us3_cpufreq.c

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/* us3_cpufreq.c: UltraSPARC-III cpu frequency support
 *
 * Copyright (C) 2003 David S. Miller ([email protected])
 *
 * Many thanks to Dominik Brodowski for fixing up the cpufreq
 * infrastructure in order to make this driver easier to implement.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/cpufreq.h>
#include <linux/threads.h>
#include <linux/slab.h>
#include <linux/init.h>

#include <asm/head.h>
#include <asm/timer.h>

static struct cpufreq_driver *cpufreq_us3_driver;

struct us3_freq_percpu_info {
    struct cpufreq_frequency_table table[4];
};

/* Indexed by cpu number. */
static struct us3_freq_percpu_info *us3_freq_table;

/* UltraSPARC-III has three dividers: 1, 2, and 32.  These are controlled
 * in the Safari config register.
 */
#define SAFARI_CFG_DIV_1    0x0000000000000000UL
#define SAFARI_CFG_DIV_2    0x0000000040000000UL
#define SAFARI_CFG_DIV_32   0x0000000080000000UL
#define SAFARI_CFG_DIV_MASK 0x00000000C0000000UL

static unsigned long read_safari_cfg(void)
{
    unsigned long ret;

    __asm__ __volatile__("ldxa  [%%g0] %1, %0"
                 : "=&r" (ret)
                 : "i" (ASI_SAFARI_CONFIG));
    return ret;
}

static void write_safari_cfg(unsigned long val)
{
    __asm__ __volatile__("stxa  %0, [%%g0] %1\n\t"
                 "membar    #Sync"
                 : /* no outputs */
                 : "r" (val), "i" (ASI_SAFARI_CONFIG)
                 : "memory");
}

static unsigned long get_current_freq(unsigned int cpu, unsigned long safari_cfg)
{
    unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000;
    unsigned long ret;

    switch (safari_cfg & SAFARI_CFG_DIV_MASK) {
    case SAFARI_CFG_DIV_1:
        ret = clock_tick / 1;
        break;
    case SAFARI_CFG_DIV_2:
        ret = clock_tick / 2;
        break;
    case SAFARI_CFG_DIV_32:
        ret = clock_tick / 32;
        break;
    default:
        BUG();
    }

    return ret;
}

static unsigned int us3_freq_get(unsigned int cpu)
{
    cpumask_t cpus_allowed;
    unsigned long reg;
    unsigned int ret;

    if (!cpu_online(cpu))
        return 0;

    cpumask_copy(&cpus_allowed, tsk_cpus_allowed(current));
    set_cpus_allowed_ptr(current, cpumask_of(cpu));

    reg = read_safari_cfg();
    ret = get_current_freq(cpu, reg);

    set_cpus_allowed_ptr(current, &cpus_allowed);

    return ret;
}

static void us3_set_cpu_divider_index(unsigned int cpu, unsigned int index)
{
    unsigned long new_bits, new_freq, reg;
    cpumask_t cpus_allowed;
    struct cpufreq_freqs freqs;

    if (!cpu_online(cpu))
        return;

    cpumask_copy(&cpus_allowed, tsk_cpus_allowed(current));
    set_cpus_allowed_ptr(current, cpumask_of(cpu));

    new_freq = sparc64_get_clock_tick(cpu) / 1000;
    switch (index) {
    case 0:
        new_bits = SAFARI_CFG_DIV_1;
        new_freq /= 1;
        break;
    case 1:
        new_bits = SAFARI_CFG_DIV_2;
        new_freq /= 2;
        break;
    case 2:
        new_bits = SAFARI_CFG_DIV_32;
        new_freq /= 32;
        break;

    default:
        BUG();
    }

    reg = read_safari_cfg();

    freqs.old = get_current_freq(cpu, reg);
    freqs.new = new_freq;
    freqs.cpu = cpu;
    cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

    reg &= ~SAFARI_CFG_DIV_MASK;
    reg |= new_bits;
    write_safari_cfg(reg);

    cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

    set_cpus_allowed_ptr(current, &cpus_allowed);
}

static int us3_freq_target(struct cpufreq_policy *policy,
              unsigned int target_freq,
              unsigned int relation)
{
    unsigned int new_index = 0;

    if (cpufreq_frequency_table_target(policy,
                       &us3_freq_table[policy->cpu].table[0],
                       target_freq,
                       relation,
                       &new_index))
        return -EINVAL;

    us3_set_cpu_divider_index(policy->cpu, new_index);

    return 0;
}

static int us3_freq_verify(struct cpufreq_policy *policy)
{
    return cpufreq_frequency_table_verify(policy,
                          &us3_freq_table[policy->cpu].table[0]);
}

static int __init us3_freq_cpu_init(struct cpufreq_policy *policy)
{
    unsigned int cpu = policy->cpu;
    unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000;
    struct cpufreq_frequency_table *table =
        &us3_freq_table[cpu].table[0];

    table[0].index = 0;
    table[0].frequency = clock_tick / 1;
    table[1].index = 1;
    table[1].frequency = clock_tick / 2;
    table[2].index = 2;
    table[2].frequency = clock_tick / 32;
    table[3].index = 0;
    table[3].frequency = CPUFREQ_TABLE_END;

    policy->cpuinfo.transition_latency = 0;
    policy->cur = clock_tick;

    return cpufreq_frequency_table_cpuinfo(policy, table);
}

static int us3_freq_cpu_exit(struct cpufreq_policy *policy)
{
    if (cpufreq_us3_driver)
        us3_set_cpu_divider_index(policy->cpu, 0);

    return 0;
}

static int __init us3_freq_init(void)
{
    unsigned long manuf, impl, ver;
    int ret;

    if (tlb_type != cheetah && tlb_type != cheetah_plus)
        return -ENODEV;

    __asm__("rdpr %%ver, %0" : "=r" (ver));
    manuf = ((ver >> 48) & 0xffff);
    impl  = ((ver >> 32) & 0xffff);

    if (manuf == CHEETAH_MANUF &&
        (impl == CHEETAH_IMPL ||
         impl == CHEETAH_PLUS_IMPL ||
         impl == JAGUAR_IMPL ||
         impl == PANTHER_IMPL)) {
        struct cpufreq_driver *driver;

        ret = -ENOMEM;
        driver = kzalloc(sizeof(struct cpufreq_driver), GFP_KERNEL);
        if (!driver)
            goto err_out;

        us3_freq_table = kzalloc(
            (NR_CPUS * sizeof(struct us3_freq_percpu_info)),
            GFP_KERNEL);
        if (!us3_freq_table)
            goto err_out;

        driver->init = us3_freq_cpu_init;
        driver->verify = us3_freq_verify;
        driver->target = us3_freq_target;
        driver->get = us3_freq_get;
        driver->exit = us3_freq_cpu_exit;
        driver->owner = THIS_MODULE,
        strcpy(driver->name, "UltraSPARC-III");

        cpufreq_us3_driver = driver;
        ret = cpufreq_register_driver(driver);
        if (ret)
            goto err_out;

        return 0;

err_out:
        if (driver) {
            kfree(driver);
            cpufreq_us3_driver = NULL;
        }
        kfree(us3_freq_table);
        us3_freq_table = NULL;
        return ret;
    }

    return -ENODEV;
}

static void __exit us3_freq_exit(void)
{
    if (cpufreq_us3_driver) {
        cpufreq_unregister_driver(cpufreq_us3_driver);
        kfree(cpufreq_us3_driver);
        cpufreq_us3_driver = NULL;
        kfree(us3_freq_table);
        us3_freq_table = NULL;
    }
}

MODULE_AUTHOR("David S. Miller <[email protected]>");
MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-III");
MODULE_LICENSE("GPL");

module_init(us3_freq_init);
module_exit(us3_freq_exit);