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

Anup Patel
2019-01-18T06:14:59Z

> -----Original Message-----
> From: Alexander Graf [mailto:agraf at suse.de]
> Sent: Thursday, January 17, 2019 11:51 PM
> To: Anup Patel <Anup.Patel@wdc.com>; Rick Chen <rick@andestech.com>;
> Bin Meng <bmeng.cn@gmail.com>; Joe Hershberger
> <joe.hershberger@ni.com>; Lukas Auer <lukas.auer@aisec.fraunhofer.de>;
> Masahiro Yamada <yamada.masahiro@socionext.com>; Simon Glass
> <sjg@chromium.org>
> Cc: Palmer Dabbelt <palmer@sifive.com>; Paul Walmsley
> <paul.walmsley@sifive.com>; Atish Patra <Atish.Patra@wdc.com>;
> Christoph Hellwig <hch@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@wdc.com>
> > Signed-off-by: Atish Patra <atish.patra@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@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"?

>
> Alex
>
> > + int err;
> > + struct clk_fixed_factor *ff = to_clk_fixed_factor(dev);
> > +
> > + err = clk_get_by_index(dev, 0, &ff->parent);
> > + if (err)
> > + return err;
> > +
> > + ff->div = dev_read_u32_default(dev, "clock-div", 1);
> > + ff->mult = dev_read_u32_default(dev, "clock-mult", 1); #endif
> > +
> > + return 0;
> > +}
> > +
> > +static const struct udevice_id clk_fixed_factor_match[] = {
> > + {
> > + .compatible = "fixed-factor-clock",
> > + },
> > + { /* sentinel */ }
> > +};
> > +
> > +U_BOOT_DRIVER(clk_fixed_factor) = {
> > + .name = "fixed_factor_clock",
> > + .id = UCLASS_CLK,
> > + .of_match = clk_fixed_factor_match,
> > + .ofdata_to_platdata = clk_fixed_factor_ofdata_to_platdata,
> > + .platdata_auto_alloc_size = sizeof(struct clk_fixed_factor),
> > + .ops = &clk_fixed_factor_ops,
> > +};

Regards,
Anup