/* $OpenBSD: longrun.c,v 1.13 2007/05/25 20:32:29 krw Exp $ */
/*
 * Copyright (c) 2003 Ted Unangst
 * Copyright (c) 2001 Tamotsu Hattori
 * 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.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/timeout.h>

#include <machine/cpufunc.h>

union msrinfo {
	u_int64_t msr;
	uint32_t regs[2];
};

/*
 * Crusoe model specific registers which interest us.
 */
#define MSR_TMx86_LONGRUN       0x80868010
#define MSR_TMx86_LONGRUN_FLAGS 0x80868011

#define LONGRUN_MODE_MASK(x) ((x) & 0x000000007f)
#define LONGRUN_MODE_RESERVED(x) ((x) & 0xffffff80)
#define LONGRUN_MODE_WRITE(x, y) (LONGRUN_MODE_RESERVED(x) | LONGRUN_MODE_MASK(y))

void	longrun_update(void *);

struct timeout longrun_timo;

void
longrun_init(void)
{
	cpu_setperf = longrun_setperf;

	timeout_set(&longrun_timo, longrun_update, NULL);
	timeout_add(&longrun_timo, hz);
}

/*
 * These are the instantaneous values used by the CPU.
 * regs[0] = Frequency is self-evident.
 * regs[1] = Voltage is returned in millivolts.
 * regs[2] = Percent is amount of performance window being used, not
 * percentage of top megahertz.  (0 values are typical.)
 */
void
longrun_update(void *arg)
{
	uint32_t eflags, regs[4];

	eflags = read_eflags();
	disable_intr();
	cpuid(0x80860007, regs);
	enable_intr();
	write_eflags(eflags);

	cpuspeed = regs[0];

	timeout_add(&longrun_timo, hz);
}

/*
 * Transmeta documentation says performance window boundaries
 * must be between 0 and 100 or a GP0 exception is generated.
 * mode is really only a bit, 0 or 1
 * These values will be rounded by the CPU to within the
 * limits it handles.  Typically, there are about 5 performance
 * levels selectable.
 */
void
longrun_setperf(int high)
{
	uint32_t eflags, mode;
 	union msrinfo msrinfo;

	if (high >= 50)
		mode = 1;	/* power */
	else
		mode = 0;	/* battery */

	eflags = read_eflags();
	disable_intr();

	msrinfo.msr = rdmsr(MSR_TMx86_LONGRUN);
	msrinfo.regs[0] = LONGRUN_MODE_WRITE(msrinfo.regs[0], 0); /* low */
	msrinfo.regs[1] = LONGRUN_MODE_WRITE(msrinfo.regs[1], high);
	wrmsr(MSR_TMx86_LONGRUN, msrinfo.msr);

	msrinfo.msr = rdmsr(MSR_TMx86_LONGRUN_FLAGS);
	msrinfo.regs[0] = (msrinfo.regs[0] & ~0x01) | mode;
	wrmsr(MSR_TMx86_LONGRUN_FLAGS, msrinfo.msr);

	enable_intr();
	write_eflags(eflags);

	longrun_update(NULL);
}