Messages in this thread | | | From | Linus Walleij <> | Date | Fri, 3 Feb 2017 14:51:15 +0100 | Subject | Re: [PATCH 4/6] bus: add driver for the Technologic Systems NBUS |
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On Wed, Feb 1, 2017 at 8:56 PM, Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com> wrote: > On 12/30/2016 02:58 AM, Linus Walleij wrote:
>>> +static struct ts_nbus *ts_nbus; >> >> Nopes. No singletons please. >> >> Use the state container pattern: >> Documentation/driver-model/design-patterns.txt > > I understand the idea but have problem to find a good way to implement it. > > Other drivers using the NBUS which are child nodes in the device tree > will use the ts_nbus_write() and ts_nbus_read() functions, it means these > drivers should have a pointer to the allocated ts_nbus and pass it to > the write() and read() functions as an argument if i'm not using a > singleton here. > But i'm lacking knowledge on how to properly share this pointer when > initializing the NBUS driver with the child nodes.
Your child nodes I guess will be instatiated as devices as well.
These devices will have the NBUS driver as .parent in their struct device I guess. Else the design of this bus is tilted.
If the NBUS driver use dev_set_drvdata(dev, state_container_cookie) the children can use dev_get_drvdata(dev->parent); to get a pointer to the same cookie.
The subdrivers don't even need to know the members of the state container as long as you're just passing a pointer to it. It's enough if you forward-declare it as a "pointer to some struct":
struct foo;
{ struct foo *fooptr = dev_get_drvdata(dev->parent); write(fooptr, 0x10);
etc
Yours, Linus Walleij
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