[PATCH v11 02/11] reset: Add Realtek basic reset support

[Yu-Chun Lin <eleanor.lin@realtek.com>]

From: Cheng-Yu Lee <cylee12@realtek.com>

Define the common reset operations backed by a regmap-based register
interface for Realtek SoCs.

This library exports the standard reset control operations (assert,
deassert, and status) to be utilized by other specific Realtek reset
drivers. The implementation supports handling an optional write-enable bit
required by certain Realtek reset controllers.

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
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 v11:
- Update the commit message and Kconfig description.
- Remove unused header and add the header I use.
- Add Reviewed-by tag from Philipp.
---
 MAINTAINERS                              |  1 +
 drivers/reset/Kconfig                    |  1 +
 drivers/reset/Makefile                   |  1 +
 drivers/reset/realtek/Kconfig            |  8 +++
 drivers/reset/realtek/Makefile           |  2 +
 drivers/reset/realtek/reset-rtk-common.c | 73 ++++++++++++++++++++++++
 drivers/reset/realtek/reset-rtk-common.h | 29 ++++++++++
 7 files changed, 115 insertions(+)
 create mode 100644 drivers/reset/realtek/Kconfig
 create mode 100644 drivers/reset/realtek/Makefile
 create mode 100644 drivers/reset/realtek/reset-rtk-common.c
 create mode 100644 drivers/reset/realtek/reset-rtk-common.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 65dd2be63903..130440224e55 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22748,6 +22748,7 @@ 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 d009eb0849a3..45a4227b5f44 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -418,6 +418,7 @@ 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 3e52569bd276..7330fee91365 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..5ddf8e5c09c7
--- /dev/null
+++ b/drivers/reset/realtek/Kconfig
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config RESET_RTK_COMMON
+	tristate "Realtek common reset driver" if COMPILE_TEST
+	help
+	  This option enables the common reset controller library for
+	  Realtek SoCs. It provides shared reset control operations
+	  (assert, deassert, status) that other Realtek-specific reset
+	  drivers can use.
diff --git a/drivers/reset/realtek/Makefile b/drivers/reset/realtek/Makefile
new file mode 100644
index 000000000000..6d68e41748bf
--- /dev/null
+++ b/drivers/reset/realtek/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_RESET_RTK_COMMON) += reset-rtk-common.o
diff --git a/drivers/reset/realtek/reset-rtk-common.c b/drivers/reset/realtek/reset-rtk-common.c
new file mode 100644
index 000000000000..6900932b0a32
--- /dev/null
+++ b/drivers/reset/realtek/reset-rtk-common.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2019-2026 Realtek Semiconductor Corporation
+ */
+
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include "reset-rtk-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 const 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);
+	const struct rtk_reset_desc *desc;
+	unsigned int mask, val;
+
+	desc = rtk_reset_get_desc(data, idx);
+	mask = desc->write_en ? (0x3U << desc->bit) : BIT(desc->bit);
+	val  = desc->write_en ? (0x2U << 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);
+	const struct rtk_reset_desc *desc;
+	unsigned int mask;
+
+	desc = rtk_reset_get_desc(data, idx);
+	mask = desc->write_en ? (0x3U << desc->bit) : BIT(desc->bit);
+
+	return regmap_set_bits(data->regmap, desc->ofs, mask);
+}
+
+static int rtk_reset_status(struct reset_controller_dev *rcdev,
+			    unsigned long idx)
+{
+	struct rtk_reset_data *data = to_rtk_reset_controller(rcdev);
+	const struct rtk_reset_desc *desc;
+	unsigned int val;
+	int ret;
+
+	desc = rtk_reset_get_desc(data, idx);
+	ret = regmap_read(data->regmap, desc->ofs, &val);
+	if (ret)
+		return ret;
+
+	return !((val >> desc->bit) & 1);
+}
+
+const struct reset_control_ops rtk_reset_ops = {
+	.assert   = rtk_reset_assert,
+	.deassert = rtk_reset_deassert,
+	.status   = rtk_reset_status,
+};
+EXPORT_SYMBOL_NS_GPL(rtk_reset_ops, "REALTEK_RESET");
+
+MODULE_DESCRIPTION("realtek reset infrastructure");
+MODULE_LICENSE("GPL");
diff --git a/drivers/reset/realtek/reset-rtk-common.h b/drivers/reset/realtek/reset-rtk-common.h
new file mode 100644
index 000000000000..3ea35d9573a4
--- /dev/null
+++ b/drivers/reset/realtek/reset-rtk-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>
+#include <linux/types.h>
+
+struct regmap;
+
+struct rtk_reset_desc {
+	u32 ofs;
+	u32 bit;
+	bool write_en;
+};
+
+struct rtk_reset_data {
+	struct reset_controller_dev rcdev;
+	const struct rtk_reset_desc *descs;
+	struct regmap *regmap;
+};
+
+extern const struct reset_control_ops rtk_reset_ops;
+
+#endif /* __RESET_REALTEK_COMMON_H */
-- 
2.43.0