[PATCH 4/7] clk: mediatek: add CLK_PARENT_EXT

[David Lechner]

Add support for external clock parent type in MediaTek clock driver to
allow multiple external clock sources.

This is intended to eventually replace CLK_PARENT_XTAL which only allows
a single external clock source. Replacing CLK_PARENT_XTAL is not trivial
since it would required touching all chip-specific drivers. So that is
saved for another day.

Before this change, the only way to add additional external clocks was
to use a clock ID mapping and add the external clock in the fixed clocks
portion of the CLK_PARENT_TOPCKGEN clocks. After this change, such hacks
are no longer necessary and external clocks can be added in a cleaner
way.

Signed-off-by: David Lechner <dlechner at baylibre.com>
---
 drivers/clk/mediatek/clk-mtk.c | 17 +++++++++++++++++
 drivers/clk/mediatek/clk-mtk.h |  8 ++++++--
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/mediatek/clk-mtk.c b/drivers/clk/mediatek/clk-mtk.c
index 3bd9021b9cf..6f7e2144332 100644
--- a/drivers/clk/mediatek/clk-mtk.c
+++ b/drivers/clk/mediatek/clk-mtk.c
@@ -168,6 +168,14 @@ static int mtk_gate_disable(void __iomem *base, const struct mtk_gate *gate)
 	return 0;
 }
 
+static ulong mtk_ext_clock_get_rate(const struct mtk_clk_tree *tree, int id)
+{
+	if (!tree->ext_clk_rates || id >= tree->num_ext_clks)
+		return -ENOENT;
+
+	return tree->ext_clk_rates[id];
+}
+
 /*
  * In case the rate change propagation to parent clocks is undesirable,
  * this function is recursively called to find the parent to calculate
@@ -235,6 +243,8 @@ static ulong mtk_find_parent_rate(struct mtk_clk_priv *priv, struct clk *clk,
 		break;
 	case CLK_PARENT_XTAL:
 		return priv->tree->xtal_rate;
+	case CLK_PARENT_EXT:
+		return mtk_ext_clock_get_rate(priv->tree, parent);
 	default:
 		parent_dev = NULL;
 		break;
@@ -337,6 +347,9 @@ static void mtk_clk_print_parent(const char *prefix, int parent, u32 flags)
 	case CLK_PARENT_XTAL:
 		parent_type_str = "xtal";
 		break;
+	case CLK_PARENT_EXT:
+		parent_type_str = "ext";
+		break;
 	case CLK_PARENT_MIXED:
 		parent_type_str = "mixed";
 		break;
@@ -1027,6 +1040,8 @@ static ulong mtk_infrasys_get_rate(struct clk *clk)
 		 */
 		else if (gate->flags & CLK_PARENT_XTAL)
 			return priv->tree->xtal_rate;
+		else if (gate->flags & CLK_PARENT_EXT)
+			return mtk_ext_clock_get_rate(priv->tree, gate->parent);
 
 		rate = mtk_clk_find_parent_rate(clk, gate->parent, parent);
 	}
@@ -1143,6 +1158,8 @@ static ulong mtk_clk_gate_get_rate(struct clk *clk)
 	 */
 	} else if (gate->flags & CLK_PARENT_XTAL) {
 		return priv->tree->xtal_rate;
+	} else 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);
diff --git a/drivers/clk/mediatek/clk-mtk.h b/drivers/clk/mediatek/clk-mtk.h
index f3d2377aee4..c6874445dbe 100644
--- a/drivers/clk/mediatek/clk-mtk.h
+++ b/drivers/clk/mediatek/clk-mtk.h
@@ -34,12 +34,13 @@
 #define CLK_PARENT_TOPCKGEN		BIT(5)
 #define CLK_PARENT_INFRASYS		BIT(6)
 #define CLK_PARENT_XTAL			BIT(7)
+#define CLK_PARENT_EXT			BIT(8)
 /*
  * For CLK_PARENT_MIXED to correctly work, is required to
  * define in clk_tree flags the clk type using the alias.
  */
-#define CLK_PARENT_MIXED		BIT(8)
-#define CLK_PARENT_MASK			GENMASK(8, 4)
+#define CLK_PARENT_MIXED		BIT(9)
+#define CLK_PARENT_MASK			GENMASK(9, 4)
 
 #define ETHSYS_HIFSYS_RST_CTRL_OFS	0x34
 
@@ -255,6 +256,9 @@ struct mtk_gate {
 struct mtk_clk_tree {
 	unsigned long xtal_rate;
 	unsigned long xtal2_rate;
+	/* External fixed clocks - excluded from mapping. */
+	const ulong *ext_clk_rates;
+	const int num_ext_clks;
 	/*
 	 * Clock IDs may be remapped with an auxiliary table. Enable this by
 	 * defining .id_offs_map and .id_offs_map_size. This is needed e.g. when

-- 
2.43.0