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