[PATCH v4 01/11] clk: at91: rework main clk implementation

AT91 main clk is a clk multiplexer and not a simple fixed rate clk as currently implemented. In some SoCs (sam9x5, sama5, sam9g45 families) this multiplexer can choose among 2 sources: an internal RC oscillator circuit and an oscillator using an external crystal. In other Socs (sam9260, rm9200

[PATCH v4 01/11] clk: at91: rework main clk implementation

AT91 main clk is a clk multiplexer and not a simple fixed rate clk as currently implemented. In some SoCs (sam9x5, sama5, sam9g45 families) this multiplexer can choose among 2 sources: an internal RC oscillator circuit and an oscillator using an external crystal. In other Socs (sam9260, rm9200