Merge a rudimentary gxemul "oldtestmips" port. This consists almost

entirely of one machdep file lifted from the MALTA port, as well as
a low-level console and tty driver for the gxemul debugging console
device (the emulators stdio).  As with many low-level embedded and
hypervisor console devices, it is polled only, so we drive TTY I/O
from a callout; we are perhaps a bit too aware of the MIPS physical
maps in order to attach the console before newbus comes to life.

The sample kernel configuration depends on an MD-based root file
system, which is not provided.  However, any 64-bit, big-endian
userspace image (such as one generated for MALTA) should work.

This will hopefully be supplemented by additional device drivers for
gxemul-specific hardware simulations from Juli Mallett.  We have
found oldtestmips quite useful for testing and improving aspects of
the MIPS port, so it's worth supporting better in FreeBSD.

Requested by:	theraven, jmallett
Sponsored by:	DARPA, AFRL
MFC after:	3 weeks

sys/dev/gxemul/cons/gxemul_cons.c

@@ -0,0 +1,334 @@
+/*-
+ * Copyright (c) 2011-2012 Robert N. M. Watson
+ * All rights reserved.
+ *
+ * This software was developed by SRI International and the University of
+ * Cambridge Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237)
+ * ("CTSRD"), as part of the DARPA CRASH research programme.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/cons.h>
+#include <sys/endian.h>
+#include <sys/kdb.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/tty.h>
+
+#include <ddb/ddb.h>
+
+#define	GC_LOCK_INIT()		mtx_init(&gc_lock, "gc_lock", NULL, MTX_SPIN)
+
+#define	GC_LOCK() do {							\
+	if (!kdb_active)						\
+		mtx_lock_spin(&gc_lock);				\
+} while (0)
+
+#define	GC_LOCK_ASSERT() do {						\
+	if (!kdb_active)						\
+		mtx_assert(&gc_lock, MA_OWNED);				\
+} while (0)
+
+#define	GC_UNLOCK() do {						\
+	if (!kdb_active)						\
+		mtx_unlock_spin(&gc_lock);				\
+} while (0)
+
+
+static struct mtx	gc_lock;
+
+/*
+ * Low-level console driver functions.
+ */
+static cn_probe_t	gxemul_cons_cnprobe;
+static cn_init_t	gxemul_cons_cninit;
+static cn_term_t	gxemul_cons_cnterm;
+static cn_getc_t	gxemul_cons_cngetc;
+static cn_putc_t	gxemul_cons_cnputc;
+static cn_grab_t	gxemul_cons_cngrab;
+static cn_ungrab_t	gxemul_cons_cnungrab;
+
+/*
+ * TTY-level fields.
+ */
+static tsw_outwakeup_t	gxemul_cons_outwakeup;
+
+static struct ttydevsw gxemul_cons_ttydevsw = {
+	.tsw_flags	= TF_NOPREFIX,
+	.tsw_outwakeup	= gxemul_cons_outwakeup,
+};
+
+static struct callout	gxemul_cons_callout;
+static u_int		gxemul_cons_polltime = 10;
+#ifdef KDB
+static int		gxemul_cons_alt_break_state;
+#endif
+
+static void		gxemul_cons_timeout(void *);
+
+/*
+ * I/O routines lifted from Deimos.
+ *
+ * XXXRW: Should be using FreeBSD's bus routines here, but they are not
+ * available until later in the boot.
+ */
+#define	MIPS_XKPHYS_UNCACHED_BASE	0x9000000000000000
+
+typedef	uint64_t	paddr_t;
+typedef	uint64_t	vaddr_t;
+
+static inline vaddr_t
+mips_phys_to_uncached(paddr_t phys)            
+{
+
+	return (phys | MIPS_XKPHYS_UNCACHED_BASE);
+}
+
+static inline uint8_t
+mips_ioread_uint8(vaddr_t vaddr)
+{
+	uint8_t v;
+
+	__asm__ __volatile__ ("lbu %0, 0(%1)" : "=r" (v) : "r" (vaddr));
+	return (v);
+}
+
+static inline void
+mips_iowrite_uint8(vaddr_t vaddr, uint8_t v)
+{
+
+	__asm__ __volatile__ ("sb %0, 0(%1)" : : "r" (v), "r" (vaddr));
+}
+
+/*
+ * gxemul-specific constants.
+ */
+#define	GXEMUL_CONS_BASE	0x10000000	/* gxemul console device. */
+
+/*
