LXR linux/arch/arm/kernel/smp

   1/*
   2 *  linux/arch/arm/kernel/smp_twd.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/clockchips.h>
  18#include <linux/irq.h>
  19#include <linux/io.h>
  20
  21#include <asm/smp_twd.h>
  22#include <asm/hardware/gic.h>
  23
  24#define TWD_TIMER_LOAD                  0x00
  25#define TWD_TIMER_COUNTER               0x04
  26#define TWD_TIMER_CONTROL               0x08
  27#define TWD_TIMER_INTSTAT               0x0C
  28
  29#define TWD_WDOG_LOAD                   0x20
  30#define TWD_WDOG_COUNTER                0x24
  31#define TWD_WDOG_CONTROL                0x28
  32#define TWD_WDOG_INTSTAT                0x2C
  33#define TWD_WDOG_RESETSTAT              0x30
  34#define TWD_WDOG_DISABLE                0x34
  35
  36#define TWD_TIMER_CONTROL_ENABLE        (1 << 0)
  37#define TWD_TIMER_CONTROL_ONESHOT       (0 << 1)
  38#define TWD_TIMER_CONTROL_PERIODIC      (1 << 1)
  39#define TWD_TIMER_CONTROL_IT_ENABLE     (1 << 2)
  40
  41/* set up by the platform code */
  42void __iomem *twd_base;
  43
  44static unsigned long twd_timer_rate;
  45
  46static void twd_set_mode(enum clock_event_mode mode,
  47                        struct clock_event_device *clk)
  48{
  49        unsigned long ctrl;
  50
  51        switch (mode) {
  52        case CLOCK_EVT_MODE_PERIODIC:
  53                /* timer load already set up */
  54                ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
  55                        | TWD_TIMER_CONTROL_PERIODIC;
  56                break;
  57        case CLOCK_EVT_MODE_ONESHOT:
  58                /* period set, and timer enabled in 'next_event' hook */
  59                ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
  60                break;
  61        case CLOCK_EVT_MODE_UNUSED:
  62        case CLOCK_EVT_MODE_SHUTDOWN:
  63        default:
  64                ctrl = 0;
  65        }
  66
  67        __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
  68}
  69
  70static int twd_set_next_event(unsigned long evt,
  71                        struct clock_event_device *unused)
  72{
  73        unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);
  74
  75        ctrl |= TWD_TIMER_CONTROL_ENABLE;
  76
  77        __raw_writel(evt, twd_base + TWD_TIMER_COUNTER);
  78        __raw_writel(ctrl, twd_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 */
  89int twd_timer_ack(void)
  90{
  91        if (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) {
  92                __raw_writel(1, twd_base + TWD_TIMER_INTSTAT);
  93                return 1;
  94        }
  95
  96        return 0;
  97}
  98
  99static void __cpuinit twd_calibrate_rate(void)
 100{
 101        unsigned long load, count;
 102        u64 waitjiffies;
 103
 104        /*
 105         * If this is the first time round, we need to work out how fast
 106         * the timer ticks
 107         */
 108        if (twd_timer_rate == 0) {
 109                printk(KERN_INFO "Calibrating local timer... ");
 110
 111                /* Wait for a tick to start */
 112                waitjiffies = get_jiffies_64() + 1;
 113
 114                while (get_jiffies_64() < waitjiffies)
 115                        udelay(10);
 116
 117                /* OK, now the tick has started, let's get the timer going */
 118                waitjiffies += 5;
 119
 120                                 /* enable, no interrupt or reload */
 121                __raw_writel(0x1, twd_base + TWD_TIMER_CONTROL);
 122
 123                                 /* maximum value */
 124                __raw_writel(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
 125
 126                while (get_jiffies_64() < waitjiffies)
 127                        udelay(10);
 128
 129                count = __raw_readl(twd_base + TWD_TIMER_COUNTER);
 130
 131                twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
 132
 133                printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
 134                        (twd_timer_rate / 100000) % 100);
 135        }
 136
 137        load = twd_timer_rate / HZ;
 138
 139        __raw_writel(load, twd_base + TWD_TIMER_LOAD);
 140}
 141
 142/*
 143 * Setup the local clock events for a CPU.
 144 */
 145void __cpuinit twd_timer_setup(struct clock_event_device *clk)
 146{
 147        unsigned long flags;
 148
 149        twd_calibrate_rate();
 150
 151        clk->name = "local_timer";
 152        clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
 153        clk->rating = 350;
 154        clk->set_mode = twd_set_mode;
 155        clk->set_next_event = twd_set_next_event;
 156        clk->shift = 20;
 157        clk->mult = div_sc(twd_timer_rate, NSEC_PER_SEC, clk->shift);
 158        clk->max_delta_ns = clockevent_delta2ns(0xffffffff, clk);
 159        clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
 160
 161        /* Make sure our local interrupt controller has this enabled */
 162        local_irq_save(flags);
 163        get_irq_chip(clk->irq)->unmask(clk->irq);
 164        local_irq_restore(flags);
 165
 166        clockevents_register_device(clk);
 167}
 168
 169#ifdef CONFIG_HOTPLUG_CPU
 170/*
 171 * take a local timer down
 172 */
 173void twd_timer_stop(void)
 174{
 175        __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
 176}
 177#endif
 178