smp_twd.c

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/*
 *  linux/arch/arm/kernel/smp_twd.c
 *
 *  Copyright (C) 2002 ARM Ltd.
 *  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 version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/smp.h>
#include <linux/jiffies.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>

#include <asm/smp_twd.h>
#include <asm/localtimer.h>
#include <asm/hardware/gic.h>

/* set up by the platform code */
static void __iomem *twd_base;

static struct clk *twd_clk;
static unsigned long twd_timer_rate;

static struct clock_event_device __percpu **twd_evt;
static int twd_ppi;

static void twd_set_mode(enum clock_event_mode mode,
            struct clock_event_device *clk)
{
    unsigned long ctrl;

    switch (mode) {
    case CLOCK_EVT_MODE_PERIODIC:
        ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
            | TWD_TIMER_CONTROL_PERIODIC;
        __raw_writel(DIV_ROUND_CLOSEST(twd_timer_rate, HZ),
            twd_base + TWD_TIMER_LOAD);
        break;
    case CLOCK_EVT_MODE_ONESHOT:
        /* period set, and timer enabled in 'next_event' hook */
        ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
        break;
    case CLOCK_EVT_MODE_UNUSED:
    case CLOCK_EVT_MODE_SHUTDOWN:
    default:
        ctrl = 0;
    }

    __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
}

static int twd_set_next_event(unsigned long evt,
            struct clock_event_device *unused)
{
    unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);

    ctrl |= TWD_TIMER_CONTROL_ENABLE;

    __raw_writel(evt, twd_base + TWD_TIMER_COUNTER);
    __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);

    return 0;
}

/*
 * local_timer_ack: checks for a local timer interrupt.
 *
 * If a local timer interrupt has occurred, acknowledge and return 1.
 * Otherwise, return 0.
 */
static int twd_timer_ack(void)
{
    if (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) {
        __raw_writel(1, twd_base + TWD_TIMER_INTSTAT);
        return 1;
    }

    return 0;
}

static void twd_timer_stop(struct clock_event_device *clk)
{
    twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
    disable_percpu_irq(clk->irq);
}

#ifdef CONFIG_COMMON_CLK

/*
 * Updates clockevent frequency when the cpu frequency changes.
 * Called on the cpu that is changing frequency with interrupts disabled.
 */
static void twd_update_frequency(void *new_rate)
{
    twd_timer_rate = *((unsigned long *) new_rate);

    clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
}

static int twd_rate_change(struct notifier_block *nb,
    unsigned long flags, void *data)
{
    struct clk_notifier_data *cnd = data;

    /*
     * The twd clock events must be reprogrammed to account for the new
     * frequency.  The timer is local to a cpu, so cross-call to the
     * changing cpu.
     */
    if (flags == POST_RATE_CHANGE)
        smp_call_function(twd_update_frequency,
                  (void *)&cnd->new_rate, 1);

    return NOTIFY_OK;
}

static struct notifier_block twd_clk_nb = {
    .notifier_call = twd_rate_change,
};

static int twd_clk_init(void)
{
    if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
        return clk_notifier_register(twd_clk, &twd_clk_nb);

    return 0;
}
core_initcall(twd_clk_init);

#elif defined (CONFIG_CPU_FREQ)

#include <linux/cpufreq.h>

/*
 * Updates clockevent frequency when the cpu frequency changes.
 * Called on the cpu that is changing frequency with interrupts disabled.
 */
static void twd_update_frequency(void *data)
{
    twd_timer_rate = clk_get_rate(twd_clk);

    clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
}

static int twd_cpufreq_transition(struct notifier_block *nb,
    unsigned long state, void *data)
{
    struct cpufreq_freqs *freqs = data;

    /*
     * The twd clock events must be reprogrammed to account for the new
     * frequency.  The timer is local to a cpu, so cross-call to the
     * changing cpu.
     */
    if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
        smp_call_function_single(freqs->cpu, twd_update_frequency,
            NULL, 1);

    return NOTIFY_OK;
}

static struct notifier_block twd_cpufreq_nb = {
    .notifier_call = twd_cpufreq_transition,
};

static int twd_cpufreq_init(void)
{
    if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
        return cpufreq_register_notifier(&twd_cpufreq_nb,
            CPUFREQ_TRANSITION_NOTIFIER);

    return 0;
}
core_initcall(twd_cpufreq_init);

#endif

static void __cpuinit twd_calibrate_rate(void)
{
    unsigned long count;
    u64 waitjiffies;

    /*
     * If this is the first time round, we need to work out how fast
     * the timer ticks
     */
    if (twd_timer_rate == 0) {
        printk(KERN_INFO "Calibrating local timer... ");

