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

Yu-Chun Lin
2026-04-02T07:42:55Z

From: Cheng-Yu Lee <cylee12@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@realtek.com>
Co-developed-by: Yu-Chun Lin <eleanor.lin@realtek.com>
Signed-off-by: Yu-Chun Lin <eleanor.lin@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@vger.kernel.org
L: linux-clk@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
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;
+ data->rcdev.ops = &rtk_reset_ops;
+ data->rcdev.dev = dev;
+ data->rcdev.of_node = parent->of_node;
+
+ return devm_reset_controller_register(dev, &data->rcdev);
+}
+EXPORT_SYMBOL_NS_GPL(rtk_reset_controller_add, "REALTEK_RESET");
diff --git a/drivers/reset/realtek/common.h b/drivers/reset/realtek/common.h
new file mode 100644
index 000000000000..ed69bca458de
--- /dev/null
+++ b/drivers/reset/realtek/common.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2026 Realtek Semiconductor Corporation
+ * Author: Yu-Chun Lin <eleanor.lin@realtek.com>
+ */
+
+#ifndef __RESET_REALTEK_COMMON_H
+#define __RESET_REALTEK_COMMON_H
+
+#include <linux/reset-controller.h>
+
+struct regmap;
+
+struct rtk_reset_desc {
+ u32 ofs;
+ u32 bit;
+ bool write_en;
+};
+
+struct rtk_reset_data {
+ struct reset_controller_dev rcdev;
+ struct rtk_reset_desc *descs;
+ struct regmap *regmap;
+};
+
+int rtk_reset_controller_add(struct device *dev,
+ struct rtk_reset_data *initdata);
+
+#endif /* __RESET_REALTEK_COMMON_H */
--
2.34.1