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/*
* 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>
/* set up by the platform code */
void __iomem *twd_base;
static unsigned long twd_timer_rate;
static unsigned long twd_periphclk_prescaler;
static unsigned long twd_target_rate;
static void twd_set_mode(enum clock_event_mode mode,
struct clock_event_device *clk)
{
unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);
ctrl &= TWD_TIMER_CONTROL_PRESCALE_MASK;
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:
break;
}
__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;
}
void twd_recalc_prescaler(unsigned long new_rate)
{
u32 ctrl;
int prescaler;
unsigned long periphclk_rate;
BUG_ON(twd_periphclk_prescaler == 0 || twd_timer_rate == 0);
periphclk_rate = new_rate / twd_periphclk_prescaler;
prescaler = DIV_ROUND_UP(periphclk_rate, twd_timer_rate);
prescaler = clamp(prescaler - 1, 0, 0xFF);
ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);
ctrl &= ~TWD_TIMER_CONTROL_PRESCALE_MASK;
ctrl |= prescaler << 8;
__raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
}
static void __cpuinit twd_calibrate_rate(unsigned long target_rate,
unsigned int periphclk_prescaler)
{
unsigned long load, count;
u64 waitjiffies;
unsigned long cpu_rate;
/*
* If this is the first time round, we need to work out how fast
* the timer ticks
*/
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);
/*
* If a target rate has been requested, adjust the TWD prescaler
* to get the closest lower frequency.
*/
if (target_rate) {
twd_periphclk_prescaler = periphclk_prescaler;
twd_target_rate = target_rate;
printk("%lu.%02luMHz, setting to ",
twd_timer_rate / 1000000,
(twd_timer_rate / 10000) % 100);
cpu_rate = twd_timer_rate * periphclk_prescaler;
twd_timer_rate = twd_target_rate;
twd_recalc_prescaler(cpu_rate);
}
printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
(twd_timer_rate / 10000) % 100);
load = twd_timer_rate / HZ;
__raw_writel(load, twd_base + TWD_TIMER_LOAD);
}
/*
* Setup the local clock events for a CPU.
*/
static void __cpuinit __twd_timer_setup(struct clock_event_device *clk,
unsigned long target_rate, unsigned int periphclk_prescaler)
{
unsigned long flags;
twd_calibrate_rate(target_rate, periphclk_prescaler);
clk->name = "local_timer";
clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
CLOCK_EVT_FEAT_C3STOP;
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);
irq_to_desc(clk->irq)->status |= IRQ_NOPROBE;
get_irq_chip(clk->irq)->unmask(clk->irq);
local_irq_restore(flags);
clockevents_register_device(clk);
}
void __cpuinit twd_timer_setup_scalable(struct clock_event_device *clk,
unsigned long target_rate, unsigned int periphclk_prescaler)
{
__twd_timer_setup(clk, target_rate, periphclk_prescaler);
}
void __cpuinit twd_timer_setup(struct clock_event_device *clk)
{
__twd_timer_setup(clk, 0, 0);
}
#ifdef CONFIG_HOTPLUG_CPU
/*
* take a local timer down
*/
void twd_timer_stop(void)
{
__raw_writel(0, twd_base + TWD_TIMER_CONTROL);
}
#endif
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