[MIPS] Rewrite all the assembler interrupt handlers to C.

Saves like 1,600 lines of code, is way easier to debug, compilers
frequently do a better job than the cut and paste type of handlers many
boards had.  And finally having all the stuff done in a single place
also means alot of bug potencial for the MT ASE is gone.

The only surviving handler in assembler is the DECstation one; I hope
Maciej will rewrite it.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

3 files changed, 73 insertions, 154 deletions

diff --git a/arch/mips/sibyte/sb1250/Makefile b/arch/mips/sibyte/sb1250/Makefile
index a8af8469758..a2fdbd62f8a 100644
--- a/arch/mips/sibyte/sb1250/Makefile
+++ b/arch/mips/sibyte/sb1250/Makefile
@@ -1,4 +1,4 @@
-obj-y := setup.o irq.o irq_handler.o time.o
+obj-y := setup.o irq.o time.o
 
 obj-$(CONFIG_SMP)			+= smp.o
 obj-$(CONFIG_SIBYTE_TBPROF)		+= bcm1250_tbprof.o
diff --git a/arch/mips/sibyte/sb1250/irq.c b/arch/mips/sibyte/sb1250/irq.c
index 589537bfcc3..0f6e54db488 100644
--- a/arch/mips/sibyte/sb1250/irq.c
+++ b/arch/mips/sibyte/sb1250/irq.c
@@ -163,10 +163,6 @@ static void sb1250_set_affinity(unsigned int irq, cpumask_t mask)
 }
 #endif
 
-
-/* Defined in arch/mips/sibyte/sb1250/irq_handler.S */
-extern void sb1250_irq_handler(void);
-
 /*****************************************************************************/
 
 static unsigned int startup_sb1250_irq(unsigned int irq)
@@ -379,7 +375,6 @@ void __init arch_init_irq(void)
 #endif
 	/* Enable necessary IPs, disable the rest */
 	change_c0_status(ST0_IM, imask);
-	set_except_vector(0, sb1250_irq_handler);
 
 #ifdef CONFIG_KGDB
 	if (kgdb_flag) {
@@ -409,7 +404,7 @@ void __init arch_init_irq(void)
 #define duart_out(reg, val)     csr_out32(val, IOADDR(A_DUART_CHANREG(kgdb_port,reg)))
 #define duart_in(reg)           csr_in32(IOADDR(A_DUART_CHANREG(kgdb_port,reg)))
 
-void sb1250_kgdb_interrupt(struct pt_regs *regs)
+static void sb1250_kgdb_interrupt(struct pt_regs *regs)
 {
 	/*
 	 * Clear break-change status (allow some time for the remote
@@ -424,3 +419,74 @@ void sb1250_kgdb_interrupt(struct pt_regs *regs)
 }
 
