metag: handle low level kicks directly

Kick interrupts trigger the LWK (low level kick) signal, usually handled
by the __TBIDoStdLWK() function which is the only handler inherited from
the bootloader. The LWK signal is converted either to a SWK (plain
software kick) or a SWS (software kick with an attached message).

Linux has kick_handler() to handle SWK and call registered kick handlers
(IPIs and inter-thread comms), but SWS is as far as I'm aware unused
with Linux.

Therefore remove that abstraction and have Linux handle LWK directly.
This will reduce kick latency slightly, and reduce our dependence on the
bootloader, which makes it easier to directly boot a kernel in QEMU
(particularly for SMP).

Signed-off-by: James Hogan <james.hogan@imgtec.com>

1 files changed, 1 insertions, 5 deletions

diff --git a/arch/metag/kernel/setup.c b/arch/metag/kernel/setup.c
index c396cd0..e639bae 100644
--- a/arch/metag/kernel/setup.c
+++ b/arch/metag/kernel/setup.c
@@ -302,13 +302,9 @@ void __init setup_arch(char **cmdline_p)
 	 * rather than the version from the bootloader. This makes call
 	 * stacks easier to understand and may allow us to unmap the
 	 * bootloader at some point.
-	 *
-	 * We need to keep the LWK handler that TBI installed in order to
-	 * be able to do inter-thread comms.
 	 */
 	for (i = 0; i <= TBID_SIGNUM_MAX; i++)
-		if (i != TBID_SIGNUM_LWK)
-			_pTBI->fnSigs[i] = __TBIUnExpXXX;
+		_pTBI->fnSigs[i] = __TBIUnExpXXX;
 
 	/* A Meta requirement is that the kernel is loaded (virtually)
 	 * at the PAGE_OFFSET.