1/* 2 * arch/arm/plat-iop/time.c 3 * 4 * Timer code for IOP32x and IOP33x based systems 5 * 6 * Author: Deepak Saxena <dsaxena@mvista.com> 7 * 8 * Copyright 2002-2003 MontaVista Software Inc. 9 * 10 * This program is free software; you can redistribute it and/or modify it 11 * under the terms of the GNU General Public License as published by the 12 * Free Software Foundation; either version 2 of the License, or (at your 13 * option) any later version. 14 */ 15 16#include <linux/kernel.h> 17#include <linux/interrupt.h> 18#include <linux/time.h> 19#include <linux/init.h> 20#include <linux/timex.h> 21#include <asm/hardware.h> 22#include <asm/io.h> 23#include <asm/irq.h> 24#include <asm/uaccess.h> 25#include <asm/mach/irq.h> 26#include <asm/mach/time.h> 27#include <asm/arch/time.h> 28 29static unsigned long ticks_per_jiffy; 30static unsigned long ticks_per_usec; 31static unsigned long next_jiffy_time; 32 33unsigned long iop_gettimeoffset(void) 34{ 35 unsigned long offset, temp; 36 37 /* enable cp6, if necessary, to avoid taking the overhead of an 38 * undefined instruction trap 39 */ 40 asm volatile ( 41 "mrc p15, 0, %0, c15, c1, 0\n\t" 42 "tst %0, #(1 << 6)\n\t" 43 "orreq %0, %0, #(1 << 6)\n\t" 44 "mcreq p15, 0, %0, c15, c1, 0\n\t" 45#ifdef CONFIG_CPU_XSCALE 46 "mrceq p15, 0, %0, c15, c1, 0\n\t" 47 "moveq %0, %0\n\t" 48 "subeq pc, pc, #4\n\t" 49#endif 50 : "=r"(temp) : : "cc"); 51 52 offset = next_jiffy_time - read_tcr1(); 53 54 return offset / ticks_per_usec; 55} 56 57static irqreturn_t 58iop_timer_interrupt(int irq, void *dev_id) 59{ 60 write_seqlock(&xtime_lock); 61 62 write_tisr(1); 63 64 while ((signed long)(next_jiffy_time - read_tcr1()) 65 >= ticks_per_jiffy) { 66 timer_tick(); 67 next_jiffy_time -= ticks_per_jiffy; 68 } 69 70 write_sequnlock(&xtime_lock); 71 72 return IRQ_HANDLED; 73} 74 75static struct irqaction iop_timer_irq = { 76 .name = "IOP Timer Tick", 77 .handler = iop_timer_interrupt, 78 .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, 79}; 80 81void __init iop_init_time(unsigned long tick_rate) 82{ 83 u32 timer_ctl; 84 85 ticks_per_jiffy = (tick_rate + HZ/2) / HZ; 86 ticks_per_usec = tick_rate / 1000000; 87 next_jiffy_time = 0xffffffff; 88 89 timer_ctl = IOP_TMR_EN | IOP_TMR_PRIVILEGED | 90 IOP_TMR_RELOAD | IOP_TMR_RATIO_1_1; 91 92 /* 93 * We use timer 0 for our timer interrupt, and timer 1 as 94 * monotonic counter for tracking missed jiffies. 95 */ 96 write_trr0(ticks_per_jiffy - 1); 97 write_tmr0(timer_ctl); 98 write_trr1(0xffffffff); 99 write_tmr1(timer_ctl); 100 101 setup_irq(IRQ_IOP_TIMER0, &iop_timer_irq); 102} 103