Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver | Date | Tue, 08 Nov 2016 12:45:20 +0100 |
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On Tuesday, November 8, 2016 11:23:35 AM CET John Garry wrote: > On 07/11/2016 20:08, Arnd Bergmann wrote: > > On Monday, November 7, 2016 2:15:10 PM CET John Garry wrote: > >> > >> Hi Arnd, > >> > >> The new bus type tries to model the djtag in a similar way to I2C/USB > >> driver arch, where we have a host bus adapter and child devices attached > >> to the bus. The child devices are bus driver devices and have bus > >> addresses. We think of the djtag as a separate bus, so we are modelling > >> it as such. > >> > >> The bus driver offers a simple host interface for clients to read/write > >> to the djtag bus: bus accesses are hidden from the client, the host > >> drives the bus. > > > > Ok, in that case we should probably start out by having a bus specific > > DT binding, and separating the description from that of the bus master > > device. > > OK > > > > > I'd suggest requiring #address-cells=<1> and #size-cells=<0> in the master > > node, and listing the children by reg property. If the address is not > > easily expressed as a single integer, use a larger #address-cells value. > > We already have something equivalent to reg in "module-id" (see patch > 02/11), which is the slave device bus address; here's a sample: > + /* For L3 cache PMU */ > + pmul3c0 { > + compatible = "hisilicon,hisi-pmu-l3c-v1"; > + scl-id = <0x02>; > + num-events = <0x16>; > + num-counters = <0x08>; > + module-id = <0x04>; > + num-banks = <0x04>; > + cfgen-map = <0x02 0x04 0x01 0x08>; > + counter-reg = <0x170>; > + evctrl-reg = <0x04>; > + event-en = <0x1000000>; > + evtype-reg = <0x140>; > + }; > > FYI, "module-id" is our own internal hw nomenclature.
Yes, that was my interpretation as well. Please use the standard "reg" property for this then.
> > Another option that we have previously used was to actually pretend that > > a vendor specific bus is an i2c bus and use the i2c probing infrastructure, > > but that only makes sense if the software side closely resembles i2c > > (this was the case for Allwinner I think, but I have not looked at > > your driver in enough detail to know if it is true here as well). > > > > OK, let me check this. By chance do you remember the specific AllWinner > driver/hw?
drivers/i2c/busses/i2c-sun6i-p2wi.c
Arnd
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