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timer-gp.c

/*
 * linux/arch/arm/mach-omap2/timer-gp.c
 *
 * OMAP2 GP timer support.
 *
 * Update to use new clocksource/clockevent layers
 * Author: Kevin Hilman, MontaVista Software, Inc. <source@mvista.com>
 * Copyright (C) 2007 MontaVista Software, Inc.
 *
 * Original driver:
 * Copyright (C) 2005 Nokia Corporation
 * Author: Paul Mundt <paul.mundt@nokia.com>
 *         Juha Yrjölä <juha.yrjola@nokia.com>
 * OMAP Dual-mode timer framework support by Timo Teras
 *
 * Some parts based off of TI's 24xx code:
 *
 *   Copyright (C) 2004 Texas Instruments, Inc.
 *
 * Roughly modelled after the OMAP1 MPU timer code.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License. See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/init.h>
#include <linux/time.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>

#include <asm/mach/time.h>
#include <asm/arch/dmtimer.h>

static struct omap_dm_timer *gptimer;
static struct clock_event_device clockevent_gpt;

static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id)
{
      struct omap_dm_timer *gpt = (struct omap_dm_timer *)dev_id;
      struct clock_event_device *evt = &clockevent_gpt;

      omap_dm_timer_write_status(gpt, OMAP_TIMER_INT_OVERFLOW);

      evt->event_handler(evt);
      return IRQ_HANDLED;
}

static struct irqaction omap2_gp_timer_irq = {
      .name       = "gp timer",
      .flags            = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
      .handler    = omap2_gp_timer_interrupt,
};

static int omap2_gp_timer_set_next_event(unsigned long cycles,
                               struct clock_event_device *evt)
{
      omap_dm_timer_set_load(gptimer, 0, 0xffffffff - cycles);
      omap_dm_timer_start(gptimer);

      return 0;
}

static void omap2_gp_timer_set_mode(enum clock_event_mode mode,
                            struct clock_event_device *evt)
{
      u32 period;

      omap_dm_timer_stop(gptimer);

      switch (mode) {
      case CLOCK_EVT_MODE_PERIODIC:
            period = clk_get_rate(omap_dm_timer_get_fclk(gptimer)) / HZ;
            period -= 1;

            omap_dm_timer_set_load(gptimer, 1, 0xffffffff - period);
            omap_dm_timer_start(gptimer);
            break;
      case CLOCK_EVT_MODE_ONESHOT:
            break;
      case CLOCK_EVT_MODE_UNUSED:
      case CLOCK_EVT_MODE_SHUTDOWN:
      case CLOCK_EVT_MODE_RESUME:
            break;
      }
}

static struct clock_event_device clockevent_gpt = {
      .name       = "gp timer",
      .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
      .shift            = 32,
      .set_next_event   = omap2_gp_timer_set_next_event,
      .set_mode   = omap2_gp_timer_set_mode,
};

static void __init omap2_gp_clockevent_init(void)
{
      u32 tick_rate;

      gptimer = omap_dm_timer_request_specific(1);
      BUG_ON(gptimer == NULL);

#if defined(CONFIG_OMAP_32K_TIMER)
      omap_dm_timer_set_source(gptimer, OMAP_TIMER_SRC_32_KHZ);
#else
      omap_dm_timer_set_source(gptimer, OMAP_TIMER_SRC_SYS_CLK);
#endif
      tick_rate = clk_get_rate(omap_dm_timer_get_fclk(gptimer));

      omap2_gp_timer_irq.dev_id = (void *)gptimer;
      setup_irq(omap_dm_timer_get_irq(gptimer), &omap2_gp_timer_irq);
      omap_dm_timer_set_int_enable(gptimer, OMAP_TIMER_INT_OVERFLOW);

      clockevent_gpt.mult = div_sc(tick_rate, NSEC_PER_SEC,
                             clockevent_gpt.shift);
      clockevent_gpt.max_delta_ns =
            clockevent_delta2ns(0xffffffff, &clockevent_gpt);
      clockevent_gpt.min_delta_ns =
            clockevent_delta2ns(1, &clockevent_gpt);

      clockevent_gpt.cpumask = cpumask_of_cpu(0);
      clockevents_register_device(&clockevent_gpt);
}

#ifdef CONFIG_OMAP_32K_TIMER
/* 
 * When 32k-timer is enabled, don't use GPTimer for clocksource
 * instead, just leave default clocksource which uses the 32k
 * sync counter.  See clocksource setup in see plat-omap/common.c. 
 */

static inline void __init omap2_gp_clocksource_init(void) {}
#else
/*
 * clocksource
 */
static struct omap_dm_timer *gpt_clocksource;
static cycle_t clocksource_read_cycles(void)
{
      return (cycle_t)omap_dm_timer_read_counter(gpt_clocksource);
}

static struct clocksource clocksource_gpt = {
      .name       = "gp timer",
      .rating           = 300,
      .read       = clocksource_read_cycles,
      .mask       = CLOCKSOURCE_MASK(32),
      .shift            = 24,
      .flags            = CLOCK_SOURCE_IS_CONTINUOUS,
};

/* Setup free-running counter for clocksource */
static void __init omap2_gp_clocksource_init(void)
{
      static struct omap_dm_timer *gpt;
      u32 tick_rate, tick_period;
      static char err1[] __initdata = KERN_ERR
            "%s: failed to request dm-timer\n";
      static char err2[] __initdata = KERN_ERR
            "%s: can't register clocksource!\n";

      gpt = omap_dm_timer_request();
      if (!gpt)
            printk(err1, clocksource_gpt.name);
      gpt_clocksource = gpt;

      omap_dm_timer_set_source(gpt, OMAP_TIMER_SRC_SYS_CLK);
      tick_rate = clk_get_rate(omap_dm_timer_get_fclk(gpt));
      tick_period = (tick_rate / HZ) - 1;

      omap_dm_timer_set_load(gpt, 1, 0);
      omap_dm_timer_start(gpt);

      clocksource_gpt.mult =
            clocksource_khz2mult(tick_rate/1000, clocksource_gpt.shift);
      if (clocksource_register(&clocksource_gpt))
            printk(err2, clocksource_gpt.name);
}
#endif

static void __init omap2_gp_timer_init(void)
{
      omap_dm_timer_init();

      omap2_gp_clockevent_init();
      omap2_gp_clocksource_init();
}

struct sys_timer omap_timer = {
      .init = omap2_gp_timer_init,
};

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