linux-kernel - Re: [PATCH v2 3/5] phy: mediatek: add helpers to update bits of registers

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Date:   Thu, 30 Dec 2021 10:06:31 +0800
From:   Chunfeng Yun <chunfeng.yun@...iatek.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Vinod Koul <vkoul@...nel.org>
CC:     Kishon Vijay Abraham I <kishon@...com>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-phy@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Eddie Hung <eddie.hung@...iatek.com>
Subject: Re: [PATCH v2 3/5] phy: mediatek: add helpers to update bits of
 registers

On Fri, 2021-12-24 at 11:10 +0100, AngeloGioacchino Del Regno wrote:
> Il 18/12/21 09:28, Chunfeng Yun ha scritto:
> > Add three helpers mtk_phy_clear/set/update_bits() for registers
> > operation
> > 
> > Signed-off-by: Chunfeng Yun <chunfeng.yun@...iatek.com>
> > ---
> > v2: new patch, add register access helpers,
> >      Add updatel() macro suggested by Vinod, here add more ones
> > instead.
> > ---
> >   drivers/phy/mediatek/phy-mtk-io.h | 38
> > +++++++++++++++++++++++++++++++
> >   1 file changed, 38 insertions(+)
> >   create mode 100644 drivers/phy/mediatek/phy-mtk-io.h
> > 
> > diff --git a/drivers/phy/mediatek/phy-mtk-io.h
> > b/drivers/phy/mediatek/phy-mtk-io.h
> > new file mode 100644
> > index 000000000000..500fcdab165d
> > --- /dev/null
> > +++ b/drivers/phy/mediatek/phy-mtk-io.h
> > @@ -0,0 +1,38 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * Copyright (C) 2021 MediaTek Inc.
> > + *
> > + * Author: Chunfeng Yun <chunfeng.yun@...iatek.com>
> > + */
> > +
> > +#ifndef __PHY_MTK_H__
> > +#define __PHY_MTK_H__
> > +
> > +#include <linux/io.h>
> > +
> > +static inline void mtk_phy_clear_bits(void __iomem *reg, u32 bits)
> > +{
> > +	u32 tmp = readl(reg);
> > +
> > +	tmp &= ~bits;
> > +	writel(tmp, reg);
> > +}
> > +
> > +static inline void mtk_phy_set_bits(void __iomem *reg, u32 bits)
> > +{
> > +	u32 tmp = readl(reg);
> > +
> > +	tmp |= bits;
> > +	writel(tmp, reg);
> > +}
> > +
> > +static inline void mtk_phy_update_bits(void __iomem *reg, u32
> > mask, u32 val)
> > +{
> > +	u32 tmp = readl(reg);
> > +
> > +	tmp &= ~mask;
> > +	tmp |= val & mask;
> > +	writel(tmp, reg);
> > +}
> > +
> > +#endif
> > 
> 
> These helpers are almost exactly duplicating what
> regmap_update_bits() is doing.
> I appreciate the effort to stop open-coding the same sequences over
> and over by
> adding such helper functions, 
I agree with you.
> but I think that the proper way of doing what you
> are proposing is not to add custom functions but rather reuse what
> the Linux APIs
> give you.
I also like to use common APIs ASAP, but not found suitable ones.
This may be a problem, I found that some similar custom helps already
added under phy fold.

> 
> What about doing a conversion to use regmap on this driver?
No, we don't use regmap here, these registers are monopolized by t-phy, 
it's not syscon.