cpufreq.c

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/*
 * Copyright (C) 2007 PA Semi, Inc
 *
 * Authors: Egor Martovetsky <[email protected]>
 *      Olof Johansson <[email protected]>
 *
 * Maintained by: Olof Johansson <[email protected]>
 *
 * Based on arch/powerpc/platforms/cell/cbe_cpufreq.c:
 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
 *
 * 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, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/cpufreq.h>
#include <linux/timer.h>
#include <linux/module.h>

#include <asm/hw_irq.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/time.h>
#include <asm/smp.h>

#define SDCASR_REG      0x0100
#define SDCASR_REG_STRIDE   0x1000
#define SDCPWR_CFGA0_REG    0x0100
#define SDCPWR_PWST0_REG    0x0000
#define SDCPWR_GIZTIME_REG  0x0440

/* SDCPWR_GIZTIME_REG fields */
#define SDCPWR_GIZTIME_GR   0x80000000
#define SDCPWR_GIZTIME_LONGLOCK 0x000000ff

/* Offset of ASR registers from SDC base */
#define SDCASR_OFFSET       0x120000

static void __iomem *sdcpwr_mapbase;
static void __iomem *sdcasr_mapbase;

static DEFINE_MUTEX(pas_switch_mutex);

/* Current astate, is used when waking up from power savings on
 * one core, in case the other core has switched states during
 * the idle time.
 */
static int current_astate;

/* We support 5(A0-A4) power states excluding turbo(A5-A6) modes */
static struct cpufreq_frequency_table pas_freqs[] = {
    {0, 0},
    {1, 0},
    {2, 0},
    {3, 0},
    {4, 0},
    {0, CPUFREQ_TABLE_END},
};

static struct freq_attr *pas_cpu_freqs_attr[] = {
    &cpufreq_freq_attr_scaling_available_freqs,
    NULL,
};

/*
 * hardware specific functions
 */

static int get_astate_freq(int astate)
{
    u32 ret;
    ret = in_le32(sdcpwr_mapbase + SDCPWR_CFGA0_REG + (astate * 0x10));

    return ret & 0x3f;
}

static int get_cur_astate(int cpu)
{
    u32 ret;

    ret = in_le32(sdcpwr_mapbase + SDCPWR_PWST0_REG);
    ret = (ret >> (cpu * 4)) & 0x7;

    return ret;
}

static int get_gizmo_latency(void)
{
    u32 giztime, ret;

    giztime = in_le32(sdcpwr_mapbase + SDCPWR_GIZTIME_REG);

    /* just provide the upper bound */
    if (giztime & SDCPWR_GIZTIME_GR)
        ret = (giztime & SDCPWR_GIZTIME_LONGLOCK) * 128000;
    else
        ret = (giztime & SDCPWR_GIZTIME_LONGLOCK) * 1000;

    return ret;
}

static void set_astate(int cpu, unsigned int astate)
{
    unsigned long flags;

    /* Return if called before init has run */
    if (unlikely(!sdcasr_mapbase))
        return;

    local_irq_save(flags);

    out_le32(sdcasr_mapbase + SDCASR_REG + SDCASR_REG_STRIDE*cpu, astate);

    local_irq_restore(flags);
}

int check_astate(void)
{
    return get_cur_astate(hard_smp_processor_id());
}

void restore_astate(int cpu)
{
    set_astate(cpu, current_astate);
}

/*
 * cpufreq functions
 */

static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
    const u32 *max_freqp;
    u32 max_freq;
    int i, cur_astate;
    struct resource res;
    struct device_node *cpu, *dn;
    int err = -ENODEV;

    cpu = of_get_cpu_node(policy->cpu, NULL);

    if (!cpu)
        goto out;

    dn = of_find_compatible_node(NULL, NULL, "1682m-sdc");
    if (!dn)
        dn = of_find_compatible_node(NULL, NULL,
                         "pasemi,pwrficient-sdc");
    if (!dn)
        goto out;
    err = of_address_to_resource(dn, 0, &res);
    of_node_put(dn);
    if (err)
        goto out;
    sdcasr_mapbase = ioremap(res.start + SDCASR_OFFSET, 0x2000);
    if (!sdcasr_mapbase) {
        err = -EINVAL;
        goto out;
    }

    dn = of_find_compatible_node(NULL, NULL, "1682m-gizmo");
    if (!dn)
        dn = of_find_compatible_node(NULL, NULL,
                         "pasemi,pwrficient-gizmo");
    if (!dn) {
        err = -ENODEV;
        goto out_unmap_sdcasr;
    }
    err = of_address_to_resource(dn, 0, &res);
    of_node_put(dn);
    if (err)
        goto out_unmap_sdcasr;
    sdcpwr_mapbase = ioremap(res.start, 0x1000);
    if (!sdcpwr_mapbase) {
        err = -EINVAL;
        goto out_unmap_sdcasr;
    }

    pr_debug("init cpufreq on CPU %d\n", policy->cpu);

    max_freqp = of_get_property(cpu, "clock-frequency", NULL);
    if (!max_freqp) {
        err = -EINVAL;
        goto out_unmap_sdcpwr;
    }

