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 v4: Documentation (Patches 1/4 and 4/4) now points to the authoritative file in the QEMU source tree for any details related to the "hardware interface" of the fw_cfg device; Only details specific to sysfs (1/4) and DT (4/4) should stay in the kernel docs. Thanks, --Gabriel >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. > >> 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 | 100 +++ Documentation/devicetree/bindings/arm/fw-cfg.txt | 38 +- drivers/firmware/Kconfig | 19 + drivers/firmware/Makefile | 1 + drivers/firmware/qemu_fw_cfg.c | 714 +++++++++++++++++++++ lib/kobject.c | 1 + 6 files changed, 837 insertions(+), 36 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg create mode 100644 drivers/firmware/qemu_fw_cfg.c -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html