clk: tegra: Add quirk for getting CDEV1/2 clocks on Tegra20

CDEV1 and CDEV2 clocks are a bit special case, their parent clock is
created by the pinctrl driver. It should be possible for clk user to
request these clocks before pinctrl driver got probed and hence user will
get an orphaned clock. That might be undesirable because user may expect
parent clock to be enabled by the child, so let's return -EPROBE_DEFER
till parent clock appears.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/clk/tegra/clk-tegra20.c

@@ -1089,6 +1089,36 @@ static const struct of_device_id pmc_match[] __initconst = {
 	{ },
 };
 
+static struct clk *tegra20_clk_src_onecell_get(struct of_phandle_args *clkspec,
+					       void *data)
+{
+	struct clk_hw *parent_hw;
+	struct clk_hw *hw;
+	struct clk *clk;
+
+	clk = of_clk_src_onecell_get(clkspec, data);
+	if (IS_ERR(clk))
+		return clk;
+
+	/*
+	 * Tegra20 CDEV1 and CDEV2 clocks are a bit special case, their parent
+	 * clock is created by the pinctrl driver. It is possible for clk user
+	 * to request these clocks before pinctrl driver got probed and hence
+	 * user will get an orphaned clock. That might be undesirable because
+	 * user may expect parent clock to be enabled by the child.
+	 */
+	if (clkspec->args[0] == TEGRA20_CLK_CDEV1 ||
+	    clkspec->args[0] == TEGRA20_CLK_CDEV2) {
+		hw = __clk_get_hw(clk);
+
+		parent_hw = clk_hw_get_parent(hw);
+		if (!parent_hw)
+			return ERR_PTR(-EPROBE_DEFER);
+	}
+
+	return clk;
+}
+
 static void __init tegra20_clock_init(struct device_node *np)
 {
 	struct device_node *node;
@@ -1127,7 +1157,7 @@ static void __init tegra20_clock_init(struct device_node *np)
 
 	tegra_init_dup_clks(tegra_clk_duplicates, clks, TEGRA20_CLK_CLK_MAX);
 
-	tegra_add_of_provider(np);
+	tegra_add_of_provider(np, tegra20_clk_src_onecell_get);
 	tegra_register_devclks(devclks, ARRAY_SIZE(devclks));
 
 	tegra_clk_apply_init_table = tegra20_clock_apply_init_table;