1 /*
2  * ad2s120x.c simple support for the ADI Resolver to Digital Converters: AD2S1200/1205
3  *
4  * Copyright (c) 2010-2010 Analog Devices Inc.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  *
10  */
11 #include <linux/types.h>
12 #include <linux/mutex.h>
13 #include <linux/device.h>
14 #include <linux/spi/spi.h>
15 #include <linux/slab.h>
16 #include <linux/sysfs.h>
17 #include <linux/delay.h>
18 #include <linux/gpio.h>
19 
20 #include "../iio.h"
21 #include "../sysfs.h"
22 
23 #define DRV_NAME "ad2s120x"
24 
25 /* input pin sample and rdvel is controlled by driver */
26 #define AD2S120X_PN	2
27 
28 /* input clock on serial interface */
29 #define AD2S120X_HZ	8192000
30 /* clock period in nano second */
31 #define AD2S120X_TSCLK	(1000000000/AD2S120X_HZ)
32 
33 struct ad2s120x_state {
34 	struct mutex lock;
35 	struct iio_dev *idev;
36 	struct spi_device *sdev;
37 	unsigned short sample;
38 	unsigned short rdvel;
39 	u8 rx[2];
40 	u8 tx[2];
41 };
42 
ad2s120x_show_pos_vel(struct device * dev,struct device_attribute * attr,char * buf)43 static ssize_t ad2s120x_show_pos_vel(struct device *dev,
44 			struct device_attribute *attr, char *buf)
45 {
46 	struct spi_message msg;
47 	struct spi_transfer xfer;
48 	int ret = 0;
49 	ssize_t len = 0;
50 	u16 pos;
51 	s16 vel;
52 	u8 status;
53 	struct iio_dev *idev = dev_get_drvdata(dev);
54 	struct ad2s120x_state *st = idev->dev_data;
55 
56 	xfer.len = 1;
57 	xfer.tx_buf = st->tx;
58 	xfer.rx_buf = st->rx;
59 	mutex_lock(&st->lock);
60 
61 	gpio_set_value(st->sample, 0);
62 	/* delay (6 * AD2S120X_TSCLK + 20) nano seconds */
63 	udelay(1);
64 	gpio_set_value(st->sample, 1);
65 
66 	spi_message_init(&msg);
67 	spi_message_add_tail(&xfer, &msg);
68 	ret = spi_sync(st->sdev, &msg);
69 	if (ret)
70 		goto error_ret;
71 	status = st->rx[1];
72 	pos = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
73 	len = sprintf(buf, "%d %c%c%c%c ", pos,
74 				(status & 0x8) ? 'P' : 'V',
75 				(status & 0x4) ? 'd' : '_',
76 				(status & 0x2) ? 'l' : '_',
77 				(status & 0x1) ? '1' : '0');
78 
79 	/* delay 18 ns */
80 	/* ndelay(18); */
81 
82 	gpio_set_value(st->rdvel, 0);
83 	/* ndelay(5);*/
84 
85 	spi_message_init(&msg);
86 	spi_message_add_tail(&xfer, &msg);
87 	ret = spi_sync(st->sdev, &msg);
88 	if (ret)
89 		goto error_ret;
90 	status = st->rx[1];
91 	vel = (st->rx[0] & 0x80) ? 0xf000 : 0;
92 	vel |= (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
93 	len += sprintf(buf + len, "%d %c%c%c%c\n", vel,
94 				(status & 0x8) ? 'P' : 'V',
95 				(status & 0x4) ? 'd' : '_',
96 				(status & 0x2) ? 'l' : '_',
97 				(status & 0x1) ? '1' : '0');
98 error_ret:
99 	gpio_set_value(st->rdvel, 1);
100 	/* delay (2 * AD2S120X_TSCLK + 20) ns for sample pulse */
101 	udelay(1);
102 	mutex_unlock(&st->lock);
103 
104 	return ret ? ret : len;
105 }
106 
ad2s120x_show_pos(struct device * dev,struct device_attribute * attr,char * buf)107 static ssize_t ad2s120x_show_pos(struct device *dev,
