arch/arm/mach-realview/localtimer.c

   1 /*
   2  *  linux/arch/arm/mach-realview/localtimer.c
   3  *
   4  *  Copyright (C) 2002 ARM Ltd.
   5  *  All Rights Reserved
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/delay.h>
  14 #include <linux/device.h>
  15 #include <linux/smp.h>
  16 #include <linux/jiffies.h>
  17 #include <linux/percpu.h>
  18 #include <linux/clockchips.h>
  19 #include <linux/irq.h>
  20
  21 #include <asm/hardware/arm_twd.h>
  22 #include <asm/hardware/gic.h>
  23 #include <asm/hardware.h>
  24 #include <asm/io.h>
  25 #include <asm/irq.h>
  26
  27 #define TWD_BASE(cpu)   (__io_address(REALVIEW_EB11MP_TWD_BASE) + \
  28                          ((cpu) * REALVIEW_EB11MP_TWD_SIZE))
  29
  30 static DEFINE_PER_CPU(struct clock_event_device, local_clockevent);
  31
  32 /*
  33  * Used on SMP for either the local timer or IPI_TIMER
  34  */
  35 void local_timer_interrupt(void)
  36 {
  37         struct clock_event_device *clk = &__get_cpu_var(local_clockevent);
  38
  39         clk->event_handler(clk);
  40 }
  41
  42 #ifdef CONFIG_LOCAL_TIMERS
  43
  44 static unsigned long mpcore_timer_rate;
  45
  46 static void local_timer_set_mode(enum clock_event_mode mode,
  47                                  struct clock_event_device *clk)
  48 {
  49         void __iomem *base = TWD_BASE(smp_processor_id());
  50         unsigned long ctrl;
  51
  52         switch(mode) {
  53         case CLOCK_EVT_MODE_PERIODIC:
  54                 /* timer load already set up */
  55                 ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
  56                         | TWD_TIMER_CONTROL_PERIODIC;
  57                 break;
  58         case CLOCK_EVT_MODE_ONESHOT:
  59                 /* period set, and timer enabled in 'next_event' hook */
  60                 ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
  61                 break;
  62         case CLOCK_EVT_MODE_UNUSED:
  63         case CLOCK_EVT_MODE_SHUTDOWN:
  64         default:
  65                 ctrl = 0;
  66         }
  67
  68         __raw_writel(ctrl, base + TWD_TIMER_CONTROL);
  69 }
  70
  71 static int local_timer_set_next_event(unsigned long evt,
  72                                       struct clock_event_device *unused)
  73 {
  74         void __iomem *base = TWD_BASE(smp_processor_id());
  75         unsigned long ctrl = __raw_readl(base + TWD_TIMER_CONTROL);
  76
  77         __raw_writel(evt, base + TWD_TIMER_COUNTER);
  78         __raw_writel(ctrl | TWD_TIMER_CONTROL_ENABLE, base + TWD_TIMER_CONTROL);
  79
  80         return 0;
  81 }
  82
  83 /*
  84  * local_timer_ack: checks for a local timer interrupt.
  85  *
  86  * If a local timer interrupt has occurred, acknowledge and return 1.
  87  * Otherwise, return 0.
  88  */
  89 int local_timer_ack(void)
  90 {
  91         void __iomem *base = TWD_BASE(smp_processor_id());
  92
  93         if (__raw_readl(base + TWD_TIMER_INTSTAT)) {
  94                 __raw_writel(1, base + TWD_TIMER_INTSTAT);
  95                 return 1;
  96         }
  97
  98         return 0;
  99 }
 100
 101 static void __cpuinit twd_calibrate_rate(unsigned int cpu)
 102 {
 103         void __iomem *base = TWD_BASE(cpu);
 104         unsigned long load, count;
 105         u64 waitjiffies;
 106
 107         /*
 108          * If this is the first time round, we need to work out how fast
 109          * the timer ticks
 110          */
 111         if (mpcore_timer_rate == 0) {
 112                 printk("Calibrating local timer... ");
 113
 114                 /* Wait for a tick to start */
 115                 waitjiffies = get_jiffies_64() + 1;
 116
 117                 while (get_jiffies_64() < waitjiffies)
 118                         udelay(10);
 119
 120                 /* OK, now the tick has started, let's get the timer going */
 121                 waitjiffies += 5;
 122
 123                                  /* enable, no interrupt or reload */
 124                 __raw_writel(0x1, base + TWD_TIMER_CONTROL);
 125
 126                                  /* maximum value */
 127                 __raw_writel(0xFFFFFFFFU, base + TWD_TIMER_COUNTER);
 128
 129                 while (get_jiffies_64() < waitjiffies)
 130                         udelay(10);
 131
 132                 count = __raw_readl(base + TWD_TIMER_COUNTER);
 133
 134                 mpcore_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
 135
 136                 printk("%lu.%02luMHz.\n", mpcore_timer_rate / 1000000,
 137                         (mpcore_timer_rate / 100000) % 100);
 138         }
 139
 140         load = mpcore_timer_rate / HZ;
 141
 142         __raw_writel(load, base + TWD_TIMER_LOAD);
 143 }
 144
 145 /*
 146  * Setup the local clock events for a CPU.
 147  */
 148 void __cpuinit local_timer_setup(unsigned int cpu)
 149 {
 150         struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
 151         unsigned long flags;
 152
 153         twd_calibrate_rate(cpu);
 154
 155         clk->name               = "local_timer";
 156         clk->features           = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
 157         clk->rating             = 350;
 158         clk->set_mode           = local_timer_set_mode;
 159         clk->set_next_event     = local_timer_set_next_event;
 160         clk->irq                = IRQ_LOCALTIMER;
 161         clk->cpumask            = cpumask_of_cpu(cpu);
 162         clk->shift              = 20;
 163         clk->mult               = div_sc(mpcore_timer_rate, NSEC_PER_SEC, clk->shift);
 164         clk->max_delta_ns       = clockevent_delta2ns(0xffffffff, clk);
 165         clk->min_delta_ns       = clockevent_delta2ns(0xf, clk);
 166
 167         /* Make sure our local interrupt controller has this enabled */
 168         local_irq_save(flags);
 169         get_irq_chip(IRQ_LOCALTIMER)->unmask(IRQ_LOCALTIMER);
 170         local_irq_restore(flags);
 171
 172         clockevents_register_device(clk);
 173 }
 174
 175 /*
 176  * take a local timer down
 177  */
 178 void __cpuexit local_timer_stop(unsigned int cpu)
 179 {
 180         __raw_writel(0, TWD_BASE(cpu) + TWD_TIMER_CONTROL);
 181 }
 182
 183 #else   /* CONFIG_LOCAL_TIMERS */
 184
 185 static void dummy_timer_set_mode(enum clock_event_mode mode,
 186                                  struct clock_event_device *clk)
 187 {
 188 }
 189
 190 void __cpuinit local_timer_setup(unsigned int cpu)
 191 {
 192         struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
 193
 194         clk->name               = "dummy_timer";
 195         clk->features           = CLOCK_EVT_FEAT_DUMMY;
 196         clk->rating             = 200;
 197         clk->set_mode           = dummy_timer_set_mode;
 198         clk->broadcast          = smp_timer_broadcast;
 199         clk->cpumask            = cpumask_of_cpu(cpu);
 200
 201         clockevents_register_device(clk);
 202 }
 203
 204 #endif  /* !CONFIG_LOCAL_TIMERS */