Commit 442c8176 authored by Russell King's avatar Russell King
Browse files

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: default avatar"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: default avatarNicolas Pitre <nico@fluxnic.net>
Cc: Olof Johansson <olof@lixom.net>
Tested-by: default avatarSascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarTony Lindgren <tony@atomide.com>
Reviewed-by: default avatarViresh Kumar <viresh.kumar@st.com>
Cc: Wan ZongShun <mcuos.com@gmail.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 1ba4c3cb

drivers/clocksource/Kconfig

+3 −0
Original line number Diff line number Diff line 
config CLKSRC_I8253

	bool



config CLKSRC_MMIO

	bool

drivers/clocksource/Makefile

+1 −0
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@@ -7,3 +7,4 @@ obj-$(CONFIG_SH_TIMER_CMT) += sh_cmt.o 
obj-$(CONFIG_SH_TIMER_MTU2)	+= sh_mtu2.o

obj-$(CONFIG_SH_TIMER_TMU)	+= sh_tmu.o

obj-$(CONFIG_CLKSRC_I8253)	+= i8253.o

obj-$(CONFIG_CLKSRC_MMIO)	+= mmio.o

drivers/clocksource/mmio.c

0 → 100644
+73 −0
Original line number Diff line number Diff line 
/*

 * 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);

}

include/linux/clocksource.h

+8 −0
Original line number Diff line number Diff line
@@ -337,6 +337,14 @@ static inline void update_vsyscall_tz(void) 


extern void timekeeping_notify(struct clocksource *clock);



extern cycle_t clocksource_mmio_readl_up(struct clocksource *);

extern cycle_t clocksource_mmio_readl_down(struct clocksource *);

extern cycle_t clocksource_mmio_readw_up(struct clocksource *);

extern cycle_t clocksource_mmio_readw_down(struct clocksource *);



extern int clocksource_mmio_init(void __iomem *, const char *,

	unsigned long, int, unsigned, cycle_t (*)(struct clocksource *));



extern int clocksource_i8253_init(void);



#endif /* _LINUX_CLOCKSOURCE_H */

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