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timer-gp.c

/*
 * linux/arch/arm/mach-omap2/timer-gp.c
 *
 * OMAP2 GP timer support.
 *
 * 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 <asm/mach/time.h>
#include <asm/arch/dmtimer.h>

static struct omap_dm_timer *gptimer;

static inline void omap2_gp_timer_start(unsigned long load_val)
{
      omap_dm_timer_set_load(gptimer, 1, 0xffffffff - load_val);
      omap_dm_timer_set_int_enable(gptimer, OMAP_TIMER_INT_OVERFLOW);
      omap_dm_timer_start(gptimer);
}

static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id,
                                  struct pt_regs *regs)
{
      write_seqlock(&xtime_lock);

      omap_dm_timer_write_status(gptimer, OMAP_TIMER_INT_OVERFLOW);
      timer_tick(regs);

      write_sequnlock(&xtime_lock);

      return IRQ_HANDLED;
}

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

static void __init omap2_gp_timer_init(void)
{
      u32 tick_period;

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

      omap_dm_timer_set_source(gptimer, OMAP_TIMER_SRC_SYS_CLK);
      tick_period = clk_get_rate(omap_dm_timer_get_fclk(gptimer)) / 100;
      tick_period -= 1;

      setup_irq(omap_dm_timer_get_irq(gptimer), &omap2_gp_timer_irq);
      omap2_gp_timer_start(tick_period);
}

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

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