On 2016-04-29 11:29, Peter Rosin wrote: > On 2016-04-28 12:39, Crestez Dan Leonard wrote: >> On 04/27/2016 11:39 AM, Peter Rosin wrote: >>> On 2016-04-23 23:32, Jonathan Cameron wrote: >>>> On 20/04/16 18:17, Crestez Dan Leonard wrote: >>>>> The MPU has an auxiliary I2C bus for connecting external >>>>> sensors. This bus has two operating modes: >>>>> * pass-through, which connects the primary and auxiliary busses >>>>> together. This is already supported via an i2c mux. >>>>> * I2C master mode, where the mpu60x0 acts as a master to any external >>>>> connected sensors. This is implemented by this patch. >>>>> >>>>> This I2C master mode also works when the MPU itself is connected via >>>>> SPI. >>>>> >>>>> I2C master supports up to 5 slaves. Slaves 0-3 have a common operating >>>>> mode while slave 4 is different. This patch implements an i2c adapter >>>>> using slave 4 because it has a cleaner interface and it has an >>>>> interrupt that signals when data from slave to master arrived. >>>>> >>>>> Signed-off-by: Crestez Dan Leonard <leonard.crestez@xxxxxxxxx> >>>> This one needs acks from: >>>> >>>> Device tree maintainer (odd binding ;) >>>> Peter Rosin (odd binding interacting with the mux support) >>>> Wolfram (it has a whole i2c master driver in here). >>>> >>>> (just thought I'd list these for the avoidance of doubt). >>> I spot some overlap with the questions in "[RFC] i2c: device-tree: >>> Handling child nodes which are not i2c devices" >>> http://marc.info/?l=linux-i2c&m=146073452819116&w=2 >>> >>> And I think I agree with Stephen Warren that an intermediate placeholder >>> node would make sense. I.e. >>> >>> mpu6050@68 { >>> compatible = "..."; >>> reg = <0x68>; >>> ... >>> i2c-aux-mux { >>> i2c@0 { >>> #address-cells = <1>; >>> #size-cells = <0>; >>> reg = <0>; >>> >>> foo@44 { >>> compatible = "bar"; >>> reg = <0x44>; >>> ... >>> } >>> } >>> } >>> } >>> >>> Or >>> >>> mpu6050@68 { >>> compatible = "..."; >>> reg = <0x68>; >>> ... >>> i2c-aux-master { >>> #address-cells = <1>; >>> #size-cells = <0>; >>> >>> gazonk@44 { >>> compatible = "baz"; >>> reg = <0x44>; >>> ... >>> } >>> } >>> } >>> >>> depending on if you want an aux-mux or an aux-master. >>> >>> But I don't know if that intermediate i2c-aux-mux node causes any >>> problems? >> It's not clear how that would be implemented. It seems to me that right >> now i2c_add_mux_adapter assumes that the parent device is a dedicated >> mux device and all it's children are mux branches. Would this require >> introducing a new "struct device" for the i2c-aux-master node? >> >> It might make sense to make the automatic processing of the parents >> node's of_node optional and let the caller assign the of_node describing >> the attached devices. >> >> I think the most natural solution would be to require child nodes named >> i2c-aux-mux and i2c-aux-master to describe aux devices. For backwards >> compatibility it would be easiest to go with i2c@0/i2c@1 (identified by >> reg=0/1). >> >> But I don't know much about devicetree and I'd rather accept an external >> suggestion. >> > I was thinking that with the new i2c_mux_core in place, it should be pretty simple > to add a hook to point to another node and only use dev->of_node as a default > value for where to look for the mux child adapters? > Or maybe always look for an intermediate "i2c-mux" node and look there if it exists? Something like this (totally untested) on top of the i2c-mux-core cleanup already in next (should be easy to adapt to 4.5 if you want that). Cheers, Peter diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c index 25e9336b0e6e..ff1374f5b4f6 100644 --- a/drivers/i2c/i2c-mux.c +++ b/drivers/i2c/i2c-mux.c @@ -179,10 +179,15 @@ int i2c_mux_add_adapter(struct i2c_mux_core *muxc, * nothing if !CONFIG_OF. */ if (muxc->dev->of_node) { + struct device_node *mux; struct device_node *child; u32 reg; - for_each_child_of_node(muxc->dev->of_node, child) { + mux = of_get_child_by_name(muxc->dev->of_node, "i2c-mux"); + if (!mux) + mux = muxc->dev->of_node; + + for_each_child_of_node(mux, child) { ret = of_property_read_u32(child, "reg", ®); if (ret) continue; -- 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
