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Commit 2a98beb6 authored by Russell King's avatar Russell King Committed by Russell King
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[ARM SMP] Add local timer support for Realview MPcore 



Add platform specific parts for local timer support for the
Realview board.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 37ee16ae

arch/arm/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -358,7 +358,7 @@ config HOTPLUG_CPU 


config LOCAL_TIMERS

	bool "Use local timer interrupts"

	depends on SMP && n

	depends on SMP && REALVIEW_MPCORE

	default y

	help

	  Enable support for local timers on SMP platforms, rather then the

arch/arm/mach-realview/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -5,3 +5,4 @@ 
obj-y					:= core.o clock.o

obj-$(CONFIG_MACH_REALVIEW_EB)		+= realview_eb.o

obj-$(CONFIG_SMP)			+= platsmp.o headsmp.o

obj-$(CONFIG_LOCAL_TIMERS)		+= localtimer.o

arch/arm/mach-realview/core.c

+1 −1
Original line number Diff line number Diff line
@@ -550,7 +550,7 @@ static irqreturn_t realview_timer_interrupt(int irq, void *dev_id, struct pt_reg 


	timer_tick(regs);



#ifdef CONFIG_SMP

#if defined(CONFIG_SMP) && !defined(CONFIG_LOCAL_TIMERS)

	smp_send_timer();

	update_process_times(user_mode(regs));

#endif

arch/arm/mach-realview/localtimer.c

0 → 100644
+130 −0
Original line number Diff line number Diff line 
/*

 *  linux/arch/arm/mach-realview/localtimer.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 <asm/mach/time.h>

#include <asm/hardware/arm_twd.h>

#include <asm/hardware/gic.h>

#include <asm/hardware.h>

#include <asm/io.h>

#include <asm/irq.h>



#include "core.h"



#define TWD_BASE(cpu)	(__io_address(REALVIEW_TWD_BASE) + \

			 ((cpu) * REALVIEW_TWD_SIZE))



static unsigned long mpcore_timer_rate;



/*

 * local_timer_ack: checks for a local timer interrupt.

 *

 * If a local timer interrupt has occured, acknowledge and return 1.

 * Otherwise, return 0.

 */

int local_timer_ack(void)

{

	void __iomem *base = TWD_BASE(smp_processor_id());



	if (__raw_readl(base + TWD_TIMER_INTSTAT)) {

		__raw_writel(1, base + TWD_TIMER_INTSTAT);

		return 1;

	}



	return 0;

}



void __cpuinit local_timer_setup(unsigned int cpu)

{

	void __iomem *base = TWD_BASE(cpu);

	unsigned int load, offset;

	u64 waitjiffies;

	unsigned int count;



	/*

	 * If this is the first time round, we need to work out how fast

	 * the timer ticks

	 */

	if (mpcore_timer_rate == 0) {

		printk("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, base + TWD_TIMER_CONTROL);



				 /* maximum value */

		__raw_writel(0xFFFFFFFFU, base + TWD_TIMER_COUNTER);



		while (get_jiffies_64() < waitjiffies)

			udelay(10);



		count = __raw_readl(base + TWD_TIMER_COUNTER);



		mpcore_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);



		printk("%lu.%02luMHz.\n", mpcore_timer_rate / 1000000,

			(mpcore_timer_rate / 100000) % 100);

	}



	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.

	 */

	offset = ((mpcore_timer_rate / HZ) / (NR_CPUS + 1)) * (cpu + 1);



	/*

	 * 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;



	/* Add on our offset to get the load value */

	load = (load + offset) % (mpcore_timer_rate / HZ);



	__raw_writel(load, base + TWD_TIMER_COUNTER);



	/* Make sure our local interrupt controller has this enabled */

	__raw_writel(1 << IRQ_LOCALTIMER,

		     __io_address(REALVIEW_GIC_DIST_BASE) + GIC_DIST_ENABLE_SET);

}



/*

 * take a local timer down

 */

void __cpuexit local_timer_stop(unsigned int cpu)

{

	__raw_writel(0, TWD_BASE(cpu) + TWD_TIMER_CONTROL);

}

arch/arm/mach-realview/platsmp.c

+5 −0
Original line number Diff line number Diff line
@@ -174,6 +174,11 @@ void __init smp_prepare_cpus(unsigned int max_cpus) 
	if (max_cpus > ncores)

		max_cpus = ncores;



	/*

	 * Enable the local timer for primary CPU

	 */

	local_timer_setup(cpu);



	/*

	 * Initialise the possible/present maps.

	 * cpu_possible_map describes the set of CPUs which may be present