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clocksource: Sched clock source for Versatile Express

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This patch adds a trival sched clock source using free
running, 24MHz clocked counter present in the ARM Ltd.
reference platforms (Versatile, RealView, Versatile
Express) System Registers block.

This code replaces the call in the VE machine code.

Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Pawel Moll 2014-04-16 18:22:59 +01:00
parent 5ee2b87779
commit 220e2a8d22
4 changed files with 52 additions and 2 deletions
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2
arch/arm/mach-vexpress/v2m.c
View File

@ -418,8 +418,6 @@ void __init v2m_dt_init_early(void)
pr_warning("vexpress: DT HBI (%x) is not matching "
"hardware (%x)!\n", dt_hbi, hbi);
}
versatile_sched_clock_init(vexpress_get_24mhz_clock_base(), 24000000);
}

11
drivers/clocksource/Kconfig
View File

@ -191,3 +191,14 @@ config EM_TIMER_STI
config CLKSRC_QCOM
bool
config CLKSRC_VERSATILE
bool "ARM Versatile (Express) reference platforms clock source"
depends on GENERIC_SCHED_CLOCK
select CLKSRC_OF
default y if MFD_VEXPRESS_SYSREG
help
This option enables clock source based on free running
counter available in the "System Registers" block of
ARM Versatile, RealView and Versatile Express reference
platforms.

1
drivers/clocksource/Makefile
View File

@ -39,3 +39,4 @@ obj-$(CONFIG_ARM_GLOBAL_TIMER) += arm_global_timer.o
obj-$(CONFIG_CLKSRC_METAG_GENERIC) += metag_generic.o
obj-$(CONFIG_ARCH_HAS_TICK_BROADCAST) += dummy_timer.o
obj-$(CONFIG_ARCH_KEYSTONE) += timer-keystone.o
obj-$(CONFIG_CLKSRC_VERSATILE) += versatile.o

40
drivers/clocksource/versatile.c Normal file
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@ -0,0 +1,40 @@
/*
* 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.
*
* Copyright (C) 2014 ARM Limited
*/
#include <linux/clocksource.h>
#include <linux/io.h>
#include <linux/of_address.h>
#include <linux/sched_clock.h>
#define SYS_24MHZ 0x05c
static void __iomem *versatile_sys_24mhz;
static u32 notrace versatile_sys_24mhz_read(void)
{
return readl(versatile_sys_24mhz);
}
static void __init versatile_sched_clock_init(struct device_node *node)
{
void __iomem *base = of_iomap(node, 0);
if (!base)
return;
versatile_sys_24mhz = base + SYS_24MHZ;
setup_sched_clock(versatile_sys_24mhz_read, 32, 24000000);
}
CLOCKSOURCE_OF_DECLARE(versatile, "arm,vexpress-sysreg",
versatile_sched_clock_init);