diff mbox

[06/13] clocksource: add common mmio clocksource

Message ID E1QJhNe-0000yh-HS@rmk-PC.arm.linux.org.uk (mailing list archive)
State New, archived
Headers show

Commit Message

Russell King - ARM Linux May 10, 2011, 7:29 a.m. UTC 
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>
Cc: "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
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Olof Johansson <olof@lixom.net>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Viresh Kumar <viresh.kumar@st.com>
Cc: Wan ZongShun <mcuos.com@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 drivers/Kconfig              |    3 ++
 drivers/clocksource/Kconfig  |    2 +
 drivers/clocksource/Makefile |    1 +
 drivers/clocksource/mmio.c   |   72 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/clocksource.h  |    8 +++++
 5 files changed, 86 insertions(+), 0 deletions(-)
 create mode 100644 drivers/clocksource/Kconfig
 create mode 100644 drivers/clocksource/mmio.c

Comments

Sascha Hauer May 10, 2011, 8:38 a.m. UTC | #1 
On Tue, May 10, 2011 at 08:29:18AM +0100, Russell King - ARM Linux wrote:
> 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>
> Cc: "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
> Cc: Nicolas Pitre <nico@fluxnic.net>
> Cc: Olof Johansson <olof@lixom.net>
> Cc: Sascha Hauer <kernel@pengutronix.de>
> Cc: Tony Lindgren <tony@atomide.com>
> Cc: Viresh Kumar <viresh.kumar@st.com>
> Cc: Wan ZongShun <mcuos.com@gmail.com>
> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
> ---
>  drivers/Kconfig              |    3 ++
>  drivers/clocksource/Kconfig  |    2 +
>  drivers/clocksource/Makefile |    1 +
>  drivers/clocksource/mmio.c   |   72 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/clocksource.h  |    8 +++++
>  5 files changed, 86 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/clocksource/Kconfig
>  create mode 100644 drivers/clocksource/mmio.c
> 
> diff --git a/drivers/Kconfig b/drivers/Kconfig
> index 177c7d1..557a469 100644
> --- a/drivers/Kconfig
> +++ b/drivers/Kconfig
> @@ -119,4 +119,7 @@ source "drivers/platform/Kconfig"
>  source "drivers/clk/Kconfig"
>  
>  source "drivers/hwspinlock/Kconfig"
> +
> +source "drivers/clocksource/Kconfig"
> +
>  endmenu
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> new file mode 100644
> index 0000000..47f37b1
> --- /dev/null
> +++ b/drivers/clocksource/Kconfig
> @@ -0,0 +1,2 @@
> +config CLKSRC_MMIO
> +	bool
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index be61ece..9b2ba29 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -6,3 +6,4 @@ obj-$(CONFIG_CS5535_CLOCK_EVENT_SRC)	+= cs5535-clockevt.o
>  obj-$(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_MMIO)	+= mmio.o
> diff --git a/drivers/clocksource/mmio.c b/drivers/clocksource/mmio.c
> new file mode 100644
> index 0000000..71ad3a3
> --- /dev/null
> +++ b/drivers/clocksource/mmio.c
> @@ -0,0 +1,72 @@
> +/*
> + * 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->clksrc.name = name;
> +	cs->clksrc.rating = rating;
> +	cs->clksrc.read = read;
> +	cs->clksrc.mask = CLOCKSOURCE_MASK(bits);
> +	cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS;

You forgot to initialize cs->reg. With this:

Tested-by: Sascha Hauer <s.hauer@pengutronix.de>

(For the i.MX part)

Sascha
Russell King - ARM Linux May 10, 2011, 8:46 a.m. UTC | #2 
On Tue, May 10, 2011 at 10:38:41AM +0200, Sascha Hauer wrote:
> You forgot to initialize cs->reg. With this:

Damnit.  Fixed.

> Tested-by: Sascha Hauer <s.hauer@pengutronix.de>

Thanks.
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Russell King - ARM Linux May 10, 2011, 9:59 a.m. UTC | #3 
On Tue, May 10, 2011 at 08:29:18AM +0100, Russell King - ARM Linux wrote:
> +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);
> +}

I probably ought to point out why that cast is there: readw* returns an
u16.

u16 will be promoted to 'int' by the compiler, then not'd, and then
extended to cycle_t (64-bit).  This extension is a signed extension
which not only results in more code than required, but also results in
a delay slot not being filled.

It's the u16 -> signed int -> cycle_t which causes the signed extension.

u16 -> cycle_t doesn't involve changing the signed-ness of the type, so
doesn't suffer.

Neither does readl as it returns a u32 which doesn't need any promotion
to an int type.

