[PATCH 06/13] clocksource: add common mmio clocksource

[Sascha Hauer]

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 at unipv.it>
> Cc: Colin Cross <ccross at android.com>
> Cc: Eric Miao <eric.y.miao at gmail.com>
> Cc: Erik Gilling <konkers at android.com>
> Cc: "Hans J. Koch" <hjk at hansjkoch.de>
> Cc: Imre Kaloz <kaloz at openwrt.org>
> Cc: Krzysztof Halasa <khc at pm.waw.pl>
> Cc: Kukjin Kim <kgene.kim at samsung.com>
> Cc: Lennert Buytenhek <kernel at wantstofly.org>
> Cc: Linus Walleij <linus.walleij at stericsson.com>
> Cc: linux-omap at vger.kernel.org
> Cc: Nicolas Pitre <nico at fluxnic.net>
> Cc: Olof Johansson <olof at lixom.net>
> Cc: Sascha Hauer <kernel at pengutronix.de>
> Cc: Tony Lindgren <tony at atomide.com>
> Cc: Viresh Kumar <viresh.kumar at st.com>
> Cc: Wan ZongShun <mcuos.com at gmail.com>
> Signed-off-by: Russell King <rmk+kernel at 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 at pengutronix.de>

(For the i.MX part)

Sascha


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