timer32k.c

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/*
 * linux/arch/arm/mach-omap1/timer32k.c
 *
 * OMAP 32K Timer
 *
 * Copyright (C) 2004 - 2005 Nokia Corporation
 * Partial timer rewrite and additional dynamic tick timer support by
 * Tony Lindgen <[email protected]> and
 * Tuukka Tikkanen <[email protected]>
 * OMAP Dual-mode timer framework support by Timo Teras
 *
 * MPU timer code based on the older MPU timer code for OMAP
 * Copyright (C) 2000 RidgeRun, Inc.
 * Author: Greg Lonnon <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
 * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * 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.,
 * 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/io.h>

#include <asm/irq.h>
#include <asm/mach/irq.h>
#include <asm/mach/time.h>

#include <plat/dmtimer.h>

#include <mach/hardware.h>

#include "common.h"

/*
 * ---------------------------------------------------------------------------
 * 32KHz OS timer
 *
 * This currently works only on 16xx, as 1510 does not have the continuous
 * 32KHz synchronous timer. The 32KHz synchronous timer is used to keep track
 * of time in addition to the 32KHz OS timer. Using only the 32KHz OS timer
 * on 1510 would be possible, but the timer would not be as accurate as
 * with the 32KHz synchronized timer.
 * ---------------------------------------------------------------------------
 */

/* 16xx specific defines */
#define OMAP1_32K_TIMER_BASE        0xfffb9000
#define OMAP1_32KSYNC_TIMER_BASE    0xfffbc400
#define OMAP1_32K_TIMER_CR      0x08
#define OMAP1_32K_TIMER_TVR     0x00
#define OMAP1_32K_TIMER_TCR     0x04

#define OMAP_32K_TICKS_PER_SEC      (32768)

/*
 * TRM says 1 / HZ = ( TVR + 1) / 32768, so TRV = (32768 / HZ) - 1
 * so with HZ = 128, TVR = 255.
 */
#define OMAP_32K_TIMER_TICK_PERIOD  ((OMAP_32K_TICKS_PER_SEC / HZ) - 1)

#define JIFFIES_TO_HW_TICKS(nr_jiffies, clock_rate)         \
                (((nr_jiffies) * (clock_rate)) / HZ)

static inline void omap_32k_timer_write(int val, int reg)
{
    omap_writew(val, OMAP1_32K_TIMER_BASE + reg);
}

static inline unsigned long omap_32k_timer_read(int reg)
{
    return omap_readl(OMAP1_32K_TIMER_BASE + reg) & 0xffffff;
}

static inline void omap_32k_timer_start(unsigned long load_val)
{
    if (!load_val)
        load_val = 1;
    omap_32k_timer_write(load_val, OMAP1_32K_TIMER_TVR);
    omap_32k_timer_write(0x0f, OMAP1_32K_TIMER_CR);
}

static inline void omap_32k_timer_stop(void)
{
    omap_32k_timer_write(0x0, OMAP1_32K_TIMER_CR);
}

#define omap_32k_timer_ack_irq()

static int omap_32k_timer_set_next_event(unsigned long delta,
                     struct clock_event_device *dev)
{
    omap_32k_timer_start(delta);

    return 0;
}

static void omap_32k_timer_set_mode(enum clock_event_mode mode,
                    struct clock_event_device *evt)
{
    omap_32k_timer_stop();

    switch (mode) {
    case CLOCK_EVT_MODE_PERIODIC:
        omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
        break;
    case CLOCK_EVT_MODE_ONESHOT:
    case CLOCK_EVT_MODE_UNUSED:
    case CLOCK_EVT_MODE_SHUTDOWN:
        break;
    case CLOCK_EVT_MODE_RESUME:
        break;
    }
}

static struct clock_event_device clockevent_32k_timer = {
    .name       = "32k-timer",
    .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
    .shift      = 32,
    .set_next_event = omap_32k_timer_set_next_event,
    .set_mode   = omap_32k_timer_set_mode,
};

static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id)
{
    struct clock_event_device *evt = &clockevent_32k_timer;
    omap_32k_timer_ack_irq();

    evt->event_handler(evt);

    return IRQ_HANDLED;
}

static struct irqaction omap_32k_timer_irq = {
    .name       = "32KHz timer",
    .flags      = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
    .handler    = omap_32k_timer_interrupt,
};

static __init void omap_init_32k_timer(void)
{
    setup_irq(INT_OS_TIMER, &omap_32k_timer_irq);

    clockevent_32k_timer.mult = div_sc(OMAP_32K_TICKS_PER_SEC,
                       NSEC_PER_SEC,
                       clockevent_32k_timer.shift);
    clockevent_32k_timer.max_delta_ns =
        clockevent_delta2ns(0xfffffffe, &clockevent_32k_timer);
    clockevent_32k_timer.min_delta_ns =
        clockevent_delta2ns(1, &clockevent_32k_timer);

    clockevent_32k_timer.cpumask = cpumask_of(0);
    clockevents_register_device(&clockevent_32k_timer);
}

/*
 * ---------------------------------------------------------------------------
 * Timer initialization
 * ---------------------------------------------------------------------------
 */
int __init omap_32k_timer_init(void)
{
    int ret = -ENODEV;

    if (cpu_is_omap16xx()) {
        void __iomem *base;
        struct clk *sync32k_ick;

        base = ioremap(OMAP1_32KSYNC_TIMER_BASE, SZ_1K);
        if (!base) {
            pr_err("32k_counter: failed to map base addr\n");
            return -ENODEV;
        }

        sync32k_ick = clk_get(NULL, "omap_32ksync_ick");
        if (!IS_ERR(sync32k_ick))
            clk_enable(sync32k_ick);

        ret = omap_init_clocksource_32k(base);
    }

    if (!ret)
        omap_init_32k_timer();

    return ret;
}