iio: proximity: vl53l0x-i2c: claim direct mode for raw readsgrafted

vl53l0x_read_raw() starts a single-shot ranging measurement and reads
back the result. Once the triggered buffer is enabled the sensor runs in
continuous mode and its data-ready interrupt is routed to the trigger,
so a concurrent in_distance_raw read disturbs the streaming setup and
never gets its completion, returning -ETIMEDOUT.

The original submission claimed direct mode here, but it was dropped
during review because the driver had no buffer support at the time [1].
Continuous (buffered) mode was later added without restoring the
claim [2], reintroducing the conflict.

Reject direct reads while buffered capture is active by claiming direct
mode around the measurement, as the vl53l1x sibling already does.

Fixes: 762186c6e7b1 ("iio: proximity: vl53l0x-i2c: Added continuous mode support")
Link: https://lore.kernel.org/linux-iio/20180911160300.GA9212@himanshu-Vostro-3559/ [1]
Link: https://lore.kernel.org/linux-iio/20240909101508.263085-3-abhashkumarjha123@gmail.com/ [2]
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

3 files changed, 88 insertions, 0 deletions

diff --git a/samples/binderfs/.gitignore b/samples/binderfs/.gitignore
new file mode 100644
index 000000000..8fa415a36
--- /dev/null
+++ b/samples/binderfs/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0
+/binderfs_example
diff --git a/samples/binderfs/Makefile b/samples/binderfs/Makefile
new file mode 100644
index 000000000..629e43b9b
--- /dev/null
+++ b/samples/binderfs/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+userprogs-always-y += binderfs_example
+
+userccflags += -I usr/include
diff --git a/samples/binderfs/binderfs_example.c b/samples/binderfs/binderfs_example.c
new file mode 100644
index 000000000..0fd92cdda
--- /dev/null
+++ b/samples/binderfs/binderfs_example.c
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <linux/android/binder.h>
+#include <linux/android/binderfs.h>
+
+int main(int argc, char *argv[])
+{
+	int fd, ret, saved_errno;
+	struct binderfs_device device = { 0 };
+
+	ret = unshare(CLONE_NEWNS);
+	if (ret < 0) {
+		fprintf(stderr, "%s - Failed to unshare mount namespace\n",
+			strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
+	if (ret < 0) {
+		fprintf(stderr, "%s - Failed to mount / as private\n",
+			strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	ret = mkdir("/dev/binderfs", 0755);
+	if (ret < 0 && errno != EEXIST) {
+		fprintf(stderr, "%s - Failed to create binderfs mountpoint\n",
+			strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	ret = mount(NULL, "/dev/binderfs", "binder", 0, 0);
+	if (ret < 0) {
+		fprintf(stderr, "%s - Failed to mount binderfs\n",
+			strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	memcpy(device.name, "my-binder", strlen("my-binder"));
+
+	fd = open("/dev/binderfs/binder-control", O_RDONLY | O_CLOEXEC);
+	if (fd < 0) {
+		fprintf(stderr, "%s - Failed to open binder-control device\n",
+			strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	ret = ioctl(fd, BINDER_CTL_ADD, &device);
+	saved_errno = errno;
+	close(fd);
+	errno = saved_errno;
+	if (ret < 0) {
+		fprintf(stderr, "%s - Failed to allocate new binder device\n",
+			strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	printf("Allocated new binder device with major %d, minor %d, and name %s\n",
+	       device.major, device.minor, device.name);
+
+	ret = unlink("/dev/binderfs/my-binder");
+	if (ret < 0) {
+		fprintf(stderr, "%s - Failed to delete binder device\n",
+			strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	/* Cleanup happens when the mount namespace dies. */
+	exit(EXIT_SUCCESS);
+}