+ * Routines for interacting with the gxemul test console.  Programming details
+ * are a result of manually inspecting the source code for gxemul's
+ * dev_cons.cc and dev_cons.h.
+ *
+ * Offsets of I/O channels relative to the base.
+ */
+#define	GXEMUL_PUTGETCHAR_OFF		0x00000000
+#define	GXEMUL_CONS_HALT		0x00000010
+
+/*
+ * One-byte buffer as we can't check whether the console is readable without
+ * actually reading from it.
+ */
+static char	buffer_data;
+static int	buffer_valid;
+
+/*
+ * Low-level read and write routines.
+ */
+static inline uint8_t
+gxemul_cons_data_read(void)
+{
+
+	return (mips_ioread_uint8(mips_phys_to_uncached(GXEMUL_CONS_BASE +
+	    GXEMUL_PUTGETCHAR_OFF)));
+}
+
+static inline void
+gxemul_cons_data_write(uint8_t v)
+{
+
+	mips_iowrite_uint8(mips_phys_to_uncached(GXEMUL_CONS_BASE +
+	    GXEMUL_PUTGETCHAR_OFF), v);
+}
+
+static int
+gxemul_cons_writable(void)
+{
+
+	return (1);
+}
+
+static int
+gxemul_cons_readable(void)
+{
+	uint32_t v;
+
+	GC_LOCK_ASSERT();
+
+	if (buffer_valid)
+		return (1);
+	v = gxemul_cons_data_read();
+	if (v != 0) {
+		buffer_valid = 1;
+		buffer_data = v;
+		return (1);
+	}
+	return (0);
+}
+
+static void
+gxemul_cons_write(char ch)
+{
+
+	GC_LOCK_ASSERT();
+
+	while (!gxemul_cons_writable());
+	gxemul_cons_data_write(ch);
+}
+
+static char
+gxemul_cons_read(void)
+{
+
+	GC_LOCK_ASSERT();
+
+	while (!gxemul_cons_readable());
+	buffer_valid = 0;
+	return (buffer_data);
+}
+
+/*
+ * Implementation of a FreeBSD low-level, polled console driver.
+ */
+static void
+gxemul_cons_cnprobe(struct consdev *cp)
+{
+
+	sprintf(cp->cn_name, "gxcons");
+	cp->cn_pri = CN_NORMAL;
+}
+
+static void
+gxemul_cons_cninit(struct consdev *cp)
+{
+
+	GC_LOCK_INIT();
+}
+
+static void
+gxemul_cons_cnterm(struct consdev *cp)
+{
+
+}
+
+static int
+gxemul_cons_cngetc(struct consdev *cp)
+{
+	int ret;
+
+	GC_LOCK();
+	ret = gxemul_cons_read();
+	GC_UNLOCK();
+	return (ret);
+}
+
+static void
+gxemul_cons_cnputc(struct consdev *cp, int c)
+{
+
+	GC_LOCK();
+	gxemul_cons_write(c);
+	GC_UNLOCK();
+}
+
+static void
+gxemul_cons_cngrab(struct consdev *cp)
+{
+
+}
+
+static void
+gxemul_cons_cnungrab(struct consdev *cp)
+{
+
+}
+
+CONSOLE_DRIVER(gxemul_cons);
+
+/*
+ * TTY-level functions for gxemul_cons.
+ */
+static void
+gxemul_cons_ttyinit(void *unused)
+{
+	struct tty *tp;
+
+	tp = tty_alloc(&gxemul_cons_ttydevsw, NULL);
+	tty_init_console(tp, 0);
+	tty_makedev(tp, NULL, "%s", "gxcons");
+	callout_init(&gxemul_cons_callout, CALLOUT_MPSAFE);
+	callout_reset(&gxemul_cons_callout, gxemul_cons_polltime,
+	    gxemul_cons_timeout, tp);
+
+}
+SYSINIT(gxemul_cons_ttyinit, SI_SUB_CONFIGURE, SI_ORDER_MIDDLE,
+    gxemul_cons_ttyinit, NULL);
+
+static void
+gxemul_cons_outwakeup(struct tty *tp)
+{
+	int len;
+	u_char ch;
+
+	/*
+	 * XXXRW: Would be nice not to do blocking writes to the console here,
+	 * rescheduling on our timer tick if work remains to be done..
+	 */
+	for (;;) {
+		len = ttydisc_getc(tp, &ch, sizeof(ch));
+		if (len == 0)
+			break;
+		GC_LOCK();
+		gxemul_cons_write(ch);
+		GC_UNLOCK();
+	}
+}
+
+static void
+gxemul_cons_timeout(void *v)
+{
+	struct tty *tp;
+	int c;
+
+	tp = v;
+	tty_lock(tp);
+	GC_LOCK();
+	while (gxemul_cons_readable()) {
+		c = gxemul_cons_read();
+		GC_UNLOCK();
+#ifdef KDB
+		kdb_alt_break(c, &gxemul_cons_alt_break_state);
+#endif
+		ttydisc_rint(tp, c, 0);
+		GC_LOCK();
+	}
+	GC_UNLOCK();
+	ttydisc_rint_done(tp);
+	tty_unlock(tp);
+	callout_reset(&gxemul_cons_callout, gxemul_cons_polltime,
+	    gxemul_cons_timeout, tp);
+}