 #endif 	/* CONFIG_KGDB */
+
+static inline int dclz(unsigned long long x)
+{
+	int lz;
+
+	__asm__ (
+	"	.set	push						\n"
+	"	.set	mips64						\n"
+	"	dclz	%0, %1						\n"
+	"	.set	pop						\n"
+	: "=r" (lz)
+	: "r" (x));
+
+	return lz;
+}
+
+asmlinkage void plat_irq_dispatch(struct pt_regs *regs)
+{
+	unsigned int pending;
+
+#ifdef CONFIG_SIBYTE_SB1250_PROF
+	/* Set compare to count to silence count/compare timer interrupts */
+	write_c0_count(read_c0_count());
+#endif
+
+	/*
+	 * What a pain. We have to be really careful saving the upper 32 bits
+	 * of any * register across function calls if we don't want them
+	 * trashed--since were running in -o32, the calling routing never saves
+	 * the full 64 bits of a register across a function call.  Being the
+	 * interrupt handler, we're guaranteed that interrupts are disabled
+	 * during this code so we don't have to worry about random interrupts
+	 * blasting the high 32 bits.
+	 */
+
+	pending = read_c0_cause();
+
+#ifdef CONFIG_SIBYTE_SB1250_PROF
+	if (pending & CAUSEF_IP7) { /* Cpu performance counter interrupt */
+		sbprof_cpu_intr(exception_epc(regs));
+	}
+#endif
+
+	if (pending & CAUSEF_IP4)
+		sb1250_timer_interrupt(regs);
+
+#ifdef CONFIG_SMP
+	if (pending & CAUSEF_IP3)
+		sb1250_mailbox_interrupt(regs);
+#endif
+
+#ifdef CONFIG_KGDB
+	if (pending & CAUSEF_IP6)			/* KGDB (uart 1) */
+		sb1250_kgdb_interrupt(regs);
+#endif
+
+	if (pending & CAUSEF_IP2) {
+		unsigned long long mask;
+
+		/*
+		 * Default...we've hit an IP[2] interrupt, which means we've
+		 * got to check the 1250 interrupt registers to figure out what
+		 * to do.  Need to detect which CPU we're on, now that
+		 ~ smp_affinity is supported.
+		 */
+		mask = __raw_readq(IOADDR(A_IMR_REGISTER(smp_processor_id(),
+		                              R_IMR_INTERRUPT_STATUS_BASE)));
+		if (mask)
+			do_IRQ(63 - dclz(mask), regs);
+	}
+}
diff --git a/arch/mips/sibyte/sb1250/irq_handler.S b/arch/mips/sibyte/sb1250/irq_handler.S
deleted file mode 100644
index 60edc8fb302..00000000000
--- a/arch/mips/sibyte/sb1250/irq_handler.S
+++ /dev/null
@@ -1,147 +0,0 @@
-/*
- * Copyright (C) 2000, 2001, 2002, 2003 Broadcom Corporation
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that 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.
- */
-
-/*
- * sb1250_handle_int() is the routine that is actually called when an interrupt
- * occurs.  It is installed as the exception vector handler in arch_init_irq()
- * in arch/mips/sibyte/sb1250/irq.c
- *
- * In the handle we figure out which interrupts need handling, and use that to
- * call the dispatcher, which will take care of actually calling registered
- * handlers
- *
- * Note that we take care of all raised interrupts in one go at the handler.
- * This is more BSDish than the Indy code, and also, IMHO, more sane.
- */
-#include <linux/config.h>
-
-#include <asm/addrspace.h>
-#include <asm/asm.h>
-#include <asm/mipsregs.h>
-#include <asm/regdef.h>
-#include <asm/stackframe.h>
-#include <asm/sibyte/sb1250_defs.h>
-#include <asm/sibyte/sb1250_regs.h>
-#include <asm/sibyte/sb1250_int.h>
-
-/*
- * What a pain. We have to be really careful saving the upper 32 bits of any
- * register across function calls if we don't want them trashed--since were
- * running in -o32, the calling routing never saves the full 64 bits of a
- * register across a function call.  Being the interrupt handler, we're
- * guaranteed that interrupts are disabled during this code so we don't have
- * to worry about random interrupts blasting the high 32 bits.
- */
-
-	.text
-	.set	push
-	.set	noreorder
-	.set	noat
-	.set	mips64
-	.align	5
-	NESTED(sb1250_irq_handler, PT_SIZE, sp)
-	SAVE_ALL
-	CLI
-
-#ifdef CONFIG_SIBYTE_SB1250_PROF
-	/* Set compare to count to silence count/compare timer interrupts */
-	mfc0	t1, CP0_COUNT
-	mtc0	t1, CP0_COMPARE /* pause to clear IP[7] bit of cause ? */
-#endif
-	/* Read cause */
-	mfc0	s0, CP0_CAUSE
-
-#ifdef CONFIG_SIBYTE_SB1250_PROF
-	/* Cpu performance counter interrupt is routed to IP[7] */
-	andi	t1, s0, CAUSEF_IP7
-	beqz	t1, 0f
-	 srl	t1, s0, (CAUSEB_BD-2)  /* Shift BD bit to bit 2 */
-	and	t1, t1, 0x4		/* mask to get just BD bit */
-	mfc0	a0, CP0_EPC
-	jal	sbprof_cpu_intr
-	 addu	a0, a0, t1		/* a0 = EPC + (BD ? 4 :	0) */
-	j	ret_from_irq
-	 nop
-0:
-#endif
-
-	/* Timer interrupt is routed to IP[4] */
-	andi	t1, s0, CAUSEF_IP4
-	beqz	t1, 1f
-	 nop
-	jal	sb1250_timer_interrupt
-	 move	a0, sp			/* Pass the registers along */
-	j	ret_from_irq
-	 nop				# delay slot
-1:
-
-#ifdef CONFIG_SMP
-	/* Mailbox interrupt is routed to IP[3] */
-	andi	 t1, s0, CAUSEF_IP3
-	beqz	 t1, 2f
-	 nop
-	jal	 sb1250_mailbox_interrupt
-	 move    a0, sp
-	j	ret_from_irq
-	 nop				# delay slot
-2:
-#endif
-
-#ifdef CONFIG_KGDB
-	/* KGDB (uart 1) interrupt is routed to IP[6] */
-	andi	t1, s0, CAUSEF_IP6
-	beqz	t1, 1f
-	nop                            # delay slot
-	jal	sb1250_kgdb_interrupt
-         move	a0, sp
-	j	ret_from_irq
-	nop                            # delay slot
-1:
-#endif
-
-	and      t1, s0, CAUSEF_IP2
-	beqz     t1, 4f
-	 nop
-
-	/*
-	 * Default...we've hit an IP[2] interrupt, which means we've got to
-	 * check the 1250 interrupt registers to figure out what to do
-	 * Need to detect which CPU we're on, now that smp_affinity is supported.
-	 */
-	PTR_LA	v0, CKSEG1 + A_IMR_CPU0_BASE
-#ifdef CONFIG_SMP
-	lw	t1, TI_CPU($28)
-	sll	t1, IMR_REGISTER_SPACING_SHIFT
-	addu	v0, t1
-#endif
-	ld	s0, R_IMR_INTERRUPT_STATUS_BASE(v0)	/* read IP[2] status */
-
-	beqz	s0, 4f		/* No interrupts.  Return */
-	 move	a1, sp
-
-3:	dclz	s1, s0		/* Find the next interrupt */
-	dsubu	a0, zero, s1
-	daddiu	a0, a0, 63
-	jal	 do_IRQ
-	 nop
-
-4:	j        ret_from_irq
-	 nop
-
-	.set pop
-	END(sb1250_irq_handler)