generic_buffer.c

/* Industrialio buffer test code.
 *
 * Copyright (c) 2008 Jonathan Cameron
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is primarily intended as an example application.
 * Reads the current buffer setup from sysfs and starts a short capture
 * from the specified device, pretty printing the result after appropriate
 * conversion.
 *
 * Command line parameters
 * generic_buffer -n <device_name> -t <trigger_name>
 * If trigger name is not specified the program assumes you want a dataready
 * trigger associated with the device and goes looking for it.
 *
 */

#include <unistd.h>
#include <stdlib.h>
#include <dirent.h>
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/dir.h>
#include <linux/types.h>
#include <string.h>
#include <poll.h>
#include <endian.h>
#include <getopt.h>
#include <inttypes.h>
#include "iio_utils.h"

/**
 * size_from_channelarray() - calculate the storage size of a scan
 * @channels:		the channel info array
 * @num_channels:	number of channels
 *
 * Has the side effect of filling the channels[i].location values used
 * in processing the buffer output.
 **/
int size_from_channelarray(struct iio_channel_info *channels, int num_channels)
{
	int bytes = 0;
	int i = 0;

	while (i < num_channels) {
		if (bytes % channels[i].bytes == 0)
			channels[i].location = bytes;
		else
			channels[i].location = bytes - bytes % channels[i].bytes
					       + channels[i].bytes;

		bytes = channels[i].location + channels[i].bytes;
		i++;
	}

	return bytes;
}

void print1byte(uint8_t input, struct iio_channel_info *info)
{
	/*
	 * Shift before conversion to avoid sign extension
	 * of left aligned data
	 */
	input >>= info->shift;
	input &= info->mask;
	if (info->is_signed) {
		int8_t val = (int8_t)(input << (8 - info->bits_used)) >>
			     (8 - info->bits_used);
		printf("%05f ", ((float)val + info->offset) * info->scale);
	} else {
		printf("%05f ", ((float)input + info->offset) * info->scale);
	}
}

void print2byte(uint16_t input, struct iio_channel_info *info)
{
	/* First swap if incorrect endian */
	if (info->be)
		input = be16toh(input);
	else
		input = le16toh(input);

	/*
	 * Shift before conversion to avoid sign extension
	 * of left aligned data
	 */
	input >>= info->shift;
	input &= info->mask;
	if (info->is_signed) {
		int16_t val = (int16_t)(input << (16 - info->bits_used)) >>
			      (16 - info->bits_used);
		printf("%05f ", ((float)val + info->offset) * info->scale);
	} else {
		printf("%05f ", ((float)input + info->offset) * info->scale);
	}
}

void print4byte(uint32_t input, struct iio_channel_info *info)
{
	/* First swap if incorrect endian */
	if (info->be)
		input = be32toh(input);
	else
		input = le32toh(input);

	/*
	 * Shift before conversion to avoid sign extension
	 * of left aligned data
	 */
	input >>= info->shift;
	input &= info->mask;
	if (info->is_signed) {
		int32_t val = (int32_t)(input << (32 - info->bits_used)) >>
			      (32 - info->bits_used);
		printf("%05f ", ((float)val + info->offset) * info->scale);
	} else {
		printf("%05f ", ((float)input + info->offset) * info->scale);
	}
}

void print8byte(uint64_t input, struct iio_channel_info *info)
{
	/* First swap if incorrect endian */
	if (info->be)
		input = be64toh(input);
	else
		input = le64toh(input);

	/*
	 * Shift before conversion to avoid sign extension
	 * of left aligned data
	 */
	input >>= info->shift;
	input &= info->mask;
	if (info->is_signed) {
		int64_t val = (int64_t)(input << (64 - info->bits_used)) >>
			      (64 - info->bits_used);
		/* special case for timestamp */
		if (info->scale == 1.0f && info->offset == 0.0f)
			printf("%" PRId64 " ", val);
		else
			printf("%05f ",
			       ((float)val + info->offset) * info->scale);
	} else {
		printf("%05f ", ((float)input + info->offset) * info->scale);
	}
}

