clk: imx: Pass CCM udevice into clk_register_composite()

Pass the clock controller udevice into clk_register_composite(),
so it can be passed further to any registered composite clocks
and used for look up of parent clock referenced in DT "clocks"
and "clock-names" properties by phandle and name pair.

Use the clock controller udevice in imx8m_clk_mux_set_parent()
to perform accurate look up of parent clock referenced in the
CCM driver by name. If the clock name that is being looked up
matches one of the names listed in the clock controller DT node
"clock-names" array property, then the offset of the name is
looked up in the "clocks" DT property and the phandle at that
offset is resolved to the parent clock udevice. The test to
determine whether a particular driver instance registered with
clock uclass matches the parent clock is done by comparing the
OF nodes of the clock registered with clock uclass and parent
clock resolved from the phandle.

Example:

drivers/clk/imx/clk-imx8mm.c:
static const char * const imx8mm_a53_sels[] = {"osc_24m", "arm_pll_out", ...
                                      _____________|
arch/arm/dts/imx8mm.dtsi:            |
clk: clock-controller@30380000 {     v
        clock-names = "osc_32k", "osc_24m", ...
	                           |
				   v
        clocks = <&osc_32k>, <&osc_24m>, ...
};          _______________________|
...        |
/ {        v
        osc_24m: clock-osc-24m {
                compatible = "fixed-clock";
...
};

Signed-off-by: Marek Vasut <[email protected]>
Reported-by: Francesco Dolcini <[email protected]>
Tested-by: Fabio Estevam <[email protected]>
Tested-by: Adam Ford <[email protected]> # imx8mp-beacon

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 5ea2171492e..267757939e0 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -219,6 +219,8 @@ struct clk_composite {
 	const struct clk_ops	*mux_ops;
 	const struct clk_ops	*rate_ops;
 	const struct clk_ops	*gate_ops;
+
+	struct udevice *dev;
 };
 
 #define to_clk_composite(_clk) container_of(_clk, struct clk_composite, clk)