[MIPS] Add support for BCM47XX CPUs.

Note that the BCM4710 does not support the wait instruction, this
is not a mistake in the code.
    
It originally comes from the OpenWrt patches.
    
Cc: Michael Buesch <mb@bu3sch.de>
Cc: Felix Fietkau <nbd@openwrt.org>
Cc: Florian Schirmer <jolt@tuxbox.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/bcm47xx/irq.c b/arch/mips/bcm47xx/irq.c
new file mode 100644
index 0000000..325757a
--- /dev/null
+++ b/arch/mips/bcm47xx/irq.c
@@ -0,0 +1,55 @@
+/*
+ *  Copyright (C) 2004 Florian Schirmer <jolt@tuxbox.org>
+ *
+ *  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  SOFTWARE  IS PROVIDED   ``AS  IS'' AND   ANY  EXPRESS OR IMPLIED
+ *  WARRANTIES,   INCLUDING, BUT NOT  LIMITED  TO, THE IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
+ *  NO  EVENT  SHALL   THE AUTHOR  BE    LIABLE FOR ANY   DIRECT, INDIRECT,
+ *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ *  NOT LIMITED   TO, PROCUREMENT OF  SUBSTITUTE GOODS  OR SERVICES; LOSS OF
+ *  USE, DATA,  OR PROFITS; OR  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ *  ANY THEORY OF LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT
+ *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ *  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.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <asm/irq_cpu.h>
+
+void plat_irq_dispatch(void)
+{
+	u32 cause;
+
+	cause = read_c0_cause() & read_c0_status() & CAUSEF_IP;
+
+	clear_c0_status(cause);
+
+	if (cause & CAUSEF_IP7)
+		do_IRQ(7);
+	if (cause & CAUSEF_IP2)
+		do_IRQ(2);
+	if (cause & CAUSEF_IP3)
+		do_IRQ(3);
+	if (cause & CAUSEF_IP4)
+		do_IRQ(4);
+	if (cause & CAUSEF_IP5)
+		do_IRQ(5);
+	if (cause & CAUSEF_IP6)
+		do_IRQ(6);
+}
+
+void __init arch_init_irq(void)
+{
+	mips_cpu_irq_init();
+}