[PATCH v3] clk: thead: th1520-ap: Describe mux clocks with clk_mux

[Yao Zi <ziyao@disroot.org>]

Mux clocks are now described with a customized ccu_mux structure
consisting of ccu_internal and ccu_common substructures, and registered
later with devm_clk_hw_register_mux_parent_data_table(). As this helper
always allocates a new clk_hw structure, it's extremely hard to use mux
clocks as parents statically by clk_hw pointers, since CCF has no
knowledge about the clk_hw structure embedded in ccu_mux.

This scheme already causes issues for clock c910, which takes a mux
clock, c910-i0, as a possible parent. With mainline U-Boot that
reparents c910 to c910-i0 at boottime, c910 is considered as an orphan
by CCF.

This patch refactors handling of mux clocks, embeds a clk_mux structure
in ccu_mux directly. Instead of calling devm_clk_hw_register_mux_*(),
we could register mux clocks on our own without allocating any new
clk_hw pointer, fixing c910 clock's issue.

Fixes: ae81b69fd2b1 ("clk: thead: Add support for T-Head TH1520 AP_SUBSYS clocks")
Signed-off-by: Yao Zi <ziyao@disroot.org>
---

This replaces the second patch in v2 of series "Fix orphan clocks in
clk-th1520-ap driver".

Note that the c910's issue cannot be reproduced with vendor U-Boot,
which always reparents c910 to its second parent, cpu-pll1. Another way
to confirm the bug is to examine
/sys/kernel/debug/clk/c910/clk_possible_parents, which obviously doesn't
match c910's definition. There's another patch[1] explaining and fixing
the issue that the unknown parent isn't shown as "(missing)" in debugfs.

[1]: https://lore.kernel.org/linux-clk/20250705095816.29480-2-ziyao@disroot.org/

Changed from v2:
- Avoid referring c910-i0 as parent for c910 with global names. Instead,
  refactor mux clock handling to make referring to mux clocks by clk_hw
  pointers possible
- Link to v2: https://lore.kernel.org/linux-riscv/20250710092135.61049-1-ziyao@disroot.org/

Changed from v1:
- Split the two fixes into separate patches
- Link to v1: https://lore.kernel.org/all/20250705052028.24611-1-ziyao@disroot.org/

 drivers/clk/thead/clk-th1520-ap.c | 95 ++++++++++++-------------------
 1 file changed, 37 insertions(+), 58 deletions(-)

diff --git a/drivers/clk/thead/clk-th1520-ap.c b/drivers/clk/thead/clk-th1520-ap.c
index 5a102beb6ac1..cf1bba58f641 100644
--- a/drivers/clk/thead/clk-th1520-ap.c
+++ b/drivers/clk/thead/clk-th1520-ap.c
@@ -42,8 +42,9 @@ struct ccu_common {
 };
 
 struct ccu_mux {
-	struct ccu_internal	mux;
-	struct ccu_common	common;
+	int			clkid;
+	u32			reg;
+	struct clk_mux		mux;
 };
 
 struct ccu_gate {
@@ -75,6 +76,17 @@ struct ccu_pll {
 		.flags	= _flags,					\
 	}
 
+#define TH_CCU_MUX(_name, _parents, _shift, _width)			\
+	{								\
+		.mask		= GENMASK(_width - 1, 0),		\
+		.shift		= _shift,				\
+		.hw.init	= CLK_HW_INIT_PARENTS_DATA(		\
+					_name,				\
+					_parents,			\
+					&clk_mux_ops,			\
+					0),				\
+	}
+
 #define CCU_GATE(_clkid, _struct, _name, _parent, _reg, _gate, _flags)	\
 	struct ccu_gate _struct = {					\
 		.enable	= _gate,					\
@@ -94,13 +106,6 @@ static inline struct ccu_common *hw_to_ccu_common(struct clk_hw *hw)
 	return container_of(hw, struct ccu_common, hw);
 }
 
