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

Thu Apr 2 02:15:49 PDT 2026

On Do, 2026-04-02 at 15:39 +0800, Yu-Chun Lin wrote:
> From: Cheng-Yu Lee <cylee12 at realtek.com>
> 
> 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 <cylee12 at realtek.com>
> Co-developed-by: Yu-Chun Lin <eleanor.lin at realtek.com>
> Signed-off-by: Yu-Chun Lin <eleanor.lin at realtek.com>
> ---
> 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:	devicetree at vger.kernel.org
>  L:	linux-clk at vger.kernel.org
>  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.

> 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).

regards
Philipp