From: "Gabriel Somlo" <somlo@xxxxxxx>
Allow access to QEMU firmware blobs, passed into the guest VM via
the fw_cfg device, through SysFS entries. Blob meta-data (e.g. name,
size, and fw_cfg key), as well as the raw binary blob data may be
accessed.
The SysFS access location is /sys/firmware/qemu_fw_cfg/... and was
selected based on overall similarity to the type of information
exposed under /sys/firmware/dmi/entries/...
New (since v3):
Patch 1/4: Device probing now works with either ACPI, DT, or
optionally by manually specifying a base, size, and
register offsets on the command line. This way, all
architectures offering fw_cfg can be supported, although
x86 and ARM get *automatic* support via ACPI and/or DT.
HUGE thanks to Laszlo Ersek <lersek@xxxxxxxxxx> for
pointing out drivers/virtio/virtio_mmio.c, as an example
on how to pull this off !!!
Stefan: I saw Marc's DMA patches to fw_cfg. Since only
x86 and ARM will support it starting with QEMU 2.5, and
since I expect to get lots of otherwise interesting (but
otherwise orthogonal) feedback on this series, I'd like
to stick with ioread8() across the board for now. We can
always patch in DMA support in a backward compatible way
later, once this series gets (hopefully) accepted :)
Patch 2/4: (was 3/4 in v3): unchanged. Exports kset_find_obj() so
modules can call it.
Patch 3/4: (was 4/4 in v3): rebased, but otherwise the same.
Essentially, creates a "human readable" directory
hierarchy from "path-like" tokens making up fw_cfg
blob names. I'm not really sure there's a way to make
this happen via udev rules, but I have at least one
potential use case for doing it *before* udev becomes
available (cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>),
so I'd be happy to leave this functionality in the
kernel module. See further below for an illustration
of this.
Patch 4/4: Updates the existing ARM DT documentation for fw_cfg,
mainly by pointing at the more comprehensive document
introduced with Patch 1/4 for details on the fw_cfg
device interface, leaving only the specific ARM/DT
address/size node information in place.
Thanks much,
--Gabriel
> In addition to the "by_key" blob listing, e.g.:
>
> $ tree /sys/firmware/qemu_fw_cfg/
> /sys/firmware/qemu_fw_cfg/
> |-- by_key
> | |-- 32
> | | |-- key
> | | |-- name ("etc/boot-fail-wait")
> | | |-- raw
> | | `-- size
> | |-- 33
> | | |-- key
> | | |-- name ("etc/smbios/smbios-tables")
> | | |-- raw
> | | `-- size
> | |-- 34
> | | |-- key
> | | |-- name ("etc/smbios/smbios-anchor")
> | | |-- raw
> | | `-- size
> | |-- 35
> | | |-- key
> | | |-- name ("etc/e820")
> | | |-- raw
> | | `-- size
> | |-- 36
> | | |-- key
> | | |-- name ("genroms/kvmvapic.bin")
> | | |-- raw
> | | `-- size
> | |-- 37
> | | |-- key
> | | |-- name ("etc/system-states")
> | | |-- raw
> | | `-- size
> | |-- 38
> | | |-- key
> | | |-- name ("etc/acpi/tables")
> | | |-- raw
> | | `-- size
> | |-- 39
> | | |-- key
> | | |-- name ("etc/table-loader")
> | | |-- raw
> | | `-- size
> | |-- 40
> | | |-- key
> | | |-- name ("etc/tpm/log")
> | | |-- raw
> | | `-- size
> | |-- 41
> | | |-- key
> | | |-- name ("etc/acpi/rsdp")
> | | |-- raw
> | | `-- size
> | `-- 42
> | |-- key
> | |-- name ("bootorder")
> | |-- raw
> | `-- size
> |
> ...
>
> Patch 3/4 also gets us a "human readable" "by_name" listing, like so:
>
> ...
> |-- by_name
> | |-- bootorder -> ../by_key/42
> | |-- etc
> | | |-- acpi
> | | | |-- rsdp -> ../../../by_key/41
> | | | `-- tables -> ../../../by_key/38
> | | |-- boot-fail-wait -> ../../by_key/32
> | | |-- e820 -> ../../by_key/35
> | | |-- smbios
> | | | |-- smbios-anchor -> ../../../by_key/34
> | | | `-- smbios-tables -> ../../../by_key/33
> | | |-- system-states -> ../../by_key/37
> | | |-- table-loader -> ../../by_key/39
> | | `-- tpm
> | | `-- log -> ../../../by_key/40
> | `-- genroms
> | `-- kvmvapic.bin -> ../../by_key/36
> `-- rev
Gabriel Somlo (4):
firmware: introduce sysfs driver for QEMU's fw_cfg device
kobject: export kset_find_obj() for module use
firmware: create directory hierarchy for sysfs fw_cfg entries
devicetree: update documentation for fw_cfg ARM bindings
.../ABI/testing/sysfs-firmware-qemu_fw_cfg | 240 +++++++
Documentation/devicetree/bindings/arm/fw-cfg.txt | 37 +-
drivers/firmware/Kconfig | 19 +
drivers/firmware/Makefile | 1 +
drivers/firmware/qemu_fw_cfg.c | 714 +++++++++++++++++++++
lib/kobject.c | 1 +
6 files changed, 977 insertions(+), 35 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg
create mode 100644 drivers/firmware/qemu_fw_cfg.c
--
2.4.3
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