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92aed5d6ba
Remove fw_cfg hardware interface details from Documentation/devicetree/bindings/arm/fw-cfg.txt, and replace them with a pointer to the authoritative documentation in the QEMU source tree. Signed-off-by: Gabriel Somlo <somlo@cmu.edu> Cc: Laszlo Ersek <lersek@redhat.com> Acked-by: Rob Herring <robh@kernel.org> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
39 lines
1.1 KiB
Plaintext
39 lines
1.1 KiB
Plaintext
* QEMU Firmware Configuration bindings for ARM
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QEMU's arm-softmmu and aarch64-softmmu emulation / virtualization targets
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provide the following Firmware Configuration interface on the "virt" machine
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type:
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- A write-only, 16-bit wide selector (or control) register,
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- a read-write, 64-bit wide data register.
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QEMU exposes the control and data register to ARM guests as memory mapped
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registers; their location is communicated to the guest's UEFI firmware in the
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DTB that QEMU places at the bottom of the guest's DRAM.
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The authoritative guest-side hardware interface documentation to the fw_cfg
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device can be found in "docs/specs/fw_cfg.txt" in the QEMU source tree.
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Required properties:
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- compatible: "qemu,fw-cfg-mmio".
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- reg: the MMIO region used by the device.
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* Bytes 0x0 to 0x7 cover the data register.
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* Bytes 0x8 to 0x9 cover the selector register.
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* Further registers may be appended to the region in case of future interface
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revisions / feature bits.
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Example:
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/ {
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#size-cells = <0x2>;
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#address-cells = <0x2>;
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fw-cfg@9020000 {
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compatible = "qemu,fw-cfg-mmio";
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reg = <0x0 0x9020000 0x0 0xa>;
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};
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};
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