Commit 8827faab authored by Alexandru Ardelean's avatar Alexandru Ardelean Committed by Jonathan Cameron
Browse files

tools: iio: convert iio_generic_buffer to use new IIO buffer API 



This change makes use of the new IIO buffer API to read data from an IIO
buffer.
It doesn't read the /sys/bus/iio/devices/iio:deviceX/scan_elements dir
anymore, it reads /sys/bus/iio/devices/iio:deviceX/bufferY, where all the
scan_elements have been merged together with the old/classical buffer
attributes.

And it makes use of the new IIO_BUFFER_GET_FD_IOCTL ioctl to get an FD for
the IIO buffer for which to read data from.
It also does a quick sanity check to see that -EBUSY is returned if reading
the chardev after the ioctl() has succeeded.

This was tested with the following cases:
 1. Tested buffer0 works with ioctl()
 2. Tested that buffer0 can't be opened via /dev/iio:deviceX after ioctl()
    This check should be omitted under normal operation; it's being done
    here to check that the driver change is sane
 3. Moved valid buffer0 to be buffer1, and tested that data comes from it

Signed-off-by: default avatarAlexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210215104043.91251-25-alexandru.ardelean@analog.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent ebe51125

tools/iio/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ include $(srctree)/tools/build/Makefile.include 
#

$(OUTPUT)include/linux/iio: ../../include/uapi/linux/iio

	mkdir -p $(OUTPUT)include/linux/iio 2>&1 || true

	ln -sf $(CURDIR)/../../include/uapi/linux/iio/buffer.h $@

	ln -sf $(CURDIR)/../../include/uapi/linux/iio/events.h $@

	ln -sf $(CURDIR)/../../include/uapi/linux/iio/types.h $@

tools/iio/iio_generic_buffer.c

+96 −26
Original line number Diff line number Diff line
@@ -30,6 +30,8 @@ 
#include <inttypes.h>

#include <stdbool.h>

#include <signal.h>

#include <sys/ioctl.h>

#include <linux/iio/buffer.h>

#include "iio_utils.h"



/**
@@ -197,7 +199,7 @@ static void process_scan(char *data, struct iio_channel_info *channels, 
	printf("\n");

}



static int enable_disable_all_channels(char *dev_dir_name, int enable)

static int enable_disable_all_channels(char *dev_dir_name, int buffer_idx, int enable)

{

	const struct dirent *ent;

	char scanelemdir[256];
@@ -205,7 +207,7 @@ static int enable_disable_all_channels(char *dev_dir_name, int enable) 
	int ret;



	snprintf(scanelemdir, sizeof(scanelemdir),

		 FORMAT_SCAN_ELEMENTS_DIR, dev_dir_name);

		 FORMAT_SCAN_ELEMENTS_DIR, dev_dir_name, buffer_idx);

	scanelemdir[sizeof(scanelemdir)-1] = '\0';



	dp = opendir(scanelemdir);
@@ -243,6 +245,7 @@ static void print_usage(void) 
		"Capture, convert and output data from IIO device buffer\n"

		"  -a         Auto-activate all available channels\n"

		"  -A         Force-activate ALL channels\n"

		"  -b <n>     The buffer which to open (by index), default 0\n"

		"  -c <n>     Do n conversions, or loop forever if n < 0\n"

		"  -e         Disable wait for event (new data)\n"

		"  -g         Use trigger-less mode\n"
@@ -259,6 +262,7 @@ static void print_usage(void) 
static enum autochan autochannels = AUTOCHANNELS_DISABLED;

static char *dev_dir_name = NULL;

static char *buf_dir_name = NULL;

static int buffer_idx = 0;

static bool current_trigger_set = false;



static void cleanup(void)
@@ -286,7 +290,7 @@ static void cleanup(void) 


	/* Disable channels if auto-enabled */

	if (dev_dir_name && autochannels == AUTOCHANNELS_ACTIVE) {

		ret = enable_disable_all_channels(dev_dir_name, 0);

		ret = enable_disable_all_channels(dev_dir_name, buffer_idx, 0);

		if (ret)

			fprintf(stderr, "Failed to disable all channels\n");

		autochannels = AUTOCHANNELS_DISABLED;
@@ -333,7 +337,9 @@ int main(int argc, char **argv) 
	unsigned long long j;

	unsigned long toread;

	int ret, c;

	int fp = -1;

	struct stat st;

	int fd = -1;

	int buf_fd = -1;



	int num_channels = 0;

	char *trigger_name = NULL, *device_name = NULL;
@@ -352,7 +358,7 @@ int main(int argc, char **argv) 


	register_cleanup();



	while ((c = getopt_long(argc, argv, "aAc:egl:n:N:t:T:w:?", longopts,

	while ((c = getopt_long(argc, argv, "aAb:c:egl:n:N:t:T:w:?", longopts,

				NULL)) != -1) {

		switch (c) {

		case 'a':
@@ -361,6 +367,19 @@ int main(int argc, char **argv) 
		case 'A':

			autochannels = AUTOCHANNELS_ENABLED;

			force_autochannels = true;

			break;

		case 'b':

			errno = 0;

			buffer_idx = strtoll(optarg, &dummy, 10);

			if (errno) {

				ret = -errno;

				goto error;

