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Subject[PATCH v4 17/17] tools: iio: convert iio_generic_buffer to use new IIO buffer API
Date
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()
3. Moved valid buffer0 to be buffer1, and tested that data comes from it

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
tools/iio/Makefile | 1 +
tools/iio/iio_generic_buffer.c | 102 +++++++++++++++++++++++++++------
tools/iio/iio_utils.c | 13 +++--
tools/iio/iio_utils.h | 4 +-
4 files changed, 96 insertions(+), 24 deletions(-)

diff --git a/tools/iio/Makefile b/tools/iio/Makefile
index 3de763d9ab70..5d12ac4e7f8f 100644
--- a/tools/iio/Makefile
+++ b/tools/iio/Makefile
@@ -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 $@

diff --git a/tools/iio/iio_generic_buffer.c b/tools/iio/iio_generic_buffer.c
index 7c7240553777..c796a1d9ed20 100644
--- a/tools/iio/iio_generic_buffer.c
+++ b/tools/iio/iio_generic_buffer.c
@@ -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':
@@ -361,7 +367,20 @@ int main(int argc, char **argv)
case 'A':
autochannels = AUTOCHANNELS_ENABLED;
force_autochannels = true;
- break;
+ 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;
num_loops = strtoll(optarg, &dummy, 10);
@@ -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);
/*
@@ -607,7 +639,8 @@ 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;
}

@@ -625,17 +658,50 @@ int main(int argc, char **argv)
}

/* 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 */
+ 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,
+ "This device does not support buffers\n");
+ else
+ fprintf(stderr, "Failed to retrieve buffer fd\n");
+ if (close(fd) == -1)
+ perror("Failed to close character device file");
+
+ goto error;
+ }
+
+ /* if this is buffer0, 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;
+ }
+ }
+
+ /* 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 +719,7 @@ 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 +736,9 @@ 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);
diff --git a/tools/iio/iio_utils.c b/tools/iio/iio_utils.c
index a96002f2c2d5..aadee6d34c74 100644
--- a/tools/iio/iio_utils.c
+++ b/tools/iio/iio_utils.c
@@ -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)
diff --git a/tools/iio/iio_utils.h b/tools/iio/iio_utils.h
index a5d0aa8a57d3..336752cade4f 100644
--- a/tools/iio/iio_utils.h
+++ b/tools/iio/iio_utils.h
@@ -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);
--
2.17.1
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