generic_buffer.c revision 1d633fd153844c8e954b0b72789279bf588cd025 
1/* Industrialio buffer test code.
2 *
3 * Copyright (c) 2008 Jonathan Cameron
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 as published by
7 * the Free Software Foundation.
8 *
9 * This program is primarily intended as an example application.
10 * Reads the current buffer setup from sysfs and starts a short capture
11 * from the specified device, pretty printing the result after appropriate
12 * conversion.
13 *
14 * Command line parameters
15 * generic_buffer -n <device_name> -t <trigger_name>
16 * If trigger name is not specified the program assumes you want a dataready
17 * trigger associated with the device and goes looking for it.
18 *
19 */
20
21#include <unistd.h>
22#include <dirent.h>
23#include <fcntl.h>
24#include <stdio.h>
25#include <errno.h>
26#include <sys/stat.h>
27#include <sys/dir.h>
28#include <linux/types.h>
29#include <string.h>
30#include <poll.h>
31#include <endian.h>
32#include "iio_utils.h"
33
34/**
35 * size_from_channelarray() - calculate the storage size of a scan
36 * @channels: the channel info array
37 * @num_channels: size of the channel info array
38 *
39 * Has the side effect of filling the channels[i].location values used
40 * in processing the buffer output.
41 **/
42int size_from_channelarray(struct iio_channel_info *channels, int num_channels)
43{
44	int bytes = 0;
45	int i = 0;
46	while (i < num_channels) {
47		if (bytes % channels[i].bytes == 0)
48			channels[i].location = bytes;
49		else
50			channels[i].location = bytes - bytes%channels[i].bytes
51				+ channels[i].bytes;
52		bytes = channels[i].location + channels[i].bytes;
53		i++;
54	}
55	return bytes;
56}
57
58void print2byte(int input, struct iio_channel_info *info)
59{
60	/* First swap if incorrect endian */
61
62	if (info->be)
63		input = be16toh((uint16_t)input);
64	else
65		input = le16toh((uint16_t)input);
66
67	/* shift before conversion to avoid sign extension
68	   of left aligned data */
69	input = input >> info->shift;
70	if (info->is_signed) {
71		int16_t val = input;
72		val &= (1 << info->bits_used) - 1;
73		val = (int16_t)(val << (16 - info->bits_used)) >>
74			(16 - info->bits_used);
75		printf("%05f ", ((float)val + info->offset)*info->scale);
76	} else {
77		uint16_t val = input;
78		val &= (1 << info->bits_used) - 1;
79		printf("%05f ", ((float)val + info->offset)*info->scale);
80	}
81}
82/**
83 * process_scan() - print out the values in SI units
84 * @data:		pointer to the start of the scan
85 * @infoarray:		information about the channels. Note
86 *  size_from_channelarray must have been called first to fill the
87 *  location offsets.
88 * @num_channels:	the number of active channels
89 **/
90void process_scan(char *data,
91		  struct iio_channel_info *infoarray,
92		  int num_channels)
93{
94	int k;
95	for (k = 0; k < num_channels; k++)
96		switch (infoarray[k].bytes) {
97			/* only a few cases implemented so far */
98		case 2:
99			print2byte(*(uint16_t *)(data + infoarray[k].location),
100				   &infoarray[k]);
101			break;
102		case 8:
103			if (infoarray[k].is_signed) {
104				int64_t val = *(int64_t *)
105					(data +
106					 infoarray[k].location);
107				if ((val >> infoarray[k].bits_used) & 1)
108					val = (val & infoarray[k].mask) |
109						~infoarray[k].mask;
110				/* special case for timestamp */
111				if (infoarray[k].scale == 1.0f &&
112				    infoarray[k].offset == 0.0f)
113					printf(" %lld", val);
114				else
115					printf("%05f ", ((float)val +
116							 infoarray[k].offset)*
117					       infoarray[k].scale);
118			}
119			break;
120		default:
121			break;
122		}
123	printf("\n");
124}
125
126int main(int argc, char **argv)
127{
128	unsigned long num_loops = 2;
129	unsigned long timedelay = 1000000;
130	unsigned long buf_len = 128;
131
132
133	int ret, c, i, j, toread;
134
135	FILE *fp_ev;
136	int fp;
137
138	int num_channels;
139	char *trigger_name = NULL, *device_name = NULL;
140	char *dev_dir_name, *buf_dir_name;
141
142	int datardytrigger = 1;
143	char *data;
144	ssize_t read_size;
145	int dev_num, trig_num;
146	char *buffer_access;
147	int scan_size;
148	int noevents = 0;
149	char *dummy;
150
151	struct iio_channel_info *infoarray;
152
153	while ((c = getopt(argc, argv, "l:w:c:et:n:")) != -1) {
154		switch (c) {
155		case 'n':
156			device_name = optarg;
157			break;
158		case 't':
159			trigger_name = optarg;
160			datardytrigger = 0;
161			break;
162		case 'e':
163			noevents = 1;
