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 "../iio.h"
23 #include "../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 default:
74 mutex_unlock(&st->lock);
75 return -EINVAL;
76 }
77 /* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
78 udelay(1);
79 mutex_unlock(&st->lock);
80 return IIO_VAL_INT;
81 }
82
83 static const struct iio_chan_spec ad2s1200_channels[] = {
84 {
85 .type = IIO_ANGL,
86 .indexed = 1,
87 .channel = 0,
88 }, {
89 .type = IIO_ANGL_VEL,
90 .indexed = 1,
91 .channel = 0,
92 }
93 };
94
95 static const struct iio_info ad2s1200_info = {
96 .read_raw = &ad2s1200_read_raw,
97 .driver_module = THIS_MODULE,
98 };
99
ad2s1200_probe(struct spi_device * spi)100 static int __devinit ad2s1200_probe(struct spi_device *spi)
101 {
102 struct ad2s1200_state *st;
103 struct iio_dev *indio_dev;
104 int pn, ret = 0;
105 unsigned short *pins = spi->dev.platform_data;
106
107 for (pn = 0; pn < AD2S1200_PN; pn++)
108 if (gpio_request_one(pins[pn], GPIOF_DIR_OUT, DRV_NAME)) {
109 pr_err("%s: request gpio pin %d failed\n",
110 DRV_NAME, pins[pn]);
111 goto error_ret;
112 }
113 indio_dev = iio_allocate_device(sizeof(*st));
114 if (indio_dev == NULL) {
115 ret = -ENOMEM;
116 goto error_ret;
117 }
118 spi_set_drvdata(spi, indio_dev);
119 st = iio_priv(indio_dev);
120 mutex_init(&st->lock);
121 st->sdev = spi;
122 st->sample = pins[0];
123 st->rdvel = pins[1];
124
125 indio_dev->dev.parent = &spi->dev;
126 indio_dev->info = &ad2s1200_info;
127 indio_dev->modes = INDIO_DIRECT_MODE;
128 indio_dev->channels = ad2s1200_channels;
129 indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
130 indio_dev->name = spi_get_device_id(spi)->name;
131
132 ret = iio_device_register(indio_dev);
133 if (ret)
134 goto error_free_dev;
135
136 spi->max_speed_hz = AD2S1200_HZ;
137 spi->mode = SPI_MODE_3;
138 spi_setup(spi);
139
140 return 0;
141
142 error_free_dev:
143 iio_free_device(indio_dev);
144 error_ret:
145 for (--pn; pn >= 0; pn--)
146 gpio_free(pins[pn]);
147 return ret;
148 }
149
ad2s1200_remove(struct spi_device * spi)150 static int __devexit ad2s1200_remove(struct spi_device *spi)
151 {
152 iio_device_unregister(spi_get_drvdata(spi));
153 iio_free_device(spi_get_drvdata(spi));
154
155 return 0;
156 }
157
158 static const struct spi_device_id ad2s1200_id[] = {
159 { "ad2s1200" },
160 { "ad2s1205" },
161 {}
162 };
163 MODULE_DEVICE_TABLE(spi, ad2s1200_id);
164
165 static struct spi_driver ad2s1200_driver = {
166 .driver = {
167 .name = DRV_NAME,
168 .owner = THIS_MODULE,
169 },
170 .probe = ad2s1200_probe,
171 .remove = __devexit_p(ad2s1200_remove),
172 .id_table = ad2s1200_id,
173 };
174 module_spi_driver(ad2s1200_driver);
175
176 MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
177 MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
178 MODULE_LICENSE("GPL v2");
179