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>

arch/metag/tbx/tbicore.S

@@ -0,0 +1,136 @@
+/*
+ * tbicore.S
+ *
+ * Copyright (C) 2001, 2002, 2007, 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.
+ *
+ * Core functions needed to support use of the thread binary interface for META
+ * processors
+ */
+
+	.file	"tbicore.S"
+/* Get data structures and defines from the TBI C header */
+#include <asm/metag_mem.h>
+#include <asm/metag_regs.h>
+#include <asm/tbx.h>
+
+	.data
+	.balign	8
+	.global	___pTBISegs
+	.type	___pTBISegs,object
+___pTBISegs:
+	.quad	0		/* Segment list pointer with it's */
+	.size	___pTBISegs,.-___pTBISegs
+					/* own id or spin-lock location */
+/*
+ * Return ___pTBISegs value specific to privilege level - not very complicated
+ * at the moment
+ *
+ * Register Usage: D0Re0 is the result, D1Re0 is used as a scratch
+ */
+	.text
+	.balign	4
+	.global	___TBISegList
+	.type	___TBISegList,function
+___TBISegList:
+	MOVT	A1LbP,#HI(___pTBISegs)
+	ADD	A1LbP,A1LbP,#LO(___pTBISegs)
+	GETL	D0Re0,D1Re0,[A1LbP]
+	MOV	PC,D1RtP
+	.size	___TBISegList,.-___TBISegList
+
+/*
+ * Search the segment list for a match given Id, pStart can be NULL
+ *
+ * Register Usage: D1Ar1 is pSeg, D0Ar2 is Id, D0Re0 is the result
+ *                 D0Ar4, D1Ar3 are used as a scratch
+ *                 NB: The PSTAT bit if Id in D0Ar2 may be toggled
+ */
+	.text
+	.balign	4
+	.global	___TBIFindSeg
+	.type	___TBIFindSeg,function
+___TBIFindSeg:
+	MOVT	A1LbP,#HI(___pTBISegs)
+	ADD	A1LbP,A1LbP,#LO(___pTBISegs)
+	GETL	D1Ar3,D0Ar4,[A1LbP]	/* Read segment list head */
+	MOV	D0Re0,TXSTATUS		/* What priv level are we at? */
+	CMP	D1Ar1,#0		/* Is pStart provided? */
+/* Disable privilege adaption for now */
+	ANDT	D0Re0,D0Re0,#0	/*HI(TXSTATUS_PSTAT_BIT)  ; Is PSTAT set? Zero if not */
+	LSL	D0Re0,D0Re0,#(TBID_PSTAT_S-TXSTATUS_PSTAT_S)
+	XOR	D0Ar2,D0Ar2,D0Re0	/* Toggle Id PSTAT if privileged */
+	MOVNZ	D1Ar3,D1Ar1		/* Use pStart if provided */
+$LFindSegLoop:			
+	ADDS	D0Re0,D1Ar3,#0		/* End of list? Load result into D0Re0 */
+	MOVZ	PC,D1RtP		/* If result is NULL we leave */
+	GETL	D1Ar3,D0Ar4,[D1Ar3]	/* Read pLink and Id */
+	CMP	D0Ar4,D0Ar2		/* Does it match? */
+	BNZ	$LFindSegLoop		/* Loop if there is no match */
+	TST	D0Re0,D0Re0		/* Clear zero flag - we found it! */
+	MOV	PC,D1RtP		/* Return */
+	.size	___TBIFindSeg,.-___TBIFindSeg
+
+/* Useful offsets to encode the lower bits of the lock/unlock addresses */
+#define UON  (LINSYSEVENT_WR_ATOMIC_LOCK   & 0xFFF8)
+#define UOFF (LINSYSEVENT_WR_ATOMIC_UNLOCK & 0xFFF8)
+
+/*
+ * Perform a whole spin-lock sequence as used by the TBISignal routine
+ *
+ * Register Usage: D1Ar1 is pLock, D0Ar2 is Mask, D0Re0 is the result
+ *                 (All other usage due to ___TBIPoll - D0Ar6, D1Re0)
+ */
+	.text
+	.balign	4
+	.global	___TBISpin
+	.type	___TBISpin,function
+___TBISpin:
+	SETL	[A0StP++],D0FrT,D1RtP	/* Save our return address */
+	ORS	D0Re0,D0Re0,#1		/* Clear zero flag */
+	MOV	D1RtP,PC		/* Setup return address to form loop */
+$LSpinLoop:
+	BNZ	___TBIPoll		/* Keep repeating if fail to set */
+	GETL	D0FrT,D1RtP,[--A0StP]	/* Restore return address */
+	MOV	PC,D1RtP		/* Return */
+	.size	___TBISpin,.-___TBISpin
+
+/*
+ * Perform an attempt to gain access to a spin-lock and set some bits
+ * 
+ * Register Usage: D1Ar1 is pLock, D0Ar2 is Mask, D0Re0 is the result
+ *                 !!On return Zero flag is SET if we are sucessfull!!
+ *                 A0.3 is used to hold base address of system event region
+ *                 D1Re0 use to hold TXMASKI while interrupts are off
+ */
+	.text
+	.balign	4
+	.global	___TBIPoll
+	.type	___TBIPoll,function
+___TBIPoll:
+	MOV	D1Re0,#0		/* Prepare to disable ints */
+	MOVT	A0.3,#HI(LINSYSEVENT_WR_ATOMIC_LOCK)
+	SWAP	D1Re0,TXMASKI		/* Really stop ints */
+	LOCK2				/* Gain all locks */
+	SET	[A0.3+#UON],D1RtP	/* Stop shared memory access too */
+	DCACHE	[D1Ar1],A0.3		/* Flush Cache line */
+	GETD	D0Re0,[D1Ar1]		/* Get new state from memory or hit */
+	DCACHE	[D1Ar1],A0.3		/* Flush Cache line */
+	GETD	D0Re0,[D1Ar1]		/* Get current state */
+	TST	D0Re0,D0Ar2		/* Are we clear to send? */
+	ORZ	D0Re0,D0Re0,D0Ar2	/* Yes: So set bits and */
+	SETDZ	[D1Ar1],D0Re0		/*      transmit new state */
+	SET	[A0.3+#UOFF],D1RtP	/* Allow shared memory access */
+	LOCK0				/* Release all locks */
+	MOV	TXMASKI,D1Re0		/* Allow ints */
+$LPollEnd:
+	XORNZ	D0Re0,D0Re0,D0Re0	/* No: Generate zero result */
+	MOV	PC,D1RtP		/* Return (NZ indicates failure) */
+	.size	___TBIPoll,.-___TBIPoll
+
+/*
+ * End of tbicore.S
+ */