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>

1 files changed, 62 insertions, 0 deletions

diff --git a/lib/kunit/string-stream.h b/lib/kunit/string-stream.h
new file mode 100644
index 000000000..7be2450c7
--- /dev/null
+++ b/lib/kunit/string-stream.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * C++ stream style string builder used in KUnit for building messages.
+ *
+ * Copyright (C) 2019, Google LLC.
+ * Author: Brendan Higgins <brendanhiggins@google.com>
+ */
+
+#ifndef _KUNIT_STRING_STREAM_H
+#define _KUNIT_STRING_STREAM_H
+
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/stdarg.h>
+
+struct string_stream_fragment {
+	struct list_head node;
+	char *fragment;
+};
+
+struct string_stream {
+	size_t length;
+	struct list_head fragments;
+	/* length and fragments are protected by this lock */
+	spinlock_t lock;
+	gfp_t gfp;
+	bool append_newlines;
+};
+
+struct kunit;
+
+struct string_stream *kunit_alloc_string_stream(struct kunit *test, gfp_t gfp);
+void kunit_free_string_stream(struct kunit *test, struct string_stream *stream);
+
+struct string_stream *alloc_string_stream(gfp_t gfp);
+void free_string_stream(struct string_stream *stream);
+
+int __printf(2, 3) string_stream_add(struct string_stream *stream,
+				     const char *fmt, ...);
+
+int __printf(2, 0) string_stream_vadd(struct string_stream *stream,
+				      const char *fmt,
+				      va_list args);
+
+void string_stream_clear(struct string_stream *stream);
+
+char *string_stream_get_string(struct string_stream *stream);
+
+int string_stream_append(struct string_stream *stream,
+			 struct string_stream *other);
+
+bool string_stream_is_empty(struct string_stream *stream);
+
+void string_stream_destroy(struct string_stream *stream);
+
+static inline void string_stream_set_append_newlines(struct string_stream *stream,
+						     bool append_newlines)
+{
+	stream->append_newlines = append_newlines;
+}
+
+#endif /* _KUNIT_STRING_STREAM_H */