clk: bcm281xx: define kona clock binding

Broadcom Kona Family Clocks

This binding is associated with Broadcom SoCs having "Kona" style

clock control units (CCUs).  A CCU is a clock provider that manages

a set of clock signals.  Each CCU is represented by a node in the

device tree.

This binding uses the common clock binding:

    Documentation/devicetree/bindings/clock/clock-bindings.txt

Required properties:

- compatible

	Shall have one of the following values:

	- "brcm,bcm11351-root-ccu"

	- "brcm,bcm11351-aon-ccu"

	- "brcm,bcm11351-hub-ccu"

	- "brcm,bcm11351-master-ccu"

	- "brcm,bcm11351-slave-ccu"

- reg

	Shall define the base and range of the address space

	containing clock control registers

- #clock-cells

	Shall have value <1>.  The permitted clock-specifier values

	are defined below.

- clock-output-names

	Shall be an ordered list of strings defining the names of

	the clocks provided by the CCU.

BCM281XX family SoCs use Kona CCUs.  The following table defines

the set of CCUs and clock specifiers for BCM281XX clocks.  When

a clock consumer references a clocks, its symbolic specifier

(rather than its numeric index value) should be used.  These

specifiers are defined in "include/dt-bindings/clock/bcm281xx.h".

    CCU     Clock           Type    Index   Specifier

    ---     -----           ----    -----   ---------

    root    frac_1m         peri      0     BCM281XX_ROOT_CCU_FRAC_1M

    aon     hub_timer       peri      0     BCM281XX_AON_CCU_HUB_TIMER

    aon     pmu_bsc         peri      1     BCM281XX_AON_CCU_PMU_BSC

    aon     pmu_bsc_var     peri      2     BCM281XX_AON_CCU_PMU_BSC_VAR

    hub     tmon_1m         peri      0     BCM281XX_HUB_CCU_TMON_1M

    master  sdio1           peri      0     BCM281XX_MASTER_CCU_SDIO1

    master  sdio2           peri      1     BCM281XX_MASTER_CCU_SDIO2

    master  sdio3           peri      2     BCM281XX_MASTER_CCU_SDIO3

    master  sdio4           peri      3     BCM281XX_MASTER_CCU_SDIO4

    master  dmac            peri      4     BCM281XX_MASTER_CCU_DMAC

    master  usb_ic          peri      5     BCM281XX_MASTER_CCU_USB_IC

    master  hsic2_48m       peri      6     BCM281XX_MASTER_CCU_HSIC_48M

    master  hsic2_12m       peri      7     BCM281XX_MASTER_CCU_HSIC_12M

    slave   uartb           peri      0     BCM281XX_SLAVE_CCU_UARTB

    slave   uartb2          peri      1     BCM281XX_SLAVE_CCU_UARTB2

    slave   uartb3          peri      2     BCM281XX_SLAVE_CCU_UARTB3

    slave   uartb4          peri      3     BCM281XX_SLAVE_CCU_UARTB4

    slave   ssp0            peri      4     BCM281XX_SLAVE_CCU_SSP0

    slave   ssp2            peri      5     BCM281XX_SLAVE_CCU_SSP2

    slave   bsc1            peri      6     BCM281XX_SLAVE_CCU_BSC1

    slave   bsc2            peri      7     BCM281XX_SLAVE_CCU_BSC2

    slave   bsc3            peri      8     BCM281XX_SLAVE_CCU_BSC3

    slave   pwm             peri      9     BCM281XX_SLAVE_CCU_PWM

Device tree example:

	slave_ccu: slave_ccu {

		compatible = "brcm,bcm11351-slave-ccu";

		reg = <0x3e011000 0x0f00>;

		#clock-cells = <1>;

		clock-output-names = "uartb",

				     "uartb2",

				     "uartb3",

				     "uartb4";

	};

	ref_crystal_clk: ref_crystal {

		#clock-cells = <0>;

		compatible = "fixed-clock";

		clock-frequency = <26000000>;

	};

	uart@3e002000 {

		compatible = "brcm,bcm11351-dw-apb-uart", "snps,dw-apb-uart";

		status = "disabled";

		reg = <0x3e002000 0x1000>;

		clocks = <&slave_ccu BCM281XX_SLAVE_CCU_UARTB3>;

		interrupts = <GIC_SPI 65 IRQ_TYPE_LEVEL_HIGH>;

		reg-shift = <2>;

		reg-io-width = <4>;

	};