The sysfs_emit_at() function is used by mhi host driver.
The code was copied from mainline Linux kernel.
Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
---
backport/backport-include/linux/sysfs.h | 9 ++++++++
backport/compat/backport-5.10.c | 28 +++++++++++++++++++++++++
2 files changed, 37 insertions(+)
diff --git a/backport/backport-include/linux/sysfs.h b/backport/backport-include/linux/sysfs.h
index 7126fb03..5fd25c9c 100644
--- a/backport/backport-include/linux/sysfs.h
+++ b/backport/backport-include/linux/sysfs.h
@@ -10,15 +10,24 @@
#if LINUX_VERSION_IS_LESS(5,10,0)
#define sysfs_emit LINUX_BACKPORT(sysfs_emit)
+#define sysfs_emit_at LINUX_BACKPORT(sysfs_emit_at)
#ifdef CONFIG_SYSFS
__printf(2, 3)
int sysfs_emit(char *buf, const char *fmt, ...);
+__printf(3, 4)
+int sysfs_emit_at(char *buf, int at, const char *fmt, ...);
#else /* CONFIG_SYSFS */
__printf(2, 3)
static inline int sysfs_emit(char *buf, const char *fmt, ...)
{
return 0;
}
+
+__printf(3, 4)
+static inline int sysfs_emit_at(char *buf, int at, const char *fmt, ...)
+{
+ retur 0;
+}
#endif /* CONFIG_SYSFS */
#endif /* < 5.10 */
diff --git a/backport/compat/backport-5.10.c b/backport/compat/backport-5.10.c
index c3a7b7d3..c3b8e336 100644
--- a/backport/compat/backport-5.10.c
+++ b/backport/compat/backport-5.10.c
@@ -79,3 +79,31 @@ int sysfs_emit(char *buf, const char *fmt, ...)
return len;
}
EXPORT_SYMBOL_GPL(sysfs_emit);
+
+/**
+ * sysfs_emit_at - scnprintf equivalent, aware of PAGE_SIZE buffer.
+ * @buf: start of PAGE_SIZE buffer.
+ * @at: offset in @buf to start write in bytes
+ * @at must be >= 0 && < PAGE_SIZE
+ * @fmt: format
+ * @...: optional arguments to @fmt
+ *
+ *
+ * Returns number of characters written starting at &@buf[@at].
+ */
+int sysfs_emit_at(char *buf, int at, const char *fmt, ...)
+{
+ va_list args;
+ int len;
+
+ if (WARN(!buf || offset_in_page(buf) || at < 0 || at >= PAGE_SIZE,
+ "invalid sysfs_emit_at: buf:%p at:%d\n", buf, at))
+ return 0;
+
+ va_start(args, fmt);
+ len = vscnprintf(buf + at, PAGE_SIZE - at, fmt, args);
+ va_end(args);
+
+ return len;
+}
+EXPORT_SYMBOL_GPL(sysfs_emit_at);
--
2.45.2
