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/of_clk.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 struct ccount_timer { 56 struct clock_event_device evt; 57 int irq_enabled; 58 char name[24]; 59 }; 60 61 static int ccount_timer_set_next_event(unsigned long delta, 62 struct clock_event_device *dev) 63 { 64 unsigned long flags, next; 65 int ret = 0; 66 67 local_irq_save(flags); 68 next = get_ccount() + delta; 69 set_linux_timer(next); 70 if (next - get_ccount() > delta) 71 ret = -ETIME; 72 local_irq_restore(flags); 73 74 return ret; 75 } 76 77 /* 78 * There is no way to disable the timer interrupt at the device level, 79 * only at the intenable register itself. Since enable_irq/disable_irq 80 * calls are nested, we need to make sure that these calls are 81 * balanced. 82 */ 83 static int ccount_timer_shutdown(struct clock_event_device *evt) 84 { 85 struct ccount_timer *timer = 86 container_of(evt, struct ccount_timer, evt); 87 88 if (timer->irq_enabled) { 89 disable_irq_nosync(evt->irq); 90 timer->irq_enabled = 0; 91 } 92 return 0; 93 } 94 95 static int ccount_timer_set_oneshot(struct clock_event_device *evt) 96 { 97 struct ccount_timer *timer = 98 container_of(evt, struct ccount_timer, evt); 99 100 if (!timer->irq_enabled) { 101 enable_irq(evt->irq); 102 timer->irq_enabled = 1; 103 } 104 return 0; 105 } 106 107 static DEFINE_PER_CPU(struct ccount_timer, ccount_timer) = { 108 .evt = { 109 .features = CLOCK_EVT_FEAT_ONESHOT, 110 .rating = 300, 111 .set_next_event = ccount_timer_set_next_event, 112 .set_state_shutdown = ccount_timer_shutdown, 113 .set_state_oneshot = ccount_timer_set_oneshot, 114 .tick_resume = ccount_timer_set_oneshot, 115 }, 116 }; 117 118 static irqreturn_t timer_interrupt(int irq, void *dev_id) 119 { 120 struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt; 121 122 set_linux_timer(get_linux_timer()); 123 evt->event_handler(evt); 124 125 /* Allow platform to do something useful (Wdog). */ 126 platform_heartbeat(); 127 128 return IRQ_HANDLED; 129 } 130 131 void local_timer_setup(unsigned cpu) 132 { 133 struct ccount_timer *timer = &per_cpu(ccount_timer, cpu); 134 struct clock_event_device *clockevent = &timer->evt; 135 136 timer->irq_enabled = 1; 137 snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu); 138 clockevent->name = timer->name; 139 clockevent->cpumask = cpumask_of(cpu); 140 clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT); 141 if (WARN(!clockevent->irq, "error: can't map timer irq")) 142 return; 143 clockevents_config_and_register(clockevent, ccount_freq, 144 0xf, 0xffffffff); 145 } 146 147 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 148 #ifdef CONFIG_OF 149 static void __init calibrate_ccount(void) 150 { 151 struct device_node *cpu; 152 struct clk *clk; 153 154 cpu = of_find_compatible_node(NULL, NULL, "cdns,xtensa-cpu"); 155 if (cpu) { 156 clk = of_clk_get(cpu, 0); 157 if (!IS_ERR(clk)) { 158 ccount_freq = clk_get_rate(clk); 159 return; 160 } else { 161 pr_warn("%s: CPU input clock not found\n", 162 __func__); 163 } 164 } else { 165 pr_warn("%s: CPU node not found in the device tree\n", 166 __func__); 167 } 168 169 platform_calibrate_ccount(); 170 } 171 #else 172 static inline void calibrate_ccount(void) 173 { 174 platform_calibrate_ccount(); 175 } 176 #endif 177 #endif 178 179 void __init time_init(void) 180 { 181 int irq; 182 183 of_clk_init(NULL); 184 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 185 pr_info("Calibrating CPU frequency "); 186 calibrate_ccount(); 187 pr_cont("%d.%02d MHz\n", 188 (int)ccount_freq / 1000000, 189 (int)(ccount_freq / 10000) % 100); 190 #else 191 ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL; 192 #endif 193 WARN(!ccount_freq, 194 "%s: CPU clock frequency is not set up correctly\n", 195 __func__); 196 clocksource_register_hz(&ccount_clocksource, ccount_freq); 197 local_timer_setup(0); 198 irq = this_cpu_ptr(&ccount_timer)->evt.irq; 199 if (request_irq(irq, timer_interrupt, IRQF_TIMER, "timer", NULL)) 200 pr_err("Failed to request irq %d (timer)\n", irq); 201 sched_clock_register(ccount_sched_clock_read, 32, ccount_freq); 202 timer_probe(); 203 } 204 205 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY 206 void calibrate_delay(void) 207 { 208 loops_per_jiffy = ccount_freq / HZ; 209 pr_info("Calibrating delay loop (skipped)... %lu.%02lu BogoMIPS preset\n", 210 loops_per_jiffy / (1000000 / HZ), 211 (loops_per_jiffy / (10000 / HZ)) % 100); 212 } 213 #endif 214