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timer32k.c

/*
 * 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 <tony@atomide.com> and
 * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
 * 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 <glonnon@ridgerun.com>
 *
 * 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 <asm/system.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/leds.h>
#include <asm/irq.h>
#include <asm/mach/irq.h>
#include <asm/mach/time.h>
#include <asm/arch/dmtimer.h>

struct sys_timer omap_timer;

/*
 * ---------------------------------------------------------------------------
 * 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.
 * ---------------------------------------------------------------------------
 */

#if defined(CONFIG_ARCH_OMAP16XX)
#define TIMER_32K_SYNCHRONIZED            0xfffbc410
#else
#error OMAP 32KHz timer does not currently work on 15XX!
#endif

/* 16xx specific defines */
#define OMAP1_32K_TIMER_BASE        0xfffb9000
#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,
};

/*
 * The 32KHz synchronized timer is an additional timer on 16xx.
 * It is always running.
 */
static inline unsigned long omap_32k_sync_timer_read(void)
{
      return omap_readl(TIMER_32K_SYNCHRONIZED);
}

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_cpu(0);
      clockevents_register_device(&clockevent_32k_timer);
}

/*
 * ---------------------------------------------------------------------------
 * Timer initialization
 * ---------------------------------------------------------------------------
 */
static void __init omap_timer_init(void)
{
#ifdef CONFIG_OMAP_DM_TIMER
      omap_dm_timer_init();
#endif
      omap_init_32k_timer();
}

struct sys_timer omap_timer = {
      .init       = omap_timer_init,
};

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