* Freescale i.MX AHCI SATA Controller

The Freescale i.MX SATA controller mostly conforms to the AHCI interface
with some special extensions at integration level.

Required properties:
- compatible : should be one of the following:
   - "fsl,imx53-ahci" for i.MX53 SATA controller
   - "fsl,imx6q-ahci" for i.MX6Q SATA controller
   - "fsl,imx8qm-ahci" for i.MX8QM SATA controller
- interrupts : interrupt mapping for SATA IRQ
- reg : registers mapping
- clocks : list of clock specifiers, must contain an entry for each
  required entry in clock-names
- clock-names : should include "sata", "sata_ref" and "ahb" entries

Optional properties:
- fsl,transmit-level-mV : transmit voltage level, in millivolts.
- fsl,transmit-boost-mdB : transmit boost level, in milli-decibels
- fsl,transmit-atten-16ths : transmit attenuation, in 16ths
- fsl,receive-eq-mdB : receive equalisation, in milli-decibels
  Please refer to the technical documentation or the driver source code
  for the list of legal values for these options.
- fsl,no-spread-spectrum : disable spread-spectrum clocking on the SATA
  link.
- fsl,phy-imp: PHY impedance ratio value refer to the differnt HW design.
  Set it to 0x6c when 85OHM is used, keep it to default value 0x80 when
  100OHM is used.

Examples:

sata@02200000 {
	compatible = "fsl,imx6q-ahci";
	reg = <0x02200000 0x4000>;
	interrupts = <0 39 IRQ_TYPE_LEVEL_HIGH>;
	clocks = <&clks IMX6QDL_CLK_SATA>,
		 <&clks IMX6QDL_CLK_SATA_REF_100M>,
		 <&clks IMX6QDL_CLK_AHB>;
	clock-names = "sata", "sata_ref", "ahb";
};