1/* 2 * linux/arch/arm/mach-imx/time.c 3 * 4 * Copyright (C) 2000-2001 Deep Blue Solutions 5 * Copyright (C) 2002 Shane Nay (shane@minirl.com) 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11#include <linux/kernel.h> 12#include <linux/sched.h> 13#include <linux/init.h> 14#include <linux/interrupt.h> 15#include <linux/irq.h> 16#include <linux/time.h> 17#include <linux/clocksource.h> 18 19#include <asm/hardware.h> 20#include <asm/io.h> 21#include <asm/leds.h> 22#include <asm/irq.h> 23#include <asm/mach/time.h> 24 25/* Use timer 1 as system timer */ 26#define TIMER_BASE IMX_TIM1_BASE 27 28static unsigned long evt_diff; 29 30/* 31 * IRQ handler for the timer 32 */ 33static irqreturn_t 34imx_timer_interrupt(int irq, void *dev_id) 35{ 36 uint32_t tstat; 37 38 /* clear the interrupt */ 39 tstat = IMX_TSTAT(TIMER_BASE); 40 IMX_TSTAT(TIMER_BASE) = 0; 41 42 if (tstat & TSTAT_COMP) { 43 do { 44 45 write_seqlock(&xtime_lock); 46 timer_tick(); 47 write_sequnlock(&xtime_lock); 48 IMX_TCMP(TIMER_BASE) += evt_diff; 49 50 } while (unlikely((int32_t)(IMX_TCMP(TIMER_BASE) 51 - IMX_TCN(TIMER_BASE)) < 0)); 52 } 53 54 return IRQ_HANDLED; 55} 56 57static struct irqaction imx_timer_irq = { 58 .name = "i.MX Timer Tick", 59 .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, 60 .handler = imx_timer_interrupt, 61}; 62 63/* 64 * Set up timer hardware into expected mode and state. 65 */ 66static void __init imx_timer_hardware_init(void) 67{ 68 /* 69 * Initialise to a known state (all timers off, and timing reset) 70 */ 71 IMX_TCTL(TIMER_BASE) = 0; 72 IMX_TPRER(TIMER_BASE) = 0; 73 IMX_TCMP(TIMER_BASE) = LATCH - 1; 74 75 IMX_TCTL(TIMER_BASE) = TCTL_FRR | TCTL_CLK_PCLK1 | TCTL_IRQEN | TCTL_TEN; 76 evt_diff = LATCH; 77} 78 79cycle_t imx_get_cycles(void) 80{ 81 return IMX_TCN(TIMER_BASE); 82} 83 84static struct clocksource clocksource_imx = { 85 .name = "imx_timer1", 86 .rating = 200, 87 .read = imx_get_cycles, 88 .mask = 0xFFFFFFFF, 89 .shift = 20, 90 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 91}; 92 93static int __init imx_clocksource_init(void) 94{ 95 clocksource_imx.mult = 96 clocksource_hz2mult(imx_get_perclk1(), clocksource_imx.shift); 97 clocksource_register(&clocksource_imx); 98 99 return 0; 100} 101 102static void __init imx_timer_init(void) 103{ 104 imx_timer_hardware_init(); 105 imx_clocksource_init(); 106 107 /* 108 * Make irqs happen for the system timer 109 */ 110 setup_irq(TIM1_INT, &imx_timer_irq); 111} 112 113struct sys_timer imx_timer = { 114 .init = imx_timer_init, 115}; 116