/**
 * process_scan() - print out the values in SI units
 * @data:		pointer to the start of the scan
 * @channels:		information about the channels.
 *			Note: size_from_channelarray must have been called first
 *			      to fill the location offsets.
 * @num_channels:	number of channels
 **/
void process_scan(char *data,
		  struct iio_channel_info *channels,
		  int num_channels)
{
	int k;

	for (k = 0; k < num_channels; k++)
		switch (channels[k].bytes) {
			/* only a few cases implemented so far */
		case 1:
			print1byte(*(uint8_t *)(data + channels[k].location),
				   &channels[k]);
			break;
		case 2:
			print2byte(*(uint16_t *)(data + channels[k].location),
				   &channels[k]);
			break;
		case 4:
			print4byte(*(uint32_t *)(data + channels[k].location),
				   &channels[k]);
			break;
		case 8:
			print8byte(*(uint64_t *)(data + channels[k].location),
				   &channels[k]);
			break;
		default:
			break;
		}
	printf("\n");
}

void print_usage(void)
{
	fprintf(stderr, "Usage: generic_buffer [options]...\n"
		"Capture, convert and output data from IIO device buffer\n"
		"  -c <n>     Do n conversions\n"
		"  -e         Disable wait for event (new data)\n"
		"  -g         Use trigger-less mode\n"
		"  -l <n>     Set buffer length to n samples\n"
		"  -n <name>  Set device name (mandatory)\n"
		"  -t <name>  Set trigger name\n"
		"  -w <n>     Set delay between reads in us (event-less mode)\n");
}

int main(int argc, char **argv)
{
	unsigned long num_loops = 2;
	unsigned long timedelay = 1000000;
	unsigned long buf_len = 128;

	int ret, c, i, j, toread;
	int fp;

	int num_channels;
	char *trigger_name = NULL, *device_name = NULL;
	char *dev_dir_name, *buf_dir_name;

	int datardytrigger = 1;
	char *data;
	ssize_t read_size;
	int dev_num, trig_num;
	char *buffer_access;
	int scan_size;
	int noevents = 0;
	int notrigger = 0;
	char *dummy;

	struct iio_channel_info *channels;

	while ((c = getopt(argc, argv, "c:egl:n:t:w:")) != -1) {
		switch (c) {
		case 'c':
			errno = 0;
			num_loops = strtoul(optarg, &dummy, 10);
			if (errno)
				return -errno;

			break;
		case 'e':
			noevents = 1;
			break;
		case 'g':
			notrigger = 1;
			break;
		case 'l':
			errno = 0;
			buf_len = strtoul(optarg, &dummy, 10);
			if (errno)
				return -errno;

			break;
		case 'n':
			device_name = optarg;
			break;
		case 't':
			trigger_name = optarg;
			datardytrigger = 0;
			break;
		case 'w':
			errno = 0;
			timedelay = strtoul(optarg, &dummy, 10);
			if (errno)
				return -errno;
			break;
		case '?':
			print_usage();
			return -1;
		}
	}

	if (!device_name) {
		fprintf(stderr, "Device name not set\n");
		print_usage();
		return -1;
	}

	/* Find the device requested */
	dev_num = find_type_by_name(device_name, "iio:device");
	if (dev_num < 0) {
		fprintf(stderr, "Failed to find the %s\n", device_name);
		return dev_num;
	}

	printf("iio device number being used is %d\n", dev_num);

	ret = asprintf(&dev_dir_name, "%siio:device%d", iio_dir, dev_num);
	if (ret < 0)
		return -ENOMEM;

	if (!notrigger) {
		if (!trigger_name) {
			/*
			 * Build the trigger name. If it is device associated
			 * its name is <device_name>_dev[n] where n matches
			 * the device number found above.
			 */
			ret = asprintf(&trigger_name,
				       "%s-dev%d", device_name, dev_num);
			if (ret < 0) {
				ret = -ENOMEM;
				goto error_free_dev_dir_name;
			}
		}

		/* Verify the trigger exists */
		trig_num = find_type_by_name(trigger_name, "trigger");
		if (trig_num < 0) {
			fprintf(stderr, "Failed to find the trigger %s\n",
				trigger_name);
			ret = trig_num;
			goto error_free_triggername;
		}

		printf("iio trigger number being used is %d\n", trig_num);
	} else {
		printf("trigger-less mode selected\n");
	}

