ARM Broadcom STB platforms Device Tree Bindings
Boards with Broadcom Brahma15 ARM-based BCMxxxx (generally BCM7xxx variants)
SoC shall have the following DT organization:
Required root node properties:
- compatible: “brcm,bcm
example:
/ {
#address-cells = <2>;
#size-cells = <2>;
model = “Broadcom STB (bcm7445)”;
compatible = “brcm,bcm7445”, “brcm,brcmstb”;
Further, syscon nodes that map platform-specific registers used for general
system control is required:
- compatible: "brcm,bcm<chip_id>-sun-top-ctrl", "syscon"
- compatible: "brcm,bcm<chip_id>-cpu-biu-ctrl",
"brcm,brcmstb-cpu-biu-ctrl",
"syscon"
- compatible: "brcm,bcm<chip_id>-hif-continuation", "syscon"
cpu-biu-ctrl node
SoCs with Broadcom Brahma15 ARM-based and Brahma53 ARM64-based CPUs have a
specific Bus Interface Unit (BIU) block which controls and interfaces the CPU
complex to the different Memory Controller Ports (MCP), one per memory
controller (MEMC). This BIU block offers a feature called Write Pairing which
consists in collapsing two adjacent cache lines into a single (bursted) write
transaction towards the memory controller (MEMC) to maximize write bandwidth.
Required properties:
- compatible: must be "brcm,bcm7445-cpu-biu-ctrl", "brcm,brcmstb-cpu-biu-ctrl", "syscon"
Optional properties:
- brcm,write-pairing:
Boolean property, which when present indicates that the chip
supports write-pairing.
example:
rdb {
#address-cells = <1>;
#size-cells = <1>;
compatible = “simple-bus”;
ranges = <0 0x00 0xf0000000 0x1000000>;
sun_top_ctrl: syscon@404000 {
compatible = "brcm,bcm7445-sun-top-ctrl", "syscon";
reg = <0x404000 0x51c>;
};
hif_cpubiuctrl: syscon@3e2400 {
compatible = "brcm,bcm7445-cpu-biu-ctrl", "brcm,brcmstb-cpu-biu-ctrl", "syscon";
reg = <0x3e2400 0x5b4>;
brcm,write-pairing;
};
hif_continuation: syscon@452000 {
compatible = "brcm,bcm7445-hif-continuation", "syscon";
reg = <0x452000 0x100>;
};
};
Nodes that allow for support of SMP initialization and reboot are required:
smpboot
Required properties:
- compatible
The string "brcm,brcmstb-smpboot".
- syscon-cpu
A phandle / integer array property which lets the BSP know the location
of certain CPU power-on registers.
The layout of the property is as follows:
o a phandle to the "hif_cpubiuctrl" syscon node
o offset to the base CPU power zone register
o offset to the base CPU reset register
- syscon-cont
A phandle pointing to the syscon node which describes the CPU boot
continuation registers.
o a phandle to the "hif_continuation" syscon node
example:
smpboot {
compatible = “brcm,brcmstb-smpboot”;
syscon-cpu = <&hif_cpubiuctrl 0x88 0x178>;
syscon-cont = <&hif_continuation>;
};
reboot
Required properties
- compatible
The string property "brcm,brcmstb-reboot" for 40nm/28nm chips with
the new SYS_CTRL interface, or "brcm,bcm7038-reboot" for 65nm
chips with the old SUN_TOP_CTRL interface.
- syscon
A phandle / integer array that points to the syscon node which describes
the general system reset registers.
o a phandle to "sun_top_ctrl"
o offset to the "reset source enable" register
o offset to the "software master reset" register
example:
reboot {
compatible = “brcm,brcmstb-reboot”;
syscon = <&sun_top_ctrl 0x304 0x308>;
};
Power management
For power management (particularly, S2/S3/S5 system suspend), the following SoC
components are needed:
= Always-On control block (AON CTRL)
This hardware provides control registers for the “always-on” (even in low-power
modes) hardware, such as the Power Management State Machine (PMSM).
Required properties:
- compatible : should contain “brcm,brcmstb-aon-ctrl”
- reg : the register start and length for the AON CTRL block
Example:
aon-ctrl@410000 {
compatible = “brcm,brcmstb-aon-ctrl”;
reg = <0x410000 0x400>;
};
= Memory controllers
A Broadcom STB SoC typically has a number of independent memory controllers,
each of which may have several associated hardware blocks, which are versioned
independently (control registers, DDR PHYs, etc.). One might consider
describing these controllers as a parent “memory controllers” block, which
contains N sub-nodes (one for each controller in the system), each of which is
associated with a number of hardware register resources (e.g., its PHY). See
the example device tree snippet below.
== MEMC (MEMory Controller)
Represents a single memory controller instance.
Required properties:
- compatible : should contain “brcm,brcmstb-memc” and “simple-bus”
Should contain subnodes for any of the following relevant hardware resources:
== DDR PHY control
Control registers for this memory controller’s DDR PHY.
Required properties:
compatible : should contain one of these
“brcm,brcmstb-ddr-phy-v71.1”
“brcm,brcmstb-ddr-phy-v72.0”
“brcm,brcmstb-ddr-phy-v225.1”
“brcm,brcmstb-ddr-phy-v240.1”
“brcm,brcmstb-ddr-phy-v240.2”reg : the DDR PHY register range
== DDR SHIMPHY
Control registers for this memory controller’s DDR SHIMPHY.
Required properties:
- compatible : should contain “brcm,brcmstb-ddr-shimphy-v1.0”
- reg : the DDR SHIMPHY register range
== MEMC DDR control
Sequencer DRAM parameters and control registers. Used for Self-Refresh
Power-Down (SRPD), among other things.
Required properties:
- compatible : should contain one of these
“brcm,brcmstb-memc-ddr-rev-b.2.2”
“brcm,brcmstb-memc-ddr” - reg : the MEMC DDR register range
Example:
memory_controllers {
ranges;
compatible = “simple-bus”;
memc@0 {
compatible = "brcm,brcmstb-memc", "simple-bus";
ranges;
ddr-phy@f1106000 {
compatible = "brcm,brcmstb-ddr-phy-v240.1";
reg = <0xf1106000 0x21c>;
};
shimphy@f1108000 {
compatible = "brcm,brcmstb-ddr-shimphy-v1.0";
reg = <0xf1108000 0xe4>;
};
memc-ddr@f1102000 {
reg = <0xf1102000 0x800>;
compatible = "brcm,brcmstb-memc-ddr";
};
};
memc@1 {
compatible = "brcm,brcmstb-memc", "simple-bus";
ranges;
ddr-phy@f1186000 {
compatible = "brcm,brcmstb-ddr-phy-v240.1";
reg = <0xf1186000 0x21c>;
};
shimphy@f1188000 {
compatible = "brcm,brcmstb-ddr-shimphy-v1.0";
reg = <0xf1188000 0xe4>;
};
memc-ddr@f1182000 {
reg = <0xf1182000 0x800>;
compatible = "brcm,brcmstb-memc-ddr";
};
};
memc@2 {
compatible = "brcm,brcmstb-memc", "simple-bus";
ranges;
ddr-phy@f1206000 {
compatible = "brcm,brcmstb-ddr-phy-v240.1";
reg = <0xf1206000 0x21c>;
};
shimphy@f1208000 {
compatible = "brcm,brcmstb-ddr-shimphy-v1.0";
reg = <0xf1208000 0xe4>;
};
memc-ddr@f1202000 {
reg = <0xf1202000 0x800>;
compatible = "brcm,brcmstb-memc-ddr";
};
};
};
