linux-stable/drivers/clocksource/mmio.c
Russell King 442c8176d2 clocksource: add common mmio clocksource
Add a generic mmio clocksource, covering both 32-bit and 16-bit register
access sizes, for up or down counters.  This can be used to easily
create clocksources for simple counter-based implementations.

Cc: Alessandro Rubini <rubini@unipv.it>
Cc: Colin Cross <ccross@android.com>
Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Erik Gilling <konkers@android.com>
Acked-by: "Hans J. Koch" <hjk@hansjkoch.de>
Cc: Imre Kaloz <kaloz@openwrt.org>
Cc: Krzysztof Halasa <khc@pm.waw.pl>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: Lennert Buytenhek <kernel@wantstofly.org>
Cc: Linus Walleij <linus.walleij@stericsson.com>
Cc: linux-omap@vger.kernel.org
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Cc: Olof Johansson <olof@lixom.net>
Tested-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Viresh Kumar <viresh.kumar@st.com>
Cc: Wan ZongShun <mcuos.com@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-05-23 18:04:51 +01:00

73 lines
1.9 KiB
C

/*
* Generic MMIO clocksource support
*
* 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/clocksource.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
struct clocksource_mmio {
void __iomem *reg;
struct clocksource clksrc;
};
static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c)
{
return container_of(c, struct clocksource_mmio, clksrc);
}
cycle_t clocksource_mmio_readl_up(struct clocksource *c)
{
return readl_relaxed(to_mmio_clksrc(c)->reg);
}
cycle_t clocksource_mmio_readl_down(struct clocksource *c)
{
return ~readl_relaxed(to_mmio_clksrc(c)->reg);
}
cycle_t clocksource_mmio_readw_up(struct clocksource *c)
{
return readw_relaxed(to_mmio_clksrc(c)->reg);
}
cycle_t clocksource_mmio_readw_down(struct clocksource *c)
{
return ~(unsigned)readw_relaxed(to_mmio_clksrc(c)->reg);
}
/**
* clocksource_mmio_init - Initialize a simple mmio based clocksource
* @base: Virtual address of the clock readout register
* @name: Name of the clocksource
* @hz: Frequency of the clocksource in Hz
* @rating: Rating of the clocksource
* @bits: Number of valid bits
* @read: One of clocksource_mmio_read*() above
*/
int __init clocksource_mmio_init(void __iomem *base, const char *name,
unsigned long hz, int rating, unsigned bits,
cycle_t (*read)(struct clocksource *))
{
struct clocksource_mmio *cs;
if (bits > 32 || bits < 16)
return -EINVAL;
cs = kzalloc(sizeof(struct clocksource_mmio), GFP_KERNEL);
if (!cs)
return -ENOMEM;
cs->reg = base;
cs->clksrc.name = name;
cs->clksrc.rating = rating;
cs->clksrc.read = read;
cs->clksrc.mask = CLOCKSOURCE_MASK(bits);
cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS;
return clocksource_register_hz(&cs->clksrc, hz);
}