linux-imx

/*

 *  Pentium 4/Xeon CPU on demand clock modulation/speed scaling

 *  (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>

 *  (C) 2002 Zwane Mwaikambo <zwane@commfireservices.com>

 *  (C) 2002 Arjan van de Ven <arjanv@redhat.com>

 *  (C) 2002 Tora T. Engstad

 *  All Rights Reserved

 *

 *  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.

 *

 *      The author(s) of this software shall not be held liable for damages

 *      of any nature resulting due to the use of this software. This

 *      software is provided AS-IS with no warranties.

 *

 *  Date        Errata          Description

 *  20020525    N44, O17    12.5% or 25% DC causes lockup

 *

 */

​

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

​

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/smp.h>

#include <linux/cpufreq.h>

#include <linux/cpumask.h>

#include <linux/timex.h>

​

#include <asm/processor.h>

#include <asm/msr.h>

#include <asm/timer.h>

#include <asm/cpu_device_id.h>

​

#include "speedstep-lib.h"

​

/*

 * Duty Cycle (3bits), note DC_DISABLE is not specified in

 * intel docs i just use it to mean disable

 */

enum {

    DC_RESV, DC_DFLT, DC_25PT, DC_38PT, DC_50PT,

    DC_64PT, DC_75PT, DC_88PT, DC_DISABLE

};

​

#define DC_ENTRIES  8

​

​

static int has_N44_O17_errata[NR_CPUS];

static unsigned int stock_freq;

static struct cpufreq_driver p4clockmod_driver;

static unsigned int cpufreq_p4_get(unsigned int cpu);

​

static int cpufreq_p4_setdc(unsigned int cpu, unsigned int newstate)

{

    u32 l, h;

​

    if ((newstate > DC_DISABLE) || (newstate == DC_RESV))

        return -EINVAL;

​

    rdmsr_on_cpu(cpu, MSR_IA32_THERM_STATUS, &l, &h);

​

    if (l & 0x01)

        pr_debug("CPU#%d currently thermal throttled\n", cpu);

​

    if (has_N44_O17_errata[cpu] &&

        (newstate == DC_25PT || newstate == DC_DFLT))

        newstate = DC_38PT;

​

    rdmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, &l, &h);

    if (newstate == DC_DISABLE) {

        pr_debug("CPU#%d disabling modulation\n", cpu);

        wrmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, l & ~(1<<4), h);

    } else {

        pr_debug("CPU#%d setting duty cycle to %d%%\n",

            cpu, ((125 * newstate) / 10));

        /* bits 63 - 5  : reserved

         * bit  4   : enable/disable

         * bits 3-1 : duty cycle

         * bit  0   : reserved

         */

        l = (l & ~14);

        l = l | (1<<4) | ((newstate & 0x7)<<1);

        wrmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, l, h);

    }

​

    return 0;

}

​