	/*
	 * Parse the files in scan_elements to identify what channels are
	 * present
	 */
	ret = build_channel_array(dev_dir_name, &channels, &num_channels);
	if (ret) {
		fprintf(stderr, "Problem reading scan element information\n"
			"diag %s\n", dev_dir_name);
		goto error_free_triggername;
	}
	if (!num_channels) {
		fprintf(stderr,
			"No channels are enabled, we have nothing to scan.\n");
		fprintf(stderr, "Enable channels manually in "
			FORMAT_SCAN_ELEMENTS_DIR
			"/*_en and try again.\n", dev_dir_name);
		ret = -ENOENT;
		goto error_free_triggername;
	}

	/*
	 * Construct the directory name for the associated buffer.
	 * As we know that the lis3l02dq has only one buffer this may
	 * be built rather than found.
	 */
	ret = asprintf(&buf_dir_name,
		       "%siio:device%d/buffer", iio_dir, dev_num);
	if (ret < 0) {
		ret = -ENOMEM;
		goto error_free_channels;
	}

	if (!notrigger) {
		printf("%s %s\n", dev_dir_name, trigger_name);
		/*
		 * Set the device trigger to be the data ready trigger found
		 * above
		 */
		ret = write_sysfs_string_and_verify("trigger/current_trigger",
						    dev_dir_name,
						    trigger_name);
		if (ret < 0) {
			fprintf(stderr,
				"Failed to write current_trigger file\n");
			goto error_free_buf_dir_name;
		}
	}

	/* Setup ring buffer parameters */
	ret = write_sysfs_int("length", buf_dir_name, buf_len);
	if (ret < 0)
		goto error_free_buf_dir_name;

	/* Enable the buffer */
	ret = write_sysfs_int("enable", buf_dir_name, 1);
	if (ret < 0) {
		fprintf(stderr,
			"Failed to enable buffer: %s\n", strerror(-ret));
		goto error_free_buf_dir_name;
	}

	scan_size = size_from_channelarray(channels, num_channels);
	data = malloc(scan_size * buf_len);
	if (!data) {
		ret = -ENOMEM;
		goto error_free_buf_dir_name;
	}

	ret = asprintf(&buffer_access, "/dev/iio:device%d", dev_num);
	if (ret < 0) {
		ret = -ENOMEM;
		goto error_free_data;
	}

	/* Attempt to open non blocking the access dev */
	fp = open(buffer_access, O_RDONLY | O_NONBLOCK);
	if (fp == -1) { /* TODO: If it isn't there make the node */
		ret = -errno;
		fprintf(stderr, "Failed to open %s\n", buffer_access);
		goto error_free_buffer_access;
	}

	for (j = 0; j < num_loops; j++) {
		if (!noevents) {
			struct pollfd pfd = {
				.fd = fp,
				.events = POLLIN,
			};

			ret = poll(&pfd, 1, -1);
			if (ret < 0) {
				ret = -errno;
				goto error_close_buffer_access;
			} else if (ret == 0) {
				continue;
			}

			toread = buf_len;
		} else {
			usleep(timedelay);
			toread = 64;
		}

		read_size = read(fp, data, toread * scan_size);
		if (read_size < 0) {
			if (errno == EAGAIN) {
				fprintf(stderr, "nothing available\n");
				continue;
			} else {
				break;
			}
		}
		for (i = 0; i < read_size / scan_size; i++)
			process_scan(data + scan_size * i, channels,
				     num_channels);
	}

	/* Stop the buffer */
	ret = write_sysfs_int("enable", buf_dir_name, 0);
	if (ret < 0)
		goto error_close_buffer_access;

	if (!notrigger)
		/* Disconnect the trigger - just write a dummy name. */
		ret = write_sysfs_string("trigger/current_trigger",
					 dev_dir_name, "NULL");
		if (ret < 0)
			fprintf(stderr, "Failed to write to %s\n",
				dev_dir_name);

error_close_buffer_access:
	if (close(fp) == -1)
		perror("Failed to close buffer");

error_free_buffer_access:
	free(buffer_access);
error_free_data:
	free(data);
error_free_buf_dir_name:
	free(buf_dir_name);
error_free_channels:
	for (i = num_channels - 1; i >= 0; i--) {
		free(channels[i].name);
		free(channels[i].generic_name);
	}
	free(channels);
error_free_triggername:
	if (datardytrigger)
		free(trigger_name);

error_free_dev_dir_name:
	free(dev_dir_name);

	return ret;
}