On 03/11/2011 07:12 PM, Somebody in the thread at some point said:
Hi -
I don't believe I referred to class devices anywhere. It does not
matter if the main chip function is class device or not.
It matters because the class specification for a USB device is never
going to mention information sources that are outside the USB protocol,
such as board definitions. Consequently a class driver will never need
to use such a thing.
Is a gadget driver a class driver? Because I can set the MAC address
for my g_ether from the kernel commandline which is most definitely an
"information source outside the USB protocol". That is exactly the kind
of thing I am talking about enabling also to be taken from
usb_device->dev.platform_data.
Also, do you have a real example of a USB driver today that needs this?
I think you find without devpath -> platform_data mapping, the kind of
layout given above is made quite difficult to support in Linux.
What would be needed to support such a mapping? It seems to me that we
probably have all the necessary ingredients in place already.
What I was imagining is getting the platform data structs from a header
in include/linux/
#include <linux/onboard_device_1.h>
#include <linux/onboard_device_2.h>
Using a .name defined to be the first member to match to specific bus
member devpath prepended with bus class:
struct onboard_device_1_platform_data device_1_platform_data {
.name = "usb\1-0",
.some_feature = 1,
};
struct onboard_device_2_platform_data device_2_platform_data {
.name = "usb\1-1",
.some_feature = 2,
};
Aggregating them into an array
void *devpath_to_platform_data_mapping[] = {
device_1_platform_data,
device_2_platform_data,
};
Registering the array in the machine file
register_platform_data_by_devpath(devpath_to_platform_data_mapping,
ARRAY_SIZE(devpath_to_platform_data_mapping));
It needs to set two globals for pointer and member count
void
register_platform_data_by_devpath(void *map, int count)
{
platform_data_mapping = map;
platform_data_mapping_count = count;
}
Later, when a USB device is instantiated, if platform_data_mapping is
not NULL, it checks to see if the devname it just synthesized matches
any in the table that have static usb/ prefix, and if so, sets
usb_device->dev.platform_data to the table entry.
Well, it's an RFC so if you have a better plan I am all ears.
-Andy
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
