Re: [PATCH v13 04/11] clk: realtek: Introduce common probe() and remove()

[Brian Masney]

Hi Yu-Chun,

On Wed, Aug 12, 2026 at 10:00:02AM +0800, Yu-Chun Lin wrote:
> From: Cheng-Yu Lee <cylee12@xxxxxxxxxxx>
> 
> Add rtk_clk_probe() to set up the shared regmap, register clock hardware,
> and add the clock provider.
> 
> Add rtk_clk_remove() to clear the regmap pointers in the clock descriptors
> during driver unbind to prevent dangling pointers.
> 
> Additionally, if the "#reset-cells" property is present in the device tree,
> it creates and registers an auxiliary device using the provided aux_name.
> This allows the dedicated reset driver to bind to this device, enabling
> both clock and reset drivers to share the same regmap.
> 
> Reviewed-by: Brian Masney <bmasney@xxxxxxxxxx>
> Signed-off-by: Cheng-Yu Lee <cylee12@xxxxxxxxxxx>
> Co-developed-by: Yu-Chun Lin <eleanor.lin@xxxxxxxxxxx>
> Signed-off-by: Yu-Chun Lin <eleanor.lin@xxxxxxxxxxx>
> ---
> Changes in v13:
> - None.
> ---
>  MAINTAINERS                          |  1 +
>  drivers/clk/Kconfig                  |  1 +
>  drivers/clk/Makefile                 |  1 +
>  drivers/clk/realtek/Kconfig          | 30 ++++++++++
>  drivers/clk/realtek/Makefile         |  4 ++
>  drivers/clk/realtek/clk-rtk-common.c | 83 ++++++++++++++++++++++++++++
>  drivers/clk/realtek/clk-rtk-common.h | 38 +++++++++++++
>  7 files changed, 158 insertions(+)
>  create mode 100644 drivers/clk/realtek/Kconfig
>  create mode 100644 drivers/clk/realtek/Makefile
>  create mode 100644 drivers/clk/realtek/clk-rtk-common.c
>  create mode 100644 drivers/clk/realtek/clk-rtk-common.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index a752551f32f9..e55eb1c06119 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -22746,6 +22746,7 @@ M:	Cheng-Yu Lee <cylee12@xxxxxxxxxxx>
>  M:	Yu-Chun Lin <eleanor.lin@xxxxxxxxxxx>
>  S:	Supported
>  F:	Documentation/devicetree/bindings/clock/realtek*
> +F:	drivers/clk/realtek/*
>  F:	drivers/reset/realtek/*
>  F:	include/dt-bindings/clock/realtek*
>  F:	include/dt-bindings/reset/realtek*
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index 1717ce75a907..97ad817457db 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -525,6 +525,7 @@ 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 cc108a75a900..b1aa373e9f84 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-$(CONFIG_COMMON_CLK_ROCKCHIP)	+= rockchip/
>  obj-$(CONFIG_COMMON_CLK_SAMSUNG)	+= samsung/
> diff --git a/drivers/clk/realtek/Kconfig b/drivers/clk/realtek/Kconfig
> new file mode 100644
> index 000000000000..ed97531e321d
> --- /dev/null
> +++ b/drivers/clk/realtek/Kconfig
> @@ -0,0 +1,30 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +config COMMON_CLK_REALTEK
> +	tristate "Clock driver for Realtek SoCs"
> +	depends on ARCH_REALTEK || COMPILE_TEST
> +	default ARCH_REALTEK
> +	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"
> +	depends on RESET_CONTROLLER
> +	select AUXILIARY_BUS
> +	select MFD_SYSCON
> +	select RESET_RTK_COMMON
> +	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..13000ed4ba11
> --- /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 += clk-rtk-common.o
> diff --git a/drivers/clk/realtek/clk-rtk-common.c b/drivers/clk/realtek/clk-rtk-common.c
> new file mode 100644
> index 000000000000..e8422ecbad79
> --- /dev/null
> +++ b/drivers/clk/realtek/clk-rtk-common.c
> @@ -0,0 +1,83 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2019-2026 Realtek Semiconductor Corporation
> + * Author: Cheng-Yu Lee <cylee12@xxxxxxxxxxx>
> + */
> +
> +#include <linux/auxiliary_bus.h>
> +#include <linux/device.h>
> +#include <linux/export.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include "clk-rtk-common.h"
> +
> +static int rtk_reset_controller_register(struct device *dev, const char *aux_name,
> +					 struct regmap *map)
> +{
> +	struct auxiliary_device *adev;
> +
> +	if (!of_property_present(dev->of_node, "#reset-cells"))
> +		return 0;
> +
> +	if (!aux_name) {
> +		dev_err(dev, "DTS requires reset controller, but aux_name is missing\n");
> +		return -EINVAL;
> +	}
> +
> +	adev = devm_auxiliary_device_create(dev, aux_name, (void *)map);
> +	if (!adev)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +int rtk_clk_probe(struct platform_device *pdev, const struct rtk_clk_desc *desc)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct regmap *regmap;
> +	struct clk_hw *hw;
> +	int i, ret;
> +
> +	regmap = device_node_to_regmap(dev->of_node);

Looking at the Sashiko comments for this series. device_node_to_regmap()
has this note in drivers/mfd/syscon.c:

/**
 * device_node_to_regmap() - Get or create a regmap for specified device node
 * @np: Device tree node
 *
 * Get a regmap for the specified device node. If there's not an existing
 * regmap, then one is instantiated. This function should not be used if the
 * device node has a custom regmap driver or has resources (clocks, resets) to
 * be managed. Use syscon_node_to_regmap() instead for those cases.
 *
 * Return: regmap ptr on success, negative error code on failure.
 */

Should this be moved to syscon_node_to_regmap()?

> +	if (IS_ERR(regmap))
> +		return dev_err_probe(dev, PTR_ERR(regmap), "failed to get regmap\n");
> +
> +	for (i = 0; i < desc->num_clks; i++)
> +		desc->clks[i]->regmap = regmap;
> +
> +	for (i = 0; i < desc->clk_data->num; i++) {
> +		hw = desc->clk_data->hws[i];
> +		if (!hw)
> +			continue;
> +
> +		ret = devm_clk_hw_register(dev, hw);
> +		if (ret)
> +			return dev_err_probe(dev, ret, "failed to register hw of clk%d\n", i);
> +	}
> +
> +	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
> +					  desc->clk_data);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to add clock provider\n");
> +
> +	platform_set_drvdata(pdev, (void *)desc);
> +
> +	return rtk_reset_controller_register(dev, desc->aux_name, regmap);
> +}
> +EXPORT_SYMBOL_NS_GPL(rtk_clk_probe, "CLK_REALTEK");
> +
> +void rtk_clk_remove(struct platform_device *pdev)
> +{
> +	const struct rtk_clk_desc *desc = platform_get_drvdata(pdev);
> +
> +	if (!desc)
> +		return;
> +
> +	for (int i = 0; i < desc->num_clks; i++)
> +		desc->clks[i]->regmap = NULL;

Looking at the Sashiko comments, is this remove callback really needed?

Brian