https://github.com/torvalds/linux
Tip revision: d1c3ed669a2d452cacfb48c2d171a1f364dae2ed authored by Linus Torvalds on 03 January 2013, 02:13:21 UTC
Linux 3.8-rc2
Linux 3.8-rc2
Tip revision: d1c3ed6
smp_twd.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/clk.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/smp.h>
#include <linux/jiffies.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>
#include <asm/smp_twd.h>
#include <asm/localtimer.h>
#include <asm/hardware/gic.h>
/* set up by the platform code */
static void __iomem *twd_base;
static struct clk *twd_clk;
static unsigned long twd_timer_rate;
static bool common_setup_called;
static DEFINE_PER_CPU(bool, percpu_setup_called);
static struct clock_event_device __percpu **twd_evt;
static int twd_ppi;
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:
ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
| TWD_TIMER_CONTROL_PERIODIC;
__raw_writel(DIV_ROUND_CLOSEST(twd_timer_rate, HZ),
twd_base + TWD_TIMER_LOAD);
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.
*/
static 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 twd_timer_stop(struct clock_event_device *clk)
{
twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
disable_percpu_irq(clk->irq);
}
#ifdef CONFIG_COMMON_CLK
/*
* Updates clockevent frequency when the cpu frequency changes.
* Called on the cpu that is changing frequency with interrupts disabled.
*/
static void twd_update_frequency(void *new_rate)
{
twd_timer_rate = *((unsigned long *) new_rate);
clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
}
static int twd_rate_change(struct notifier_block *nb,
unsigned long flags, void *data)
{
struct clk_notifier_data *cnd = data;
/*
* The twd clock events must be reprogrammed to account for the new
* frequency. The timer is local to a cpu, so cross-call to the
* changing cpu.
*/
if (flags == POST_RATE_CHANGE)
smp_call_function(twd_update_frequency,
(void *)&cnd->new_rate, 1);
return NOTIFY_OK;
}
static struct notifier_block twd_clk_nb = {
.notifier_call = twd_rate_change,
};
static int twd_clk_init(void)
{
if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
return clk_notifier_register(twd_clk, &twd_clk_nb);
return 0;
}
core_initcall(twd_clk_init);
#elif defined (CONFIG_CPU_FREQ)
#include <linux/cpufreq.h>
/*
* Updates clockevent frequency when the cpu frequency changes.
* Called on the cpu that is changing frequency with interrupts disabled.
*/
static void twd_update_frequency(void *data)
{
twd_timer_rate = clk_get_rate(twd_clk);
clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
}
static int twd_cpufreq_transition(struct notifier_block *nb,
unsigned long state, void *data)
{
struct cpufreq_freqs *freqs = data;
/*
* The twd clock events must be reprogrammed to account for the new
* frequency. The timer is local to a cpu, so cross-call to the
* changing cpu.
*/
if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
smp_call_function_single(freqs->cpu, twd_update_frequency,
NULL, 1);
return NOTIFY_OK;
}
static struct notifier_block twd_cpufreq_nb = {
.notifier_call = twd_cpufreq_transition,
};
static int twd_cpufreq_init(void)
{
if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
return cpufreq_register_notifier(&twd_cpufreq_nb,
CPUFREQ_TRANSITION_NOTIFIER);
return 0;
}
core_initcall(twd_cpufreq_init);
#endif
static void __cpuinit twd_calibrate_rate(void)
{
unsigned long 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 / 10000) % 100);
}
}
static irqreturn_t twd_handler(int irq, void *dev_id)
{
struct clock_event_device *evt = *(struct clock_event_device **)dev_id;
if (twd_timer_ack()) {
evt->event_handler(evt);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
static struct clk *twd_get_clock(void)
{
struct clk *clk;
int err;
clk = clk_get_sys("smp_twd", NULL);
if (IS_ERR(clk)) {
pr_err("smp_twd: clock not found: %d\n", (int)PTR_ERR(clk));
return clk;
}
err = clk_prepare_enable(clk);
if (err) {
pr_err("smp_twd: clock failed to prepare+enable: %d\n", err);
clk_put(clk);
return ERR_PTR(err);
}
return clk;
}
/*
* Setup the local clock events for a CPU.
*/
static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
{
struct clock_event_device **this_cpu_clk;
int cpu = smp_processor_id();
/*
* If the basic setup for this CPU has been done before don't
* bother with the below.
*/
if (per_cpu(percpu_setup_called, cpu)) {
__raw_writel(0, twd_base + TWD_TIMER_CONTROL);
clockevents_register_device(*__this_cpu_ptr(twd_evt));
enable_percpu_irq(clk->irq, 0);
return 0;
}
per_cpu(percpu_setup_called, cpu) = true;
/*
* This stuff only need to be done once for the entire TWD cluster
* during the runtime of the system.
*/
if (!common_setup_called) {
twd_clk = twd_get_clock();
/*
* We use IS_ERR_OR_NULL() here, because if the clock stubs
* are active we will get a valid clk reference which is
* however NULL and will return the rate 0. In that case we
* need to calibrate the rate instead.
*/
if (!IS_ERR_OR_NULL(twd_clk))
twd_timer_rate = clk_get_rate(twd_clk);
else
twd_calibrate_rate();
common_setup_called = true;
}
/*
* The following is done once per CPU the first time .setup() is
* called.
*/
__raw_writel(0, twd_base + TWD_TIMER_CONTROL);
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->irq = twd_ppi;
this_cpu_clk = __this_cpu_ptr(twd_evt);
*this_cpu_clk = clk;
clockevents_config_and_register(clk, twd_timer_rate,
0xf, 0xffffffff);
enable_percpu_irq(clk->irq, 0);
return 0;
}
static struct local_timer_ops twd_lt_ops __cpuinitdata = {
.setup = twd_timer_setup,
.stop = twd_timer_stop,
};
static int __init twd_local_timer_common_register(void)
{
int err;
twd_evt = alloc_percpu(struct clock_event_device *);
if (!twd_evt) {
err = -ENOMEM;
goto out_free;
}
err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
if (err) {
pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
goto out_free;
}
err = local_timer_register(&twd_lt_ops);
if (err)
goto out_irq;
return 0;
out_irq:
free_percpu_irq(twd_ppi, twd_evt);
out_free:
iounmap(twd_base);
twd_base = NULL;
free_percpu(twd_evt);
return err;
}
int __init twd_local_timer_register(struct twd_local_timer *tlt)
{
if (twd_base || twd_evt)
return -EBUSY;
twd_ppi = tlt->res[1].start;
twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
if (!twd_base)
return -ENOMEM;
return twd_local_timer_common_register();
}
#ifdef CONFIG_OF
const static struct of_device_id twd_of_match[] __initconst = {
{ .compatible = "arm,cortex-a9-twd-timer", },
{ .compatible = "arm,cortex-a5-twd-timer", },
{ .compatible = "arm,arm11mp-twd-timer", },
{ },
};
void __init twd_local_timer_of_register(void)
{
struct device_node *np;
int err;
np = of_find_matching_node(NULL, twd_of_match);
if (!np)
return;
twd_ppi = irq_of_parse_and_map(np, 0);
if (!twd_ppi) {
err = -EINVAL;
goto out;
}
twd_base = of_iomap(np, 0);
if (!twd_base) {
err = -ENOMEM;
goto out;
}
err = twd_local_timer_common_register();
out:
WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
}
#endif