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/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