Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 1 | /* |
| 2 | * i8253.c 8253/PIT functions |
| 3 | * |
| 4 | */ |
| 5 | #include <linux/clockchips.h> |
| 6 | #include <linux/init.h> |
| 7 | #include <linux/interrupt.h> |
| 8 | #include <linux/jiffies.h> |
| 9 | #include <linux/module.h> |
Ralf Baechle | 631330f | 2009-06-19 14:05:26 +0100 | [diff] [blame] | 10 | #include <linux/smp.h> |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 11 | #include <linux/spinlock.h> |
David Howells | ca4d3e67 | 2010-10-07 14:08:54 +0100 | [diff] [blame] | 12 | #include <linux/irq.h> |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 13 | |
| 14 | #include <asm/delay.h> |
| 15 | #include <asm/i8253.h> |
| 16 | #include <asm/io.h> |
Ralf Baechle | dd3db6e | 2007-11-01 14:38:20 +0000 | [diff] [blame] | 17 | #include <asm/time.h> |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 18 | |
Thomas Gleixner | ced918e | 2010-02-17 16:47:10 +0000 | [diff] [blame] | 19 | DEFINE_RAW_SPINLOCK(i8253_lock); |
Ralf Baechle | a05e623 | 2008-03-14 14:15:08 +0000 | [diff] [blame] | 20 | EXPORT_SYMBOL(i8253_lock); |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 21 | |
| 22 | /* |
| 23 | * Initialize the PIT timer. |
| 24 | * |
| 25 | * This is also called after resume to bring the PIT into operation again. |
| 26 | */ |
| 27 | static void init_pit_timer(enum clock_event_mode mode, |
| 28 | struct clock_event_device *evt) |
| 29 | { |
Thomas Gleixner | ced918e | 2010-02-17 16:47:10 +0000 | [diff] [blame] | 30 | raw_spin_lock(&i8253_lock); |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 31 | |
| 32 | switch(mode) { |
| 33 | case CLOCK_EVT_MODE_PERIODIC: |
| 34 | /* binary, mode 2, LSB/MSB, ch 0 */ |
| 35 | outb_p(0x34, PIT_MODE); |
| 36 | outb_p(LATCH & 0xff , PIT_CH0); /* LSB */ |
| 37 | outb(LATCH >> 8 , PIT_CH0); /* MSB */ |
| 38 | break; |
| 39 | |
| 40 | case CLOCK_EVT_MODE_SHUTDOWN: |
| 41 | case CLOCK_EVT_MODE_UNUSED: |
| 42 | if (evt->mode == CLOCK_EVT_MODE_PERIODIC || |
| 43 | evt->mode == CLOCK_EVT_MODE_ONESHOT) { |
| 44 | outb_p(0x30, PIT_MODE); |
| 45 | outb_p(0, PIT_CH0); |
| 46 | outb_p(0, PIT_CH0); |
| 47 | } |
| 48 | break; |
| 49 | |
| 50 | case CLOCK_EVT_MODE_ONESHOT: |
| 51 | /* One shot setup */ |
| 52 | outb_p(0x38, PIT_MODE); |
| 53 | break; |
| 54 | |
| 55 | case CLOCK_EVT_MODE_RESUME: |
| 56 | /* Nothing to do here */ |
| 57 | break; |
| 58 | } |
Thomas Gleixner | ced918e | 2010-02-17 16:47:10 +0000 | [diff] [blame] | 59 | raw_spin_unlock(&i8253_lock); |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 60 | } |
| 61 | |
| 62 | /* |
| 63 | * Program the next event in oneshot mode |
| 64 | * |
| 65 | * Delta is given in PIT ticks |
| 66 | */ |
| 67 | static int pit_next_event(unsigned long delta, struct clock_event_device *evt) |
| 68 | { |
Thomas Gleixner | ced918e | 2010-02-17 16:47:10 +0000 | [diff] [blame] | 69 | raw_spin_lock(&i8253_lock); |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 70 | outb_p(delta & 0xff , PIT_CH0); /* LSB */ |
| 71 | outb(delta >> 8 , PIT_CH0); /* MSB */ |
Thomas Gleixner | ced918e | 2010-02-17 16:47:10 +0000 | [diff] [blame] | 72 | raw_spin_unlock(&i8253_lock); |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 73 | |
