Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/arch/arm/mach-footbridge/isa-timer.c |
| 3 | * |
| 4 | * Copyright (C) 1998 Russell King. |
| 5 | * Copyright (C) 1998 Phil Blundell |
| 6 | */ |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 7 | #include <linux/clockchips.h> |
| 8 | #include <linux/clocksource.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 9 | #include <linux/init.h> |
| 10 | #include <linux/interrupt.h> |
Thomas Gleixner | 55e8698 | 2006-07-01 22:32:17 +0100 | [diff] [blame] | 11 | #include <linux/irq.h> |
Russell King | fced80c | 2008-09-06 12:10:45 +0100 | [diff] [blame] | 12 | #include <linux/io.h> |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 13 | #include <linux/timex.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 14 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 15 | #include <asm/irq.h> |
| 16 | |
| 17 | #include <asm/mach/time.h> |
| 18 | |
| 19 | #include "common.h" |
| 20 | |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 21 | #define PIT_MODE 0x43 |
| 22 | #define PIT_CH0 0x40 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 23 | |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 24 | #define PIT_LATCH ((PIT_TICK_RATE + HZ / 2) / HZ) |
| 25 | |
| 26 | static cycle_t pit_read(struct clocksource *cs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 27 | { |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 28 | unsigned long flags; |
| 29 | static int old_count; |
| 30 | static u32 old_jifs; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | int count; |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 32 | u32 jifs; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 33 | |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 34 | raw_local_irq_save(flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 35 | |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 36 | jifs = jiffies; |
| 37 | outb_p(0x00, PIT_MODE); /* latch the count */ |
| 38 | count = inb_p(PIT_CH0); /* read the latched count */ |
| 39 | count |= inb_p(PIT_CH0) << 8; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 40 | |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 41 | if (count > old_count && jifs == old_jifs) |
| 42 | count = old_count; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 44 | old_count = count; |
| 45 | old_jifs = jifs; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 46 | |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 47 | raw_local_irq_restore(flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 48 | |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 49 | count = (PIT_LATCH - 1) - count; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 50 | |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 51 | return (cycle_t)(jifs * PIT_LATCH) + count; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 52 | } |
| 53 | |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 54 | static struct clocksource pit_cs = { |
| 55 | .name = "pit", |
| 56 | .rating = 110, |
| 57 | .read = pit_read, |
| 58 | .mask = CLOCKSOURCE_MASK(32), |
| 59 | }; |
| 60 | |
| 61 | static void pit_set_mode(enum clock_event_mode mode, |
| 62 | struct clock_event_device *evt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 63 | { |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 64 | unsigned long flags; |
| 65 | |
| 66 | raw_local_irq_save(flags); |
| 67 | |
| 68 | switch (mode) { |
| 69 | case CLOCK_EVT_MODE_PERIODIC: |
| 70 | outb_p(0x34, PIT_MODE); |
| 71 | outb_p(PIT_LATCH & 0xff, PIT_CH0); |
| 72 | outb_p(PIT_LATCH >> 8, PIT_CH0); |
| 73 | break; |
| 74 | |
| 75 | case CLOCK_EVT_MODE_SHUTDOWN: |
| 76 | case CLOCK_EVT_MODE_UNUSED: |
| 77 | outb_p(0x30, PIT_MODE); |
| 78 | outb_p(0, PIT_CH0); |
| 79 | outb_p(0, PIT_CH0); |
| 80 | break; |
| 81 | |
| 82 | case CLOCK_EVT_MODE_ONESHOT: |
| 83 | case CLOCK_EVT_MODE_RESUME: |
| 84 | break; |
| 85 | } |
| 86 | local_irq_restore(flags); |
| 87 | } |
| 88 | |
| 89 | static int pit_set_next_event(unsigned long delta, |
| 90 | struct clock_event_device *evt) |
| 91 | { |
| 92 | return 0; |
| 93 | } |
| 94 | |
| 95 | static struct clock_event_device pit_ce = { |
| 96 | .name = "pit", |
| 97 | .features = CLOCK_EVT_FEAT_PERIODIC, |
| 98 | .set_mode = pit_set_mode, |
| 99 | .set_next_event = pit_set_next_event, |
| 100 | .shift = 32, |
| 101 | }; |
| 102 | |
| 103 | static irqreturn_t pit_timer_interrupt(int irq, void *dev_id) |
| 104 | { |
| 105 | struct clock_event_device *ce = dev_id; |
| 106 | ce->event_handler(ce); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 107 | return IRQ_HANDLED; |
| 108 | } |
| 109 | |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 110 | static struct irqaction pit_timer_irq = { |
| 111 | .name = "pit", |
| 112 | .handler = pit_timer_interrupt, |
Bernhard Walle | b30faba | 2007-05-08 00:35:39 -0700 | [diff] [blame] | 113 | .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 114 | .dev_id = &pit_ce, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 115 | }; |
| 116 | |
| 117 | static void __init isa_timer_init(void) |
| 118 | { |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 119 | pit_ce.cpumask = cpumask_of(smp_processor_id()); |
| 120 | pit_ce.mult = div_sc(PIT_TICK_RATE, NSEC_PER_SEC, pit_ce.shift); |
| 121 | pit_ce.max_delta_ns = clockevent_delta2ns(0x7fff, &pit_ce); |
| 122 | pit_ce.min_delta_ns = clockevent_delta2ns(0x000f, &pit_ce); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 123 | |
Russell King | 4e8d763 | 2011-01-28 21:00:39 +0000 | [diff] [blame] | 124 | clocksource_register_hz(&pit_cs, PIT_TICK_RATE); |
| 125 | |
| 126 | setup_irq(pit_ce.irq, &pit_timer_irq); |
| 127 | clockevents_register_device(&pit_ce); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 128 | } |
| 129 | |
| 130 | struct sys_timer isa_timer = { |
| 131 | .init = isa_timer_init, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 132 | }; |