[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>

arch/mips/qemu/Makefile

@@ -0,0 +1,5 @@
+#
+# Makefile for Qemu specific kernel interface routines under Linux.
+#
+
+obj-y		= q-firmware.o q-int.o q-irq.o q-mem.o q-setup.o

arch/mips/qemu/q-firmware.c

@@ -0,0 +1,7 @@
+#include <linux/init.h>
+#include <asm/bootinfo.h>
+
+void __init prom_init(void)
+{
+	add_memory_region(0x0<<20, 0x10<<20, BOOT_MEM_RAM);
+}

arch/mips/qemu/q-int.S

@@ -0,0 +1,17 @@
+/*
+ * Qemu interrupt handler code.
+ *
+ * Copyright (C) 2005 by Ralf Baechle
+ */
+#include <asm/asm.h>
+#include <asm/regdef.h>
+#include <asm/stackframe.h>
+
+	.align	5
+	NESTED(qemu_handle_int, PT_SIZE, sp)
+	SAVE_ALL
+	CLI
+	move	a0, sp
+	PTR_LA	ra, ret_from_irq
+	j	do_qemu_int
+	END(qemu_handle_int)

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);
+}

arch/mips/qemu/q-mem.c

@@ -0,0 +1,6 @@
+#include <linux/init.h>
+
+unsigned long __init prom_free_prom_memory(void)
+{
+	return 0UL;
+}

arch/mips/qemu/q-setup.c

@@ -0,0 +1,20 @@
+#include <linux/init.h>
+#include <asm/io.h>
+#include <asm/time.h>
+
+#define QEMU_PORT_BASE 0xb4000000
+
+static void __init qemu_timer_setup(struct irqaction *irq)
+{
+	/* set the clock to 100 Hz */
+	outb_p(0x34,0x43);		/* binary, mode 2, LSB/MSB, ch 0 */
+	outb_p(LATCH & 0xff , 0x40);	/* LSB */
+	outb(LATCH >> 8 , 0x40);	/* MSB */
+	setup_irq(0, irq);
+}
+
+void __init plat_setup(void)
+{
+	set_io_port_base(QEMU_PORT_BASE);
+	board_timer_setup = qemu_timer_setup;
+}