| 74 | return 0; |
| 75 | } |
| 76 | |
| 77 | /* |
| 78 | * On UP the PIT can serve all of the possible timer functions. On SMP systems |
| 79 | * it can be solely used for the global tick. |
| 80 | * |
| 81 | * The profiling and update capabilites are switched off once the local apic is |
| 82 | * registered. This mechanism replaces the previous #ifdef LOCAL_APIC - |
| 83 | * !using_apic_timer decisions in do_timer_interrupt_hook() |
| 84 | */ |
Dmitri Vorobiev | 1ea6428 | 2008-06-18 10:18:19 +0300 | [diff] [blame] | 85 | static struct clock_event_device pit_clockevent = { |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 86 | .name = "pit", |
| 87 | .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, |
| 88 | .set_mode = init_pit_timer, |
| 89 | .set_next_event = pit_next_event, |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 90 | .irq = 0, |
| 91 | }; |
| 92 | |
Ralf Baechle | dd3db6e | 2007-11-01 14:38:20 +0000 | [diff] [blame] | 93 | static irqreturn_t timer_interrupt(int irq, void *dev_id) |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 94 | { |
| 95 | pit_clockevent.event_handler(&pit_clockevent); |
| 96 | |
| 97 | return IRQ_HANDLED; |
| 98 | } |
| 99 | |
| 100 | static struct irqaction irq0 = { |
| 101 | .handler = timer_interrupt, |
Wu Zhangjin | f45e518 | 2009-10-08 21:17:54 +0800 | [diff] [blame] | 102 | .flags = IRQF_DISABLED | IRQF_NOBALANCING | IRQF_TIMER, |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 103 | .name = "timer" |
| 104 | }; |
| 105 | |
| 106 | /* |
| 107 | * Initialize the conversion factor and the min/max deltas of the clock event |
| 108 | * structure and register the clock event source with the framework. |
| 109 | */ |
| 110 | void __init setup_pit_timer(void) |
| 111 | { |
Ralf Baechle | dd3db6e | 2007-11-01 14:38:20 +0000 | [diff] [blame] | 112 | struct clock_event_device *cd = &pit_clockevent; |
| 113 | unsigned int cpu = smp_processor_id(); |
| 114 | |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 115 | /* |
| 116 | * Start pit with the boot cpu mask and make it global after the |
| 117 | * IO_APIC has been initialized. |
| 118 | */ |
Rusty Russell | 320ab2b | 2008-12-13 21:20:26 +1030 | [diff] [blame] | 119 | cd->cpumask = cpumask_of(cpu); |
Ralf Baechle | dd3db6e | 2007-11-01 14:38:20 +0000 | [diff] [blame] | 120 | clockevent_set_clock(cd, CLOCK_TICK_RATE); |
| 121 | cd->max_delta_ns = clockevent_delta2ns(0x7FFF, cd); |
| 122 | cd->min_delta_ns = clockevent_delta2ns(0xF, cd); |
| 123 | clockevents_register_device(cd); |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 124 | |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 125 | setup_irq(0, &irq0); |
| 126 | } |
| 127 | |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 128 | static int __init init_pit_clocksource(void) |
| 129 | { |
| 130 | if (num_possible_cpus() > 1) /* PIT does not scale! */ |
| 131 | return 0; |
| 132 | |
Russell King | 798778b | 2011-05-08 19:03:03 +0100 | [diff] [blame^] | 133 | return clocksource_i8253_init(); |
Ralf Baechle | d865bea | 2007-10-11 23:46:10 +0100 | [diff] [blame] | 134 | } |
| 135 | arch_initcall(init_pit_clocksource); |