[PATCH 18/24] clk: mediatek: use registered provider for parent lookup

[David Lechner]

Replace complex and fragile parent/grandparent lookup logic with a
simple lookup that matches CLK_PARENT_* flags to registered clock
providers.

Previously, we were walking priv->parent path to find a the matching
provider by either looking at driver name or driver ops. This was
fragile because more than one udevice could match the criteria and the
search depth had different rules depending on the clock type and the
parent type.

This will also enable more simplification in the future since we no
longer have to keep track of the udevice parents.

Signed-off-by: David Lechner <dlechner at baylibre.com>
---
 drivers/clk/mediatek/clk-mtk.c | 98 ++++++++++++++++++------------------------
 1 file changed, 42 insertions(+), 56 deletions(-)

diff --git a/drivers/clk/mediatek/clk-mtk.c b/drivers/clk/mediatek/clk-mtk.c
index 362e4c1c6a9..d1cfa70e5a6 100644
--- a/drivers/clk/mediatek/clk-mtk.c
+++ b/drivers/clk/mediatek/clk-mtk.c
@@ -41,6 +41,33 @@ static bool mtk_clk_tree_type_is_provider(enum mtk_clk_tree_type type)
 	return type != MTK_CLK_TREE_NONE && type < MTK_CLK_TREE_NUM_TYPES;
 }
 
+static enum mtk_clk_tree_type mtk_clk_tree_type_from_parent_flags(u16 flags)
+{
+	switch (flags & CLK_PARENT_MASK) {
+	case CLK_PARENT_APMIXED:
+		return MTK_CLK_TREE_APMIXED;
+	case CLK_PARENT_TOPCKGEN:
+		return MTK_CLK_TREE_TOPCKGEN;
+	case CLK_PARENT_INFRASYS:
+		return MTK_CLK_TREE_INFRASYS;
+	default:
+		return MTK_CLK_TREE_NONE;
+	}
+}
+
+static struct udevice *mtk_clk_tree_get_provider(enum mtk_clk_tree_type type)
+{
+	if (!mtk_clk_tree_type_is_provider(type))
+		return NULL;
+
+	return mtk_clk_providers[type] ?: ERR_PTR(-ENOENT);
+}
+
+static struct udevice *mtk_clk_parent_get_provider(u16 flags)
+{
+	return mtk_clk_tree_get_provider(mtk_clk_tree_type_from_parent_flags(flags));
+}
+
 static int mtk_clk_tree_register_provider(struct udevice *dev,
 					  const struct mtk_clk_tree *tree)
 {
@@ -228,50 +255,16 @@ static ulong mtk_clk_find_parent_rate(struct clk *clk, int id,
 static ulong mtk_find_parent_rate(struct mtk_clk_priv *priv, struct clk *clk,
 				  const int parent, u16 flags)
 {
-	struct udevice *parent_dev;
+	struct udevice *pdev;
 
-	switch (flags & CLK_PARENT_MASK) {
-	case CLK_PARENT_APMIXED:
-		/* APMIXEDSYS can be parent or grandparent. */
-		if (dev_get_driver_ops(clk->dev) == &mtk_clk_apmixedsys_ops ||
-		    dev_get_driver_ops(clk->dev) == &mtk_clk_fixed_pll_ops) {
-			parent_dev = clk->dev;
-		} else if (dev_get_driver_ops(priv->parent) == &mtk_clk_apmixedsys_ops ||
-			   dev_get_driver_ops(priv->parent) == &mtk_clk_fixed_pll_ops) {
-			parent_dev = priv->parent;
-		} else {
-			struct udevice *grandparent_dev = dev_get_parent(priv->parent);
-
-			if (dev_get_driver_ops(grandparent_dev) == &mtk_clk_apmixedsys_ops ||
-			    dev_get_driver_ops(grandparent_dev) == &mtk_clk_fixed_pll_ops)
-				parent_dev = grandparent_dev;
-			else
-				return -EINVAL;
-		}
-		break;
-	case CLK_PARENT_TOPCKGEN:
-		if (dev_get_driver_ops(clk->dev) == &mtk_clk_topckgen_ops)
-			parent_dev = clk->dev;
-		else if (dev_get_driver_ops(priv->parent) == &mtk_clk_topckgen_ops)
-			parent_dev = priv->parent;
-		else
-			return -EINVAL;
-
-		break;
-	case CLK_PARENT_INFRASYS:
-		if (dev_get_driver_ops(clk->dev) != &mtk_clk_infrasys_ops)
-			return -EINVAL;
-
-		parent_dev = clk->dev;
-		break;
-	case CLK_PARENT_EXT:
+	if ((flags & CLK_PARENT_MASK) == CLK_PARENT_EXT)
 		return mtk_ext_clock_get_rate(priv->tree, parent);
-	default:
-		parent_dev = NULL;
-		break;
-	}
 
-	return mtk_clk_find_parent_rate(clk, parent, parent_dev);
+	pdev = mtk_clk_parent_get_provider(flags);
+	if (IS_ERR(pdev))
+		return PTR_ERR(pdev);
+
+	return mtk_clk_find_parent_rate(clk, parent, pdev);
 }
 
 static ulong mtk_clk_mux_get_rate(struct clk *clk, u32 off)
@@ -1104,29 +1097,22 @@ static int mtk_clk_gate_disable(struct clk *clk)
 static ulong mtk_clk_gate_get_rate(struct clk *clk)
 {
 	struct mtk_cg_priv *priv = dev_get_priv(clk->dev);
-	struct udevice *parent = priv->parent;
 	const struct mtk_gate *gate;
+	struct udevice *pdev;
 
 	if (clk->id < priv->gates_offs)
 		return -EINVAL;
 
 	gate = &priv->gates[clk->id - priv->gates_offs];
-	/*
-	 * With requesting a TOPCKGEN parent, make sure the dev parent
-	 * is actually topckgen. This might not be the case for an
-	 * infracfg-ao implementation where:
-	 * parent = infracfg
-	 * parent->parent = topckgen
-	 */
-	if (gate->flags & CLK_PARENT_TOPCKGEN &&
-	    parent->driver != DM_DRIVER_GET(mtk_clk_topckgen)) {
-		priv = dev_get_priv(parent);
-		parent = priv->parent;
-	} else if (gate->flags & CLK_PARENT_EXT) {
+
+	if (gate->flags & CLK_PARENT_EXT)
 		return mtk_ext_clock_get_rate(priv->tree, gate->parent);
-	}
 
-	return mtk_clk_find_parent_rate(clk, gate->parent, parent);
+	pdev = mtk_clk_parent_get_provider(gate->flags);
+	if (IS_ERR(pdev))
+		return -ENOENT;
+
+	return mtk_clk_find_parent_rate(clk, gate->parent, pdev);
 }
 
 #if CONFIG_IS_ENABLED(CMD_CLK)

-- 
2.43.0