108 			struct device_attribute *attr, char *buf)
109 {
110 	struct spi_message msg;
111 	struct spi_transfer xfer;
112 	int ret = 0;
113 	ssize_t len = 0;
114 	u16 pos;
115 	u8 status;
116 	struct iio_dev *idev = dev_get_drvdata(dev);
117 	struct ad2s120x_state *st = idev->dev_data;
118 
119 	xfer.len = 1;
120 	xfer.tx_buf = st->tx;
121 	xfer.rx_buf = st->rx;
122 	mutex_lock(&st->lock);
123 
124 	gpio_set_value(st->sample, 0);
125 	/* delay (6 * AD2S120X_TSCLK + 20) nano seconds */
126 	udelay(1);
127 	gpio_set_value(st->sample, 1);
128 	gpio_set_value(st->rdvel, 1);
129 
130 	spi_message_init(&msg);
131 	spi_message_add_tail(&xfer, &msg);
132 	ret = spi_sync(st->sdev, &msg);
133 	if (ret)
134 		goto error_ret;
135 	status = st->rx[1];
136 	pos = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
137 	len = sprintf(buf, "%d %c%c%c%c ", pos,
138 				(status & 0x8) ? 'P' : 'V',
139 				(status & 0x4) ? 'd' : '_',
140 				(status & 0x2) ? 'l' : '_',
141 				(status & 0x1) ? '1' : '0');
142 error_ret:
143 	/* delay (2 * AD2S120X_TSCLK + 20) ns for sample pulse */
144 	udelay(1);
145 	mutex_unlock(&st->lock);
146 
147 	return ret ? ret : len;
148 }
149 
ad2s120x_show_vel(struct device * dev,struct device_attribute * attr,char * buf)150 static ssize_t ad2s120x_show_vel(struct device *dev,
151 			struct device_attribute *attr, char *buf)
152 {
153 	struct spi_message msg;
154 	struct spi_transfer xfer;
155 	int ret = 0;
156 	ssize_t len = 0;
157 	s16 vel;
158 	u8 status;
159 	struct iio_dev *idev = dev_get_drvdata(dev);
160 	struct ad2s120x_state *st = idev->dev_data;
161 
162 	xfer.len = 1;
163 	xfer.tx_buf = st->tx;
164 	xfer.rx_buf = st->rx;
165 	mutex_lock(&st->lock);
166 
167 	gpio_set_value(st->sample, 0);
168 	/* delay (6 * AD2S120X_TSCLK + 20) nano seconds */
169 	udelay(1);
170 	gpio_set_value(st->sample, 1);
171 
172 	gpio_set_value(st->rdvel, 0);
173 	/* ndelay(5);*/
174 
175 	spi_message_init(&msg);
176 	spi_message_add_tail(&xfer, &msg);
177 	ret = spi_sync(st->sdev, &msg);
178 	if (ret)
179 		goto error_ret;
180 	status = st->rx[1];
181 	vel = (st->rx[0] & 0x80) ? 0xf000 : 0;
182 	vel |= (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
183 	len += sprintf(buf + len, "%d %c%c%c%c\n", vel,
184 				(status & 0x8) ? 'P' : 'V',
185 				(status & 0x4) ? 'd' : '_',
186 				(status & 0x2) ? 'l' : '_',
187 				(status & 0x1) ? '1' : '0');
188 error_ret:
189 	gpio_set_value(st->rdvel, 1);
190 	/* delay (2 * AD2S120X_TSCLK + 20) ns for sample pulse */
191 	udelay(1);
192 	mutex_unlock(&st->lock);
193 
194 	return ret ? ret : len;
195 }
196 
197 static IIO_CONST_ATTR(description,
198 	"12-Bit R/D Converter with Reference Oscillator");
199 static IIO_DEVICE_ATTR(pos_vel, S_IRUGO, ad2s120x_show_pos_vel, NULL, 0);
200 static IIO_DEVICE_ATTR(pos, S_IRUGO, ad2s120x_show_pos, NULL, 0);
201 static IIO_DEVICE_ATTR(vel, S_IRUGO, ad2s120x_show_vel, NULL, 0);
