sched/deadline: Don't balance during wakeup if wakee is pinned

[linux/fpc-iii.git] / drivers / clocksource / timer-atmel-pit.c

/*
 * at91sam926x_time.c - Periodic Interval Timer (PIT) for at91sam926x
 *
 * Copyright (C) 2005-2006 M. Amine SAYA, ATMEL Rousset, France
 * Revision      2005 M. Nicolas Diremdjian, ATMEL Rousset, France
 * Converted to ClockSource/ClockEvents by David Brownell.
 *
 * 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.
 */

#define pr_fmt(fmt)     "AT91: PIT: " fmt

#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/slab.h>

#define AT91_PIT_MR             0x00                    /* Mode Register */
#define AT91_PIT_PITIEN                 BIT(25)                 /* Timer Interrupt Enable */
#define AT91_PIT_PITEN                  BIT(24)                 /* Timer Enabled */
#define AT91_PIT_PIV                    GENMASK(19, 0)          /* Periodic Interval Value */

#define AT91_PIT_SR             0x04                    /* Status Register */
#define AT91_PIT_PITS                   BIT(0)                  /* Timer Status */

#define AT91_PIT_PIVR           0x08                    /* Periodic Interval Value Register */
#define AT91_PIT_PIIR           0x0c                    /* Periodic Interval Image Register */
#define AT91_PIT_PICNT                  GENMASK(31, 20)         /* Interval Counter */
#define AT91_PIT_CPIV                   GENMASK(19, 0)          /* Inverval Value */

#define PIT_CPIV(x)     ((x) & AT91_PIT_CPIV)
#define PIT_PICNT(x)    (((x) & AT91_PIT_PICNT) >> 20)

struct pit_data {
        struct clock_event_device       clkevt;
        struct clocksource              clksrc;

        void __iomem    *base;
        u32             cycle;
        u32             cnt;
        unsigned int    irq;
        struct clk      *mck;
};

static inline struct pit_data *clksrc_to_pit_data(struct clocksource *clksrc)
{
        return container_of(clksrc, struct pit_data, clksrc);
}

static inline struct pit_data *clkevt_to_pit_data(struct clock_event_device *clkevt)
{
        return container_of(clkevt, struct pit_data, clkevt);
}

static inline unsigned int pit_read(void __iomem *base, unsigned int reg_offset)
{
        return __raw_readl(base + reg_offset);
}

static inline void pit_write(void __iomem *base, unsigned int reg_offset, unsigned long value)
{
        __raw_writel(value, base + reg_offset);
}

/*
 * Clocksource:  just a monotonic counter of MCK/16 cycles.
 * We don't care whether or not PIT irqs are enabled.
 */
static cycle_t read_pit_clk(struct clocksource *cs)
{
        struct pit_data *data = clksrc_to_pit_data(cs);
        unsigned long flags;
        u32 elapsed;
        u32 t;

        raw_local_irq_save(flags);
        elapsed = data->cnt;
        t = pit_read(data->base, AT91_PIT_PIIR);
        raw_local_irq_restore(flags);

        elapsed += PIT_PICNT(t) * data->cycle;
        elapsed += PIT_CPIV(t);
        return elapsed;
}

/*
 * Clockevent device:  interrupts every 1/HZ (== pit_cycles * MCK/16)
 */
static void
pit_clkevt_mode(enum clock_event_mode mode, struct clock_event_device *dev)
{
        struct pit_data *data = clkevt_to_pit_data(dev);

        switch (mode) {
        case CLOCK_EVT_MODE_PERIODIC:
                /* update clocksource counter */
                data->cnt += data->cycle * PIT_PICNT(pit_read(data->base, AT91_PIT_PIVR));
                pit_write(data->base, AT91_PIT_MR,
                          (data->cycle - 1) | AT91_PIT_PITEN | AT91_PIT_PITIEN);
                break;
        case CLOCK_EVT_MODE_ONESHOT:
                BUG();
                /* FALLTHROUGH */
        case CLOCK_EVT_MODE_SHUTDOWN:
        case CLOCK_EVT_MODE_UNUSED:
                /* disable irq, leaving the clocksource active */
                pit_write(data->base, AT91_PIT_MR,
                          (data->cycle - 1) | AT91_PIT_PITEN);
                break;
        case CLOCK_EVT_MODE_RESUME:
                break;
        }
}

static void at91sam926x_pit_suspend(struct clock_event_device *cedev)
{
        struct pit_data *data = clkevt_to_pit_data(cedev);

        /* Disable timer */
        pit_write(data->base, AT91_PIT_MR, 0);
}

static void at91sam926x_pit_reset(struct pit_data *data)
{
        /* Disable timer and irqs */
        pit_write(data->base, AT91_PIT_MR, 0);

        /* Clear any pending interrupts, wait for PIT to stop counting */
        while (PIT_CPIV(pit_read(data->base, AT91_PIT_PIVR)) != 0)
                cpu_relax();

