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
22 #include <linux/iio/iio.h>
23 #include <linux/iio/sysfs.h>
24
25 #define DRV_NAME "ad2s1200"
26
27 /* input pin sample and rdvel is controlled by driver */
28 #define AD2S1200_PN 2
29
30 /* input clock on serial interface */
31 #define AD2S1200_HZ 8192000
32 /* clock period in nano second */
33 #define AD2S1200_TSCLK (1000000000/AD2S1200_HZ)
34
35 struct ad2s1200_state {
36 struct mutex lock;
37 struct spi_device *sdev;
38 int sample;
39 int rdvel;
40 u8 rx[2] ____cacheline_aligned;
41 };
42
ad2s1200_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long m)43 static int ad2s1200_read_raw(struct iio_dev *indio_dev,
44 struct iio_chan_spec const *chan,
45 int *val,
46 int *val2,
47 long m)
48 {
49 int ret = 0;
50 s16 vel;
51 struct ad2s1200_state *st = iio_priv(indio_dev);
52
53 mutex_lock(&st->lock);
54 gpio_set_value(st->sample, 0);
55 /* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
56 udelay(1);
57 gpio_set_value(st->sample, 1);
58 gpio_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
59 ret = spi_read(st->sdev, st->rx, 2);
60 if (ret < 0) {
61 mutex_unlock(&st->lock);
62 return ret;
63 }
64
65 switch (chan->type) {
66 case IIO_ANGL:
67 *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
68 break;
69 case IIO_ANGL_VEL:
70 vel = (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
71 vel = (vel << 4) >> 4;
72 *val = vel;
73 break;
74 default:
75 mutex_unlock(&st->lock);
76 return -EINVAL;
77 }
78 /* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
79 udelay(1);
80 mutex_unlock(&st->lock);
81 return IIO_VAL_INT;
82 }
83
84 static const struct iio_chan_spec ad2s1200_channels[] = {
85 {
86 .type = IIO_ANGL,
87 .indexed = 1,
88 .channel = 0,
89 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
90 }, {
91 .type = IIO_ANGL_VEL,
92 .indexed = 1,
93 .channel = 0,
94 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
95 }
96 };
97
98 static const struct iio_info ad2s1200_info = {
99 .read_raw = &ad2s1200_read_raw,
100 .driver_module = THIS_MODULE,
101 };
102
ad2s1200_probe(struct spi_device * spi)103 static int ad2s1200_probe(struct spi_device *spi)
104 {
105 struct ad2s1200_state *st;
106 struct iio_dev *indio_dev;
107 int pn, ret = 0;
108 unsigned short *pins = spi->dev.platform_data;
109
110 for (pn = 0; pn < AD2S1200_PN; pn++) {
111 ret = devm_gpio_request_one(&spi->dev, pins[pn], GPIOF_DIR_OUT,
112 DRV_NAME);
113 if (ret) {
114 dev_err(&spi->dev, "request gpio pin %d failed\n",
115 pins[pn]);
116 return ret;
117 }
118 }
119 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
120 if (!indio_dev)
121 return -ENOMEM;
122 spi_set_drvdata(spi, indio_dev);
123 st = iio_priv(indio_dev);
124 mutex_init(&st->lock);
125 st->sdev = spi;
126 st->sample = pins[0];
127 st->rdvel = pins[1];
128
129 indio_dev->dev.parent = &spi->dev;
130 indio_dev->info = &ad2s1200_info;
131 indio_dev->modes = INDIO_DIRECT_MODE;
132 indio_dev->channels = ad2s1200_channels;
133 indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
134 indio_dev->name = spi_get_device_id(spi)->name;
135
136 ret = devm_iio_device_register(&spi->dev, indio_dev);
137 if (ret)
138 return ret;
139
140 spi->max_speed_hz = AD2S1200_HZ;
141 spi->mode = SPI_MODE_3;
142 spi_setup(spi);
143
144 return 0;
145 }
146
147 static const struct spi_device_id ad2s1200_id[] = {
148 { "ad2s1200" },
149 { "ad2s1205" },
150 {}
151 };
152 MODULE_DEVICE_TABLE(spi, ad2s1200_id);
153
154 static struct spi_driver ad2s1200_driver = {
155 .driver = {
156 .name = DRV_NAME,
157 .owner = THIS_MODULE,
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