metag: TBX source

Add source files from the Thread Binary Interface (TBI) library which
provides useful low level operations and traps/context management.

Among other things it handles interrupt/exception/syscall entry (in
tbipcx.S).

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

1 files changed, 175 insertions, 0 deletions

diff --git a/arch/metag/tbx/tbidefr.S b/arch/metag/tbx/tbidefr.S
new file mode 100644
index 000000000000..3eb165ebf540
--- /dev/null
+++ b/arch/metag/tbx/tbidefr.S
@@ -0,0 +1,175 @@
+/*
+ * tbidefr.S
+ *
+ * Copyright (C) 2009, 2012 Imagination Technologies.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation.
+ *
+ * Routing deferred exceptions
+ */
+
+#include <asm/metag_regs.h>
+#include <asm/tbx.h>
+
+	.text
+	.balign	4
+	.global	___TBIHandleDFR
+	.type	___TBIHandleDFR,function
+/* D1Ar1:D0Ar2 -- State
+ * D0Ar3       -- SigNum
+ * D0Ar4       -- Triggers
+ * D1Ar5       -- InstOrSWSId
+ * D0Ar6       -- pTBI (volatile)
+ */
+___TBIHandleDFR:
+#ifdef META_BUG_MBN100212
+	MSETL	[A0StP++], D0FrT, D0.5
+
+	/* D1Ar1,D0Ar2,D1Ar5,D0Ar6 -- Arguments to handler, must be preserved
+	 * D0Ar4       -- The deferred exceptions
+	 * D1Ar3       -- As per D0Ar4 but just the trigger bits
+	 * D0.5        -- The bgnd deferred exceptions
+	 * D1.5        -- TXDEFR with bgnd re-added
+	 */
+
+	/* - Collect the pending deferred exceptions using TXSTAT,
+	 *   (ack's the bgnd exceptions as a side-effect)
+	 * - Manually collect remaining (interrupt) deferred exceptions
+	 *   using TXDEFR
+	 * - Replace the triggers (from TXSTATI) with the int deferred
+	 *   exceptions DEFR ..., TXSTATI would have returned if it was valid
+	 *   from bgnd code
+	 * - Reconstruct TXDEFR by or'ing bgnd deferred exceptions (except
+	 *   the DEFER bit) and the int deferred exceptions. This will be
+	 *   restored later
+	 */
+	DEFR	D0.5,  TXSTAT
+	MOV	D1.5,  TXDEFR
+	ANDT	D0.5,  D0.5, #HI(0xFFFF0000)
+	MOV	D1Ar3, D1.5
+	ANDT	D1Ar3, D1Ar3, #HI(0xFFFF0000)
+	OR	D0Ar4, D1Ar3, #TXSTAT_DEFER_BIT
+	OR	D1.5, D1.5, D0.5
+
+	/* Mask off anything unrelated to the deferred exception triggers */
+	ANDT	D1Ar3, D1Ar3, #HI(TXSTAT_BUSERR_BIT | TXSTAT_FPE_BITS)
+
+	/* Can assume that at least one exception happened since this
+	 * handler wouldnt have been called otherwise.
+	 * 
+	 * Replace the signal number and at the same time, prepare
+	 * the mask to acknowledge the exception
+	 *
+	 * D1Re0 -- The bits to acknowledge
+	 * D1Ar3 -- The signal number
+	 * D1RtP -- Scratch to deal with non-conditional insns
+	 */
+	MOVT	D1Re0, #HI(TXSTAT_FPE_BITS & ~TXSTAT_FPE_DENORMAL_BIT)
+	MOV	D1RtP, #TXSTAT_FPE_INVALID_S
+	FFB	D1Ar3, D1Ar3
+	CMP	D1Ar3, #TXSTAT_FPE_INVALID_S
+	MOVLE	D1Ar3, D1RtP /* Collapse FPE triggers to a single signal */
+	MOV	D1RtP, #1
+	LSLGT	D1Re0, D1RtP, D1Ar3
+
+	/* Get the handler using the signal number
+	 *
+	 * D1Ar3 -- The signal number
+	 * D0Re0 -- Offset into TBI struct containing handler address
