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+/*
+ * Carsten Langgaard, carstenl@mips.com
+ * Copyright (C) 1999, 2000 MIPS Technologies, Inc. All rights reserved.
+ *
+ * This program is free software; you can distribute it and/or modify it
+ * under the terms of the GNU General Public License (Version 2) as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ * Interrupt exception dispatch code.
+ */
+#include <linux/config.h>
+
+#include <asm/asm.h>
+#include <asm/mipsregs.h>
+#include <asm/regdef.h>
+#include <asm/stackframe.h>
+#include <asm/mips-boards/atlasint.h>
+
+/*
+ * Furthermore, the IRQs on the MIPS board look basically (barring software
+ * IRQs which we don't use at all and all external interrupt sources are
+ * combined together on hardware interrupt 0 (MIPS IRQ 2)) like:
+ *
+ * MIPS IRQ Source
+ * -------- ------
+ * 0 Software (ignored)
+ * 1 Software (ignored)
+ * 2 Combined hardware interrupt (hw0)
+ * 3 Hardware (ignored)
+ * 4 Hardware (ignored)
+ * 5 Hardware (ignored)
+ * 6 Hardware (ignored)
+ * 7 R4k timer (what we use)
+ *
+ * Note: On the SEAD board thing are a little bit different.
+ * Here IRQ 2 (hw0) is wired to the UART0 and IRQ 3 (hw1) is wired
+ * wired to UART1.
+ *
+ * We handle the IRQ according to _our_ priority which is:
+ *
+ * Highest ---- R4k Timer
+ * Lowest ---- Combined hardware interrupt
+ *
+ * then we just return, if multiple IRQs are pending then we will just take
+ * another exception, big deal.
+ */
+
+ .text
+ .set noreorder
+ .set noat
+ .align 5
+ NESTED(mipsIRQ, PT_SIZE, sp)
+ SAVE_ALL
+ CLI
+ .set at
+
+ mfc0 s0, CP0_CAUSE # get irq bits
+ mfc0 s1, CP0_STATUS # get irq mask
+ andi s0, ST0_IM # CAUSE.CE may be non-zero!
+ and s0, s1
+
+#if defined(CONFIG_CPU_MIPS32) || defined(CONFIG_CPU_MIPS64)
+ .set mips32
+ clz a0, s0
+ .set mips0
+ negu a0
+ addu a0, 31-CAUSEB_IP
+ bltz a0, spurious
+#else
+ beqz s0, spurious
+ li a0, 7
+
+ and t0, s0, 0xf000
+ sltiu t0, t0, 1
+ sll t0, 2
+ subu a0, t0
+ sll s0, t0
+
+ and t0, s0, 0xc000
+ sltiu t0, t0, 1
+ sll t0, 1
+ subu a0, t0
+ sll s0, t0
+
+ and t0, s0, 0x8000
+ sltiu t0, t0, 1
+ # sll t0, 0
+ subu a0, t0
+ # sll s0, t0
+#endif
+
+ li a1, MIPSCPU_INT_ATLAS
+ bne a0, a1, 1f
+ addu a0, MIPSCPU_INT_BASE
+
+ jal atlas_hw0_irqdispatch
+ move a0, sp
+
+ j ret_from_irq
+ nop
+
+1: jal do_IRQ
+ move a1, sp
+
+ j ret_from_irq
+ nop
+
+spurious:
+ j spurious_interrupt
+ nop
+ END(mipsIRQ)