generic_buffer.c revision 96df9799a4dd62aab7566165d887ea40b1c8aa00 
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 "iio_utils.h"
31
32/**
33 * size_from_channelarray() - calculate the storage size of a scan
34 * @channels: the channel info array
35 * @num_channels: size of the channel info array
36 *
37 * Has the side effect of filling the channels[i].location values used
38 * in processing the buffer output.
39 **/
40int size_from_channelarray(struct iio_channel_info *channels, int num_channels)
41{
42	int bytes = 0;
43	int i = 0;
44	while (i < num_channels) {
45		if (bytes % channels[i].bytes == 0)
46			channels[i].location = bytes;
47		else
48			channels[i].location = bytes - bytes%channels[i].bytes
49				+ channels[i].bytes;
50		bytes = channels[i].location + channels[i].bytes;
51		i++;
52	}
53	return bytes;
54}
55
56/**
57 * process_scan() - print out the values in SI units
58 * @data:		pointer to the start of the scan
59 * @infoarray:		information about the channels. Note
60 *  size_from_channelarray must have been called first to fill the
61 *  location offsets.
62 * @num_channels:	the number of active channels
63 **/
64void process_scan(char *data,
65		  struct iio_channel_info *infoarray,
66		  int num_channels)
67{
68	int k;
69	for (k = 0; k < num_channels; k++)
70		switch (infoarray[k].bytes) {
71			/* only a few cases implemented so far */
72		case 2:
73			if (infoarray[k].is_signed) {
74				int16_t val = *(int16_t *)
75					(data
76					 + infoarray[k].location);
77				if ((val >> infoarray[k].bits_used) & 1)
78					val = (val & infoarray[k].mask) |
79						~infoarray[k].mask;
80				printf("%05f ", ((float)val +
81						 infoarray[k].offset)*
82				       infoarray[k].scale);
83			} else {
84				uint16_t val = *(uint16_t *)
85					(data +
86					 infoarray[k].location);
87				val = (val & infoarray[k].mask);
88				printf("%05f ", ((float)val +
89						 infoarray[k].offset)*
90				       infoarray[k].scale);
91			}
92			break;
93		case 8:
94			if (infoarray[k].is_signed) {
95				int64_t val = *(int64_t *)
96					(data +
97					 infoarray[k].location);
98				if ((val >> infoarray[k].bits_used) & 1)
99					val = (val & infoarray[k].mask) |
100						~infoarray[k].mask;
101				/* special case for timestamp */
102				if (infoarray[k].scale == 1.0f &&
103				    infoarray[k].offset == 0.0f)
104					printf(" %lld", val);
105				else
106					printf("%05f ", ((float)val +
107							 infoarray[k].offset)*
108					       infoarray[k].scale);
109			}
110			break;
111		default:
112			break;
113		}
114	printf("\n");
115}
116
117int main(int argc, char **argv)
118{
119	unsigned long num_loops = 2;
120	unsigned long timedelay = 1000000;
121	unsigned long buf_len = 128;
122
123
124	int ret, c, i, j, toread;
125
126	FILE *fp_ev;
127	int fp;
128
129	int num_channels;
130	char *trigger_name = NULL, *device_name = NULL;
131	char *dev_dir_name, *buf_dir_name;
132
133	int datardytrigger = 1;
134	char *data;
135	size_t read_size;
136	struct iio_event_data dat;
137	int dev_num, trig_num;
138	char *buffer_access, *buffer_event;
139	int scan_size;
140	int noevents = 0;
141	char *dummy;
142
143	struct iio_channel_info *infoarray;
144
145	while ((c = getopt(argc, argv, "l:w:c:et:n:")) != -1) {
146		switch (c) {
147		case 'n':
148			device_name = optarg;
149			break;
150		case 't':
151			trigger_name = optarg;
152			datardytrigger = 0;
153			break;
154		case 'e':
155			noevents = 1;
156			break;
157		case 'c':
158			num_loops = strtoul(optarg, &dummy, 10);
159			break;
160		case 'w':
161			timedelay = strtoul(optarg, &dummy, 10);
162			break;
163		case 'l':
164			buf_len = strtoul(optarg, &dummy, 10);
165			break;
166		case '?':
167			return -1;
168		}
169	}
170
171	/* Find the device requested */
172	dev_num = find_type_by_name(device_name, "device");
173	if (dev_num < 0) {
174		printf("Failed to find the %s\n", device_name);
175		ret = -ENODEV;
176		goto error_ret;
177	}
178	printf("iio device number being used is %d\n", dev_num);
179
180	asprintf(&dev_dir_name, "%sdevice%d", iio_dir, dev_num);
181	if (trigger_name == NULL) {
182		/*
183		 * Build the trigger name. If it is device associated it's
184		 * name is <device_name>_dev[n] where n matches the device
185		 * number found above
186		 */
187		ret = asprintf(&trigger_name,
188			       "%s-dev%d", device_name, dev_num);
189		if (ret < 0) {
190			ret = -ENOMEM;
191			goto error_ret;
192		}
193	}
194
195	/* Verify the trigger exists */
196	trig_num = find_type_by_name(trigger_name, "trigger");
197	if (trig_num < 0) {
198		printf("Failed to find the trigger %s\n", trigger_name);
199		ret = -ENODEV;
200		goto error_free_triggername;
201	}
202	printf("iio trigger number being used is %d\n", trig_num);
203
204	/*
205	 * Parse the files in scan_elements to identify what channels are
206	 * present
207	 */
208	ret = build_channel_array(dev_dir_name, &infoarray, &num_channels);
209	if (ret) {
210		printf("Problem reading scan element information \n");
211		goto error_free_triggername;
212	}
213
214	/*
215	 * Construct the directory name for the associated buffer.
