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authorNiklas Söderlund <niklas.soderlund@ragnatech.se>2020-08-04 15:39:16 +0200
committerNiklas Söderlund <niklas.soderlund@ragnatech.se>2020-08-05 20:07:13 +0200
commit6ad3258cd34295611e871edf5e8474d4aa79af59 (patch)
tree6d1ee62eea7898103aa4c511919c3bbf22da1511 /src
parent79a834f24c6e5094876b57973f7900401ec4683f (diff)
libcamera: sysfs: Add helper to lookup sysfs path of a character device
Add a helper function to lookup the sysfs path of a character device. Store the function in a new libcamera::sysfs namespace as there is not class to host it. Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Diffstat (limited to 'src')
-rw-r--r--src/libcamera/meson.build1
-rw-r--r--src/libcamera/sysfs.cpp52
2 files changed, 53 insertions, 0 deletions
diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
index 3aad4386..bada45bc 100644
--- a/src/libcamera/meson.build
+++ b/src/libcamera/meson.build
@@ -41,6 +41,7 @@ libcamera_sources = files([
'semaphore.cpp',
'signal.cpp',
'stream.cpp',
+ 'sysfs.cpp',
'thread.cpp',
'timer.cpp',
'utils.cpp',
diff --git a/src/libcamera/sysfs.cpp b/src/libcamera/sysfs.cpp
new file mode 100644
index 00000000..398df2c2
--- /dev/null
+++ b/src/libcamera/sysfs.cpp
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2020, Google Inc.
+ *
+ * sysfs.cpp - Miscellaneous utility functions to access sysfs
+ */
+
+#include "libcamera/internal/sysfs.h"
+
+#include <sstream>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+
+#include "libcamera/internal/log.h"
+
+/**
+ * \file sysfs.h
+ * \brief Miscellaneous utility functions to access sysfs
+ */
+
+namespace libcamera {
+
+LOG_DEFINE_CATEGORY(SysFs);
+
+namespace sysfs {
+
+/**
+ * \brief Retrieve the sysfs path for a character device
+ * \param[in] deviceNode Path to character device node
+ * \return The sysfs path on success or an empty string on failure
+ */
+std::string charDevPath(const std::string &deviceNode)
+{
+ struct stat st;
+ int ret = stat(deviceNode.c_str(), &st);
+ if (ret < 0) {
+ ret = -errno;
+ LOG(SysFs, Error)
+ << "Unable to stat '" << deviceNode << "': "
+ << strerror(-ret);
+ return {};
+ }
+
+ std::ostringstream dev("/sys/dev/char/", std::ios_base::ate);
+ dev << major(st.st_rdev) << ":" << minor(st.st_rdev);
+
+ return dev.str();
+}
+
+} /* namespace sysfs */
+
+} /* namespace libcamera */