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 34 static cycle_t ccount_read(struct clocksource *cs) 35 { 36 return (cycle_t)get_ccount(); 37 } 38 39 static u32 notrace ccount_sched_clock_read(void) 40 { 41 return get_ccount(); 42 } 43 44 static struct clocksource ccount_clocksource = { 45 .name = "ccount", 46 .rating = 200, 47 .read = ccount_read, 48 .mask = CLOCKSOURCE_MASK(32), 49 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 50 }; 51 52 static int ccount_timer_set_next_event(unsigned long delta, 53 struct clock_event_device *dev); 54 static void ccount_timer_set_mode(enum clock_event_mode mode, 55 struct clock_event_device *evt); 56 struct ccount_timer { 57 struct clock_event_device evt; 58 int irq_enabled; 59 char name[24]; 60 }; 61 static DEFINE_PER_CPU(struct ccount_timer, ccount_timer); 62 63 static int ccount_timer_set_next_event(unsigned long delta, 64 struct clock_event_device *dev) 65 { 66 unsigned long flags, next; 67 int ret = 0; 68 69 local_irq_save(flags); 70 next = get_ccount() + delta; 71 set_linux_timer(next); 72 if (next - get_ccount() > delta) 73 ret = -ETIME; 74 local_irq_restore(flags); 75 76 return ret; 77 } 78 79 static void ccount_timer_set_mode(enum clock_event_mode mode, 80 struct clock_event_device *evt) 81 { 82 struct ccount_timer *timer = 83 container_of(evt, struct ccount_timer, evt); 84 85 /* 86 * There is no way to disable the timer interrupt at the device level, 87 * only at the intenable register itself. Since enable_irq/disable_irq 88 * calls are nested, we need to make sure that these calls are 89 * balanced. 90 */ 91 switch (mode) { 92 case CLOCK_EVT_MODE_SHUTDOWN: 93 case CLOCK_EVT_MODE_UNUSED: 94 if (timer->irq_enabled) { 95 disable_irq(evt->irq); 96 timer->irq_enabled = 0; 97 } 98 break; 99 case CLOCK_EVT_MODE_RESUME: 100 case CLOCK_EVT_MODE_ONESHOT: 101 if (!timer->irq_enabled) { 102 enable_irq(evt->irq); 103 timer->irq_enabled = 1; 104 } 105 default: 106 break; 107 } 108 } 109 110 static irqreturn_t timer_interrupt(int irq, void *dev_id); 111 static struct irqaction timer_irqaction = { 112 .handler = timer_interrupt, 113 .flags = IRQF_TIMER, 114 .name = "timer", 115 }; 116 117 void local_timer_setup(unsigned cpu) 118 { 119 struct ccount_timer *timer = &per_cpu(ccount_timer, cpu); 120 struct clock_event_device *clockevent = &timer->evt; 121 122 timer->irq_enabled = 1; 123 clockevent->name = timer->name; 124 snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu); 125 clockevent->features = CLOCK_EVT_FEAT_ONESHOT; 126 clockevent->rating = 300; 127 clockevent->set_next_event = ccount_timer_set_next_event; 128 clockevent->set_mode = ccount_timer_set_mode; 129 clockevent->cpumask = cpumask_of(cpu); 130 clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT); 131 if (WARN(!clockevent->irq, "error: can't map timer irq")) 132 return; 133 clockevents_config_and_register(clockevent, ccount_freq, 134 0xf, 0xffffffff); 135 } 136 137 void __init time_init(void) 138 { 139 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 140 printk("Calibrating CPU frequency "); 141 platform_calibrate_ccount(); 142 printk("%d.%02d MHz\n", (int)ccount_freq/1000000, 143 (int)(ccount_freq/10000)%100); 144 #else 145 ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL; 146 #endif 147 clocksource_register_hz(&ccount_clocksource, ccount_freq); 148 local_timer_setup(0); 149 setup_irq(this_cpu_ptr(&ccount_timer)->evt.irq, &timer_irqaction); 150 setup_sched_clock(ccount_sched_clock_read, 32, ccount_freq); 151 } 152 153 /* 154 * The timer interrupt is called HZ times per second. 155 */ 156 157 irqreturn_t timer_interrupt(int irq, void *dev_id) 158 { 159 struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt; 160 161 set_linux_timer(get_linux_timer()); 162 evt->event_handler(evt); 163 164 /* Allow platform to do something useful (Wdog). */ 165 platform_heartbeat(); 166 167 return IRQ_HANDLED; 168 } 169 170 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY 171 void calibrate_delay(void) 172 { 173 loops_per_jiffy = ccount_freq / HZ; 174 printk("Calibrating delay loop (skipped)... " 175 "%lu.%02lu BogoMIPS preset\n", 176 loops_per_jiffy/(1000000/HZ), 177 (loops_per_jiffy/(10000/HZ)) % 100); 178 } 179 #endif 180