On Fri, Nov 13, 2015 at 10:03:55PM -0500, Gabriel L. Somlo wrote: > From: Gabriel Somlo <somlo@xxxxxxx> > > Remove redundant details from > Documentation/devicetree/bindings/arm/fw-cfg.txt, > and replace them with a pointer to the more comprehensive > fw_cfg documentation privided by > Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg, > leaving the specific ARM DTB node description in place. We generally don't want DT docs to depend on other kernel documentation. That will make separating them harder. > > Signed-off-by: Gabriel Somlo <somlo@xxxxxxx> > Cc: Laszlo Ersek <lersek@xxxxxxxxxx> > --- > Documentation/devicetree/bindings/arm/fw-cfg.txt | 37 ++---------------------- > 1 file changed, 2 insertions(+), 35 deletions(-) > > diff --git a/Documentation/devicetree/bindings/arm/fw-cfg.txt b/Documentation/devicetree/bindings/arm/fw-cfg.txt > index 953fb64..7aeb48a 100644 > --- a/Documentation/devicetree/bindings/arm/fw-cfg.txt > +++ b/Documentation/devicetree/bindings/arm/fw-cfg.txt > @@ -11,43 +11,10 @@ QEMU exposes the control and data register to ARM guests as memory mapped > registers; their location is communicated to the guest's UEFI firmware in the > DTB that QEMU places at the bottom of the guest's DRAM. > > -The guest writes a selector value (a key) to the selector register, and then > -can read the corresponding data (produced by QEMU) via the data register. If > -the selected entry is writable, the guest can rewrite it through the data > -register. > > -The selector register takes keys in big endian byte order. > +For a comprehensive description of the behavior of fw_cfg, please see > +Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg. > > -The data register allows accesses with 8, 16, 32 and 64-bit width (only at > -offset 0 of the register). Accesses larger than a byte are interpreted as > -arrays, bundled together only for better performance. The bytes constituting > -such a word, in increasing address order, correspond to the bytes that would > -have been transferred by byte-wide accesses in chronological order. > - > -The interface allows guest firmware to download various parameters and blobs > -that affect how the firmware works and what tables it installs for the guest > -OS. For example, boot order of devices, ACPI tables, SMBIOS tables, kernel and > -initrd images for direct kernel booting, virtual machine UUID, SMP information, > -virtual NUMA topology, and so on. > - > -The authoritative registry of the valid selector values and their meanings is > -the QEMU source code; the structure of the data blobs corresponding to the > -individual key values is also defined in the QEMU source code. > - > -The presence of the registers can be verified by selecting the "signature" blob > -with key 0x0000, and reading four bytes from the data register. The returned > -signature is "QEMU". > - > -The outermost protocol (involving the write / read sequences of the control and > -data registers) is expected to be versioned, and/or described by feature bits. > -The interface revision / feature bitmap can be retrieved with key 0x0001. The > -blob to be read from the data register has size 4, and it is to be interpreted > -as a uint32_t value in little endian byte order. The current value > -(corresponding to the above outer protocol) is zero. > - > -The guest kernel is not expected to use these registers (although it is > -certainly allowed to); the device tree bindings are documented here because > -this is where device tree bindings reside in general. > > Required properties: > > -- > 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
