[PATCH v7 06/10] clk: realtek: Add support for mux clock

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

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

Add a simple regmap-based clk_ops implementation for Realtek mux clocks.

The implementation supports parent selection and rate determination through
regmap-backed register access.

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>
---
 drivers/clk/realtek/Makefile         |  1 +
 drivers/clk/realtek/clk-regmap-mux.c | 41 ++++++++++++++++++++++++++
 drivers/clk/realtek/clk-regmap-mux.h | 43 ++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+)
 create mode 100644 drivers/clk/realtek/clk-regmap-mux.c
 create mode 100644 drivers/clk/realtek/clk-regmap-mux.h

diff --git a/drivers/clk/realtek/Makefile b/drivers/clk/realtek/Makefile
index 74375f8127ac..f90dc57fcfdb 100644
--- a/drivers/clk/realtek/Makefile
+++ b/drivers/clk/realtek/Makefile
@@ -5,4 +5,5 @@ clk-rtk-y += common.o
 
 clk-rtk-y += clk-pll.o
 clk-rtk-y += clk-regmap-gate.o
+clk-rtk-y += clk-regmap-mux.o
 clk-rtk-y += freq_table.o
diff --git a/drivers/clk/realtek/clk-regmap-mux.c b/drivers/clk/realtek/clk-regmap-mux.c
new file mode 100644
index 000000000000..1b0b8419d651
--- /dev/null
+++ b/drivers/clk/realtek/clk-regmap-mux.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017-2026 Realtek Semiconductor Corporation
+ * Author: Cheng-Yu Lee <cylee12@realtek.com>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/export.h>
+#include <linux/regmap.h>
+#include "clk-regmap-mux.h"
+
+static u8 clk_regmap_mux_get_parent(struct clk_hw *hw)
+{
+	struct clk_regmap_mux *clkm = to_clk_regmap_mux(hw);
+	int num_parents = clk_hw_get_num_parents(hw);
+	u32 val;
+	int ret;
+
+	ret = regmap_read(clkm->clkr.regmap, clkm->mux_ofs, &val);
+	if (ret)
+		return 0;
+
+	val = (val >> clkm->shift) & clkm->mask;
+
+	return val >= num_parents ? 0 : val;
+}
+
+static int clk_regmap_mux_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct clk_regmap_mux *clkm = to_clk_regmap_mux(hw);
+
+	return regmap_update_bits(clkm->clkr.regmap, clkm->mux_ofs,
+				  clkm->mask << clkm->shift, index << clkm->shift);
+}
+
+const struct clk_ops rtk_clk_regmap_mux_ops = {
+	.set_parent = clk_regmap_mux_set_parent,
+	.get_parent = clk_regmap_mux_get_parent,
+	.determine_rate = __clk_mux_determine_rate,
+};
+EXPORT_SYMBOL_NS_GPL(rtk_clk_regmap_mux_ops, "REALTEK_CLK");
diff --git a/drivers/clk/realtek/clk-regmap-mux.h b/drivers/clk/realtek/clk-regmap-mux.h
new file mode 100644
index 000000000000..fff413222d19
--- /dev/null
+++ b/drivers/clk/realtek/clk-regmap-mux.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2017-2026 Realtek Semiconductor Corporation
+ * Author: Cheng-Yu Lee <cylee12@realtek.com>
+ */
+
+#ifndef __CLK_REALTEK_CLK_REGMAP_MUX_H
+#define __CLK_REALTEK_CLK_REGMAP_MUX_H
+
+#include "common.h"
+
+struct clk_regmap_mux {
+	struct clk_regmap clkr;
+	int mux_ofs;
+	unsigned int mask;
+	unsigned int shift;
+};
+
+#define __clk_regmap_mux_hw(_p) __clk_regmap_hw(&(_p)->clkr)
+
+#define __CLK_REGMAP_MUX(_name, _parents, _ops, _flags, _ofs, _sft, _mask)   \
+	struct clk_regmap_mux _name = {                                      \
+		.clkr.hw.init =                                              \
+			CLK_HW_INIT_PARENTS(#_name, _parents, _ops, _flags), \
+		.mux_ofs = _ofs,                                             \
+		.shift = _sft,                                               \
+		.mask = _mask,                                               \
+	}
+
+#define CLK_REGMAP_MUX(_name, _parents, _flags, _ofs, _sft, _mask)           \
+	__CLK_REGMAP_MUX(_name, _parents, &rtk_clk_regmap_mux_ops, _flags, _ofs, \
+			 _sft, _mask)
+
+static inline struct clk_regmap_mux *to_clk_regmap_mux(struct clk_hw *hw)
+{
+	struct clk_regmap *clkr = to_clk_regmap(hw);
+
+	return container_of(clkr, struct clk_regmap_mux, clkr);
+}
+
+extern const struct clk_ops rtk_clk_regmap_mux_ops;
+
+#endif /* __CLK_REALTEK_CLK_REGMAP_MUX_H */
-- 
2.34.1