178 lines
4.2 KiB
C
178 lines
4.2 KiB
C
/*
|
|
* linux/arch/arm/kernel/smp_twd.c
|
|
*
|
|
* Copyright (C) 2002 ARM Ltd.
|
|
* All Rights Reserved
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
#include <linux/init.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/device.h>
|
|
#include <linux/smp.h>
|
|
#include <linux/jiffies.h>
|
|
#include <linux/clockchips.h>
|
|
#include <linux/irq.h>
|
|
#include <linux/io.h>
|
|
|
|
#include <asm/smp_twd.h>
|
|
#include <asm/hardware/gic.h>
|
|
|
|
#define TWD_TIMER_LOAD 0x00
|
|
#define TWD_TIMER_COUNTER 0x04
|
|
#define TWD_TIMER_CONTROL 0x08
|
|
#define TWD_TIMER_INTSTAT 0x0C
|
|
|
|
#define TWD_WDOG_LOAD 0x20
|
|
#define TWD_WDOG_COUNTER 0x24
|
|
#define TWD_WDOG_CONTROL 0x28
|
|
#define TWD_WDOG_INTSTAT 0x2C
|
|
#define TWD_WDOG_RESETSTAT 0x30
|
|
#define TWD_WDOG_DISABLE 0x34
|
|
|
|
#define TWD_TIMER_CONTROL_ENABLE (1 << 0)
|
|
#define TWD_TIMER_CONTROL_ONESHOT (0 << 1)
|
|
#define TWD_TIMER_CONTROL_PERIODIC (1 << 1)
|
|
#define TWD_TIMER_CONTROL_IT_ENABLE (1 << 2)
|
|
|
|
/* set up by the platform code */
|
|
void __iomem *twd_base;
|
|
|
|
static unsigned long twd_timer_rate;
|
|
|
|
static void twd_set_mode(enum clock_event_mode mode,
|
|
struct clock_event_device *clk)
|
|
{
|
|
unsigned long ctrl;
|
|
|
|
switch (mode) {
|
|
case CLOCK_EVT_MODE_PERIODIC:
|
|
/* timer load already set up */
|
|
ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
|
|
| TWD_TIMER_CONTROL_PERIODIC;
|
|
break;
|
|
case CLOCK_EVT_MODE_ONESHOT:
|
|
/* period set, and timer enabled in 'next_event' hook */
|
|
ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
|
|
break;
|
|
case CLOCK_EVT_MODE_UNUSED:
|
|
case CLOCK_EVT_MODE_SHUTDOWN:
|
|
default:
|
|
ctrl = 0;
|
|
}
|
|
|
|
__raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
|
|
}
|
|
|
|
static int twd_set_next_event(unsigned long evt,
|
|
struct clock_event_device *unused)
|
|
{
|
|
unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);
|
|
|
|
ctrl |= TWD_TIMER_CONTROL_ENABLE;
|
|
|
|
__raw_writel(evt, twd_base + TWD_TIMER_COUNTER);
|
|
__raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* local_timer_ack: checks for a local timer interrupt.
|
|
*
|
|
* If a local timer interrupt has occurred, acknowledge and return 1.
|
|
* Otherwise, return 0.
|
|
*/
|
|
int twd_timer_ack(void)
|
|
{
|
|
if (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) {
|
|
__raw_writel(1, twd_base + TWD_TIMER_INTSTAT);
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __cpuinit twd_calibrate_rate(void)
|
|
{
|
|
unsigned long load, count;
|
|
u64 waitjiffies;
|
|
|
|
/*
|
|
* If this is the first time round, we need to work out how fast
|
|
* the timer ticks
|
|
*/
|
|
if (twd_timer_rate == 0) {
|
|
printk(KERN_INFO "Calibrating local timer... ");
|
|
|
|
/* Wait for a tick to start */
|
|
waitjiffies = get_jiffies_64() + 1;
|
|
|
|
while (get_jiffies_64() < waitjiffies)
|
|
udelay(10);
|
|
|
|
/* OK, now the tick has started, let's get the timer going */
|
|
waitjiffies += 5;
|
|
|
|
/* enable, no interrupt or reload */
|
|
__raw_writel(0x1, twd_base + TWD_TIMER_CONTROL);
|
|
|
|
/* maximum value */
|
|
__raw_writel(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
|
|
|
|
while (get_jiffies_64() < waitjiffies)
|
|
udelay(10);
|
|
|
|
count = __raw_readl(twd_base + TWD_TIMER_COUNTER);
|
|
|
|
twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
|
|
|
|
printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
|
|
(twd_timer_rate / 100000) % 100);
|
|
}
|
|
|
|
load = twd_timer_rate / HZ;
|
|
|
|
__raw_writel(load, twd_base + TWD_TIMER_LOAD);
|
|
}
|
|
|
|
/*
|
|
* Setup the local clock events for a CPU.
|
|
*/
|
|
void __cpuinit twd_timer_setup(struct clock_event_device *clk)
|
|
{
|
|
unsigned long flags;
|
|
|
|
twd_calibrate_rate();
|
|
|
|
clk->name = "local_timer";
|
|
clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
|
|
clk->rating = 350;
|
|
clk->set_mode = twd_set_mode;
|
|
clk->set_next_event = twd_set_next_event;
|
|
clk->shift = 20;
|
|
clk->mult = div_sc(twd_timer_rate, NSEC_PER_SEC, clk->shift);
|
|
clk->max_delta_ns = clockevent_delta2ns(0xffffffff, clk);
|
|
clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
|
|
|
|
/* Make sure our local interrupt controller has this enabled */
|
|
local_irq_save(flags);
|
|
get_irq_chip(clk->irq)->unmask(clk->irq);
|
|
local_irq_restore(flags);
|
|
|
|
clockevents_register_device(clk);
|
|
}
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
/*
|
|
* take a local timer down
|
|
*/
|
|
void twd_timer_stop(void)
|
|
{
|
|
__raw_writel(0, twd_base + TWD_TIMER_CONTROL);
|
|
}
|
|
#endif
|