From: Russell Currey <redacted>

The code that handles the format string in secvar-sysfs.c is entirely
OPAL specific, so create a new "format" op in secvar_operations to make
the secvar code more generic.  No functional change.

Signed-off-by: Russell Currey <redacted>
Signed-off-by: Andrew Donnellan <redacted>

---

v2: Use sysfs_emit() instead of sprintf() (gregkh)

v3: Enforce format string size limit (ruscur)
---
 arch/powerpc/include/asm/secvar.h            |  3 +++
 arch/powerpc/kernel/secvar-sysfs.c           | 23 ++++--------------
 arch/powerpc/platforms/powernv/opal-secvar.c | 25 ++++++++++++++++++++
 3 files changed, 33 insertions(+), 18 deletions(-)

diff --git a/arch/powerpc/include/asm/secvar.h b/arch/powerpc/include/asm/secvar.h
index 07ba36f868a7..8b6475589120 100644
--- a/arch/powerpc/include/asm/secvar.h
+++ b/arch/powerpc/include/asm/secvar.h

@@ -11,12 +11,15 @@
 #include <linux/types.h>
 #include <linux/errno.h>
 
+#define SECVAR_MAX_FORMAT_LEN	30 // max length of string returned by ->format()
+
 extern const struct secvar_operations *secvar_ops;
 
 struct secvar_operations {
 	int (*get)(const char *key, u64 key_len, u8 *data, u64 *data_size);
 	int (*get_next)(const char *key, u64 *key_len, u64 keybufsize);
 	int (*set)(const char *key, u64 key_len, u8 *data, u64 data_size);
+	ssize_t (*format)(char *buf);