202 
203 static struct attribute *ad2s120x_attributes[] = {
204 	&iio_const_attr_description.dev_attr.attr,
205 	&iio_dev_attr_pos_vel.dev_attr.attr,
206 	&iio_dev_attr_pos.dev_attr.attr,
207 	&iio_dev_attr_vel.dev_attr.attr,
208 	NULL,
209 };
210 
211 static const struct attribute_group ad2s120x_attribute_group = {
212 	.name = DRV_NAME,
213 	.attrs = ad2s120x_attributes,
214 };
215 
ad2s120x_probe(struct spi_device * spi)216 static int __devinit ad2s120x_probe(struct spi_device *spi)
217 {
218 	struct ad2s120x_state *st;
219 	int pn, ret = 0;
220 	unsigned short *pins = spi->dev.platform_data;
221 
222 	for (pn = 0; pn < AD2S120X_PN; pn++) {
223 		if (gpio_request(pins[pn], DRV_NAME)) {
224 			pr_err("%s: request gpio pin %d failed\n",
225 						DRV_NAME, pins[pn]);
226 			goto error_ret;
227 		}
228 		gpio_direction_output(pins[pn], 1);
229 	}
230 
231 	st = kzalloc(sizeof(*st), GFP_KERNEL);
232 	if (st == NULL) {
233 		ret = -ENOMEM;
234 		goto error_ret;
235 	}
236 	spi_set_drvdata(spi, st);
237 
238 	mutex_init(&st->lock);
239 	st->sdev = spi;
240 	st->sample = pins[0];
241 	st->rdvel = pins[1];
242 
243 	st->idev = iio_allocate_device();
244 	if (st->idev == NULL) {
245 		ret = -ENOMEM;
246 		goto error_free_st;
247 	}
248 	st->idev->dev.parent = &spi->dev;
249 	st->idev->num_interrupt_lines = 0;
250 	st->idev->event_attrs = NULL;
251 
252 	st->idev->attrs = &ad2s120x_attribute_group;
253 	st->idev->dev_data = (void *)(st);
254 	st->idev->driver_module = THIS_MODULE;
255 	st->idev->modes = INDIO_DIRECT_MODE;
256 
257 	ret = iio_device_register(st->idev);
258 	if (ret)
259 		goto error_free_dev;
260 
261 	spi->max_speed_hz = AD2S120X_HZ;
262 	spi->mode = SPI_MODE_3;
263 	spi_setup(spi);
264 
265 	return 0;
266 
267 error_free_dev:
268 	iio_free_device(st->idev);
269 error_free_st:
270 	kfree(st);
271 error_ret:
272 	for (--pn; pn >= 0; pn--)
273 		gpio_free(pins[pn]);
274 	return ret;
275 }
276 
ad2s120x_remove(struct spi_device * spi)277 static int __devexit ad2s120x_remove(struct spi_device *spi)
278 {
279 	struct ad2s120x_state *st = spi_get_drvdata(spi);
280 
281 	iio_device_unregister(st->idev);
282 	kfree(st);
283 
284 	return 0;
285 }
286 
287 static struct spi_driver ad2s120x_driver = {
288 	.driver = {
289 		.name = DRV_NAME,
290 		.owner = THIS_MODULE,
291 	},
292 	.probe = ad2s120x_probe,
293 	.remove = __devexit_p(ad2s120x_remove),
294 };
295 
ad2s120x_spi_init(void)296 static __init int ad2s120x_spi_init(void)
297 {
298 	return spi_register_driver(&ad2s120x_driver);
299 }
300 module_init(ad2s120x_spi_init);
301 
ad2s120x_spi_exit(void)302 static __exit void ad2s120x_spi_exit(void)
303 {
304 	spi_unregister_driver(&ad2s120x_driver);
305 }
306 module_exit(ad2s120x_spi_exit);
307 
308 MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
309 MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
310 MODULE_LICENSE("GPL v2");
311