Subject: RE: [PATCH v6 02/10] reset: Add Realtek basic reset support

From: Yu-Chun Lin [林祐君] <[email-masked]>
Date: Fri, 10 Apr 2026 06:49:05 +0000

> On Do, 2026-04-02 at 15:39 +0800, Yu-Chun Lin wrote:
> > From: Cheng-Yu Lee <[email-masked]>
> >
> > Define the reset operations backed by a regmap-based register
> > interface and prepare the reset controller to be registered through
> > the reset framework.
> >
> > Since the reset controllers on Realtek SoCs often share the same
> > register space with the clock controllers, this common framework is
> > designed to extract the regmap and device tree node from the parent
> > device (e.g., an auxiliary device parent).
> >
> > Signed-off-by: Cheng-Yu Lee <[email-masked]>
> > Co-developed-by: Yu-Chun Lin <[email-masked]>
> > Signed-off-by: Yu-Chun Lin <[email-masked]>
> > ---
> > Changes in v6:
> > - Remove the global header include/linux/reset/realtek.h and use a
> > local common.h instead.
> > - Extract regmap and of_node directly from the parent device.
> > - Remove struct rtk_reset_initdata. Now, pass struct rtk_reset_data
> > directly when calling rtk_reset_controller_add().
> > ---
> >  MAINTAINERS                    |  1 +
> >  drivers/reset/Kconfig          |  1 +
> >  drivers/reset/Makefile         |  1 +
> >  drivers/reset/realtek/Kconfig  |  3 ++
> > drivers/reset/realtek/Makefile |  2 +  drivers/reset/realtek/common.c
> > | 85 ++++++++++++++++++++++++++++++++++
> >  drivers/reset/realtek/common.h | 29 ++++++++++++
> >  7 files changed, 122 insertions(+)
> >  create mode 100644 drivers/reset/realtek/Kconfig  create mode 100644
> > drivers/reset/realtek/Makefile  create mode 100644
> > drivers/reset/realtek/common.c  create mode 100644
> > drivers/reset/realtek/common.h
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS index
> > 07e73bf621b0..8f355896583b 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -22240,6 +22240,7 @@ L:    [email-masked]
> >  L:   [email-masked]
> >  S:   Supported
> >  F:   Documentation/devicetree/bindings/clock/realtek*
> > +F:   drivers/reset/realtek/*
> >  F:   include/dt-bindings/clock/realtek*
> >  F:   include/dt-bindings/reset/realtek*
> >
> > diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig index
> > 7ce151f6a7e4..03be1931f264 100644
> > --- a/drivers/reset/Kconfig
> > +++ b/drivers/reset/Kconfig
> > @@ -398,6 +398,7 @@ config RESET_ZYNQMP
> >
> >  source "drivers/reset/amlogic/Kconfig"
> >  source "drivers/reset/hisilicon/Kconfig"
> > +source "drivers/reset/realtek/Kconfig"
> >  source "drivers/reset/spacemit/Kconfig"
> >  source "drivers/reset/starfive/Kconfig"
> >  source "drivers/reset/sti/Kconfig"
> > diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile index
> > fc0cc99f8514..4407d1630070 100644
> > --- a/drivers/reset/Makefile
> > +++ b/drivers/reset/Makefile
> > @@ -2,6 +2,7 @@
> >  obj-y += core.o
> >  obj-y += amlogic/
> >  obj-y += hisilicon/
> > +obj-y += realtek/
> >  obj-y += spacemit/
> >  obj-y += starfive/
> >  obj-y += sti/
> > diff --git a/drivers/reset/realtek/Kconfig
> > b/drivers/reset/realtek/Kconfig new file mode 100644 index
> > 000000000000..99a14d355803
> > --- /dev/null
> > +++ b/drivers/reset/realtek/Kconfig
> > @@ -0,0 +1,3 @@
> > +# SPDX-License-Identifier: GPL-2.0-only config RESET_RTK_COMMON
> > +     bool
> 
> Please make this build-testable with COMPILE_TEST.
>

I will change Kconfig to

config RESET_RTK_COMMON
  tristate "Realtek common reset driver" if COMPILE_TEST
  help
    Common helper code shared by Realtek reset controller drivers.

config COMMON_RESET_RTD1625
  tristate "RTD1625 Reset Controller"
  depends on ARCH_REALTEK || COMPILE_TEST
  select RESET_RTK_COMMON
  select AUXILIARY_BUS
  help
    This enables the reset controller driver for Realtek RTD1625 SoC.