        /* Start PIT but don't enable IRQ */
        pit_write(data->base, AT91_PIT_MR,
                  (data->cycle - 1) | AT91_PIT_PITEN);
}

static void at91sam926x_pit_resume(struct clock_event_device *cedev)
{
        struct pit_data *data = clkevt_to_pit_data(cedev);

        at91sam926x_pit_reset(data);
}

/*
 * IRQ handler for the timer.
 */
static irqreturn_t at91sam926x_pit_interrupt(int irq, void *dev_id)
{
        struct pit_data *data = dev_id;

        /*
         * irqs should be disabled here, but as the irq is shared they are only
         * guaranteed to be off if the timer irq is registered first.
         */
        WARN_ON_ONCE(!irqs_disabled());

        /* The PIT interrupt may be disabled, and is shared */
        if ((data->clkevt.mode == CLOCK_EVT_MODE_PERIODIC) &&
            (pit_read(data->base, AT91_PIT_SR) & AT91_PIT_PITS)) {
                unsigned nr_ticks;

                /* Get number of ticks performed before irq, and ack it */
                nr_ticks = PIT_PICNT(pit_read(data->base, AT91_PIT_PIVR));
                do {
                        data->cnt += data->cycle;
                        data->clkevt.event_handler(&data->clkevt);
                        nr_ticks--;
                } while (nr_ticks);

                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

/*
 * Set up both clocksource and clockevent support.
 */
static void __init at91sam926x_pit_common_init(struct pit_data *data)
{
        unsigned long   pit_rate;
        unsigned        bits;
        int             ret;

        /*
         * Use our actual MCK to figure out how many MCK/16 ticks per
         * 1/HZ period (instead of a compile-time constant LATCH).
         */
        pit_rate = clk_get_rate(data->mck) / 16;
        data->cycle = DIV_ROUND_CLOSEST(pit_rate, HZ);
        WARN_ON(((data->cycle - 1) & ~AT91_PIT_PIV) != 0);

        /* Initialize and enable the timer */
        at91sam926x_pit_reset(data);

        /*
         * Register clocksource.  The high order bits of PIV are unused,
         * so this isn't a 32-bit counter unless we get clockevent irqs.
         */
        bits = 12 /* PICNT */ + ilog2(data->cycle) /* PIV */;
        data->clksrc.mask = CLOCKSOURCE_MASK(bits);
        data->clksrc.name = "pit";
        data->clksrc.rating = 175;
        data->clksrc.read = read_pit_clk,
        data->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS,
        clocksource_register_hz(&data->clksrc, pit_rate);

        /* Set up irq handler */
        ret = request_irq(data->irq, at91sam926x_pit_interrupt,
                          IRQF_SHARED | IRQF_TIMER | IRQF_IRQPOLL,
                          "at91_tick", data);
        if (ret)
                panic(pr_fmt("Unable to setup IRQ\n"));

        /* Set up and register clockevents */
        data->clkevt.name = "pit";
        data->clkevt.features = CLOCK_EVT_FEAT_PERIODIC;
        data->clkevt.shift = 32;
        data->clkevt.mult = div_sc(pit_rate, NSEC_PER_SEC, data->clkevt.shift);
        data->clkevt.rating = 100;
        data->clkevt.cpumask = cpumask_of(0);

        data->clkevt.set_mode = pit_clkevt_mode;
        data->clkevt.resume = at91sam926x_pit_resume;
        data->clkevt.suspend = at91sam926x_pit_suspend;
        clockevents_register_device(&data->clkevt);
}

static void __init at91sam926x_pit_dt_init(struct device_node *node)
{
        struct pit_data *data;

        data = kzalloc(sizeof(*data), GFP_KERNEL);
        if (!data)
                panic(pr_fmt("Unable to allocate memory\n"));

        data->base = of_iomap(node, 0);
        if (!data->base)
                panic(pr_fmt("Could not map PIT address\n"));

        data->mck = of_clk_get(node, 0);
        if (IS_ERR(data->mck))
                /* Fallback on clkdev for !CCF-based boards */
                data->mck = clk_get(NULL, "mck");

        if (IS_ERR(data->mck))
                panic(pr_fmt("Unable to get mck clk\n"));

        /* Get the interrupts property */
        data->irq = irq_of_parse_and_map(node, 0);
        if (!data->irq)
                panic(pr_fmt("Unable to get IRQ from DT\n"));

        at91sam926x_pit_common_init(data);
}
CLOCKSOURCE_OF_DECLARE(at91sam926x_pit, "atmel,at91sam9260-pit",
                       at91sam926x_pit_dt_init);

static void __iomem *pit_base_addr;

void __init at91sam926x_pit_init(int irq)
{
        struct pit_data *data;

        data = kzalloc(sizeof(*data), GFP_KERNEL);
        if (!data)
                panic(pr_fmt("Unable to allocate memory\n"));

        data->base = pit_base_addr;

        data->mck = clk_get(NULL, "mck");
        if (IS_ERR(data->mck))
                panic(pr_fmt("Unable to get mck clk\n"));

        data->irq = irq;

        at91sam926x_pit_common_init(data);
}

void __init at91sam926x_ioremap_pit(u32 addr)
{
        if (of_have_populated_dt())
                return;

        pit_base_addr = ioremap(addr, 16);

        if (!pit_base_addr)
                panic(pr_fmt("Impossible to ioremap PIT\n"));
}