1 /* 2 * arch/xtensa/kernel/time.c 3 * 4 * Timer and clock support. 5 * 6 * This file is subject to the terms and conditions of the GNU General Public 7 * License. See the file "COPYING" in the main directory of this archive 8 * for more details. 9 * 10 * Copyright (C) 2005 Tensilica Inc. 11 * 12 * Chris Zankel <chris@zankel.net> 13 */ 14 15 #include <linux/errno.h> 16 #include <linux/sched.h> 17 #include <linux/time.h> 18 #include <linux/clocksource.h> 19 #include <linux/clockchips.h> 20 #include <linux/interrupt.h> 21 #include <linux/module.h> 22 #include <linux/init.h> 23 #include <linux/irq.h> 24 #include <linux/profile.h> 25 #include <linux/delay.h> 26 #include <linux/irqdomain.h> 27 #include <linux/sched_clock.h> 28 29 #include <asm/timex.h> 30 #include <asm/platform.h> 31 32 unsigned long ccount_freq; /* ccount Hz */ 33 EXPORT_SYMBOL(ccount_freq); 34 35 static cycle_t ccount_read(struct clocksource *cs) 36 { 37 return (cycle_t)get_ccount(); 38 } 39 40 static u64 notrace ccount_sched_clock_read(void) 41 { 42 return get_ccount(); 43 } 44 45 static struct clocksource ccount_clocksource = { 46 .name = "ccount", 47 .rating = 200, 48 .read = ccount_read, 49 .mask = CLOCKSOURCE_MASK(32), 50 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 51 }; 52 53 static int ccount_timer_set_next_event(unsigned long delta, 54 struct clock_event_device *dev); 55 static void ccount_timer_set_mode(enum clock_event_mode mode, 56 struct clock_event_device *evt); 57 struct ccount_timer { 58 struct clock_event_device evt; 59 int irq_enabled; 60 char name[24]; 61 }; 62 static DEFINE_PER_CPU(struct ccount_timer, ccount_timer); 63 64 static int ccount_timer_set_next_event(unsigned long delta, 65 struct clock_event_device *dev) 66 { 67 unsigned long flags, next; 68 int ret = 0; 69 70 local_irq_save(flags); 71 next = get_ccount() + delta; 72 set_linux_timer(next); 73 if (next - get_ccount() > delta) 74 ret = -ETIME; 75 local_irq_restore(flags); 76 77 return ret; 78 } 79 80 static void ccount_timer_set_mode(enum clock_event_mode mode, 81 struct clock_event_device *evt) 82 { 83 struct ccount_timer *timer = 84 container_of(evt, struct ccount_timer, evt); 85 86 /* 87 * There is no way to disable the timer interrupt at the device level, 88 * only at the intenable register itself. Since enable_irq/disable_irq 89 * calls are nested, we need to make sure that these calls are 90 * balanced. 91 */ 92 switch (mode) { 93 case CLOCK_EVT_MODE_SHUTDOWN: 94 case CLOCK_EVT_MODE_UNUSED: 95 if (timer->irq_enabled) { 96 disable_irq(evt->irq); 97 timer->irq_enabled = 0; 98 } 99 break; 100 case CLOCK_EVT_MODE_RESUME: 101 case CLOCK_EVT_MODE_ONESHOT: 102 if (!timer->irq_enabled) { 103 enable_irq(evt->irq); 104 timer->irq_enabled = 1; 105 } 106 default: 107 break; 108 } 109 } 110 111 static irqreturn_t timer_interrupt(int irq, void *dev_id); 112 static struct irqaction timer_irqaction = { 113 .handler = timer_interrupt, 114 .flags = IRQF_TIMER, 115 .name = "timer", 116 }; 117 118 void local_timer_setup(unsigned cpu) 119 { 120 struct ccount_timer *timer = &per_cpu(ccount_timer, cpu); 121 struct clock_event_device *clockevent = &timer->evt; 122 123 timer->irq_enabled = 1; 124 clockevent->name = timer->name; 125 snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu); 126 clockevent->features = CLOCK_EVT_FEAT_ONESHOT; 127 clockevent->rating = 300; 128 clockevent->set_next_event = ccount_timer_set_next_event; 129 clockevent->set_mode = ccount_timer_set_mode; 130 clockevent->cpumask = cpumask_of(cpu); 131 clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT); 132 if (WARN(!clockevent->irq, "error: can't map timer irq")) 133 return; 134 clockevents_config_and_register(clockevent, ccount_freq, 135 0xf, 0xffffffff); 136 } 137 138 void __init time_init(void) 139 { 140 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 141 printk("Calibrating CPU frequency "); 142 platform_calibrate_ccount(); 143 printk("%d.%02d MHz\n", (int)ccount_freq/1000000, 144 (int)(ccount_freq/10000)%100); 145 #else 146 ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL; 147 #endif 148 clocksource_register_hz(&ccount_clocksource, ccount_freq); 149 local_timer_setup(0); 150 setup_irq(this_cpu_ptr(&ccount_timer)->evt.irq, &timer_irqaction); 151 sched_clock_register(ccount_sched_clock_read, 32, ccount_freq); 152 clocksource_of_init(); 153 } 154 155 /* 156 * The timer interrupt is called HZ times per second. 157 */ 158 159 irqreturn_t timer_interrupt(int irq, void *dev_id) 160 { 161 struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt; 162 163 set_linux_timer(get_linux_timer()); 164 evt->event_handler(evt); 165 166 /* Allow platform to do something useful (Wdog). */ 167 platform_heartbeat(); 168 169 return IRQ_HANDLED; 170 } 171 172 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY 173 void calibrate_delay(void) 174 { 175 loops_per_jiffy = ccount_freq / HZ; 176 printk("Calibrating delay loop (skipped)... " 177 "%lu.%02lu BogoMIPS preset\n", 178 loops_per_jiffy/(1000000/HZ), 179 (loops_per_jiffy/(10000/HZ)) % 100); 180 } 181 #endif 182