[PATCH 01/10] Add a common struct clk

Rob Herring
2011-05-01T20:33:57Z

Jeremy,

On 04/15/2011 02:08 PM, Sascha Hauer wrote:
> From: Jeremy Kerr<jeremy.kerr@canonical.com>
>
> We currently have ~21 definitions of struct clk in the ARM architecture,
> each defined on a per-platform basis. This makes it difficult to define
> platform- (or architecture-) independent clock sources without making
> assumptions about struct clk, and impossible to compile two
> platforms with different struct clks into a single image.
>
> This change is an effort to unify struct clk where possible, by defining
> a common struct clk, containing a set of clock operations. Different
> clock implementations can set their own operations, and have a standard
> interface for generic code. The callback interface is exposed to the
> kernel proper, while the clock implementations only need to be seen by
> the platform internals.
>
> This allows us to share clock code among platforms, and makes it
> possible to dynamically create clock devices in platform-independent
> code.
>
> Platforms can enable the generic struct clock through
> CONFIG_USE_COMMON_STRUCT_CLK. In this case, the clock infrastructure
> consists of a common struct clk:
>
> struct clk {
> const struct clk_ops *ops;
> unsigned int enable_count;
> unsigned int prepare_count;
> spinlock_t enable_lock;
> struct mutex prepare_lock;
> };
>
> And a set of clock operations (defined per type of clock):
>
> struct clk_ops {
> int (*enable)(struct clk *);
> void (*disable)(struct clk *);
> unsigned long (*get_rate)(struct clk *);
> [...]
> };
>
> To define a hardware-specific clock, machine code can "subclass" the
> struct clock into a new struct (adding any device-specific data), and
> provide a set of operations:
>
> struct clk_foo {
> struct clk clk;
> void __iomem *some_register;
> };
>
> struct clk_ops clk_foo_ops = {
> .get_rate = clk_foo_get_rate,
> };
>
> The common clock definitions are based on a development patch from Ben
> Herrenschmidt<benh@kernel.crashing.org>.
>
> Signed-off-by: Jeremy Kerr<jeremy.kerr@canonical.com>
> Signed-off-by: Uwe Kleine-K?nig<u.kleine-koenig@pengutronix.de>
> ---
> drivers/clk/Kconfig | 3 +
> drivers/clk/Makefile | 1 +
> drivers/clk/clk.c | 132 ++++++++++++++++++++++++++++++++++++++++
> drivers/clk/clkdev.c | 7 ++
> include/linux/clk.h | 164 +++++++++++++++++++++++++++++++++++++++++++++++---
> 5 files changed, 298 insertions(+), 9 deletions(-)
> create mode 100644 drivers/clk/clk.c
>
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index 4168c88..6e3ae54 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -2,3 +2,6 @@
> config CLKDEV_LOOKUP
> bool
> select HAVE_CLK
> +
> +config USE_COMMON_STRUCT_CLK
> + bool
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index 07613fa..a1a06d3 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -1,2 +1,3 @@
>
> obj-$(CONFIG_CLKDEV_LOOKUP) += clkdev.o
> +obj-$(CONFIG_USE_COMMON_STRUCT_CLK) += clk.o
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> new file mode 100644
> index 0000000..0bc9c6f
> --- /dev/null
> +++ b/drivers/clk/clk.c
> @@ -0,0 +1,132 @@
> +/*
> + * Copyright (C) 2010-2011 Canonical Ltd<jeremy.kerr@canonical.com>
> + *
> + * 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.
> + *
> + * Standard functionality for the common clock API.
> + */
> +
> +#include<linux/clk.h>
> +#include<linux/module.h>
> +
> +int clk_prepare(struct clk *clk)
> +{
> + int ret = 0;
> +

Shouldn't all these functions have some clk pointer checks:

if (IS_ERR_OR_NULL(clk))
return -EINVAL;

Rob