omap-cpufreq.c

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/*
 *  CPU frequency scaling for OMAP using OPP information
 *
 *  Copyright (C) 2005 Nokia Corporation
 *  Written by Tony Lindgren <[email protected]>
 *
 *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
 *
 * Copyright (C) 2007-2011 Texas Instruments, Inc.
 * - OMAP3/4 support by Rajendra Nayak, Santosh Shilimkar
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/opp.h>
#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/regulator/consumer.h>

#include <asm/smp_plat.h>
#include <asm/cpu.h>

/* OPP tolerance in percentage */
#define OPP_TOLERANCE   4

static struct cpufreq_frequency_table *freq_table;
static atomic_t freq_table_users = ATOMIC_INIT(0);
static struct clk *mpu_clk;
static struct device *mpu_dev;
static struct regulator *mpu_reg;

static int omap_verify_speed(struct cpufreq_policy *policy)
{
    if (!freq_table)
        return -EINVAL;
    return cpufreq_frequency_table_verify(policy, freq_table);
}

static unsigned int omap_getspeed(unsigned int cpu)
{
    unsigned long rate;

    if (cpu >= NR_CPUS)
        return 0;

    rate = clk_get_rate(mpu_clk) / 1000;
    return rate;
}

static int omap_target(struct cpufreq_policy *policy,
               unsigned int target_freq,
               unsigned int relation)
{
    unsigned int i;
    int r, ret = 0;
    struct cpufreq_freqs freqs;
    struct opp *opp;
    unsigned long freq, volt = 0, volt_old = 0, tol = 0;

    if (!freq_table) {
        dev_err(mpu_dev, "%s: cpu%d: no freq table!\n", __func__,
                policy->cpu);
        return -EINVAL;
    }

    ret = cpufreq_frequency_table_target(policy, freq_table, target_freq,
            relation, &i);
    if (ret) {
        dev_dbg(mpu_dev, "%s: cpu%d: no freq match for %d(ret=%d)\n",
            __func__, policy->cpu, target_freq, ret);
        return ret;
    }
    freqs.new = freq_table[i].frequency;
    if (!freqs.new) {
        dev_err(mpu_dev, "%s: cpu%d: no match for freq %d\n", __func__,
            policy->cpu, target_freq);
        return -EINVAL;
    }

    freqs.old = omap_getspeed(policy->cpu);
    freqs.cpu = policy->cpu;

    if (freqs.old == freqs.new && policy->cur == freqs.new)
        return ret;

    /* notifiers */
    for_each_cpu(i, policy->cpus) {
        freqs.cpu = i;
        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
    }

    freq = freqs.new * 1000;
    ret = clk_round_rate(mpu_clk, freq);
    if (IS_ERR_VALUE(ret)) {
        dev_warn(mpu_dev,
             "CPUfreq: Cannot find matching frequency for %lu\n",
             freq);
        return ret;
    }
    freq = ret;

    if (mpu_reg) {
        opp = opp_find_freq_ceil(mpu_dev, &freq);
        if (IS_ERR(opp)) {
            dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
                __func__, freqs.new);
            return -EINVAL;
        }
        volt = opp_get_voltage(opp);
        tol = volt * OPP_TOLERANCE / 100;
        volt_old = regulator_get_voltage(mpu_reg);
    }

    dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n", 
        freqs.old / 1000, volt_old ? volt_old / 1000 : -1,
        freqs.new / 1000, volt ? volt / 1000 : -1);

    /* scaling up?  scale voltage before frequency */
    if (mpu_reg && (freqs.new > freqs.old)) {
        r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
        if (r < 0) {
            dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
                 __func__);
            freqs.new = freqs.old;
            goto done;
        }
    }

    ret = clk_set_rate(mpu_clk, freqs.new * 1000);

