[U-Boot] [PATCH 07/11] clk: Add fixed-factor clock driver

[Anup Patel]

> -----Original Message-----
> From: Alexander Graf [mailto:agraf at suse.de]
> Sent: Monday, January 21, 2019 7:49 PM
> To: Anup Patel <Anup.Patel at wdc.com>; Rick Chen <rick at andestech.com>;
> Bin Meng <bmeng.cn at gmail.com>; Joe Hershberger
> <joe.hershberger at ni.com>; Lukas Auer <lukas.auer at aisec.fraunhofer.de>;
> Masahiro Yamada <yamada.masahiro at socionext.com>; Simon Glass
> <sjg at chromium.org>
> Cc: Palmer Dabbelt <palmer at sifive.com>; Paul Walmsley
> <paul.walmsley at sifive.com>; Atish Patra <Atish.Patra at wdc.com>;
> Christoph Hellwig <hch at infradead.org>; U-Boot Mailing List <u-
> boot at lists.denx.de>
> Subject: Re: [PATCH 07/11] clk: Add fixed-factor clock driver
> 
> On 01/18/2019 07:14 AM, Anup Patel wrote:
> >
> >> -----Original Message-----
> >> From: Alexander Graf [mailto:agraf at suse.de]
> >> Sent: Thursday, January 17, 2019 11:51 PM
> >> To: Anup Patel <Anup.Patel at wdc.com>; Rick Chen
> <rick at andestech.com>;
> >> Bin Meng <bmeng.cn at gmail.com>; Joe Hershberger
> >> <joe.hershberger at ni.com>; Lukas Auer
> >> <lukas.auer at aisec.fraunhofer.de>; Masahiro Yamada
> >> <yamada.masahiro at socionext.com>; Simon Glass <sjg at chromium.org>
> >> Cc: Palmer Dabbelt <palmer at sifive.com>; Paul Walmsley
> >> <paul.walmsley at sifive.com>; Atish Patra <Atish.Patra at wdc.com>;
> >> Christoph Hellwig <hch at infradead.org>; U-Boot Mailing List <u-
> >> boot at lists.denx.de>
> >> Subject: Re: [PATCH 07/11] clk: Add fixed-factor clock driver
> >>
> >> On 01/17/2019 11:39 AM, Anup Patel wrote:
> >>> This patch adds fixed-factor clock driver which derives clock rate
> >>> by dividing (div) and multiplying (mult) fixed factors to a parent clock.
> >>>
> >>> Signed-off-by: Anup Patel <anup.patel at wdc.com>
> >>> Signed-off-by: Atish Patra <atish.patra at wdc.com>
> >>> ---
> >>>    drivers/clk/Makefile           |  4 +-
> >>>    drivers/clk/clk_fixed_factor.c | 74
> >> ++++++++++++++++++++++++++++++++++
> >>>    2 files changed, 77 insertions(+), 1 deletion(-)
> >>>    create mode 100644 drivers/clk/clk_fixed_factor.c
> >>>
> >>> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile index
> >>> 2f4446568c..fa59259ea3 100644
> >>> --- a/drivers/clk/Makefile
> >>> +++ b/drivers/clk/Makefile
> >>> @@ -4,7 +4,9 @@
> >>>    # Wolfgang Denk, DENX Software Engineering, wd at denx.de.
> >>>    #
> >>>
> >>> -obj-$(CONFIG_$(SPL_TPL_)CLK) += clk-uclass.o clk_fixed_rate.o
> >>> +obj-$(CONFIG_$(SPL_TPL_)CLK) += clk-uclass.o
> >>> +obj-$(CONFIG_$(SPL_TPL_)CLK) += clk_fixed_rate.o
> >>> +obj-$(CONFIG_$(SPL_TPL_)CLK) += clk_fixed_factor.o
> >>>
> >>>    obj-y += imx/
> >>>    obj-y += tegra/
> >>> diff --git a/drivers/clk/clk_fixed_factor.c
> >>> b/drivers/clk/clk_fixed_factor.c new file mode 100644 index
> >>> 0000000000..eab1724c26
> >>> --- /dev/null
> >>> +++ b/drivers/clk/clk_fixed_factor.c
> >>> @@ -0,0 +1,74 @@
> >>> +// SPDX-License-Identifier: GPL-2.0+
> >>> +/*
> >>> + * Copyright (c) 2019 Western Digital Corporation or its affiliates.
> >>> + *
> >>> + * Author: Anup Patel <anup.patel at wdc.com>  */
> >>> +
> >>> +#include <common.h>
> >>> +#include <clk-uclass.h>
> >>> +#include <div64.h>
> >>> +#include <dm.h>
> >>> +
> >>> +struct clk_fixed_factor {
> >>> +	struct clk parent;
> >>> +	unsigned int div;
> >>> +	unsigned int mult;
> >>> +};
> >>> +
> >>> +#define to_clk_fixed_factor(dev)	\
> >>> +	((struct clk_fixed_factor *)dev_get_platdata(dev))
> >>> +
> >>> +static ulong clk_fixed_factor_get_rate(struct clk *clk) {
> >>> +	int ret;
> >>> +	struct clk_fixed_factor *ff = to_clk_fixed_factor(clk->dev);
> >>> +
> >>> +	if (clk->id != 0)
> >>> +		return -EINVAL;
> >>> +
> >>> +	ret = clk_get_rate(&ff->parent);
> >>> +	if (IS_ERR_VALUE(ret))
> >>> +		return ret;
> >>> +
> >>> +	do_div(ret, ff->div);
> >>> +
> >>> +	return ret * ff->mult;
> >>> +}
> >>> +
> >>> +const struct clk_ops clk_fixed_factor_ops = {
> >>> +	.get_rate = clk_fixed_factor_get_rate, };
> >>> +
> >>> +static int clk_fixed_factor_ofdata_to_platdata(struct udevice *dev)
> >>> +{ #if !CONFIG_IS_ENABLED(OF_PLATDATA)
> >> Why do you need this?
> > This is for boards/configuration where OF_PLATDATA is not enabled. For
> such boards, the board support code will provide platdata.
> >
> > I saw similar thing in clk_fixed_rate.c too hence kept it here. Do you want
> me to drop this "#if"?
> 
> I would prefer if we don't advocate OF_PLATDATA more than we have to. So
> I'm all for making it harder to use it :). In other words, yes, please drop
> support for it for now.

Okay, I will drop the "#if".

Regards,
Anup