sys/mips/conf/GXEMUL

@@ -0,0 +1,52 @@
+#
+# GXEMUL "oldtestmips" sample kernel configuration.
+#
+# $FreeBSD$
+#
+
+ident		GXEMUL
+
+machine		mips mips64eb
+cpu		CPU_MIPS4KC
+
+options 	HZ=100
+
+makeoptions	ARCH_FLAGS="-march=mips64 -mabi=64"
+
+makeoptions 	KERNLOADADDR=0xffffffff80100000
+
+include		"../gxemul/std.gxemul"
+
+hints		"GXEMUL.hints"		#Default places to look for devices.
+
+makeoptions	DEBUG=-g		#Build kernel with gdb(1) debug symbols
+
+makeoptions	MODULES_OVERRIDE=""
+
+options 	DDB
+options 	KDB
+
+options 	SCHED_ULE
+
+options 	FFS			#Berkeley Fast Filesystem
+
+# Debugging for use in -current
+#options 	DEADLKRES		#Enable the deadlock resolver
+options 	INVARIANTS		#Enable calls of extra sanity checking
+options 	INVARIANT_SUPPORT	#Extra sanity checks of internal structures, required by INVARIANTS
+#options 	WITNESS			#Enable checks to detect deadlocks and cycles
+#options 	WITNESS_SKIPSPIN	#Don't run witness on spinlocks for speed
+
+#
+# This kernel configuration uses an embedded 8MB memory root file system.
+# Adjust the following path based on local requirements.
+#
+options 	MD_ROOT			# MD is a potential root device
+options 	MD_ROOT_SIZE=8192
+#makeoptions	MFS_IMAGE=/local/scratch/rnw24/mdroot.img
+options 	ROOTDEVNAME=\"ufs:md0\"
+
+device		gxemul_cons
+device		md
+device		loop
+device		random

sys/mips/conf/GXEMUL.hints

@@ -0,0 +1 @@
+# $FreeBSD$

sys/mips/gxemul/files.gxemul

@@ -0,0 +1,5 @@
+# $FreeBSD$
+dev/gxemul/cons/gxemul_cons.c		optional gxemul_cons
+mips/gxemul/gxemul_machdep.c		standard
+mips/mips/intr_machdep.c		standard
+mips/mips/tick.c			standard