164			break;
165		case 'c':
166			num_loops = strtoul(optarg, &dummy, 10);
167			break;
168		case 'w':
169			timedelay = strtoul(optarg, &dummy, 10);
170			break;
171		case 'l':
172			buf_len = strtoul(optarg, &dummy, 10);
173			break;
174		case '?':
175			return -1;
176		}
177	}
178
179	if (device_name == NULL)
180		return -1;
181
182	/* Find the device requested */
183	dev_num = find_type_by_name(device_name, "iio:device");
184	if (dev_num < 0) {
185		printf("Failed to find the %s\n", device_name);
186		ret = -ENODEV;
187		goto error_ret;
188	}
189	printf("iio device number being used is %d\n", dev_num);
190
191	asprintf(&dev_dir_name, "%siio:device%d", iio_dir, dev_num);
192	if (trigger_name == NULL) {
193		/*
194		 * Build the trigger name. If it is device associated it's
195		 * name is <device_name>_dev[n] where n matches the device
196		 * number found above
197		 */
198		ret = asprintf(&trigger_name,
199			       "%s-dev%d", device_name, dev_num);
200		if (ret < 0) {
201			ret = -ENOMEM;
202			goto error_ret;
203		}
204	}
205
206	/* Verify the trigger exists */
207	trig_num = find_type_by_name(trigger_name, "trigger");
208	if (trig_num < 0) {
209		printf("Failed to find the trigger %s\n", trigger_name);
210		ret = -ENODEV;
211		goto error_free_triggername;
212	}
213	printf("iio trigger number being used is %d\n", trig_num);
214
215	/*
216	 * Parse the files in scan_elements to identify what channels are
217	 * present
218	 */
219	ret = build_channel_array(dev_dir_name, &infoarray, &num_channels);
220	if (ret) {
221		printf("Problem reading scan element information\n");
222		printf("diag %s\n", dev_dir_name);
223		goto error_free_triggername;
224	}
225
226	/*
227	 * Construct the directory name for the associated buffer.
228	 * As we know that the lis3l02dq has only one buffer this may
229	 * be built rather than found.
230	 */
231	ret = asprintf(&buf_dir_name,
232		       "%siio:device%d/buffer", iio_dir, dev_num);
233	if (ret < 0) {
234		ret = -ENOMEM;
235		goto error_free_triggername;
236	}
237	printf("%s %s\n", dev_dir_name, trigger_name);
238	/* Set the device trigger to be the data rdy trigger found above */
239	ret = write_sysfs_string_and_verify("trigger/current_trigger",
240					dev_dir_name,
241					trigger_name);
242	if (ret < 0) {
243		printf("Failed to write current_trigger file\n");
244		goto error_free_buf_dir_name;
245	}
246
247	/* Setup ring buffer parameters */
248	ret = write_sysfs_int("length", buf_dir_name, buf_len);
249	if (ret < 0)
250		goto error_free_buf_dir_name;
251
252	/* Enable the buffer */
253	ret = write_sysfs_int("enable", buf_dir_name, 1);
254	if (ret < 0)
255		goto error_free_buf_dir_name;
256	scan_size = size_from_channelarray(infoarray, num_channels);
257	data = malloc(scan_size*buf_len);
258	if (!data) {
259		ret = -ENOMEM;
260		goto error_free_buf_dir_name;
261	}
262
263	ret = asprintf(&buffer_access, "/dev/iio:device%d", dev_num);
264	if (ret < 0) {
265		ret = -ENOMEM;
266		goto error_free_data;
267	}
268
269	/* Attempt to open non blocking the access dev */
270	fp = open(buffer_access, O_RDONLY | O_NONBLOCK);
271	if (fp == -1) { /*If it isn't there make the node */
272		printf("Failed to open %s\n", buffer_access);
273		ret = -errno;
274		goto error_free_buffer_access;
275	}
276
277	/* Wait for events 10 times */
278	for (j = 0; j < num_loops; j++) {
279		if (!noevents) {
280			struct pollfd pfd = {
281				.fd = fp,
282				.events = POLLIN,
283			};
284
285			poll(&pfd, 1, -1);
286			toread = buf_len;
287
288		} else {
289			usleep(timedelay);
290			toread = 64;
291		}
292
293		read_size = read(fp,
294				 data,
295				 toread*scan_size);
296		if (read_size == -EAGAIN) {
297			printf("nothing available\n");
298			continue;
299		}
300		for (i = 0; i < read_size/scan_size; i++)
301			process_scan(data + scan_size*i,
302				     infoarray,
303				     num_channels);
304	}
305
306	/* Stop the ring buffer */
307	ret = write_sysfs_int("enable", buf_dir_name, 0);
308	if (ret < 0)
309		goto error_close_buffer_access;
310
311	/* Disconnect from the trigger - just write a dummy name.*/
312	write_sysfs_string("trigger/current_trigger",
313			dev_dir_name, "NULL");
314
315error_close_buffer_access:
316	close(fp);
317error_free_data:
318	free(data);
319error_free_buffer_access:
320	free(buffer_access);
321error_free_buf_dir_name:
322	free(buf_dir_name);
323error_free_triggername:
324	if (datardytrigger)
325		free(trigger_name);
326error_ret:
327	return ret;
328}
329