[PATCH v10 03/10] clk: nuvoton: ma35d1: Retrieve HXT/LXT from DT when possible

[Miquel Raynal]

HXT and LXT are crystal oscillator inputs of the clock controller. As
such, they are external clock sources which should not be registered by
this driver.

HXT is already described in the DT, but is not named. In order to point
to this parent from its direct child which is HXT_GATE, we must provide
a fw_name (when it is named, new DTs) and a .name (for when it's not
named, but the fixed clock node name is used).

LXT is missing in old DTs, so we must create that clock and register it
for backward compatibility reasons. It should however be described and
pointed at in updated DTs.

Both HXT and LXT are exposed by this driver only in the backward
compatibility case. Otherwise, both clocks are expected to be retrieved
from the DT.

Fixes: 691521a367cf ("clk: nuvoton: Add clock driver for ma35d1 clock controller")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
---
 drivers/clk/nuvoton/clk-ma35d1.c | 44 +++++++++++++++++++++++++++++++++-------
 1 file changed, 37 insertions(+), 7 deletions(-)

diff --git a/drivers/clk/nuvoton/clk-ma35d1.c b/drivers/clk/nuvoton/clk-ma35d1.c
index 00d635cdb604..33b397d7b7c5 100644
--- a/drivers/clk/nuvoton/clk-ma35d1.c
+++ b/drivers/clk/nuvoton/clk-ma35d1.c
@@ -65,6 +65,14 @@ static DEFINE_SPINLOCK(ma35d1_lock);
 
 #define MA35D1_MUX_MAX_PARENTS	10
 
+static const struct clk_parent_data hxtg_parent_data[] = {
+	{ .fw_name = "hxt", .name = "clk_hxt" },
+};
+
+static const struct clk_parent_data lxtg_parent_data[] = {
+	{ .fw_name = "lxt", .name = "lxt" },
+};
+
 /* Mux parent selection, by index into the controller's clock table */
 static const int ca35clk_parent_idx[] = { HXT, CAPLL, DDRPLL };
 static const int sysclk0_parent_idx[] = { EPLL_DIV2, SYSPLL };
@@ -191,6 +199,15 @@ static struct clk_hw *ma35d1_clk_gate(struct device *dev, const char *name, cons
 				    reg, shift, 0, &ma35d1_lock);
 }
 
+static struct clk_hw *ma35d1_clk_gate_parent_data(struct device *dev, const char *name,
+						  const struct clk_parent_data *parent_data,
+						  void __iomem *reg, u8 shift)
+{
+	return devm_clk_hw_register_gate_parent_data(dev, name, parent_data,
+						     CLK_SET_RATE_PARENT,
+						     reg, shift, 0, &ma35d1_lock);
+}
+
 static int ma35d1_get_pll_setting(struct device_node *clk_node, u32 *pllmode)
 {
 	const char *of_str;
@@ -219,7 +236,7 @@ static int ma35d1_clocks_probe(struct platform_device *pdev)
 	static struct clk_hw **hws;
 	static struct clk_hw_onecell_data *ma35d1_hw_data;
 	u32 pllmode[PLL_MAX_NUM];
-	int ret;
+	int ret, num_clks;
 
 	ma35d1_hw_data = devm_kzalloc(dev,
 				      struct_size(ma35d1_hw_data, hws, MA35D1_CLK_COUNT),
@@ -240,12 +257,25 @@ static int ma35d1_clocks_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	hws[HXT] = ma35d1_clk_fixed("hxt", 24000000);
-	hws[HXT_GATE] = ma35d1_clk_gate(dev, "hxt_gate", "hxt",
-					clk_base + REG_CLK_PWRCTL, 0);
-	hws[LXT] = ma35d1_clk_fixed("lxt", 32768);
-	hws[LXT_GATE] = ma35d1_clk_gate(dev, "lxt_gate", "lxt",
-					clk_base + REG_CLK_PWRCTL, 1);
+	num_clks = of_clk_get_parent_count(clk_node);
+	if (num_clks < 1 || num_clks > 2)
+		return -EINVAL;
+
+	/*
+	 * Old DTs do not describe the low-speed crystal. They may also expect
+	 * an HXT output from this driver. In practice, nobody should use these
+	 * clocks directly, but they must be kept for backward compatility
+	 * purposes.
+	 */
+	if (num_clks == 1) {
+		hws[HXT] = ma35d1_clk_fixed("hxt", 24000000);
+		hws[LXT] = ma35d1_clk_fixed("lxt", 32768);
+	}
+
+	hws[HXT_GATE] = ma35d1_clk_gate_parent_data(dev, "hxt_gate", hxtg_parent_data,
+						    clk_base + REG_CLK_PWRCTL, 0);
+	hws[LXT_GATE] = ma35d1_clk_gate_parent_data(dev, "lxt_gate", lxtg_parent_data,
+						    clk_base + REG_CLK_PWRCTL, 1);
 	hws[HIRC] = ma35d1_clk_fixed("hirc", 12000000);
 	hws[HIRC_GATE] = ma35d1_clk_gate(dev, "hirc_gate", "hirc",
 					 clk_base + REG_CLK_PWRCTL, 2);

-- 
2.55.0