-static inline struct ccu_mux *hw_to_ccu_mux(struct clk_hw *hw)
-{
-	struct ccu_common *common = hw_to_ccu_common(hw);
-
-	return container_of(common, struct ccu_mux, common);
-}
-
 static inline struct ccu_pll *hw_to_ccu_pll(struct clk_hw *hw)
 {
 	struct ccu_common *common = hw_to_ccu_common(hw);
@@ -415,32 +420,20 @@ static const struct clk_parent_data c910_i0_parents[] = {
 };
 
 static struct ccu_mux c910_i0_clk = {
-	.mux	= TH_CCU_ARG(1, 1),
-	.common	= {
-		.clkid		= CLK_C910_I0,
-		.cfg0		= 0x100,
-		.hw.init	= CLK_HW_INIT_PARENTS_DATA("c910-i0",
-					      c910_i0_parents,
-					      &clk_mux_ops,
-					      0),
-	}
+	.clkid	= CLK_C910_I0,
+	.reg	= 0x100,
+	.mux	= TH_CCU_MUX("c910-i0", c910_i0_parents, 1, 1),
 };
 
 static const struct clk_parent_data c910_parents[] = {
-	{ .hw = &c910_i0_clk.common.hw },
+	{ .hw = &c910_i0_clk.mux.hw },
 	{ .hw = &cpu_pll1_clk.common.hw }
 };
 
 static struct ccu_mux c910_clk = {
-	.mux	= TH_CCU_ARG(0, 1),
-	.common	= {
-		.clkid		= CLK_C910,
-		.cfg0		= 0x100,
-		.hw.init	= CLK_HW_INIT_PARENTS_DATA("c910",
-					      c910_parents,
-					      &clk_mux_ops,
-					      0),
-	}
+	.clkid	= CLK_C910,
+	.reg	= 0x100,
+	.mux	= TH_CCU_MUX("c910", c910_parents, 0, 1),
 };
 
 static const struct clk_parent_data ahb2_cpusys_parents[] = {
@@ -925,15 +918,9 @@ static const struct clk_parent_data uart_sclk_parents[] = {
 };
 
 static struct ccu_mux uart_sclk = {
-	.mux	= TH_CCU_ARG(0, 1),
-	.common	= {
-		.clkid          = CLK_UART_SCLK,
-		.cfg0		= 0x210,
-		.hw.init	= CLK_HW_INIT_PARENTS_DATA("uart-sclk",
-					      uart_sclk_parents,
-					      &clk_mux_ops,
-					      0),
-	}
+	.clkid	= CLK_UART_SCLK,
+	.reg	= 0x210,
+	.mux	= TH_CCU_MUX("uart-sclk", uart_sclk_parents, 0, 1),
 };
 
 static struct ccu_common *th1520_pll_clks[] = {
@@ -970,10 +957,10 @@ static struct ccu_common *th1520_div_clks[] = {
 	&dpu1_clk.common,
 };
 
-static struct ccu_common *th1520_mux_clks[] = {
-	&c910_i0_clk.common,
-	&c910_clk.common,
-	&uart_sclk.common,
+static struct ccu_mux *th1520_mux_clks[] = {
+	&c910_i0_clk,
+	&c910_clk,
+	&uart_sclk,
 };
 
 static struct ccu_common *th1520_gate_clks[] = {
@@ -1075,7 +1062,7 @@ static const struct regmap_config th1520_clk_regmap_config = {
 struct th1520_plat_data {
 	struct ccu_common **th1520_pll_clks;
 	struct ccu_common **th1520_div_clks;
-	struct ccu_common **th1520_mux_clks;
+	struct ccu_mux	  **th1520_mux_clks;
 	struct ccu_common **th1520_gate_clks;
 
 	int nr_clks;
@@ -1162,23 +1149,15 @@ static int th1520_clk_probe(struct platform_device *pdev)
 	}
 
 	for (i = 0; i < plat_data->nr_mux_clks; i++) {
-		struct ccu_mux *cm = hw_to_ccu_mux(&plat_data->th1520_mux_clks[i]->hw);
-		const struct clk_init_data *init = cm->common.hw.init;
-
-		plat_data->th1520_mux_clks[i]->map = map;
-		hw = devm_clk_hw_register_mux_parent_data_table(dev,
-								init->name,
-								init->parent_data,
-								init->num_parents,
-								0,
-								base + cm->common.cfg0,
-								cm->mux.shift,
-								cm->mux.width,
-								0, NULL, NULL);
-		if (IS_ERR(hw))
-			return PTR_ERR(hw);
+		struct ccu_mux *cm = plat_data->th1520_mux_clks[i];
+
+		cm->mux.reg = base + cm->reg;
+
+		ret = devm_clk_hw_register(dev, &cm->mux.hw);
+		if (ret)
+			return ret;
 
-		priv->hws[cm->common.clkid] = hw;
+		priv->hws[cm->clkid] = &cm->mux.hw;
 	}
 
 	for (i = 0; i < plat_data->nr_gate_clks; i++) {
-- 
2.50.1