This patch adds USB capabilities to libpayload. It requires some
memalign implementation (eg. the one I sent yesterday).
Features:
- UHCI controller driver
- UHCI root hub driver
- USB MSC (Mass Storage Class) driver
- skeleton of a USB HID driver
(requires better interrupt transfer handling, which is TODO)
- skeleton of a USB hub driver
(needs several blank spots filled in, eg. power management.
Again: TODO)
OHCI and EHCI are not supported, though OHCI support should be rather
easy as the stack provides reasonable abstractions (or so I hope). EHCI
will probably be more complicated.
Isochronous transfers (eg. webcams, audio stuff, ...) are not supported.
They can be, but I doubt we'll have a reason for that in the boot
environment.
The MSC driver was tested against a couple of USB flash drives, and
should be reasonably tolerant by now. But I probably underestimate
the amount of bugs present in USB flash drives, so feedback is welcome.
Signed-off-by: Patrick Georgi <patrick.georgi@coresystems.de>
Acked-by: Jordan Crouse <jordan.crouse@amd.com>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@3560 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1
diff --git a/payloads/libpayload/drivers/usb/TODO b/payloads/libpayload/drivers/usb/TODO
new file mode 100644
index 0000000..1dfc9d4
--- /dev/null
+++ b/payloads/libpayload/drivers/usb/TODO
@@ -0,0 +1,22 @@
+- handle error conditions
+- handle disconnect more gracefully (ie. make calling layer aware that the device doesn't exist somehow)
+- usbhub:
+ - proper client enumeration (esp. detach)
+ - change detection
+ - power management
+- handle interrupts more cleverly:
+ create a new queue for the interrupt with a couple of TD sequences,
+ - each ending with "breadth first" flag
+ - linked as a chain
+ add that queue at the appropriate times in front of the default structure so the max latency is honored
+ - only one intr chain per framelist item, so it must be arranged appropriately
+ reads from usb device just look at "invalidated" tds and the results they got
+ handled tds get reactivated as a ring structure
+ - added as child of the oldest td
+ - queue header already dropped the td, so no issue there
+
+ this setup ensures that:
+ - the max latency of the device is honored
+ - the client knows the right order of the data
+ - there is no need for an interrupt handler
+ - but must be polled at least max latency * num tds times -> more tds = less time pressure