mirror of
https://github.com/torvalds/linux.git
synced 2024-11-24 05:02:12 +00:00
e70c412ee4
Devices sometimes have memory where all or parts of it can not be mapped to userspace. But it might still be possible to access this memory from userspace by other means. An example are PCI cards that advertise not only mappable memory but also ioport ranges. On x86 architectures, these can be accessed with ioperm, iopl, inb, outb, and friends. Mike Frysinger (CCed) reported a similar problem on Blackfin arch where it doesn't seem to be easy to mmap non-cached memory but it can still be accessed from userspace. This patch allows kernel drivers to pass information about such ports to userspace. Similar to the existing mem[] array, it adds a port[] array to struct uio_info. Each port range is described by start, size, and porttype. If a driver fills in at least one such port range, the UIO core will simply pass this information to userspace by creating a new directory "portio" underneath /sys/class/uio/uioN/. Similar to the "mem" directory, it will contain a subdirectory (portX) for each port range given. Note that UIO simply passes this information to userspace, it performs no action whatsoever with this data. It's userspace's responsibility to obtain access to these ports and to solve arch dependent issues. The "porttype" attribute tells userspace what kind of port it is dealing with. This mechanism could also be used to give userspace information about GPIOs related to a device. You frequently find such hardware in embedded devices, so I added a UIO_PORT_GPIO definition. I'm not really sure if this is a good idea since there are other solutions to this problem, but it won't hurt much anyway. Signed-off-by: Hans J. Koch <hjk@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
||
|---|---|---|
| .. | ||
| Kconfig | ||
| Makefile | ||
| uio_cif.c | ||
| uio_pdrv_genirq.c | ||
| uio_pdrv.c | ||
| uio_sercos3.c | ||
| uio_smx.c | ||
| uio.c | ||