> > diff --git a/drivers/reset/realtek/Makefile
> > b/drivers/reset/realtek/Makefile new file mode 100644 index
> > 000000000000..b59a3f7f2453
> > --- /dev/null
> > +++ b/drivers/reset/realtek/Makefile
> > @@ -0,0 +1,2 @@
> > +# SPDX-License-Identifier: GPL-2.0-only
> > +obj-$(CONFIG_RESET_RTK_COMMON) += common.o
> > diff --git a/drivers/reset/realtek/common.c
> > b/drivers/reset/realtek/common.c new file mode 100644 index
> > 000000000000..ea7ff27117e7
> > --- /dev/null
> > +++ b/drivers/reset/realtek/common.c
> > @@ -0,0 +1,85 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright (C) 2019 Realtek Semiconductor Corporation  */
> > +
> > +#include <linux/device.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/regmap.h>
> > +#include "common.h"
> > +
> > +static inline struct rtk_reset_data *to_rtk_reset_controller(struct
> > +reset_controller_dev *r) {
> > +     return container_of(r, struct rtk_reset_data, rcdev); }
> > +
> > +static inline struct rtk_reset_desc *rtk_reset_get_desc(struct rtk_reset_data
> *data,
> > +                                                     unsigned
> long
> > +idx) {
> > +     return &data->descs[idx];
> > +}
> > +
> > +static int rtk_reset_assert(struct reset_controller_dev *rcdev,
> > +                         unsigned long idx) {
> > +     struct rtk_reset_data *data = to_rtk_reset_controller(rcdev);
> > +     struct rtk_reset_desc *desc = rtk_reset_get_desc(data, idx);
> > +     u32 mask = desc->write_en ? (0x3 << desc->bit) : BIT(desc->bit);
> > +     u32 val  = desc->write_en ? (0x2 << desc->bit) : 0;
> > +
> > +     return regmap_update_bits(data->regmap, desc->ofs, mask, val); }
> > +
> > +static int rtk_reset_deassert(struct reset_controller_dev *rcdev,
> > +                           unsigned long idx) {
> > +     struct rtk_reset_data *data = to_rtk_reset_controller(rcdev);
> > +     struct rtk_reset_desc *desc = rtk_reset_get_desc(data, idx);
> > +     u32 mask = desc->write_en ? (0x3 << desc->bit) : BIT(desc->bit);
> > +     u32 val  = mask;
> > +
> > +     return regmap_update_bits(data->regmap, desc->ofs, mask, val); }
> > +
> > +static int rtk_reset_status(struct reset_controller_dev *rcdev,
> > +                         unsigned long idx) {
> > +     struct rtk_reset_data *data = to_rtk_reset_controller(rcdev);
> > +     struct rtk_reset_desc *desc = rtk_reset_get_desc(data, idx);
> > +     u32 val;
> > +     int ret;
> > +
> > +     ret = regmap_read(data->regmap, desc->ofs, &val);
> > +     if (ret)
> > +             return ret;
> > +
> > +     return !((val >> desc->bit) & 1); }
> > +
> > +static const struct reset_control_ops rtk_reset_ops = {
> > +     .assert   = rtk_reset_assert,
> > +     .deassert = rtk_reset_deassert,
> > +     .status   = rtk_reset_status,
> > +};
> > +
> > +/* The caller must initialize data->rcdev.nr_resets and data->descs
> > +before
> > + * calling rtk_reset_controller_add().
> > + */
> > +int rtk_reset_controller_add(struct device *dev,
> > +                          struct rtk_reset_data *data) {
> > +     struct device *parent = dev->parent;
> > +
> > +     data->regmap = dev_get_regmap(parent, NULL);
> > +     if (!data->regmap)
> > +             return -ENODEV;
> > +
> > +     data->rcdev.owner     = THIS_MODULE;
> 
> The rtk_reset_desc arrays used by this code live in the calling module, so it
> would be better to let the caller initialize .owner as well.
> 
> It doesn't make a difference in practice, since CONFIG_RESET_RTK_COMMON
> isn't tristate (right now).
> 

I will move 'data->rcdev.owner = THIS_MODULE' to the caller.

Best Regards,
Yu-Chun

> regards
> Philipp