time.c

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/*
 * arch/arm/mach-netx/time.c
 *
 * Copyright (c) 2005 Sascha Hauer <[email protected]>, Pengutronix
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/io.h>

#include <mach/hardware.h>
#include <asm/mach/time.h>
#include <mach/netx-regs.h>

#define TIMER_CLOCKEVENT 0
#define TIMER_CLOCKSOURCE 1

static void netx_set_mode(enum clock_event_mode mode,
        struct clock_event_device *clk)
{
    u32 tmode;

    /* disable timer */
    writel(0, NETX_GPIO_COUNTER_CTRL(TIMER_CLOCKEVENT));

    switch (mode) {
    case CLOCK_EVT_MODE_PERIODIC:
        writel(LATCH, NETX_GPIO_COUNTER_MAX(TIMER_CLOCKEVENT));
        tmode = NETX_GPIO_COUNTER_CTRL_RST_EN |
            NETX_GPIO_COUNTER_CTRL_IRQ_EN |
            NETX_GPIO_COUNTER_CTRL_RUN;
        break;

    case CLOCK_EVT_MODE_ONESHOT:
        writel(0, NETX_GPIO_COUNTER_MAX(TIMER_CLOCKEVENT));
        tmode = NETX_GPIO_COUNTER_CTRL_IRQ_EN |
            NETX_GPIO_COUNTER_CTRL_RUN;
        break;

    default:
        WARN(1, "%s: unhandled mode %d\n", __func__, mode);
        /* fall through */

    case CLOCK_EVT_MODE_SHUTDOWN:
    case CLOCK_EVT_MODE_UNUSED:
    case CLOCK_EVT_MODE_RESUME:
        tmode = 0;
        break;
    }

    writel(tmode, NETX_GPIO_COUNTER_CTRL(TIMER_CLOCKEVENT));
}

static int netx_set_next_event(unsigned long evt,
        struct clock_event_device *clk)
{
    writel(0 - evt, NETX_GPIO_COUNTER_CURRENT(TIMER_CLOCKEVENT));
    return 0;
}

static struct clock_event_device netx_clockevent = {
    .name = "netx-timer" __stringify(TIMER_CLOCKEVENT),
    .shift = 32,
    .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
    .set_next_event = netx_set_next_event,
    .set_mode = netx_set_mode,
};

/*
 * IRQ handler for the timer
 */
static irqreturn_t
netx_timer_interrupt(int irq, void *dev_id)
{
    struct clock_event_device *evt = &netx_clockevent;

    /* acknowledge interrupt */
    writel(COUNTER_BIT(0), NETX_GPIO_IRQ);

    evt->event_handler(evt);

    return IRQ_HANDLED;
}

static struct irqaction netx_timer_irq = {
    .name       = "NetX Timer Tick",
    .flags      = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
    .handler    = netx_timer_interrupt,
};

/*
 * Set up timer interrupt
 */
static void __init netx_timer_init(void)
{
    /* disable timer initially */
    writel(0, NETX_GPIO_COUNTER_CTRL(0));

    /* Reset the timer value to zero */
    writel(0, NETX_GPIO_COUNTER_CURRENT(0));

    writel(LATCH, NETX_GPIO_COUNTER_MAX(0));

    /* acknowledge interrupt */
    writel(COUNTER_BIT(0), NETX_GPIO_IRQ);

    /* Enable the interrupt in the specific timer
     * register and start timer
     */
    writel(COUNTER_BIT(0), NETX_GPIO_IRQ_ENABLE);
    writel(NETX_GPIO_COUNTER_CTRL_IRQ_EN | NETX_GPIO_COUNTER_CTRL_RUN,
            NETX_GPIO_COUNTER_CTRL(0));

    setup_irq(NETX_IRQ_TIMER0, &netx_timer_irq);

    /* Setup timer one for clocksource */
    writel(0, NETX_GPIO_COUNTER_CTRL(TIMER_CLOCKSOURCE));
    writel(0, NETX_GPIO_COUNTER_CURRENT(TIMER_CLOCKSOURCE));
    writel(0xffffffff, NETX_GPIO_COUNTER_MAX(TIMER_CLOCKSOURCE));

    writel(NETX_GPIO_COUNTER_CTRL_RUN,
            NETX_GPIO_COUNTER_CTRL(TIMER_CLOCKSOURCE));

    clocksource_mmio_init(NETX_GPIO_COUNTER_CURRENT(TIMER_CLOCKSOURCE),
        "netx_timer", CLOCK_TICK_RATE, 200, 32, clocksource_mmio_readl_up);

    netx_clockevent.mult = div_sc(CLOCK_TICK_RATE, NSEC_PER_SEC,
            netx_clockevent.shift);
    netx_clockevent.max_delta_ns =
        clockevent_delta2ns(0xfffffffe, &netx_clockevent);
    /* with max_delta_ns >= delta2ns(0x800) the system currently runs fine.
     * Adding some safety ... */
    netx_clockevent.min_delta_ns =
        clockevent_delta2ns(0xa00, &netx_clockevent);
    netx_clockevent.cpumask = cpumask_of(0);
    clockevents_register_device(&netx_clockevent);
}

struct sys_timer netx_timer = {
    .init       = netx_timer_init,
};