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/clk.h> 16 #include <linux/clk-provider.h> 17 #include <linux/errno.h> 18 #include <linux/sched.h> 19 #include <linux/time.h> 20 #include <linux/clocksource.h> 21 #include <linux/clockchips.h> 22 #include <linux/interrupt.h> 23 #include <linux/module.h> 24 #include <linux/init.h> 25 #include <linux/irq.h> 26 #include <linux/profile.h> 27 #include <linux/delay.h> 28 #include <linux/irqdomain.h> 29 #include <linux/sched_clock.h> 30 31 #include <asm/timex.h> 32 #include <asm/platform.h> 33 34 unsigned long ccount_freq; /* ccount Hz */ 35 EXPORT_SYMBOL(ccount_freq); 36 37 static u64 ccount_read(struct clocksource *cs) 38 { 39 return (u64)get_ccount(); 40 } 41 42 static u64 notrace ccount_sched_clock_read(void) 43 { 44 return get_ccount(); 45 } 46 47 static struct clocksource ccount_clocksource = { 48 .name = "ccount", 49 .rating = 200, 50 .read = ccount_read, 51 .mask = CLOCKSOURCE_MASK(32), 52 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 53 }; 54 55 static int ccount_timer_set_next_event(unsigned long delta, 56 struct clock_event_device *dev); 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 /* 81 * There is no way to disable the timer interrupt at the device level, 82 * only at the intenable register itself. Since enable_irq/disable_irq 83 * calls are nested, we need to make sure that these calls are 84 * balanced. 85 */ 86 static int ccount_timer_shutdown(struct clock_event_device *evt) 87 { 88 struct ccount_timer *timer = 89 container_of(evt, struct ccount_timer, evt); 90 91 if (timer->irq_enabled) { 92 disable_irq(evt->irq); 93 timer->irq_enabled = 0; 94 } 95 return 0; 96 } 97 98 static int ccount_timer_set_oneshot(struct clock_event_device *evt) 99 { 100 struct ccount_timer *timer = 101 container_of(evt, struct ccount_timer, evt); 102 103 if (!timer->irq_enabled) { 104 enable_irq(evt->irq); 105 timer->irq_enabled = 1; 106 } 107 return 0; 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_state_shutdown = ccount_timer_shutdown; 129 clockevent->set_state_oneshot = ccount_timer_set_oneshot; 130 clockevent->tick_resume = ccount_timer_set_oneshot; 131 clockevent->cpumask = cpumask_of(cpu); 132 clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT); 133 if (WARN(!clockevent->irq, "error: can't map timer irq")) 134 return; 135 clockevents_config_and_register(clockevent, ccount_freq, 136 0xf, 0xffffffff); 137 } 138 139 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 140 #ifdef CONFIG_OF 141 static void __init calibrate_ccount(void) 142 { 143 struct device_node *cpu; 144 struct clk *clk; 145 146 cpu = of_find_compatible_node(NULL, NULL, "cdns,xtensa-cpu"); 147 if (cpu) { 148 clk = of_clk_get(cpu, 0); 149 if (!IS_ERR(clk)) { 150 ccount_freq = clk_get_rate(clk); 151 return; 152 } else { 153 pr_warn("%s: CPU input clock not found\n", 154 __func__); 155 } 156 } else { 157 pr_warn("%s: CPU node not found in the device tree\n", 158 __func__); 159 } 160 161 platform_calibrate_ccount(); 162 } 163 #else 164 static inline void calibrate_ccount(void) 165 { 166 platform_calibrate_ccount(); 167 } 168 #endif 169 #endif 170 171 void __init time_init(void) 172 { 173 of_clk_init(NULL); 174 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 175 pr_info("Calibrating CPU frequency "); 176 calibrate_ccount(); 177 pr_cont("%d.%02d MHz\n", 178 (int)ccount_freq / 1000000, 179 (int)(ccount_freq / 10000) % 100); 180 #else 181 ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL; 182 #endif 183 WARN(!ccount_freq, 184 "%s: CPU clock frequency is not set up correctly\n", 185 __func__); 186 clocksource_register_hz(&ccount_clocksource, ccount_freq); 187 local_timer_setup(0); 188 setup_irq(this_cpu_ptr(&ccount_timer)->evt.irq, &timer_irqaction); 189 sched_clock_register(ccount_sched_clock_read, 32, ccount_freq); 190 clocksource_probe(); 191 } 192 193 /* 194 * The timer interrupt is called HZ times per second. 195 */ 196 197 irqreturn_t timer_interrupt(int irq, void *dev_id) 198 { 199 struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt; 200 201 set_linux_timer(get_linux_timer()); 202 evt->event_handler(evt); 203 204 /* Allow platform to do something useful (Wdog). */ 205 platform_heartbeat(); 206 207 return IRQ_HANDLED; 208 } 209 210 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY 211 void calibrate_delay(void) 212 { 213 loops_per_jiffy = ccount_freq / HZ; 214 pr_info("Calibrating delay loop (skipped)... %lu.%02lu BogoMIPS preset\n", 215 loops_per_jiffy / (1000000 / HZ), 216 (loops_per_jiffy / (10000 / HZ)) % 100); 217 } 218 #endif 219