db8500-cpufreq.c

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/*
 * Copyright (C) STMicroelectronics 2009
 * Copyright (C) ST-Ericsson SA 2010
 *
 * License Terms: GNU General Public License v2
 * Author: Sundar Iyer <[email protected]>
 * Author: Martin Persson <[email protected]>
 * Author: Jonas Aaberg <[email protected]>
 *
 */
#include <linux/kernel.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/mfd/dbx500-prcmu.h>
#include <mach/id.h>

static struct cpufreq_frequency_table freq_table[] = {
    [0] = {
        .index = 0,
        .frequency = 200000,
    },
    [1] = {
        .index = 1,
        .frequency = 400000,
    },
    [2] = {
        .index = 2,
        .frequency = 800000,
    },
    [3] = {
        /* Used for MAX_OPP, if available */
        .index = 3,
        .frequency = CPUFREQ_TABLE_END,
    },
    [4] = {
        .index = 4,
        .frequency = CPUFREQ_TABLE_END,
    },
};

static enum arm_opp idx2opp[] = {
    ARM_EXTCLK,
    ARM_50_OPP,
    ARM_100_OPP,
    ARM_MAX_OPP
};

static struct freq_attr *db8500_cpufreq_attr[] = {
    &cpufreq_freq_attr_scaling_available_freqs,
    NULL,
};

static int db8500_cpufreq_verify_speed(struct cpufreq_policy *policy)
{
    return cpufreq_frequency_table_verify(policy, freq_table);
}

static int db8500_cpufreq_target(struct cpufreq_policy *policy,
                unsigned int target_freq,
                unsigned int relation)
{
    struct cpufreq_freqs freqs;
    unsigned int idx;

    /* scale the target frequency to one of the extremes supported */
    if (target_freq < policy->cpuinfo.min_freq)
        target_freq = policy->cpuinfo.min_freq;
    if (target_freq > policy->cpuinfo.max_freq)
        target_freq = policy->cpuinfo.max_freq;

    /* Lookup the next frequency */
    if (cpufreq_frequency_table_target
        (policy, freq_table, target_freq, relation, &idx)) {
        return -EINVAL;
    }

    freqs.old = policy->cur;
    freqs.new = freq_table[idx].frequency;

    if (freqs.old == freqs.new)
        return 0;

    /* pre-change notification */
    for_each_cpu(freqs.cpu, policy->cpus)
        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

    /* request the PRCM unit for opp change */
    if (prcmu_set_arm_opp(idx2opp[idx])) {
        pr_err("db8500-cpufreq:  Failed to set OPP level\n");
        return -EINVAL;
    }

    /* post change notification */
    for_each_cpu(freqs.cpu, policy->cpus)
        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

    return 0;
}

static unsigned int db8500_cpufreq_getspeed(unsigned int cpu)
{
    int i;
    /* request the prcm to get the current ARM opp */
    for (i = 0; prcmu_get_arm_opp() != idx2opp[i]; i++)
        ;
    return freq_table[i].frequency;
}

static int __cpuinit db8500_cpufreq_init(struct cpufreq_policy *policy)
{
    int i, res;

    BUILD_BUG_ON(ARRAY_SIZE(idx2opp) + 1 != ARRAY_SIZE(freq_table));

    if (prcmu_has_arm_maxopp())
        freq_table[3].frequency = 1000000;

    pr_info("db8500-cpufreq : Available frequencies:\n");
    for (i = 0; freq_table[i].frequency != CPUFREQ_TABLE_END; i++)
        pr_info("  %d Mhz\n", freq_table[i].frequency/1000);

    /* get policy fields based on the table */
    res = cpufreq_frequency_table_cpuinfo(policy, freq_table);
    if (!res)
        cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
    else {
        pr_err("db8500-cpufreq : Failed to read policy table\n");
        return res;
    }

    policy->min = policy->cpuinfo.min_freq;
    policy->max = policy->cpuinfo.max_freq;
    policy->cur = db8500_cpufreq_getspeed(policy->cpu);
    policy->governor = CPUFREQ_DEFAULT_GOVERNOR;

    /*
     * FIXME : Need to take time measurement across the target()
     *     function with no/some/all drivers in the notification
     *     list.
     */
    policy->cpuinfo.transition_latency = 20 * 1000; /* in ns */

    /* policy sharing between dual CPUs */
    cpumask_copy(policy->cpus, cpu_present_mask);

    policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;

    return 0;
}

static struct cpufreq_driver db8500_cpufreq_driver = {
    .flags  = CPUFREQ_STICKY,
    .verify = db8500_cpufreq_verify_speed,
    .target = db8500_cpufreq_target,
    .get    = db8500_cpufreq_getspeed,
    .init   = db8500_cpufreq_init,
    .name   = "DB8500",
    .attr   = db8500_cpufreq_attr,
};

static int __init db8500_cpufreq_register(void)
{
    if (!cpu_is_u8500_family())
        return -ENODEV;

    pr_info("cpufreq for DB8500 started\n");
    return cpufreq_register_driver(&db8500_cpufreq_driver);
}
device_initcall(db8500_cpufreq_register);