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Message-ID: <07ba7a3a4325f927fa1db3b0f0af124ea9cd2ee4.camel@pengutronix.de>
Date: Tue, 13 Jan 2026 13:06:53 +0100
From: Philipp Zabel <p.zabel@...gutronix.de>
To: Yu-Chun Lin <eleanor.lin@...ltek.com>, mturquette@...libre.com,
sboyd@...nel.org, robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
cylee12@...ltek.com, jyanchou@...ltek.com
Cc: devicetree@...r.kernel.org, linux-clk@...r.kernel.org,
linux-kernel@...r.kernel.org, james.tai@...ltek.com, cy.huang@...ltek.com,
stanley_chang@...ltek.com
Subject: Re: [PATCH v2 2/9] clk: realtek: Add basic reset support
On Di, 2026-01-13 at 19:23 +0800, Yu-Chun Lin wrote:
> From: Cheng-Yu Lee <cylee12@...ltek.com>
>
> Define the reset operations backed by a regmap-based register
> interface and prepare the reset controller to be registered
> through the reset framework.
>
> Signed-off-by: Cheng-Yu Lee <cylee12@...ltek.com>
> Co-developed-by: Yu-Chun Lin <eleanor.lin@...ltek.com>
> Signed-off-by: Yu-Chun Lin <eleanor.lin@...ltek.com>
> ---
> Changes in v2:
> - Added missing Co-developed-by tag.
> - Added missing maintainer entry for driver/clk.
> - Removed explicit of_xlate/of_reset_n_cells assignment as it matches defaults.
> - Added error handling for rtk_reset_read() return value
> ---
> MAINTAINERS | 1 +
> drivers/clk/Kconfig | 1 +
> drivers/clk/Makefile | 1 +
> drivers/clk/realtek/Kconfig | 28 ++++++++
> drivers/clk/realtek/Makefile | 4 ++
> drivers/clk/realtek/reset.c | 125 +++++++++++++++++++++++++++++++++++
> drivers/clk/realtek/reset.h | 36 ++++++++++
> 7 files changed, 196 insertions(+)
> create mode 100644 drivers/clk/realtek/Kconfig
> create mode 100644 drivers/clk/realtek/Makefile
> create mode 100644 drivers/clk/realtek/reset.c
> create mode 100644 drivers/clk/realtek/reset.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 66c0f4924c1e..de772e0026de 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21975,6 +21975,7 @@ L: devicetree@...r.kernel.org
> L: linux-clk@...r.kernel.org
> S: Supported
> F: Documentation/devicetree/bindings/clock/realtek*
> +F: drivers/clk/realtek/*
> F: include/dt-bindings/clock/realtek*
>
> REALTEK SPI-NAND
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index 3a1611008e48..2f2cacf87c38 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -530,6 +530,7 @@ source "drivers/clk/nuvoton/Kconfig"
> source "drivers/clk/pistachio/Kconfig"
> source "drivers/clk/qcom/Kconfig"
> source "drivers/clk/ralink/Kconfig"
> +source "drivers/clk/realtek/Kconfig"
> source "drivers/clk/renesas/Kconfig"
> source "drivers/clk/rockchip/Kconfig"
> source "drivers/clk/samsung/Kconfig"
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index 61ec08404442..075a1c410b90 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -141,6 +141,7 @@ obj-$(CONFIG_COMMON_CLK_PISTACHIO) += pistachio/
> obj-$(CONFIG_COMMON_CLK_PXA) += pxa/
> obj-$(CONFIG_COMMON_CLK_QCOM) += qcom/
> obj-y += ralink/
> +obj-$(CONFIG_COMMON_CLK_REALTEK) += realtek/
> obj-y += renesas/
> obj-$(CONFIG_ARCH_ROCKCHIP) += rockchip/
> obj-$(CONFIG_COMMON_CLK_SAMSUNG) += samsung/
> diff --git a/drivers/clk/realtek/Kconfig b/drivers/clk/realtek/Kconfig
> new file mode 100644
> index 000000000000..121158f11dd1
> --- /dev/null
> +++ b/drivers/clk/realtek/Kconfig
> @@ -0,0 +1,28 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +config COMMON_CLK_REALTEK
> + bool "Clock driver for Realtek SoCs"
> + depends on ARCH_REALTEK || COMPILE_TEST
> + select MFD_SYSCON
> + default y
> + help
> + Enable the common clock framework infrastructure for Realtek
> + system-on-chip platforms.
> +
> + This provides the base support required by individual Realtek
> + clock controller drivers to expose clocks to peripheral devices.
> +
> + If you have a Realtek-based platform, say Y.
> +
> +if COMMON_CLK_REALTEK
> +
> +config RTK_CLK_COMMON
> + tristate "Realtek Clock Common"
> + select RESET_CONTROLLER
> + help
> + Common helper code shared by Realtek clock controller drivers.
> +
> + This provides utility functions and data structures used by
> + multiple Realtek clock implementations, and include integration
> + with reset controllers where required.
