[PATCH v7 00/10] usb: early: add support for early printk through USB3 debug port

[Lu Baolu]

Hi,

This patch series adds support for early printk through USB3 debug port.
USB3 debug port is described in xHCI specification as an optional extended
capability.

Patch 1 to 9 add the driver for xHCI debug capability. It interfaces with
the register set and provides the required ops (read/write/control) to upper
layers. Early printk is one consumer of these ops. The hooks for early printk
are introduced in patch 8. This design is similar to what we have done in
drivers/usb/early/ehci-dbgp.c.

Patch 10 is the design document and user guide.

Change log:
v1->v2:
(1) Patch 1 re-implemented. "debugfs" has been replaced with sysfs.
    The scope reduced from all extended capabilities to debug port
    specific.
(2) Patch 11 changed. Removed unnecessary .bulk_out_size setting.

v2->v3:
(1) Patch 11 got acked by Johan Hovold.

v3->v4:
(1) Patch 1 code refactored by using xhci_find_ext_cap_by_id() helper.
(2) Patch 3 "bus hung state" changed to "port hung state" in commit message.
(3) Patch 12 added verified platform information.

v4->v5:
(1) Patch 1 & 3 code refactored by using xhci_find_next_ext_cap() helper.
(2) Patch 12 updated with more user guide information.
(3) All patches rebased to the new usb-next branch which contains commit
    d5ddcdf(xhci: rework xhci extended capability list parsing functions).

v5->v6:
(1) refresh the patches against 4.5-rc1.
(2) change "usb: xhci: dbc" to "usb: dbc" in the patch titles as they
    are not part of xhci driver.

v6->v7:
(1) two patches removed from the patch series. One belongs to xHCI host
    controller driver, and another belongs to usb/serial.
(2) add fix for 0-DAY kernel test warning:
    drivers/usb/early/xhci-dbc.c:917:6-10: WARNING:
    Unsigned expression compared with zero: size > 0
(3) add fix for 0-DAY kernel test error:
    arch/x86/built-in.o: In function `setup_early_printk':
    early_printk.c:(.init.text+0xceba): undefined reference to `early_xdbc_init'
    early_printk.c:(.init.text+0xcec8): undefined reference to `early_xdbc_console'

Lu Baolu (10):
  x86: fixmap: add permanent fixmap for xhci debug port
  usb: dbc: probe and setup xhci debug capability
  usb: dbc: add support for Intel xHCI dbc quirk
  usb: dbc: add debug buffer
  usb: dbc: add bulk out and bulk in interfaces
  usb: dbc: handle dbc-configured exit
  usb: dbc: handle endpoint stall
  x86: early_printk: add USB3 debug port earlyprintk support
  usb: dbc: add handshake between debug target and host
  usb: doc: add document for xHCI DbC driver

 Documentation/kernel-parameters.txt |    1 +
 Documentation/usb/xhci-dbc.txt      |  350 +++++++++
 MAINTAINERS                         |    8 +
 arch/x86/Kconfig.debug              |   14 +
 arch/x86/include/asm/fixmap.h       |    4 +
 arch/x86/kernel/early_printk.c      |    5 +
 drivers/usb/Kconfig                 |    3 +
 drivers/usb/Makefile                |    2 +-
 drivers/usb/early/Makefile          |    1 +
 drivers/usb/early/xhci-dbc.c        | 1394 +++++++++++++++++++++++++++++++++++
 include/linux/usb/xhci-dbc.h        |  224 ++++++
 11 files changed, 2005 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/usb/xhci-dbc.txt
 create mode 100644 drivers/usb/early/xhci-dbc.c
 create mode 100644 include/linux/usb/xhci-dbc.h

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2.1.4