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