arch/arm/mach-omap2/timer-gp.c

   1 /*
   2  * linux/arch/arm/mach-omap2/timer-gp.c
   3  *
   4  * OMAP2 GP timer support.
   5  *
   6  * Copyright (C) 2005 Nokia Corporation
   7  * Author: Paul Mundt <paul.mundt@nokia.com>
   8  *         Juha Yrjölä <juha.yrjola@nokia.com>
   9  * OMAP Dual-mode timer framework support by Timo Teras
  10  *
  11  * Some parts based off of TI's 24xx code:
  12  *
  13  *   Copyright (C) 2004 Texas Instruments, Inc.
  14  *
  15  * Roughly modelled after the OMAP1 MPU timer code.
  16  *
  17  * This file is subject to the terms and conditions of the GNU General Public
  18  * License. See the file "COPYING" in the main directory of this archive
  19  * for more details.
  20  */
  21 #include <linux/init.h>
  22 #include <linux/time.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/err.h>
  25 #include <linux/clk.h>
  26 #include <linux/delay.h>
  27
  28 #include <asm/mach/time.h>
  29 #include <asm/arch/dmtimer.h>
  30
  31 static struct omap_dm_timer *gptimer;
  32
  33 static inline void omap2_gp_timer_start(unsigned long load_val)
  34 {
  35         omap_dm_timer_set_load(gptimer, 1, 0xffffffff - load_val);
  36         omap_dm_timer_set_int_enable(gptimer, OMAP_TIMER_INT_OVERFLOW);
  37         omap_dm_timer_start(gptimer);
  38 }
  39
  40 static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id,
  41                                             struct pt_regs *regs)
  42 {
  43         write_seqlock(&xtime_lock);
  44
  45         omap_dm_timer_write_status(gptimer, OMAP_TIMER_INT_OVERFLOW);
  46         timer_tick(regs);
  47
  48         write_sequnlock(&xtime_lock);
  49
  50         return IRQ_HANDLED;
  51 }
  52
  53 static struct irqaction omap2_gp_timer_irq = {
  54         .name           = "gp timer",
  55         .flags          = IRQF_DISABLED | IRQF_TIMER,
  56         .handler        = omap2_gp_timer_interrupt,
  57 };
  58
  59 static void __init omap2_gp_timer_init(void)
  60 {
  61         u32 tick_period;
  62
  63         omap_dm_timer_init();
  64         gptimer = omap_dm_timer_request_specific(1);
  65         BUG_ON(gptimer == NULL);
  66
  67         omap_dm_timer_set_source(gptimer, OMAP_TIMER_SRC_SYS_CLK);
  68         tick_period = clk_get_rate(omap_dm_timer_get_fclk(gptimer)) / 100;
  69         tick_period -= 1;
  70
  71         setup_irq(omap_dm_timer_get_irq(gptimer), &omap2_gp_timer_irq);
  72         omap2_gp_timer_start(tick_period);
  73 }
  74
  75 struct sys_timer omap_timer = {
  76         .init   = omap2_gp_timer_init,
  77 };