iio: tools: generic_buffer: auto-enable channels

If no channels are enabled when we run generic_buffer on a
device, add a command-line option to just enable all of them,
run the sampling and disable them all again afterwards.

This is extremely useful when I'm low-level testing my
sensors with interrupts and triggers, sample session:

root@Ux500:/ lsiio
Device 000: lsm303dlh_accel
Device 001: lis331dl_accel
Device 002: l3g4200d
Device 003: lsm303dlh_magn
Device 004: lps001wp
Trigger 000: lsm303dlh_accel-trigger
Trigger 001: lis331dl_accel-trigger
Trigger 002: l3g4200d-trigger

root@Ux500:/ generic_buffer -a -c 10 -n l3g4200d
iio device number being used is 2
iio trigger number being used is 2
No channels are enabled, enabling all channels
Enabling: in_anglvel_x_en
Enabling: in_anglvel_y_en
Enabling: in_anglvel_z_en
Enabling: in_timestamp_en
/sys/bus/iio/devices/iio:device2 l3g4200d-trigger
-3.593664 -0.713133 4.870143 946684863662292480
3.225546 0.867357 -4.945878 946684863671875000
-0.676413 0.127296 0.106641 946684863681488037
-0.661113 0.110160 0.128826 946684863690673828
-0.664173 0.113067 0.123471 946684863700683593
-0.664938 0.109395 0.124848 946684863710144042
-0.664173 0.110619 0.130203 946684863719512939
-0.666162 0.111231 0.132651 946684863729125976
-0.668610 0.111690 0.130662 946684863738739013
-0.660501 0.110466 0.131733 946684863748565673
Disabling: in_anglvel_x_en
Disabling: in_anglvel_y_en
Disabling: in_anglvel_z_en
Disabling: in_timestamp_en

Pure awesomeness. If some channels have been enabled through
scripts or manual interaction, nothing happens.

Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Acked-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

tools/iio/generic_buffer.c

@@ -34,6 +34,15 @@
 #include <inttypes.h>
 #include "iio_utils.h"
 
+/**
+ * enum autochan - state for the automatic channel enabling mechanism
+ */
+enum autochan {
+	AUTOCHANNELS_DISABLED,
+	AUTOCHANNELS_ENABLED,
+	AUTOCHANNELS_ACTIVE,
+};
+
 /**
  * size_from_channelarray() - calculate the storage size of a scan
  * @channels:		the channel info array
@@ -191,10 +200,51 @@ void process_scan(char *data,
 	printf("\n");
 }
 
+static int enable_disable_all_channels(char *dev_dir_name, int enable)
+{
+	const struct dirent *ent;
+	char scanelemdir[256];
+	DIR *dp;
+	int ret;
+
+	snprintf(scanelemdir, sizeof(scanelemdir),
+		 FORMAT_SCAN_ELEMENTS_DIR, dev_dir_name);
+	scanelemdir[sizeof(scanelemdir)-1] = '\0';
+
+	dp = opendir(scanelemdir);
+	if (!dp) {
+		fprintf(stderr, "Enabling/disabling channels: can't open %s\n",
+			scanelemdir);
+		return -EIO;
+	}
+
+	ret = -ENOENT;
+	while (ent = readdir(dp), ent) {
+		if (iioutils_check_suffix(ent->d_name, "_en")) {
+			printf("%sabling: %s\n",
+			       enable ? "En" : "Dis",
+			       ent->d_name);
+			ret = write_sysfs_int(ent->d_name, scanelemdir,
+					      enable);
+			if (ret < 0)
+				fprintf(stderr, "Failed to enable/disable %s\n",
+					ent->d_name);
+		}
+	}
+
+	if (closedir(dp) == -1) {
+		perror("Enabling/disabling channels: "
+		       "Failed to close directory");
+		return -errno;
+	}
+	return 0;
+}
+
 void print_usage(void)
 {
 	fprintf(stderr, "Usage: generic_buffer [options]...\n"
 		"Capture, convert and output data from IIO device buffer\n"
+		"  -a         Auto-activate all available channels\n"
 		"  -c <n>     Do n conversions\n"
 		"  -e         Disable wait for event (new data)\n"
 		"  -g         Use trigger-less mode\n"
@@ -225,12 +275,16 @@ int main(int argc, char **argv)
 	int scan_size;
 	int noevents = 0;
 	int notrigger = 0;
+	enum autochan autochannels = AUTOCHANNELS_DISABLED;
 	char *dummy;
 
 	struct iio_channel_info *channels;
 
-	while ((c = getopt(argc, argv, "c:egl:n:t:w:")) != -1) {
+	while ((c = getopt(argc, argv, "ac:egl:n:t:w:")) != -1) {
 		switch (c) {
+		case 'a':
+			autochannels = AUTOCHANNELS_ENABLED;
+			break;
 		case 'c':
 			errno = 0;
 			num_loops = strtoul(optarg, &dummy, 10);
@@ -340,12 +394,47 @@ int main(int argc, char **argv)
 			"diag %s\n", dev_dir_name);
 		goto error_free_triggername;
 	}
-	if (!num_channels) {
+	if (num_channels && autochannels == AUTOCHANNELS_ENABLED) {
+		fprintf(stderr, "Auto-channels selected but some channels "
+			"are already activated in sysfs\n");
+		fprintf(stderr, "Proceeding without activating any channels\n");
+	}
+
+	if (!num_channels && autochannels == AUTOCHANNELS_ENABLED) {
+		fprintf(stderr,
+			"No channels are enabled, enabling all channels\n");
+
+		ret = enable_disable_all_channels(dev_dir_name, 1);
+		if (ret) {
+			fprintf(stderr, "Failed to enable all channels\n");
+			goto error_free_triggername;
+		}
+
+		/* This flags that we need to disable the channels again */
+		autochannels = AUTOCHANNELS_ACTIVE;
+
+		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_disable_channels;
+		}
+		if (!num_channels) {
+			fprintf(stderr, "Still no channels after "
+				"auto-enabling, giving up\n");
+			goto error_disable_channels;
+		}
+	}
+
+	if (!num_channels && autochannels == AUTOCHANNELS_DISABLED) {
 		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);
+			"/*_en or pass -a to autoenable channels and "
+			"try again.\n", dev_dir_name);
 		ret = -ENOENT;
 		goto error_free_triggername;
 	}
@@ -479,7 +568,12 @@ int main(int argc, char **argv)
 error_free_triggername:
 	if (datardytrigger)
 		free(trigger_name);
-
+error_disable_channels:
+	if (autochannels == AUTOCHANNELS_ACTIVE) {
+		ret = enable_disable_all_channels(dev_dir_name, 0);
+		if (ret)
+			fprintf(stderr, "Failed to disable all channels\n");
+	}
 error_free_dev_dir_name:
 	free(dev_dir_name);
 

tools/iio/iio_utils.h

@@ -52,6 +52,13 @@ struct iio_channel_info {
 	unsigned location;
 };
 
+static inline int iioutils_check_suffix(const char *str, const char *suffix)
+{
+	return strlen(str) >= strlen(suffix) &&
+		strncmp(str+strlen(str)-strlen(suffix),
+			suffix, strlen(suffix)) == 0;
+}
+
 int iioutils_break_up_name(const char *full_name, char **generic_name);
 int iioutils_get_type(unsigned *is_signed, unsigned *bytes, unsigned *bits_used,
 		      unsigned *shift, uint64_t *mask, unsigned *be,