sys/mips/gxemul/gxemul_machdep.c

@@ -0,0 +1,191 @@
+/*-
+ * Copyright (c) 2006 Wojciech A. Koszek <wkoszek@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
+ */
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include "opt_ddb.h"
+
+#include <sys/param.h>
+#include <sys/conf.h>
+#include <sys/kernel.h>
+#include <sys/systm.h>
+#include <sys/imgact.h>
+#include <sys/bio.h>
+#include <sys/buf.h>
+#include <sys/bus.h>
+#include <sys/cpu.h>
+#include <sys/cons.h>
+#include <sys/exec.h>
+#include <sys/ucontext.h>
+#include <sys/proc.h>
+#include <sys/kdb.h>
+#include <sys/ptrace.h>
+#include <sys/reboot.h>
+#include <sys/signalvar.h>
+#include <sys/sysent.h>
+#include <sys/sysproto.h>
+#include <sys/user.h>
+
+#include <vm/vm.h>
+#include <vm/vm_object.h>
+#include <vm/vm_page.h>
+#include <vm/vm_pager.h>
+
+#include <machine/clock.h>
+#include <machine/cpu.h>
+#include <machine/cpuregs.h>
+#include <machine/hwfunc.h>
+#include <machine/md_var.h>
+#include <machine/pmap.h>
+#include <machine/trap.h>
+
+extern int	*edata;
+extern int	*end;
+
+void
+platform_cpu_init()
+{
+	/* Nothing special */
+}
+
+static void
+mips_init(void)
+{
+	int i;
+
+	for (i = 0; i < 10; i++) {
+		phys_avail[i] = 0;
+	}
+
+	/* phys_avail regions are in bytes */
+	phys_avail[0] = MIPS_KSEG0_TO_PHYS(kernel_kseg0_end);
+	phys_avail[1] = ctob(realmem);
+
+	dump_avail[0] = phys_avail[0];
+	dump_avail[1] = phys_avail[1];
+
+	physmem = realmem;
+
+	init_param1();
+	init_param2(physmem);
+	mips_cpu_init();
+	pmap_bootstrap();
+	mips_proc0_init();
+	mutex_init();
+	kdb_init();
+#ifdef KDB
+	if (boothowto & RB_KDB)
+		kdb_enter(KDB_WHY_BOOTFLAGS, "Boot flags requested debugger");
+#endif
+}
+
+void
+platform_halt(void)
+{
+
+}
+
+
+void
+platform_identify(void)
+{
+
+}
+
+/*
+ * Perform a board-level soft-reset.
+ *
+ * XXXRW: Does gxemul have a moral equivalent to board-level reset?
+ */
+void
+platform_reset(void)
+{
+
+	panic("%s: not yet", __func__);
+}
+
+void
+platform_trap_enter(void)
+{
+
+}
+
+void
+platform_trap_exit(void)
+{
+
+}
+
+void
+platform_start(__register_t a0, __register_t a1,  __register_t a2, 
+    __register_t a3)
+{
+	vm_offset_t kernend;
+	uint64_t platform_counter_freq;
+	int argc = a0;
+	char **argv = (char **)a1;
+	char **envp = (char **)a2;
+	unsigned int memsize = a3;
+	int i;
+
+	/* clear the BSS and SBSS segments */
+	kernend = (vm_offset_t)&end;
+	memset(&edata, 0, kernend - (vm_offset_t)(&edata));
+
+	mips_postboot_fixup();
+
+	mips_pcpu0_init();
+
+	/*
+	 * XXXRW: Support for the gxemul real-time clock required in order to
+	 * usefully determine our emulated timer frequency.  Go with something
+	 * classic as the default in the mean time.
+	 */
+	platform_counter_freq = MIPS_DEFAULT_HZ;
+	mips_timer_early_init(platform_counter_freq);
+
+	cninit();
+	printf("entry: platform_start()\n");
+
+	bootverbose = 1;
+	if (bootverbose) {
+		printf("cmd line: ");
+		for (i = 0; i < argc; i++)
+			printf("%s ", argv[i]);
+		printf("\n");
+
+		printf("envp:\n");
+		for (i = 0; envp[i]; i += 2)
+			printf("\t%s = %s\n", envp[i], envp[i+1]);
+
+		printf("memsize = %08x\n", memsize);
+	}
+
+	realmem = btoc(memsize);
+	mips_init();
+
+	mips_timer_init_params(platform_counter_freq, 0);
+}

sys/mips/gxemul/std.gxemul

@@ -0,0 +1,4 @@
+# $FreeBSD$
+files	"../gxemul/files.gxemul"
+
+cpu		CPU_MIPS4KC