[PATCH] mips: add support for Qemu system architecture

Add support for the virtual MIPS system that is emulated by Qemu.  See
http://www.linux-mips.org/wiki/Qemu for a detailed current status.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 37 insertions, 0 deletions

diff --git a/arch/mips/qemu/q-irq.c b/arch/mips/qemu/q-irq.c
new file mode 100644
index 000000000000..2c4e0704ff10
--- /dev/null
+++ b/arch/mips/qemu/q-irq.c
@@ -0,0 +1,37 @@
+#include <linux/init.h>
+#include <linux/linkage.h>
+
+#include <asm/i8259.h>
+#include <asm/mipsregs.h>
+#include <asm/qemu.h>
+#include <asm/system.h>
+#include <asm/time.h>
+
+extern asmlinkage void qemu_handle_int(void);
+
+asmlinkage void do_qemu_int(struct pt_regs *regs)
+{
+        unsigned int pending = read_c0_status() & read_c0_cause();
+
+        if (pending & 0x8000) {
+                ll_timer_interrupt(Q_COUNT_COMPARE_IRQ, regs);
+                return;
+        }
+        if (pending & 0x0400) {
+                int irq = i8259_irq();
+
+                if (likely(irq >= 0))
+                        do_IRQ(irq, regs);
+
+                return;
+        }
+}
+
+void __init arch_init_irq(void)
+{
+        set_except_vector(0, qemu_handle_int);
+        mips_hpt_frequency = QEMU_C0_COUNTER_CLOCK;             /* 100MHz */
+
+        init_i8259_irqs();
+        set_c0_status(0x8400);
+}