216	 * As we know that the lis3l02dq has only one buffer this may
217	 * be built rather than found.
218	 */
219	ret = asprintf(&buf_dir_name, "%sdevice%d:buffer0", iio_dir, dev_num);
220	if (ret < 0) {
221		ret = -ENOMEM;
222		goto error_free_triggername;
223	}
224	printf("%s %s\n", dev_dir_name, trigger_name);
225	/* Set the device trigger to be the data rdy trigger found above */
226	ret = write_sysfs_string_and_verify("trigger/current_trigger",
227					dev_dir_name,
228					trigger_name);
229	if (ret < 0) {
230		printf("Failed to write current_trigger file\n");
231		goto error_free_buf_dir_name;
232	}
233
234	/* Setup ring buffer parameters */
235	ret = write_sysfs_int("length", buf_dir_name, buf_len);
236	if (ret < 0)
237		goto error_free_buf_dir_name;
238
239	/* Enable the buffer */
240	ret = write_sysfs_int("enable", buf_dir_name, 1);
241	if (ret < 0)
242		goto error_free_buf_dir_name;
243	scan_size = size_from_channelarray(infoarray, num_channels);
244	data = malloc(scan_size*buf_len);
245	if (!data) {
246		ret = -ENOMEM;
247		goto error_free_buf_dir_name;
248	}
249
250	ret = asprintf(&buffer_access,
251		       "/dev/device%d:buffer0:access0",
252		       dev_num);
253	if (ret < 0) {
254		ret = -ENOMEM;
255		goto error_free_data;
256	}
257
258	ret = asprintf(&buffer_event, "/dev/device%d:buffer0:event0", dev_num);
259	if (ret < 0) {
260		ret = -ENOMEM;
261		goto error_free_buffer_access;
262	}
263	/* Attempt to open non blocking the access dev */
264	fp = open(buffer_access, O_RDONLY | O_NONBLOCK);
265	if (fp == -1) { /*If it isn't there make the node */
266		printf("Failed to open %s\n", buffer_access);
267		ret = -errno;
268		goto error_free_buffer_event;
269	}
270	/* Attempt to open the event access dev (blocking this time) */
271	fp_ev = fopen(buffer_event, "rb");
272	if (fp_ev == NULL) {
273		printf("Failed to open %s\n", buffer_event);
274		ret = -errno;
275		goto error_close_buffer_access;
276	}
277
278	/* Wait for events 10 times */
279	for (j = 0; j < num_loops; j++) {
280		if (!noevents) {
281			read_size = fread(&dat,
282					1,
283					sizeof(struct iio_event_data),
284					fp_ev);
285			switch (dat.id) {
286			case IIO_EVENT_CODE_RING_100_FULL:
287				toread = buf_len;
288				break;
289			case IIO_EVENT_CODE_RING_75_FULL:
290				toread = buf_len*3/4;
291				break;
292			case IIO_EVENT_CODE_RING_50_FULL:
293				toread = buf_len/2;
294				break;
295			default:
296				printf("Unexpecteded event code\n");
297				continue;
298			}
299		} else {
300			usleep(timedelay);
301			toread = 64;
302		}
303
304		read_size = read(fp,
305				 data,
306				 toread*scan_size);
307		if (read_size == -EAGAIN) {
308			printf("nothing available\n");
309			continue;
310		}
311		for (i = 0; i < read_size/scan_size; i++)
312			process_scan(data + scan_size*i,
313				     infoarray,
314				     num_channels);
315	}
316
317	/* Stop the ring buffer */
318	ret = write_sysfs_int("enable", buf_dir_name, 0);
319	if (ret < 0)
320		goto error_close_buffer_event;
321
322	/* Disconnect from the trigger - just write a dummy name.*/
323	write_sysfs_string("trigger/current_trigger",
324			dev_dir_name, "NULL");
325
326error_close_buffer_event:
327	fclose(fp_ev);
328error_close_buffer_access:
329	close(fp);
330error_free_data:
331	free(data);
332error_free_buffer_access:
333	free(buffer_access);
334error_free_buffer_event:
335	free(buffer_event);
336error_free_buf_dir_name:
337	free(buf_dir_name);
338error_free_triggername:
339	if (datardytrigger)
340		free(trigger_name);
341error_ret:
342	return ret;
343}
344