+	 * D1Re0 -- Mask of triggers to keep
+	 * D1RtP -- Address of handler
+	 */
+	SUB	D1Ar3, D1Ar3, #(TXSTAT_FPE_INVALID_S - TBID_SIGNUM_FPE)
+	LSL	D0Re0, D1Ar3, #2
+	XOR	D1Re0, D1Re0, #-1   /* Prepare mask for acknowledge (avoids stall) */
+	ADD	D0Re0,D0Re0,#TBI_fnSigs
+	GETD	D1RtP, [D0Ar6+D0Re0]
+
+	/* Acknowledge triggers */
+	AND	D1.5, D1.5, D1Re0
+
+	/* Restore remaining exceptions
+	 * Do this here in case the handler enables nested interrupts
+	 *
+	 * D1.5 -- TXDEFR with this exception ack'd
+	 */
+	MOV	TXDEFR, D1.5
+
+	/* Call the handler */
+	SWAP	D1RtP, PC
+
+	GETL	D0.5,  D1.5,  [--A0StP]
+	GETL	D0FrT, D1RtP, [--A0StP]
+	MOV	PC,D1RtP
+#else  /* META_BUG_MBN100212 */
+
+	/* D1Ar1,D0Ar2,D1Ar5,D0Ar6 -- Arguments to handler, must be preserved
+	 * D0Ar4       -- The deferred exceptions
+	 * D1Ar3       -- As per D0Ar4 but just the trigger bits
+	 */
+
+	/* - Collect the pending deferred exceptions using TXSTAT,
+	 *   (ack's the interrupt exceptions as a side-effect)
+	 */
+	DEFR	D0Ar4, TXSTATI
+
+	/* Mask off anything unrelated to the deferred exception triggers */
+	MOV	D1Ar3, D0Ar4
+	ANDT	D1Ar3, D1Ar3, #HI(TXSTAT_BUSERR_BIT | TXSTAT_FPE_BITS)
+
+	/* Can assume that at least one exception happened since this
+	 * handler wouldnt have been called otherwise.
+	 * 
+	 * Replace the signal number and at the same time, prepare
+	 * the mask to acknowledge the exception
+	 *
+	 * The unusual code for 1<<D1Ar3 may need explanation.
+	 * Normally this would be done using 'MOV rs,#1' and 'LSL rd,rs,D1Ar3'
+	 * but only D1Re0 is available in D1 and no crossunit insns are available
+	 * Even worse, there is no conditional 'MOV r,#uimm8'.
+	 * Since the CMP proves that D1Ar3 >= 20, we can reuse the bottom 12-bits
+	 * of D1Re0 (using 'ORGT r,#1') in the knowledge that the top 20-bits will
+	 * be discarded without affecting the result.
+	 *
+	 * D1Re0 -- The bits to acknowledge
+	 * D1Ar3 -- The signal number
+	 */
+	MOVT	D1Re0, #HI(TXSTAT_FPE_BITS & ~TXSTAT_FPE_DENORMAL_BIT)
+	MOV	D0Re0, #TXSTAT_FPE_INVALID_S
+	FFB	D1Ar3, D1Ar3
+	CMP	D1Ar3, #TXSTAT_FPE_INVALID_S
+	MOVLE	D1Ar3, D0Re0 /* Collapse FPE triggers to a single signal */
+	ORGT	D1Re0, D1Re0, #1
+	LSLGT	D1Re0, D1Re0, D1Ar3
+
+	SUB	D1Ar3, D1Ar3, #(TXSTAT_FPE_INVALID_S - TBID_SIGNUM_FPE)
+
+	/* Acknowledge triggers and restore remaining exceptions
+	 * Do this here in case the handler enables nested interrupts
+	 *
+	 * (x | y) ^ y == x & ~y. It avoids the restrictive XOR ...,#-1 insn
+	 * and is the same length
+	 */
+	MOV	D0Re0, TXDEFR
+	OR	D0Re0, D0Re0, D1Re0
+	XOR	TXDEFR, D0Re0, D1Re0
+
+	/* Get the handler using the signal number
+	 *
+	 * D1Ar3 -- The signal number
+	 * D0Re0 -- Address of handler
+	 */
+	LSL	D0Re0, D1Ar3, #2
+	ADD	D0Re0,D0Re0,#TBI_fnSigs
+	GETD	D0Re0, [D0Ar6+D0Re0]
+
+	/* Tailcall the handler */
+	MOV	PC,D0Re0
+
+#endif /* META_BUG_MBN100212 */
+	.size	___TBIHandleDFR,.-___TBIHandleDFR
+/*
+ * End of tbidefr.S
+ */