ipmi: Export ipmb_checksum()

It will be needed by the upcoming ipmb direct addressing.
Signed-off-by: Corey Minyard <minyard@acm.org>
Tested-by: Andrew Manley <andrew.manley@sealingtech.com>
Reviewed-by: Andrew Manley <andrew.manley@sealingtech.com>

drivers/char/ipmi/ipmi_msghandler.c

@@ -1710,7 +1710,7 @@ int ipmi_unregister_for_cmd(struct ipmi_user *user,
 }
 EXPORT_SYMBOL(ipmi_unregister_for_cmd);
 
-static unsigned char
+unsigned char
 ipmb_checksum(unsigned char *data, int size)
 {
 	unsigned char csum = 0;
@@ -1720,6 +1720,7 @@ ipmb_checksum(unsigned char *data, int size)
 
 	return -csum;
 }
+EXPORT_SYMBOL(ipmb_checksum);
 
 static inline void format_ipmb_msg(struct ipmi_smi_msg   *smi_msg,
 				   struct kernel_ipmi_msg *msg,

include/linux/ipmi.h

@@ -335,4 +335,7 @@ extern int ipmi_get_smi_info(int if_num, struct ipmi_smi_info *data);
 
 #define GET_DEVICE_ID_MAX_RETRY		5
 
+/* Helper function for computing the IPMB checksum of some data. */
+unsigned char ipmb_checksum(unsigned char *data, int size);
+
 #endif /* __LINUX_IPMI_H */