1 /* 2 * linux/arch/arm/mach-footbridge/isa-timer.c 3 * 4 * Copyright (C) 1998 Russell King. 5 * Copyright (C) 1998 Phil Blundell 6 */ 7 #include <linux/clockchips.h> 8 #include <linux/clocksource.h> 9 #include <linux/init.h> 10 #include <linux/interrupt.h> 11 #include <linux/irq.h> 12 #include <linux/io.h> 13 #include <linux/spinlock.h> 14 #include <linux/timex.h> 15 16 #include <asm/irq.h> 17 #include <asm/i8253.h> 18 #include <asm/mach/time.h> 19 20 #include "common.h" 21 22 DEFINE_RAW_SPINLOCK(i8253_lock); 23 24 static void pit_set_mode(enum clock_event_mode mode, 25 struct clock_event_device *evt) 26 { 27 unsigned long flags; 28 29 raw_local_irq_save(flags); 30 31 switch (mode) { 32 case CLOCK_EVT_MODE_PERIODIC: 33 outb_p(0x34, PIT_MODE); 34 outb_p(PIT_LATCH & 0xff, PIT_CH0); 35 outb_p(PIT_LATCH >> 8, PIT_CH0); 36 break; 37 38 case CLOCK_EVT_MODE_SHUTDOWN: 39 case CLOCK_EVT_MODE_UNUSED: 40 outb_p(0x30, PIT_MODE); 41 outb_p(0, PIT_CH0); 42 outb_p(0, PIT_CH0); 43 break; 44 45 case CLOCK_EVT_MODE_ONESHOT: 46 case CLOCK_EVT_MODE_RESUME: 47 break; 48 } 49 local_irq_restore(flags); 50 } 51 52 static int pit_set_next_event(unsigned long delta, 53 struct clock_event_device *evt) 54 { 55 return 0; 56 } 57 58 static struct clock_event_device pit_ce = { 59 .name = "pit", 60 .features = CLOCK_EVT_FEAT_PERIODIC, 61 .set_mode = pit_set_mode, 62 .set_next_event = pit_set_next_event, 63 .shift = 32, 64 }; 65 66 static irqreturn_t pit_timer_interrupt(int irq, void *dev_id) 67 { 68 struct clock_event_device *ce = dev_id; 69 ce->event_handler(ce); 70 return IRQ_HANDLED; 71 } 72 73 static struct irqaction pit_timer_irq = { 74 .name = "pit", 75 .handler = pit_timer_interrupt, 76 .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, 77 .dev_id = &pit_ce, 78 }; 79 80 static void __init isa_timer_init(void) 81 { 82 pit_ce.cpumask = cpumask_of(smp_processor_id()); 83 pit_ce.mult = div_sc(PIT_TICK_RATE, NSEC_PER_SEC, pit_ce.shift); 84 pit_ce.max_delta_ns = clockevent_delta2ns(0x7fff, &pit_ce); 85 pit_ce.min_delta_ns = clockevent_delta2ns(0x000f, &pit_ce); 86 87 clocksource_i8253_init(); 88 89 setup_irq(pit_ce.irq, &pit_timer_irq); 90 clockevents_register_device(&pit_ce); 91 } 92 93 struct sys_timer isa_timer = { 94 .init = isa_timer_init, 95 }; 96