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b1e5bbd6 GU |
1 | Renesas Bus State Controller (BSC) |
2 | ================================== | |
3 | ||
4 | The Renesas Bus State Controller (BSC, sometimes called "LBSC within Bus | |
5 | Bridge", or "External Bus Interface") can be found in several Renesas ARM SoCs. | |
6 | It provides an external bus for connecting multiple external devices to the | |
7 | SoC, driving several chip select lines, for e.g. NOR FLASH, Ethernet and USB. | |
8 | ||
9 | While the BSC is a fairly simple memory-mapped bus, it may be part of a PM | |
10 | domain, and may have a gateable functional clock. | |
11 | Before a device connected to the BSC can be accessed, the PM domain | |
12 | containing the BSC must be powered on, and the functional clock | |
13 | driving the BSC must be enabled. | |
14 | ||
15 | The bindings for the BSC extend the bindings for "simple-pm-bus". | |
16 | ||
17 | ||
18 | Required properties | |
19 | - compatible: Must contain an SoC-specific value, and "renesas,bsc" and | |
20 | "simple-pm-bus" as fallbacks. | |
21 | SoC-specific values can be: | |
22 | "renesas,bsc-r8a73a4" for R-Mobile APE6 (r8a73a4) | |
23 | "renesas,bsc-sh73a0" for SH-Mobile AG5 (sh73a0) | |
24 | - #address-cells, #size-cells, ranges: Must describe the mapping between | |
25 | parent address and child address spaces. | |
26 | - reg: Must contain the base address and length to access the bus controller. | |
27 | ||
28 | Optional properties: | |
29 | - interrupts: Must contain a reference to the BSC interrupt, if available. | |
30 | - clocks: Must contain a reference to the functional clock, if available. | |
31 | - power-domains: Must contain a reference to the PM domain, if available. | |
32 | ||
33 | ||
34 | Example: | |
35 | ||
36 | bsc: bus@fec10000 { | |
37 | compatible = "renesas,bsc-sh73a0", "renesas,bsc", | |
38 | "simple-pm-bus"; | |
39 | #address-cells = <1>; | |
40 | #size-cells = <1>; | |
41 | ranges = <0 0 0x20000000>; | |
42 | reg = <0xfec10000 0x400>; | |
43 | interrupts = <0 39 IRQ_TYPE_LEVEL_HIGH>; | |
44 | clocks = <&zb_clk>; | |
45 | power-domains = <&pd_a4s>; | |
46 | }; |