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[ARM] 4815/1: RealView: Add clockevents suport for the local timers

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This patch registers the local timers on ARM11MPCore as clock event
devices. The clock device can be set up as periodic or oneshot.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Catalin Marinas 2008-02-04 17:32:57 +01:00 committed by Russell King
parent a8655e83fc
commit 93c2904d50
2 changed files with 71 additions and 30 deletions
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92
arch/arm/mach-realview/localtimer.c
View File

@ -16,8 +16,8 @@
#include <linux/jiffies.h>
#include <linux/percpu.h>
#include <linux/clockchips.h>
#include <linux/irq.h>
#include <asm/mach/time.h>
#include <asm/hardware/arm_twd.h>
#include <asm/hardware/gic.h>
#include <asm/hardware.h>
@ -43,6 +43,43 @@ void local_timer_interrupt(void)
static unsigned long mpcore_timer_rate;
static void local_timer_set_mode(enum clock_event_mode mode,
struct clock_event_device *clk)
{
void __iomem *base = TWD_BASE(smp_processor_id());
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, base + TWD_TIMER_CONTROL);
}
static int local_timer_set_next_event(unsigned long evt,
struct clock_event_device *unused)
{
void __iomem *base = TWD_BASE(smp_processor_id());
unsigned long ctrl = __raw_readl(base + TWD_TIMER_CONTROL);
__raw_writel(evt, base + TWD_TIMER_COUNTER);
__raw_writel(ctrl | TWD_TIMER_CONTROL_ENABLE, base + TWD_TIMER_CONTROL);
return 0;
}
/*
* local_timer_ack: checks for a local timer interrupt.
*
@ -61,12 +98,11 @@ int local_timer_ack(void)
return 0;
}
void __cpuinit local_timer_setup(unsigned int cpu)
static void __cpuinit twd_calibrate_rate(unsigned int cpu)
{
void __iomem *base = TWD_BASE(cpu);
unsigned int load, offset;
unsigned long load, count;
u64 waitjiffies;
unsigned int count;
/*
* If this is the first time round, we need to work out how fast
@ -104,36 +140,36 @@ void __cpuinit local_timer_setup(unsigned int cpu)
load = mpcore_timer_rate / HZ;
__raw_writel(load, base + TWD_TIMER_LOAD);
__raw_writel(0x7, base + TWD_TIMER_CONTROL);
}
/*
* Now maneuver our local tick into the right part of the jiffy.
* Start by working out where within the tick our local timer
* interrupt should go.
/*
* Setup the local clock events for a CPU.
*/
offset = ((mpcore_timer_rate / HZ) / (NR_CPUS + 1)) * (cpu + 1);
void __cpuinit local_timer_setup(unsigned int cpu)
{
struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
unsigned long flags;
/*
* gettimeoffset() will return a number of us since the last tick.
* Convert this number of us to a local timer tick count.
* Be careful of integer overflow whilst keeping maximum precision.
*
* with HZ=100 and 1MHz (fpga) ~ 1GHz processor:
* load = 1 ~ 10,000
* mpcore_timer_rate/10000 = 100 ~ 100,000
*
* so the multiply value will be less than 10^9 always.
*/
load = (system_timer->offset() * (mpcore_timer_rate / 10000)) / 100;
twd_calibrate_rate(cpu);
/* Add on our offset to get the load value */
load = (load + offset) % (mpcore_timer_rate / HZ);
__raw_writel(load, base + TWD_TIMER_COUNTER);
clk->name = "local_timer";
clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
clk->rating = 350;
clk->set_mode = local_timer_set_mode;
clk->set_next_event = local_timer_set_next_event;
clk->irq = IRQ_LOCALTIMER;
clk->cpumask = cpumask_of_cpu(cpu);
clk->shift = 20;
clk->mult = div_sc(mpcore_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 */
__raw_writel(1 << IRQ_LOCALTIMER,
__io_address(REALVIEW_GIC_DIST_BASE) + GIC_DIST_ENABLE_SET);
local_irq_save(flags);
get_irq_chip(IRQ_LOCALTIMER)->unmask(IRQ_LOCALTIMER);
local_irq_restore(flags);
clockevents_register_device(clk);
}
/*

5
include/asm-arm/hardware/arm_twd.h
View File

@ -13,4 +13,9 @@
#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)
#endif