        /* Wait for a tick to start */
        waitjiffies = get_jiffies_64() + 1;

        while (get_jiffies_64() < waitjiffies)
            udelay(10);

        /* OK, now the tick has started, let's get the timer going */
        waitjiffies += 5;

                 /* enable, no interrupt or reload */
        __raw_writel(0x1, twd_base + TWD_TIMER_CONTROL);

                 /* maximum value */
        __raw_writel(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);

        while (get_jiffies_64() < waitjiffies)
            udelay(10);

        count = __raw_readl(twd_base + TWD_TIMER_COUNTER);

        twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);

        printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
            (twd_timer_rate / 10000) % 100);
    }
}

static irqreturn_t twd_handler(int irq, void *dev_id)
{
    struct clock_event_device *evt = *(struct clock_event_device **)dev_id;

    if (twd_timer_ack()) {
        evt->event_handler(evt);
        return IRQ_HANDLED;
    }

    return IRQ_NONE;
}

static struct clk *twd_get_clock(void)
{
    struct clk *clk;
    int err;

    clk = clk_get_sys("smp_twd", NULL);
    if (IS_ERR(clk)) {
        pr_err("smp_twd: clock not found: %d\n", (int)PTR_ERR(clk));
        return clk;
    }

    err = clk_prepare(clk);
    if (err) {
        pr_err("smp_twd: clock failed to prepare: %d\n", err);
        clk_put(clk);
        return ERR_PTR(err);
    }

    err = clk_enable(clk);
    if (err) {
        pr_err("smp_twd: clock failed to enable: %d\n", err);
        clk_unprepare(clk);
        clk_put(clk);
        return ERR_PTR(err);
    }

    return clk;
}

/*
 * Setup the local clock events for a CPU.
 */
static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
{
    struct clock_event_device **this_cpu_clk;

    if (!twd_clk)
        twd_clk = twd_get_clock();

    if (!IS_ERR_OR_NULL(twd_clk))
        twd_timer_rate = clk_get_rate(twd_clk);
    else
        twd_calibrate_rate();

    __raw_writel(0, twd_base + TWD_TIMER_CONTROL);

    clk->name = "local_timer";
    clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
            CLOCK_EVT_FEAT_C3STOP;
    clk->rating = 350;
    clk->set_mode = twd_set_mode;
    clk->set_next_event = twd_set_next_event;
    clk->irq = twd_ppi;

    this_cpu_clk = __this_cpu_ptr(twd_evt);
    *this_cpu_clk = clk;

    clockevents_config_and_register(clk, twd_timer_rate,
                    0xf, 0xffffffff);
    enable_percpu_irq(clk->irq, 0);

    return 0;
}

static struct local_timer_ops twd_lt_ops __cpuinitdata = {
    .setup  = twd_timer_setup,
    .stop   = twd_timer_stop,
};

static int __init twd_local_timer_common_register(void)
{
    int err;

    twd_evt = alloc_percpu(struct clock_event_device *);
    if (!twd_evt) {
        err = -ENOMEM;
        goto out_free;
    }

    err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
    if (err) {
        pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
        goto out_free;
    }

    err = local_timer_register(&twd_lt_ops);
    if (err)
        goto out_irq;

    return 0;

out_irq:
    free_percpu_irq(twd_ppi, twd_evt);
out_free:
    iounmap(twd_base);
    twd_base = NULL;
    free_percpu(twd_evt);

    return err;
}

int __init twd_local_timer_register(struct twd_local_timer *tlt)
{
    if (twd_base || twd_evt)
        return -EBUSY;

    twd_ppi = tlt->res[1].start;

    twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
    if (!twd_base)
        return -ENOMEM;

    return twd_local_timer_common_register();
}

#ifdef CONFIG_OF
const static struct of_device_id twd_of_match[] __initconst = {
    { .compatible = "arm,cortex-a9-twd-timer",  },
    { .compatible = "arm,cortex-a5-twd-timer",  },
    { .compatible = "arm,arm11mp-twd-timer",    },
    { },
};

void __init twd_local_timer_of_register(void)
{
    struct device_node *np;
    int err;

    np = of_find_matching_node(NULL, twd_of_match);
    if (!np) {
        err = -ENODEV;
        goto out;
    }

    twd_ppi = irq_of_parse_and_map(np, 0);
    if (!twd_ppi) {
        err = -EINVAL;
        goto out;
    }

    twd_base = of_iomap(np, 0);
    if (!twd_base) {
        err = -ENOMEM;
        goto out;
    }

    err = twd_local_timer_common_register();

out:
    WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
}
#endif