4 - compatible : should be "ti,omap2-uart" for OMAP2 controllers
5 - compatible : should be "ti,omap3-uart" for OMAP3 controllers
6 - compatible : should be "ti,omap4-uart" for OMAP4 controllers
7 - ti,hwmods : Must be "uart<n>", n being the instance number (1-based)
10 - clock-frequency : frequency of the clock input to the UART