/*
* Generic timers support
*
* Copyright (C) 2012 ARM Ltd.
* Author: Marc Zyngier <marc.zyngier@arm.com>
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/smp.h>
#include <linux/cpu.h>
#include <linux/jiffies.h>
#include <linux/interrupt.h>
#include <linux/clockchips.h>
#include <linux/of_irq.h>
#include <linux/io.h>
#include <clocksource/arm_generic.h>
#include <asm/arm_generic.h>
static u32 arch_timer_rate;
static u64 sched_clock_mult __read_mostly;
static DEFINE_PER_CPU(struct clock_event_device, arch_timer_evt);
static int arch_timer_ppi;
static irqreturn_t arch_timer_handle_irq(int irq, void *dev_id)
{
struct clock_event_device *evt = dev_id;
unsigned long ctrl;
ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL);
if (ctrl & ARCH_TIMER_CTRL_ISTATUS) {
ctrl |= ARCH_TIMER_CTRL_IMASK;
arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl);
evt->event_handler(evt);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
static void arch_timer_stop(void)
{
unsigned long ctrl;
ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL);
ctrl &= ~ARCH_TIMER_CTRL_ENABLE;
arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl);
}
static void arch_timer_set_mode(enum clock_event_mode mode,
struct clock_event_device *clk)
{
switch (mode) {
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
arch_timer_stop();
break;
default:
break;
}
}
static int arch_timer_set_next_event(unsigned long evt,
struct clock_event_device *unused)
{
unsigned long ctrl;
ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL);
ctrl |= ARCH_TIMER_CTRL_ENABLE;
ctrl &= ~ARCH_TIMER_CTRL_IMASK;
arch_timer_reg_write(ARCH_TIMER_REG_TVAL, evt);
arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl);
return 0;
}
static void __cpuinit arch_timer_setup(struct clock_event_device *clk)
{
/* Let's make sure the timer is off before doing anything else */
arch_timer_stop();
clk->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP;
clk->name = "arch_sys_timer";
clk->rating = 400;
clk->set_mode = arch_timer_set_mode;
clk->set_next_event = arch_timer_set_next_event;
clk->irq = arch_timer_ppi;
clk->cpumask = cpumask_of(smp_processor_id());
clockevents_config_and_register(clk, arch_timer_rate,
0xf, 0x7fffffff);
enable_percpu_irq(clk->irq, 0);
/* Ensure the virtual counter is visible to userspace for the vDSO. */
arch_counter_enable_user_access();
}
static void __init arch_timer_calibrate(void)
{
if (arch_timer_rate == 0) {
arch_timer_reg_write(ARCH_TIMER_REG_CTRL, 0);
arch_timer_rate = arch_timer_reg_read(ARCH_TIMER_REG_FREQ);
/* Check the timer frequency. */
if (arch_timer_rate == 0)
panic("Architected timer frequency is set to zero.\n"
"You must set this in your .dts file\n");
}
/* Cache the sched_clock multiplier to save a divide in the hot path. */
sched_clock_mult = DIV_ROUND_CLOSEST(NSEC_PER_SEC, arch_timer_rate);
pr_info("Architected local timer running at %u.%02uMHz.\n",
arch_timer_rate / 1000000, (arch_timer_rate / 10000) % 100);
}
static cycle_t arch_counter_read(struct clocksource *cs)
{
return arch_counter_get_cntpct();
}
static struct clocksource clocksource_counter = {
.name = "arch_sys_counter",
.rating = 400,
.read = arch_counter_read,
.mask = CLOCKSOURCE_MASK(56),
.flags = (CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_VALID_FOR_HRES),
};
int read_current_timer(unsigned long *timer_value)
{
*timer_value = arch_counter_get_cntpct();
return 0;
}
unsigned long long notrace sched_clock(void)
{
return arch_counter_get_cntvct() * sched_clock_mult;
}
static int __cpuinit arch_timer_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
int cpu = (long)hcpu;
struct clock_event_device *clk = per_cpu_ptr(&arch_timer_evt, cpu);
switch(action) {
case CPU_STARTING:
case CPU_STARTING_FROZEN:
arch_timer_setup(clk);
break;
case CPU_DYING:
case CPU_DYING_FROZEN:
pr_debug("arch_timer_teardown disable IRQ%d cpu #%d\n",
clk->irq, cpu);
disable_percpu_irq(clk->irq);
arch_timer_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
break;
}
return NOTIFY_OK;
}
static struct notifier_block __cpuinitdata arch_timer_cpu_nb = {
.notifier_call = arch_timer_cpu_notify,
};
static const struct of_device_id arch_timer_of_match[] __initconst = {
{ .compatible = "arm,armv8-timer" },
{},
};
int __init arm_generic_timer_init(void)
{
struct device_node *np;
int err;
u32 freq;
np = of_find_matching_node(NULL, arch_timer_of_match);
if (!np) {
pr_err("arch_timer: can't find DT node\n");
return -ENODEV;
}
/* Try to determine the frequency from the device tree or CNTFRQ */
if (!of_property_read_u32(np, "clock-frequency", &freq))
arch_timer_rate = freq;
arch_timer_calibrate();
arch_timer_ppi = irq_of_parse_and_map(np, 0);
pr_info("arch_timer: found %s irq %d\n", np->name, arch_timer_ppi);
err = request_percpu_irq(arch_timer_ppi, arch_timer_handle_irq,
np->name, &arch_timer_evt);
if (err) {
pr_err("arch_timer: can't register interrupt %d (%d)\n",
arch_timer_ppi, err);
return err;
}
clocksource_register_hz(&clocksource_counter, arch_timer_rate);
/* Calibrate the delay loop directly */
lpj_fine = DIV_ROUND_CLOSEST(arch_timer_rate, HZ);
/* Immediately configure the timer on the boot CPU */
arch_timer_setup(this_cpu_ptr(&arch_timer_evt));
register_cpu_notifier(&arch_timer_cpu_nb);
return 0;
}