So, rather than allow the compiler to do automatic promotion to a signed
int, the cast is there to ensure that it becomes an unsigned int instead.
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Viresh KUMAR May 11, 2011, 8:15 a.m. UTC | #4 
On 05/10/2011 12:59 PM, Russell King - ARM Linux wrote:
> 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>
> Cc: "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
> Cc: Nicolas Pitre <nico@fluxnic.net>
> Cc: Olof Johansson <olof@lixom.net>
> Cc: Sascha Hauer <kernel@pengutronix.de>
> Cc: Tony Lindgren <tony@atomide.com>
> Cc: Viresh Kumar <viresh.kumar@st.com>
> Cc: Wan ZongShun <mcuos.com@gmail.com>
> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
> ---
>  drivers/Kconfig              |    3 ++
>  drivers/clocksource/Kconfig  |    2 +
>  drivers/clocksource/Makefile |    1 +
>  drivers/clocksource/mmio.c   |   72 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/clocksource.h  |    8 +++++
>  5 files changed, 86 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/clocksource/Kconfig
>  create mode 100644 drivers/clocksource/mmio.c
> 
> diff --git a/drivers/Kconfig b/drivers/Kconfig
> index 177c7d1..557a469 100644
> --- a/drivers/Kconfig
> +++ b/drivers/Kconfig
> @@ -119,4 +119,7 @@ source "drivers/platform/Kconfig"
>  source "drivers/clk/Kconfig"
>  
>  source "drivers/hwspinlock/Kconfig"
> +
> +source "drivers/clocksource/Kconfig"
> +
>  endmenu
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> new file mode 100644
> index 0000000..47f37b1
> --- /dev/null
> +++ b/drivers/clocksource/Kconfig
> @@ -0,0 +1,2 @@
> +config CLKSRC_MMIO
> +	bool
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index be61ece..9b2ba29 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -6,3 +6,4 @@ obj-$(CONFIG_CS5535_CLOCK_EVENT_SRC)	+= cs5535-clockevt.o
>  obj-$(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_MMIO)	+= mmio.o
> diff --git a/drivers/clocksource/mmio.c b/drivers/clocksource/mmio.c
> new file mode 100644
> index 0000000..71ad3a3
> --- /dev/null
> +++ b/drivers/clocksource/mmio.c
> @@ -0,0 +1,72 @@
> +/*
> + * 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->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);
> +}
> diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
> index 94c1f38..a3558fd 100644
> --- a/include/linux/clocksource.h
> +++ b/include/linux/clocksource.h
> @@ -341,4 +341,12 @@ 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 *));
> +
>  #endif /* _LINUX_CLOCKSOURCE_H */

With cs->reg initialized,

Reviewed-by: Viresh Kumar <viresh.kumar@st.com>
Tony Lindgren May 12, 2011, 7:43 a.m. UTC | #5 
* Russell King - ARM Linux <linux@arm.linux.org.uk> [110510 01:44]:
> On Tue, May 10, 2011 at 10:38:41AM +0200, Sascha Hauer wrote:
> > You forgot to initialize cs->reg. With this:
> 
> Damnit.  Fixed.
> 
> > Tested-by: Sascha Hauer <s.hauer@pengutronix.de>

With cs->reg initialization and CONFIG_OMAP_MPU_TIMER=y things
boot tested on omap1 osk:

Tested-by: Tony Lindgren <tony@atomide.com>
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Thomas Gleixner May 12, 2011, 8:03 a.m. UTC | #6 
On Tue, 10 May 2011, Russell King - ARM Linux wrote:

> 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>
> Cc: "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
> Cc: Nicolas Pitre <nico@fluxnic.net>
> Cc: Olof Johansson <olof@lixom.net>
> Cc: Sascha Hauer <kernel@pengutronix.de>
> Cc: Tony Lindgren <tony@atomide.com>
> Cc: Viresh Kumar <viresh.kumar@st.com>
> Cc: Wan ZongShun <mcuos.com@gmail.com>
> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

Please take this through the ARM tree. It's not conflicting with
anything in my tree.

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diff mbox

Patch

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 177c7d1..557a469 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -119,4 +119,7 @@  source "drivers/platform/Kconfig"
 source "drivers/clk/Kconfig"
 
 source "drivers/hwspinlock/Kconfig"
+
+source "drivers/clocksource/Kconfig"
+
 endmenu
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
new file mode 100644
index 0000000..47f37b1
--- /dev/null
+++ b/drivers/clocksource/Kconfig
@@ -0,0 +1,2 @@ 
+config CLKSRC_MMIO
+	bool
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index be61ece..9b2ba29 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -6,3 +6,4 @@  obj-$(CONFIG_CS5535_CLOCK_EVENT_SRC)	+= cs5535-clockevt.o
 obj-$(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_MMIO)	+= mmio.o
diff --git a/drivers/clocksource/mmio.c b/drivers/clocksource/mmio.c
new file mode 100644
index 0000000..71ad3a3
--- /dev/null
+++ b/drivers/clocksource/mmio.c
@@ -0,0 +1,72 @@ 
+/*
+ * 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->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);
+}
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 94c1f38..a3558fd 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -341,4 +341,12 @@  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 *));
+
 #endif /* _LINUX_CLOCKSOURCE_H */