			}

			if (buffer_idx < 0) {

				ret = -ERANGE;

				goto error;

			}



			break;

		case 'c':

			errno = 0;
@@ -518,7 +537,7 @@ int main(int argc, char **argv) 
	 * Parse the files in scan_elements to identify what channels are

	 * present

	 */

	ret = build_channel_array(dev_dir_name, &channels, &num_channels);

	ret = build_channel_array(dev_dir_name, buffer_idx, &channels, &num_channels);

	if (ret) {

		fprintf(stderr, "Problem reading scan element information\n"

			"diag %s\n", dev_dir_name);
@@ -535,7 +554,7 @@ int main(int argc, char **argv) 
	    (autochannels == AUTOCHANNELS_ENABLED && force_autochannels)) {

		fprintf(stderr, "Enabling all channels\n");



		ret = enable_disable_all_channels(dev_dir_name, 1);

		ret = enable_disable_all_channels(dev_dir_name, buffer_idx, 1);

		if (ret) {

			fprintf(stderr, "Failed to enable all channels\n");

			goto error;
@@ -544,7 +563,7 @@ int main(int argc, char **argv) 
		/* This flags that we need to disable the channels again */

		autochannels = AUTOCHANNELS_ACTIVE;



		ret = build_channel_array(dev_dir_name, &channels,

		ret = build_channel_array(dev_dir_name, buffer_idx, &channels,

					  &num_channels);

		if (ret) {

			fprintf(stderr, "Problem reading scan element "
@@ -565,7 +584,7 @@ int main(int argc, char **argv) 
		fprintf(stderr, "Enable channels manually in "

			FORMAT_SCAN_ELEMENTS_DIR

			"/*_en or pass -a to autoenable channels and "

			"try again.\n", dev_dir_name);

			"try again.\n", dev_dir_name, buffer_idx);

		ret = -ENOENT;

		goto error;

	}
@@ -576,12 +595,25 @@ int main(int argc, char **argv) 
	 * be built rather than found.

	 */

	ret = asprintf(&buf_dir_name,

		       "%siio:device%d/buffer", iio_dir, dev_num);

		       "%siio:device%d/buffer%d", iio_dir, dev_num, buffer_idx);

	if (ret < 0) {

		ret = -ENOMEM;

		goto error;

	}



	if (stat(buf_dir_name, &st)) {

		fprintf(stderr, "Could not stat() '%s', got error %d: %s\n",

			buf_dir_name, errno, strerror(errno));

		ret = -errno;

		goto error;

	}



	if (!S_ISDIR(st.st_mode)) {

		fprintf(stderr, "File '%s' is not a directory\n", buf_dir_name);

		ret = -EFAULT;

		goto error;

	}



	if (!notrigger) {

		printf("%s %s\n", dev_dir_name, trigger_name);

		/*
@@ -598,6 +630,35 @@ int main(int argc, char **argv) 
		}

	}



	ret = asprintf(&buffer_access, "/dev/iio:device%d", dev_num);

	if (ret < 0) {

		ret = -ENOMEM;

		goto error;

	}



	/* Attempt to open non blocking the access dev */

	fd = open(buffer_access, O_RDONLY | O_NONBLOCK);

	if (fd == -1) { /* TODO: If it isn't there make the node */

		ret = -errno;

		fprintf(stderr, "Failed to open %s\n", buffer_access);

		goto error;

	}



	/* specify for which buffer index we want an FD */

	buf_fd = buffer_idx;



	ret = ioctl(fd, IIO_BUFFER_GET_FD_IOCTL, &buf_fd);

	if (ret == -1 || buf_fd == -1) {

		ret = -errno;

		if (ret == -ENODEV || ret == -EINVAL)

			fprintf(stderr,

				"Device does not have this many buffers\n");

		else

			fprintf(stderr, "Failed to retrieve buffer fd\n");



		goto error;

	}



	/* Setup ring buffer parameters */

	ret = write_sysfs_int("length", buf_dir_name, buf_len);

	if (ret < 0)
@@ -607,7 +668,8 @@ int main(int argc, char **argv) 
	ret = write_sysfs_int("enable", buf_dir_name, 1);

	if (ret < 0) {

		fprintf(stderr,

			"Failed to enable buffer: %s\n", strerror(-ret));

			"Failed to enable buffer '%s': %s\n",

			buf_dir_name, strerror(-ret));

		goto error;

	}
@@ -618,24 +680,30 @@ int main(int argc, char **argv) 
		goto error;

	}



	ret = asprintf(&buffer_access, "/dev/iio:device%d", dev_num);

	if (ret < 0) {

		ret = -ENOMEM;

	/**

	 * This check is being done here for sanity reasons, however it

	 * should be omitted under normal operation.

	 * If this is buffer0, we check that we get EBUSY after this point.

