On Tuesday, June 26, 2018 11:39 PM, Rob Herring wrote:
On Tue, Jun 19, 2018 at 3:27 PM, Daniel Mack <daniel@xxxxxxxxxx> wrote:
In order to fully move battery-supplied devices over to devicetree, the
onewire subsystem must get some updates.
Currently, the w1 bus system works like this. Device families, such as
battery controllers etc, are registered to the w1 core. Once a master
device is probed, it starts scanning the bus. Slave devices that are
revealed through this scan and that match previously registered
families are then registered, and their .add_slave() callback is
invoked.
Some devices, such as the ds2760, use that callback to call
platform_device_alloc() at runtime with a fixed device name to
instanciate their only user. That user does the actual work, while the
slave device merely functions as an I/O proxy. In the user
implementation, the w1 slave device is accessible through
dev->parent.
Looks to me like you are letting the driver structure define the DT
structure. This detail is all irrelevant to DT.
Now, for devicetree environments, this has to change a bit. First, slave
devices need to have a matching table so they can be listed as sub-nodes
of their master bus controller. Second, the core needs to match the
entries in these tables against the sub-nodes of the master node.
These two are trivial to do.
The next question is how the w1 slave device and its user(s) are linked
together. I'm proposing a DT layout with the following example:
onewire {
compatible = "w1-gpio";
w1_slave: slave@0 {
compatible = "maxim,w1-ds2760";
};
};
battery-supply {
compatible = "maxim,ds2760-supply";
w1-slave = <&w1_slave>;
};
This should just be one node and a child of the 1-wire master.
Yeah, you're right. This also makes the patch set much simpler.
Thanks for the feedback - I'll send another round of patches.
Daniel
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