> +
> +endif
> diff --git a/drivers/clk/realtek/Makefile b/drivers/clk/realtek/Makefile
> new file mode 100644
> index 000000000000..52267de2eef4
> --- /dev/null
> +++ b/drivers/clk/realtek/Makefile
> @@ -0,0 +1,4 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +obj-$(CONFIG_RTK_CLK_COMMON) += clk-rtk.o
> +
> +clk-rtk-y += reset.o
> diff --git a/drivers/clk/realtek/reset.c b/drivers/clk/realtek/reset.c
> new file mode 100644
> index 000000000000..0ba0d46811d4
> --- /dev/null
> +++ b/drivers/clk/realtek/reset.c
> @@ -0,0 +1,125 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2019 Realtek Semiconductor Corporation
> + */
> +
> +#include <linux/of.h>
> +#include <linux/device.h>
> +#include "reset.h"
> +
> +#define RTK_RESET_BANK_SHIFT 8
> +#define RTK_RESET_ID_MASK 0xff
Why are there 256 possible ids per bank? Each bank is only a 32-bit
register, containing 32 (or in the case of write_en) 16 reset controls.
> +#define to_rtk_reset_controller(r) container_of(r, struct rtk_reset_data, rcdev)
Please make this an inline function.
> +static inline struct rtk_reset_bank *
> +rtk_reset_get_bank(struct rtk_reset_data *data, unsigned long idx)
> +{
> + int bank_id = idx >> RTK_RESET_BANK_SHIFT;
> +
> + return &data->banks[bank_id];
> +}
> +
> +static inline int rtk_reset_get_id(struct rtk_reset_data *data,
> + unsigned long idx)
> +{
> + return idx & RTK_RESET_ID_MASK;
> +}
> +
> +static int rtk_reset_update_bits(struct rtk_reset_data *data, u32 offset,
> + u32 mask, u32 val)
> +{
> + int ret;
> +
> + ret = regmap_update_bits(data->regmap, offset, mask, val);
> + return ret;
> +}
> +
> +static int rtk_reset_read(struct rtk_reset_data *data, u32 offset, u32 *val)
> +{
> + int ret;
> +
> + ret = regmap_read(data->regmap, offset, val);
> + return ret;
> +}
The local variable ret is superfluous. And why not use
regmap_read/update_bits() directly below?
> +
> +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_bank *bank = rtk_reset_get_bank(data, idx);
> + u32 id = rtk_reset_get_id(data, idx);
> + u32 mask = bank->write_en ? (0x3 << id) : BIT(id);
> + u32 val = bank->write_en ? (0x2 << id) : 0;
I'd use UL(0x3) / UL(0x2) to avoid UB when compiling for 32-bit.
Only even ids are allowed for banks with write_en set?
> +
> + return rtk_reset_update_bits(data, bank->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_bank *bank = rtk_reset_get_bank(data, idx);
> + u32 id = rtk_reset_get_id(data, idx);
> + u32 mask = bank->write_en ? (0x3 << id) : BIT(id);
> + u32 val = mask;
> +
> + return rtk_reset_update_bits(data, bank->ofs, mask, val);
> +}
> +
> +static int rtk_reset_reset(struct reset_controller_dev *rcdev,
> + unsigned long idx)
> +{
> + int ret;
> +
> + ret = rtk_reset_assert(rcdev, idx);
> + if (ret)
> + return ret;
> + return rtk_reset_deassert(rcdev, idx);
> +}
> +
> +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_bank *bank = &data->banks[idx >> RTK_RESET_BANK_SHIFT];
> + u32 id = idx & RTK_RESET_ID_MASK;
> + u32 val;
> + int ret;
> +
> + ret = rtk_reset_read(data, bank->ofs, &val);
> + if (ret)
> + return ret;
> +
> + return !((val >> id) & 1);
> +}
> +
> +static const struct reset_control_ops rtk_reset_ops = {
> + .reset = rtk_reset_reset,
> + .assert = rtk_reset_assert,
> + .deassert = rtk_reset_deassert,
> + .status = rtk_reset_status,
> +};
> +
> +int rtk_reset_controller_add(struct device *dev,
> + struct rtk_reset_initdata *initdata)
> +{
> + struct rtk_reset_data *data;
> +
> + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> +
> + data->dev = dev;
> + data->num_banks = initdata->num_banks;
> + data->banks = initdata->banks;
> + data->regmap = initdata->regmap;
> + data->rcdev.owner = THIS_MODULE;
> + data->rcdev.ops = &rtk_reset_ops;
> + data->rcdev.dev = dev;
> + data->rcdev.of_node = dev->of_node;
> + data->rcdev.nr_resets = initdata->num_banks * 0x100;
This is misleading. Surely there's not num_banks * 256 resets, since
each bank can only carry 16 or 32 resets. It'd probably better to not
use nr_resets at all and implement your own of_xlate.
regards
Philipp
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