firewire: cdev: add PHY pinging

This extends the FW_CDEV_IOC_SEND_PHY_PACKET ioctl() for /dev/fw* to be
useful for ping time measurements.  One application for it would be gap
count optimization in userspace that is based on ping times rather than
hop count.  (The latter is implemented in firewire-core itself but is
not applicable to beta PHYs that act as repeater.)

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h
index 3102b6b..28621e4 100644
--- a/drivers/firewire/core.h
+++ b/drivers/firewire/core.h
@@ -234,4 +234,9 @@
 void fw_send_phy_config(struct fw_card *card,
 			int node_id, int generation, int gap_count);
 
+static inline bool is_ping_packet(u32 *data)
+{
+	return (data[0] & 0xc0ffffff) == 0 && ~data[0] == data[1];
+}
+
 #endif /* _FIREWIRE_CORE_H */