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-UniPhier System Bus
-
-The UniPhier System Bus is an external bus that connects on-board devices to
-the UniPhier SoC. It is a simple (semi-)parallel bus with address, data, and
-some control signals. It supports up to 8 banks (chip selects).
-
-Before any access to the bus, the bus controller must be configured; the bus
-controller registers provide the control for the translation from the offset
-within each bank to the CPU-viewed address. The needed setup includes the base
-address, the size of each bank. Optionally, some timing parameters can be
-optimized for faster bus access.
-
-Required properties:
-- compatible: should be "socionext,uniphier-system-bus".
-- reg: offset and length of the register set for the bus controller device.
-- #address-cells: should be 2. The first cell is the bank number (chip select).
- The second cell is the address offset within the bank.
-- #size-cells: should be 1.
-- ranges: should provide a proper address translation from the System Bus to
- the parent bus.
-
-Note:
-The address region(s) that can be assigned for the System Bus is implementation
-defined. Some SoCs can use 0x00000000-0x0fffffff and 0x40000000-0x4fffffff,
-while other SoCs can only use 0x40000000-0x4fffffff. There might be additional
-limitations depending on SoCs and the boot mode. The address translation is
-arbitrary as long as the banks are assigned in the supported address space with
-the required alignment and they do not overlap one another.
-For example, it is possible to map:
- bank 0 to 0x42000000-0x43ffffff, bank 5 to 0x46000000-0x46ffffff
-It is also possible to map:
- bank 0 to 0x48000000-0x49ffffff, bank 5 to 0x44000000-0x44ffffff
-There is no reason to stick to a particular translation mapping, but the
-"ranges" property should provide a "reasonable" default that is known to work.
-The software should initialize the bus controller according to it.
-
-Example:
-
- system-bus {
- compatible = "socionext,uniphier-system-bus";
- reg = <0x58c00000 0x400>;
- #address-cells = <2>;
- #size-cells = <1>;
- ranges = <1 0x00000000 0x42000000 0x02000000
- 5 0x00000000 0x46000000 0x01000000>;
-
- ethernet@1,01f00000 {
- compatible = "smsc,lan9115";
- reg = <1 0x01f00000 0x1000>;
- interrupts = <0 48 4>
- phy-mode = "mii";
- };
-
- uart@5,00200000 {
- compatible = "ns16550a";
- reg = <5 0x00200000 0x20>;
- interrupts = <0 49 4>
- clock-frequency = <12288000>;
- };
- };
-
-In this example,
- - the Ethernet device is connected at the offset 0x01f00000 of CS1 and
- mapped to 0x43f00000 of the parent bus.
- - the UART device is connected at the offset 0x00200000 of CS5 and
- mapped to 0x46200000 of the parent bus.