1 /* 2 * This file is subject to the terms and conditions of the GNU General Public 3 * License. See the file "COPYING" in the main directory of this archive 4 * for more details. 5 * 6 * Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved. 7 */ 8 #include <linux/clockchips.h> 9 #include <linux/cpu.h> 10 #include <linux/init.h> 11 #include <linux/interrupt.h> 12 #include <linux/irqchip/mips-gic.h> 13 #include <linux/notifier.h> 14 #include <linux/percpu.h> 15 #include <linux/smp.h> 16 #include <linux/time.h> 17 18 static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device); 19 static int gic_timer_irq; 20 static unsigned int gic_frequency; 21 22 static int gic_next_event(unsigned long delta, struct clock_event_device *evt) 23 { 24 u64 cnt; 25 int res; 26 27 cnt = gic_read_count(); 28 cnt += (u64)delta; 29 gic_write_cpu_compare(cnt, cpumask_first(evt->cpumask)); 30 res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0; 31 return res; 32 } 33 34 static void gic_set_clock_mode(enum clock_event_mode mode, 35 struct clock_event_device *evt) 36 { 37 /* Nothing to do ... */ 38 } 39 40 static irqreturn_t gic_compare_interrupt(int irq, void *dev_id) 41 { 42 struct clock_event_device *cd = dev_id; 43 44 gic_write_compare(gic_read_compare()); 45 cd->event_handler(cd); 46 return IRQ_HANDLED; 47 } 48 49 struct irqaction gic_compare_irqaction = { 50 .handler = gic_compare_interrupt, 51 .percpu_dev_id = &gic_clockevent_device, 52 .flags = IRQF_PERCPU | IRQF_TIMER, 53 .name = "timer", 54 }; 55 56 static void gic_clockevent_cpu_init(struct clock_event_device *cd) 57 { 58 unsigned int cpu = smp_processor_id(); 59 60 cd->name = "MIPS GIC"; 61 cd->features = CLOCK_EVT_FEAT_ONESHOT | 62 CLOCK_EVT_FEAT_C3STOP; 63 64 cd->rating = 350; 65 cd->irq = gic_timer_irq; 66 cd->cpumask = cpumask_of(cpu); 67 cd->set_next_event = gic_next_event; 68 cd->set_mode = gic_set_clock_mode; 69 70 clockevents_config_and_register(cd, gic_frequency, 0x300, 0x7fffffff); 71 72 enable_percpu_irq(gic_timer_irq, IRQ_TYPE_NONE); 73 } 74 75 static void gic_clockevent_cpu_exit(struct clock_event_device *cd) 76 { 77 disable_percpu_irq(gic_timer_irq); 78 } 79 80 static int gic_cpu_notifier(struct notifier_block *nb, unsigned long action, 81 void *data) 82 { 83 switch (action & ~CPU_TASKS_FROZEN) { 84 case CPU_STARTING: 85 gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device)); 86 break; 87 case CPU_DYING: 88 gic_clockevent_cpu_exit(this_cpu_ptr(&gic_clockevent_device)); 89 break; 90 } 91 92 return NOTIFY_OK; 93 } 94 95 static struct notifier_block gic_cpu_nb = { 96 .notifier_call = gic_cpu_notifier, 97 }; 98 99 static int gic_clockevent_init(void) 100 { 101 if (!cpu_has_counter || !gic_frequency) 102 return -ENXIO; 103 104 gic_timer_irq = MIPS_GIC_IRQ_BASE + 105 GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_COMPARE); 106 setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction); 107 108 register_cpu_notifier(&gic_cpu_nb); 109 110 gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device)); 111 112 return 0; 113 } 114 115 static cycle_t gic_hpt_read(struct clocksource *cs) 116 { 117 return gic_read_count(); 118 } 119 120 static struct clocksource gic_clocksource = { 121 .name = "GIC", 122 .read = gic_hpt_read, 123 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 124 }; 125 126 void __init gic_clocksource_init(unsigned int frequency) 127 { 128 gic_frequency = frequency; 129 130 /* Set clocksource mask. */ 131 gic_clocksource.mask = CLOCKSOURCE_MASK(gic_get_count_width()); 132 133 /* Calculate a somewhat reasonable rating value. */ 134 gic_clocksource.rating = 200 + frequency / 10000000; 135 136 clocksource_register_hz(&gic_clocksource, frequency); 137 138 gic_clockevent_init(); 139 } 140