On Tue, Feb 11, 2025 at 06:27:58PM +0100, Jerome Brunet wrote: > Add helper functions to create a device on the auxiliary bus. > > This is meant for fairly simple usage of the auxiliary bus, to avoid having > the same code repeated in the different drivers. > > Suggested-by: Stephen Boyd <sboyd@xxxxxxxxxx> > Cc: Arnd Bergmann <arnd@xxxxxxxx> > Signed-off-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx> > --- > drivers/base/auxiliary.c | 88 +++++++++++++++++++++++++++++++++++++++++++ > include/linux/auxiliary_bus.h | 10 +++++ > 2 files changed, 98 insertions(+) I like the idea, see much the same of what I recently did for the "faux" bus here: https://lore.kernel.org/all/2025021023-sandstorm-precise-9f5d@gregkh/ Some review comments: > diff --git a/drivers/base/auxiliary.c b/drivers/base/auxiliary.c > index afa4df4c5a3f371b91d8dd8c4325495d32ad1291..0f697c9c243dc9a50498a52362806db594345faf 100644 > --- a/drivers/base/auxiliary.c > +++ b/drivers/base/auxiliary.c > @@ -385,6 +385,94 @@ void auxiliary_driver_unregister(struct auxiliary_driver *auxdrv) > } > EXPORT_SYMBOL_GPL(auxiliary_driver_unregister); > > +static void auxiliary_device_release(struct device *dev) > +{ > + struct auxiliary_device *auxdev = to_auxiliary_dev(dev); > + > + kfree(auxdev); > +} > + > +static struct auxiliary_device *auxiliary_device_create(struct device *dev, > + const char *modname, > + const char *devname, > + void *platform_data, Can you have the caller set the platform_data if they need/want it after the device is created? Or do you need that in the probe callback? And can't this be a global function too for those that don't want to deal with devm stuff? > + int id) > +{ > + struct auxiliary_device *auxdev; > + int ret; > + > + auxdev = kzalloc(sizeof(*auxdev), GFP_KERNEL); > + if (!auxdev) > + return ERR_PTR(-ENOMEM); Ick, who cares what the error value really is? Why not just do NULL or a valid pointer? That makes the caller much simpler to handle, right? > + > + auxdev->id = id; > + auxdev->name = devname; > + auxdev->dev.parent = dev; > + auxdev->dev.platform_data = platform_data; > + auxdev->dev.release = auxiliary_device_release; > + device_set_of_node_from_dev(&auxdev->dev, dev); > + > + ret = auxiliary_device_init(auxdev); Only way this will fail is if you forgot to set parent or a valid name. So why not check for devname being non-NULL above this? > + if (ret) { > + kfree(auxdev); > + return ERR_PTR(ret); > + } > + > + ret = __auxiliary_device_add(auxdev, modname); > + if (ret) { > + /* > + * NOTE: It may look odd but auxdev should not be freed > + * here. auxiliary_device_uninit() calls device_put() > + * which call the device release function, freeing auxdev. > + */ > + auxiliary_device_uninit(auxdev); Yes it is odd, are you SURE you should be calling device_del() on the device if this fails? auxiliary_device_uninit(), makes sense so why not just call that here? > + return ERR_PTR(ret); > + } > + > + return auxdev; > +} > + > +static void auxiliary_device_destroy(void *_auxdev) > +{ > + struct auxiliary_device *auxdev = _auxdev; > + > + auxiliary_device_delete(auxdev); > + auxiliary_device_uninit(auxdev); > +} > + > +/** > + * __devm_auxiliary_device_create - create a device on the auxiliary bus > + * @dev: parent device > + * @modname: module name used to create the auxiliary driver name. > + * @devname: auxiliary bus device name > + * @platform_data: auxiliary bus device platform data > + * @id: auxiliary bus device id > + * > + * Device managed helper to create an auxiliary bus device. > + * The device create matches driver 'modname.devname' on the auxiliary bus. > + */ > +struct auxiliary_device *__devm_auxiliary_device_create(struct device *dev, > + const char *modname, > + const char *devname, > + void *platform_data, > + int id) > +{ > + struct auxiliary_device *auxdev; > + int ret; > + > + auxdev = auxiliary_device_create(dev, modname, devname, platform_data, id); > + if (IS_ERR(auxdev)) > + return auxdev; > + > + ret = devm_add_action_or_reset(dev, auxiliary_device_destroy, > + auxdev); Oh this is going to be messy, but I trust that callers know what they are doing here. Good luck! :) thanks, greg k-h
