs.h>
25
26 #define DRV_NAME "ad2s1200"
27
28 /* input pin sample and rdvel is controlled by driver */
29 #define AD2S1200_PN 2
30
31 /* input clock on serial interface */
32 #define AD2S1200_HZ 8192000
33 /* clock period in nano second */
34 #define AD2S1200_TSCLK (1000000000/AD2S1200_HZ)
35
36 struct ad2s1200_state {
37 struct mutex lock;
38 struct spi_device *sdev;
39 int sample;
40 int rdvel;
41 u8 rx[2] ____cacheline_aligned;
42 };
43
ad2s1200_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long m)44 static int ad2s1200_read_raw(struct iio_dev *indio_dev,
45 struct iio_chan_spec const *chan,
46 int *val,
47 int *val2,
48 long m)
49 {
50 int ret = 0;
51 s16 vel;
52 struct ad2s1200_state *st = iio_priv(indio_dev);
53
54 mutex_lock(&st->lock);
55 gpio_set_value(st->sample, 0);
56 /* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
57 udelay(1);
58 gpio_set_value(st->sample, 1);
59 gpio_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
60 ret = spi_read(st->sdev, st->rx, 2);
61 if (ret < 0) {
62 mutex_unlock(&st->lock);
63 return ret;
64 }
65
66 switch (chan->type) {
67 case IIO_ANGL:
68 *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
69 break;
70 case IIO_ANGL_VEL:
71 vel = (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
72 vel = sign_extend32(vel, 11);
73 *val = vel;
74 break;
75 default:
76 mutex_unlock(&st->lock);
77 return -EINVAL;
78 }
79 /* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
80 udelay(1);
81 mutex_unlock(&st->lock);
82 return IIO_VAL_INT;
83 }
84
85 static const struct iio_chan_spec ad2s1200_channels[] = {
86 {
87 .type = IIO_ANGL,
88 .indexed = 1,
89 .channel = 0,
90 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
91 }, {
92 .type = IIO_ANGL_VEL,
93 .indexed = 1,
94 .channel = 0,
95 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
96 }
97 };
98
99 static const struct iio_info ad2s1200_info = {
100 .read_raw = &ad2s1200_read_raw,
101 .driver_module = THIS_MODULE,
102 };
103
ad2s1200_probe(struct spi_device * spi)104 static int ad2s1200_probe(struct spi_device *spi)
105 {
106 struct ad2s1200_state *st;
107 struct iio_dev *indio_dev;
108 int pn, ret = 0;
109 unsigned short *pins = spi->dev.platform_data;
110
111 for (pn = 0; pn < AD2S1200_PN; pn++) {
112 ret = devm_gpio_request_one(&spi->dev, pins[pn], GPIOF_DIR_OUT,
113 DRV_NAME);
114 if (ret) {
115 dev_err(&spi->dev, "request gpio pin %d failed\n",
116 pins[pn]);
117 return ret;
118 }
119 }
120 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
121 if (!indio_dev)
122 return -ENOMEM;
123 spi_set_drvdata(spi, indio_dev);
124 st = iio_priv(indio_dev);
125 mutex_init(&st->lock);
126 st->sdev = spi;
127 st->sample = pins[0];
128 st->rdvel = pins[1];
129
130 indio_dev->dev.parent = &spi->dev;
131 indio_dev->info = &ad2s1200_info;
132 indio_dev->modes = INDIO_DIRECT_MODE;
133 indio_dev->channels = ad2s1200_channels;
134 indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
135 indio_dev->name = spi_get_device_id(spi)->name;
136
137 ret = devm_iio_device_register(&spi->dev, indio_dev);
138 if (ret)
139 return ret;
140
141 spi->max_speed_hz = AD2S1200_HZ;
142 spi->mode = SPI_MODE_3;
143 spi_setup(spi);
144
145 return 0;
146 }
147
148 static const struct spi_device_id ad2s1200_id[] = {
149 { "ad2s1200" },
150 { "ad2s1205" },
151 {}
152 };
153 MODULE_DEVICE_TABLE(spi, ad2s1200_id);
154
155 static struct spi_driver ad2s1200_driver = {
156 .driver = {
157 .name = DRV_NAME,
158 },
159 .probe = ad2s1200_probe,
160 .id_table = ad2s1200_id,
161 };
162 module_spi_driver(ad2s1200_driver);
163
164 MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
165 MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
166 MODULE_LICENSE("GPL v2");
167