On Tue, 06 Dec 2016, Andrew Jeffery wrote: > Signed-off-by: Andrew Jeffery <andrew@xxxxxxxx> Applied with Acks, thanks. > --- > .../devicetree/bindings/mfd/aspeed-lpc.txt | 111 +++++++++++++++++++++ > 1 file changed, 111 insertions(+) > create mode 100644 Documentation/devicetree/bindings/mfd/aspeed-lpc.txt > > diff --git a/Documentation/devicetree/bindings/mfd/aspeed-lpc.txt b/Documentation/devicetree/bindings/mfd/aspeed-lpc.txt > new file mode 100644 > index 000000000000..a97131aba446 > --- /dev/null > +++ b/Documentation/devicetree/bindings/mfd/aspeed-lpc.txt > @@ -0,0 +1,111 @@ > +====================================================================== > +Device tree bindings for the Aspeed Low Pin Count (LPC) Bus Controller > +====================================================================== > + > +The LPC bus is a means to bridge a host CPU to a number of low-bandwidth > +peripheral devices, replacing the use of the ISA bus in the age of PCI[0]. The > +primary use case of the Aspeed LPC controller is as a slave on the bus > +(typically in a Baseboard Management Controller SoC), but under certain > +conditions it can also take the role of bus master. > + > +The LPC controller is represented as a multi-function device to account for the > +mix of functionality it provides. The principle split is between the register > +layout at the start of the I/O space which is, to quote the Aspeed datasheet, > +"basically compatible with the [LPC registers from the] popular BMC controller > +H8S/2168[1]", and everything else, where everything else is an eclectic > +collection of functions with a esoteric register layout. "Everything else", > +here labeled the "host" portion of the controller, includes, but is not limited > +to: > + > +* An IPMI Block Transfer[2] Controller > + > +* An LPC Host Controller: Manages LPC functions such as host vs slave mode, the > + physical properties of some LPC pins, configuration of serial IRQs, and > + APB-to-LPC bridging amonst other functions. > + > +* An LPC Host Interface Controller: Manages functions exposed to the host such > + as LPC firmware hub cycles, configuration of the LPC-to-AHB mapping, UART > + management and bus snoop configuration. > + > +* A set of SuperIO[3] scratch registers: Enables implementation of e.g. custom > + hardware management protocols for handover between the host and baseboard > + management controller. > + > +Additionally the state of the LPC controller influences the pinmux > +configuration, therefore the host portion of the controller is exposed as a > +syscon as a means to arbitrate access. > + > +[0] http://www.intel.com/design/chipsets/industry/25128901.pdf > +[1] https://www.renesas.com/en-sg/doc/products/mpumcu/001/rej09b0078_h8s2168.pdf?key=7c88837454702128622bee53acbda8f4 > +[2] http://www.intel.com/content/dam/www/public/us/en/documents/product-briefs/ipmi-second-gen-interface-spec-v2-rev1-1.pdf > +[3] https://en.wikipedia.org/wiki/Super_I/O > + > +Required properties > +=================== > + > +- compatible: One of: > + "aspeed,ast2400-lpc", "simple-mfd" > + "aspeed,ast2500-lpc", "simple-mfd" > + > +- reg: contains the physical address and length values of the Aspeed > + LPC memory region. > + > +- #address-cells: <1> > +- #size-cells: <1> > +- ranges: Maps 0 to the physical address and length of the LPC memory > + region > + > +Required LPC Child nodes > +======================== > + > +BMC Node > +-------- > + > +- compatible: One of: > + "aspeed,ast2400-lpc-bmc" > + "aspeed,ast2500-lpc-bmc" > + > +- reg: contains the physical address and length values of the > + H8S/2168-compatible LPC controller memory region > + > +Host Node > +--------- > + > +- compatible: One of: > + "aspeed,ast2400-lpc-host", "simple-mfd", "syscon" > + "aspeed,ast2500-lpc-host", "simple-mfd", "syscon" > + > +- reg: contains the address and length values of the host-related > + register space for the Aspeed LPC controller > + > +- #address-cells: <1> > +- #size-cells: <1> > +- ranges: Maps 0 to the address and length of the host-related LPC memory > + region > + > +Example: > + > +lpc: lpc@1e789000 { > + compatible = "aspeed,ast2500-lpc", "simple-mfd"; > + reg = <0x1e789000 0x1000>; > + > + #address-cells = <1>; > + #size-cells = <1>; > + ranges = <0x0 0x1e789000 0x1000>; > + > + lpc_bmc: lpc-bmc@0 { > + compatible = "aspeed,ast2500-lpc-bmc"; > + reg = <0x0 0x80>; > + }; > + > + lpc_host: lpc-host@80 { > + compatible = "aspeed,ast2500-lpc-host", "simple-mfd", "syscon"; > + reg = <0x80 0x1e0>; > + reg-io-width = <4>; > + > + #address-cells = <1>; > + #size-cells = <1>; > + ranges = <0x0 0x80 0x1e0>; > + }; > +}; > + -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
