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

viresh kumar
2011-05-11T08:15:19Z

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>

--
viresh