	 */

	if (buffer_idx == 0) {

		errno = 0;

		read_size = read(fd, data, 1);

		if (read_size > -1 || errno != EBUSY) {

			ret = -EFAULT;

			perror("Reading from '%s' should not be possible after ioctl()");

			goto error;

		}



	/* 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;

	}



	/* close now the main chardev FD and let the buffer FD work */

	if (close(fd) == -1)

		perror("Failed to close character device file");

	fd = -1;



	for (j = 0; j < num_loops || num_loops < 0; j++) {

		if (!noevents) {

			struct pollfd pfd = {

				.fd = fp,

				.fd = buf_fd,

				.events = POLLIN,

			};
@@ -653,7 +721,7 @@ int main(int argc, char **argv) 
			toread = 64;

		}



		read_size = read(fp, data, toread * scan_size);

		read_size = read(buf_fd, data, toread * scan_size);

		if (read_size < 0) {

			if (errno == EAGAIN) {

				fprintf(stderr, "nothing available\n");
@@ -670,7 +738,9 @@ int main(int argc, char **argv) 
error:

	cleanup();



	if (fp >= 0 && close(fp) == -1)

	if (fd >= 0 && close(fd) == -1)

		perror("Failed to close character device");

	if (buf_fd >= 0 && close(buf_fd) == -1)

		perror("Failed to close buffer");

	free(buffer_access);

	free(data);

tools/iio/iio_utils.c

+8 −5
Original line number Diff line number Diff line
@@ -77,6 +77,7 @@ int iioutils_break_up_name(const char *full_name, char **generic_name) 
 * @mask: output a bit mask for the raw data

 * @be: output if data in big endian

 * @device_dir: the IIO device directory

 * @buffer_idx: the IIO buffer index

 * @name: the channel name

 * @generic_name: the channel type name

 *
@@ -85,8 +86,8 @@ int iioutils_break_up_name(const char *full_name, char **generic_name) 
static int iioutils_get_type(unsigned int *is_signed, unsigned int *bytes,

			     unsigned int *bits_used, unsigned int *shift,

			     uint64_t *mask, unsigned int *be,

			     const char *device_dir, const char *name,

			     const char *generic_name)

			     const char *device_dir, int buffer_idx,

			     const char *name, const char *generic_name)

{

	FILE *sysfsfp;

	int ret;
@@ -96,7 +97,7 @@ static int iioutils_get_type(unsigned int *is_signed, unsigned int *bytes, 
	unsigned padint;

	const struct dirent *ent;



	ret = asprintf(&scan_el_dir, FORMAT_SCAN_ELEMENTS_DIR, device_dir);

	ret = asprintf(&scan_el_dir, FORMAT_SCAN_ELEMENTS_DIR, device_dir, buffer_idx);

	if (ret < 0)

		return -ENOMEM;
@@ -304,12 +305,13 @@ void bsort_channel_array_by_index(struct iio_channel_info *ci_array, int cnt) 
/**

 * build_channel_array() - function to figure out what channels are present

 * @device_dir: the IIO device directory in sysfs

 * @buffer_idx: the IIO buffer for this channel array

 * @ci_array: output the resulting array of iio_channel_info

 * @counter: output the amount of array elements

 *

 * Returns 0 on success, otherwise a negative error code.

 **/

int build_channel_array(const char *device_dir,

int build_channel_array(const char *device_dir, int buffer_idx,

			struct iio_channel_info **ci_array, int *counter)

{

	DIR *dp;
@@ -322,7 +324,7 @@ int build_channel_array(const char *device_dir, 
	char *filename;



	*counter = 0;

	ret = asprintf(&scan_el_dir, FORMAT_SCAN_ELEMENTS_DIR, device_dir);

	ret = asprintf(&scan_el_dir, FORMAT_SCAN_ELEMENTS_DIR, device_dir, buffer_idx);

	if (ret < 0)

		return -ENOMEM;
@@ -503,6 +505,7 @@ int build_channel_array(const char *device_dir, 
						&current->mask,

						&current->be,

						device_dir,

						buffer_idx,

						current->name,

						current->generic_name);

			if (ret < 0)

tools/iio/iio_utils.h

+2 −2
Original line number Diff line number Diff line
@@ -12,7 +12,7 @@ 
/* Made up value to limit allocation sizes */

#define IIO_MAX_NAME_LENGTH 64



#define FORMAT_SCAN_ELEMENTS_DIR "%s/scan_elements"

#define FORMAT_SCAN_ELEMENTS_DIR "%s/buffer%d"

#define FORMAT_TYPE_FILE "%s_type"



#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
@@ -61,7 +61,7 @@ int iioutils_get_param_float(float *output, const char *param_name, 
			     const char *device_dir, const char *name,

			     const char *generic_name);

void bsort_channel_array_by_index(struct iio_channel_info *ci_array, int cnt);

int build_channel_array(const char *device_dir,

int build_channel_array(const char *device_dir, int buffer_idx,

			struct iio_channel_info **ci_array, int *counter);

int find_type_by_name(const char *name, const char *type);

int write_sysfs_int(const char *filename, const char *basedir, int val);