    /* we need the freq in kHz */
    max_freq = *max_freqp / 1000;

    pr_debug("max clock-frequency is at %u kHz\n", max_freq);
    pr_debug("initializing frequency table\n");

    /* initialize frequency table */
    for (i=0; pas_freqs[i].frequency!=CPUFREQ_TABLE_END; i++) {
        pas_freqs[i].frequency = get_astate_freq(pas_freqs[i].index) * 100000;
        pr_debug("%d: %d\n", i, pas_freqs[i].frequency);
    }

    policy->cpuinfo.transition_latency = get_gizmo_latency();

    cur_astate = get_cur_astate(policy->cpu);
    pr_debug("current astate is at %d\n",cur_astate);

    policy->cur = pas_freqs[cur_astate].frequency;
    cpumask_copy(policy->cpus, cpu_online_mask);

    ppc_proc_freq = policy->cur * 1000ul;

    cpufreq_frequency_table_get_attr(pas_freqs, policy->cpu);

    /* this ensures that policy->cpuinfo_min and policy->cpuinfo_max
     * are set correctly
     */
    return cpufreq_frequency_table_cpuinfo(policy, pas_freqs);

out_unmap_sdcpwr:
    iounmap(sdcpwr_mapbase);

out_unmap_sdcasr:
    iounmap(sdcasr_mapbase);
out:
    return err;
}

static int pas_cpufreq_cpu_exit(struct cpufreq_policy *policy)
{
    if (sdcasr_mapbase)
        iounmap(sdcasr_mapbase);
    if (sdcpwr_mapbase)
        iounmap(sdcpwr_mapbase);

    cpufreq_frequency_table_put_attr(policy->cpu);
    return 0;
}

static int pas_cpufreq_verify(struct cpufreq_policy *policy)
{
    return cpufreq_frequency_table_verify(policy, pas_freqs);
}

static int pas_cpufreq_target(struct cpufreq_policy *policy,
                  unsigned int target_freq,
                  unsigned int relation)
{
    struct cpufreq_freqs freqs;
    int pas_astate_new;
    int i;

    cpufreq_frequency_table_target(policy,
                       pas_freqs,
                       target_freq,
                       relation,
                       &pas_astate_new);

    freqs.old = policy->cur;
    freqs.new = pas_freqs[pas_astate_new].frequency;
    freqs.cpu = policy->cpu;

    mutex_lock(&pas_switch_mutex);
    cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

    pr_debug("setting frequency for cpu %d to %d kHz, 1/%d of max frequency\n",
         policy->cpu,
         pas_freqs[pas_astate_new].frequency,
         pas_freqs[pas_astate_new].index);

    current_astate = pas_astate_new;

    for_each_online_cpu(i)
        set_astate(i, pas_astate_new);

    cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
    mutex_unlock(&pas_switch_mutex);

    ppc_proc_freq = freqs.new * 1000ul;
    return 0;
}

static struct cpufreq_driver pas_cpufreq_driver = {
    .name       = "pas-cpufreq",
    .owner      = THIS_MODULE,
    .flags      = CPUFREQ_CONST_LOOPS,
    .init       = pas_cpufreq_cpu_init,
    .exit       = pas_cpufreq_cpu_exit,
    .verify     = pas_cpufreq_verify,
    .target     = pas_cpufreq_target,
    .attr       = pas_cpu_freqs_attr,
};

/*
 * module init and destoy
 */

static int __init pas_cpufreq_init(void)
{
    if (!of_machine_is_compatible("PA6T-1682M") &&
        !of_machine_is_compatible("pasemi,pwrficient"))
        return -ENODEV;

    return cpufreq_register_driver(&pas_cpufreq_driver);
}

static void __exit pas_cpufreq_exit(void)
{
    cpufreq_unregister_driver(&pas_cpufreq_driver);
}

module_init(pas_cpufreq_init);
module_exit(pas_cpufreq_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Egor Martovetsky <[email protected]>, Olof Johansson <[email protected]>");