arch/xtensa/kernel/time.c

   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_nosync(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         timer_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