Re: [PATCH RFC 1/3] clk: omap: introduce clock driver

[Grant Likely <grant.likely@secretlab.ca>]

On Mon,  3 Jun 2013 23:39:16 -0700, Mike Turquette <mturquette@linaro.org> wrote:
> Parses OMAP clock data from DT and registers those clocks with the clock
> framework.  dt_omap_clk_init must be called early during boot for timer
> initialization so it is exported and called from the existing clock code
> instead of probing like a real driver.
> 
> Cc: Benoit Cousson <b-cousson@ti.com>
> Cc: Rajendra Nayak <rnayak@ti.com>
> Cc: Joel A Fernandes <joelagnel@ti.com>
> Cc: Nishanth Menon <nm@ti.com>
> Cc: Paul Walmsley <paul@pwsan.com>
> Cc: Tony Lindgren <tony@atomide.com>
> Signed-off-by: Mike Turquette <mturquette@linaro.org>

Hi Mike,

Comments below...

> ---
> This driver simply matches the basic bindings (so far).  Eventually it
> would match omap-specific bindings for DPLLs, CLKOUTX2 and strange leaf
> clocks as well.  This doesn't scale well since non-OMAP related clock
> data (e.g. a pmic or discrete audio codec) will get grouped into this
> driver if it matches on a basic clock type.  Suggestions?

Take a look at the definition of irqchip_init(). It would be possible to
do the same think for clk chips so that merely configuring in the driver
would add the support to a global list of clk chip initializers.

drivers/irqchip/irqchip.c

> 
>  drivers/clk/Makefile      |  1 +
>  drivers/clk/omap/Makefile |  1 +
>  drivers/clk/omap/clk.c    | 55 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/clk/omap.h  | 24 +++++++++++++++++++++
>  4 files changed, 81 insertions(+)
>  create mode 100644 drivers/clk/omap/Makefile
>  create mode 100644 drivers/clk/omap/clk.c
>  create mode 100644 include/linux/clk/omap.h
> 
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index f51b52b..efd4f2a 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -31,6 +31,7 @@ obj-$(CONFIG_ARCH_VT8500)	+= clk-vt8500.o
>  obj-$(CONFIG_ARCH_ZYNQ)		+= clk-zynq.o
>  obj-$(CONFIG_ARCH_TEGRA)	+= tegra/
>  obj-$(CONFIG_PLAT_SAMSUNG)	+= samsung/
> +obj-$(CONFIG_ARCH_OMAP)		+= omap/
>  
>  obj-$(CONFIG_X86)		+= x86/
>  
> diff --git a/drivers/clk/omap/Makefile b/drivers/clk/omap/Makefile
> new file mode 100644
> index 0000000..8195931
> --- /dev/null
> +++ b/drivers/clk/omap/Makefile
> @@ -0,0 +1 @@
> +obj-y					+= clk.o
> diff --git a/drivers/clk/omap/clk.c b/drivers/clk/omap/clk.c
> new file mode 100644
> index 0000000..e9e5c95
> --- /dev/null
> +++ b/drivers/clk/omap/clk.c
> @@ -0,0 +1,55 @@
> +/*
> + * OMAP PRCM clock driver
> + *
> + * Copyright (C) 2013 Linaro.org - http://www.linaro.org
> + * 	Mike Turquette <mturquette@linaro.org>
> + *
> + * 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.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> + * kind, whether express or implied; without even the implied warranty
> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/clk-provider.h>
> +#include <linux/clk/omap.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +
> +/* FIXME - should the OMAP PRCM clock driver match generic types? */
> +static const struct of_device_id clk_match[] = {
> +	{.compatible = "fixed-clock", .data = of_fixed_clk_setup, },
> +	{.compatible = "mux-clock", .data = of_mux_clk_setup, },
> +	{.compatible = "fixed-factor-clock",
> +		.data = of_fixed_factor_clk_setup, },
> +	{},
> +};
> +
> +static int omap_clk_probe(struct platform_device *pdev)
> +{
> +	of_clk_init(clk_match);
> +	return 0;
> +}
> +
> +static struct platform_driver omap_clk_driver = {
> +	.probe = omap_clk_probe,
> +	.driver = {
> +		   .name = "omap_clk",
> +		   .of_match_table = of_match_ptr(clk_match),
> +		   },
> +};
> +
> +/* FIXME - need to initialize early; skip real driver registration & probe */
> +int __init dt_omap_clk_init(void)
> +{
> +	return omap_clk_probe(NULL);
> +}

Since this isn't remotely a platform_driver, I would drop the pretense
and cut out all the platform_drivers references. omap_clk_driver isn't
even referenced anywhere!

> +
> +MODULE_DESCRIPTION("OMAP Clock driver");
> +MODULE_AUTHOR("Texas Instruments Inc.");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/clk/omap.h b/include/linux/clk/omap.h
> new file mode 100644
> index 0000000..504e838
> --- /dev/null
> +++ b/include/linux/clk/omap.h
> @@ -0,0 +1,24 @@
> +/*
> + * Copyright (C) 2010 Broadcom
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + */
> +
> +#ifndef __LINUX_CLK_OMAP_H_
> +#define __LINUX_CLK_OMAP_H_
> +
> +int __init dt_omap_clk_init(void);

__init annotations don't generally go in the header files.

g.