1 /* 2 * linux/arch/arm/mach-footbridge/dc21285-timer.c 3 * 4 * Copyright (C) 1998 Russell King. 5 * Copyright (C) 1998 Phil Blundell 6 */ 7 #include <linux/init.h> 8 #include <linux/interrupt.h> 9 10 #include <asm/irq.h> 11 12 #include <asm/hardware/dec21285.h> 13 #include <asm/mach/time.h> 14 15 #include "common.h" 16 17 /* 18 * Footbridge timer 1 support. 19 */ 20 static unsigned long timer1_latch; 21 22 static unsigned long timer1_gettimeoffset (void) 23 { 24 unsigned long value = timer1_latch - *CSR_TIMER1_VALUE; 25 26 return ((tick_nsec / 1000) * value) / timer1_latch; 27 } 28 29 static irqreturn_t 30 timer1_interrupt(int irq, void *dev_id, struct pt_regs *regs) 31 { 32 write_seqlock(&xtime_lock); 33 34 *CSR_TIMER1_CLR = 0; 35 36 timer_tick(regs); 37 38 write_sequnlock(&xtime_lock); 39 40 return IRQ_HANDLED; 41 } 42 43 static struct irqaction footbridge_timer_irq = { 44 .name = "Timer1 timer tick", 45 .handler = timer1_interrupt, 46 .flags = SA_INTERRUPT, 47 }; 48 49 /* 50 * Set up timer interrupt. 51 */ 52 static void __init footbridge_timer_init(void) 53 { 54 isa_rtc_init(); 55 56 timer1_latch = (mem_fclk_21285 + 8 * HZ) / (16 * HZ); 57 58 *CSR_TIMER1_CLR = 0; 59 *CSR_TIMER1_LOAD = timer1_latch; 60 *CSR_TIMER1_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD | TIMER_CNTL_DIV16; 61 62 setup_irq(IRQ_TIMER1, &footbridge_timer_irq); 63 } 64 65 struct sys_timer footbridge_timer = { 66 .init = footbridge_timer_init, 67 .offset = timer1_gettimeoffset, 68 }; 69