    /* scaling down?  scale voltage after frequency */
    if (mpu_reg && (freqs.new < freqs.old)) {
        r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
        if (r < 0) {
            dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
                 __func__);
            ret = clk_set_rate(mpu_clk, freqs.old * 1000);
            freqs.new = freqs.old;
            goto done;
        }
    }

    freqs.new = omap_getspeed(policy->cpu);

done:
    /* notifiers */
    for_each_cpu(i, policy->cpus) {
        freqs.cpu = i;
        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
    }

    return ret;
}

static inline void freq_table_free(void)
{
    if (atomic_dec_and_test(&freq_table_users))
        opp_free_cpufreq_table(mpu_dev, &freq_table);
}

static int __cpuinit omap_cpu_init(struct cpufreq_policy *policy)
{
    int result = 0;

    mpu_clk = clk_get(NULL, "cpufreq_ck");
    if (IS_ERR(mpu_clk))
        return PTR_ERR(mpu_clk);

    if (policy->cpu >= NR_CPUS) {
        result = -EINVAL;
        goto fail_ck;
    }

    policy->cur = policy->min = policy->max = omap_getspeed(policy->cpu);

    if (!freq_table)
        result = opp_init_cpufreq_table(mpu_dev, &freq_table);

    if (result) {
        dev_err(mpu_dev, "%s: cpu%d: failed creating freq table[%d]\n",
                __func__, policy->cpu, result);
        goto fail_ck;
    }

    atomic_inc_return(&freq_table_users);

    result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
    if (result)
        goto fail_table;

    cpufreq_frequency_table_get_attr(freq_table, policy->cpu);

    policy->min = policy->cpuinfo.min_freq;
    policy->max = policy->cpuinfo.max_freq;
    policy->cur = omap_getspeed(policy->cpu);

    /*
     * On OMAP SMP configuartion, both processors share the voltage
     * and clock. So both CPUs needs to be scaled together and hence
     * needs software co-ordination. Use cpufreq affected_cpus
     * interface to handle this scenario. Additional is_smp() check
     * is to keep SMP_ON_UP build working.
     */
    if (is_smp()) {
        policy->shared_type = CPUFREQ_SHARED_TYPE_ANY;
        cpumask_setall(policy->cpus);
    }

    /* FIXME: what's the actual transition time? */
    policy->cpuinfo.transition_latency = 300 * 1000;

    return 0;

fail_table:
    freq_table_free();
fail_ck:
    clk_put(mpu_clk);
    return result;
}

static int omap_cpu_exit(struct cpufreq_policy *policy)
{
    freq_table_free();
    clk_put(mpu_clk);
    return 0;
}

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

static struct cpufreq_driver omap_driver = {
    .flags      = CPUFREQ_STICKY,
    .verify     = omap_verify_speed,
    .target     = omap_target,
    .get        = omap_getspeed,
    .init       = omap_cpu_init,
    .exit       = omap_cpu_exit,
    .name       = "omap",
    .attr       = omap_cpufreq_attr,
};

static int __init omap_cpufreq_init(void)
{
    mpu_dev = get_cpu_device(0);
    if (!mpu_dev) {
        pr_warning("%s: unable to get the mpu device\n", __func__);
        return -EINVAL;
    }

    mpu_reg = regulator_get(mpu_dev, "vcc");
    if (IS_ERR(mpu_reg)) {
        pr_warning("%s: unable to get MPU regulator\n", __func__);
        mpu_reg = NULL;
    } else {
        /* 
         * Ensure physical regulator is present.
         * (e.g. could be dummy regulator.)
         */
        if (regulator_get_voltage(mpu_reg) < 0) {
            pr_warn("%s: physical regulator not present for MPU\n",
                __func__);
            regulator_put(mpu_reg);
            mpu_reg = NULL;
        }
    }

    return cpufreq_register_driver(&omap_driver);
}

static void __exit omap_cpufreq_exit(void)
{
    cpufreq_unregister_driver(&omap_driver);
}

MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
MODULE_LICENSE("GPL");
module_init(omap_cpufreq_init);
module_exit(omap_cpufreq_exit);