doc: Add more missing platforms
Add meson-g12a, qemu-sbsa and rpi4 to the documentation index so
that they will have their docs rendered and integrated into the
table of contents.
Change-Id: Id972bf2fee67312dd7bff29f92bea67842e62431
Signed-off-by: Paul Beesley <paul.beesley@arm.com>
diff --git a/docs/plat/qemu-sbsa.rst b/docs/plat/qemu-sbsa.rst
new file mode 100644
index 0000000..51fe414
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+QEMU SBSA Target
+================
+
+Trusted Firmware-A (TF-A) implements the EL3 firmware layer for QEMU SBSA
+Armv8-A. While running Qemu from command line, we need to supply two Flash
+images. First Secure BootRom is supplied by -pflash argument. This Flash image
+is made by EDK2 build system by composing BL1 and FIP. Second parameter for Qemu
+is responsible for Non-secure rom which also given with -pflash argument and
+contains of UEFI and EFI variables (also made by EDK2 build system). Semihosting
+is not used
+
+When QEMU starts all CPUs are released simultaneously, BL1 selects a
+primary CPU to handle the boot and the secondaries are placed in a polling
+loop to be released by normal world via PSCI.
+
+BL2 edits the FDT, generated by QEMU at run-time to add a node describing PSCI
+and also enable methods for the CPUs.
+
+Current limitations:
+
+- Only cold boot is supported
+- No instructions for how to load a BL32 (Secure Payload)
+
+To build TF-A:
+
+::
+
+ git clone https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git tfa
+ cd tfa
+ export CROSS_COMPILE=aarch64-linux-gnu-
+ make PLAT=qemu_sbsa all fip
+
+Images will be placed at build/qemu_sbsa/release (bl1.bin and fip.bin).
+Need to copy them into top directory for EDK2 compilation.
+
+::
+
+ cp build/qemu_sbsa/release/bl1.bin ../
+ cp build/qemu_sbsa/release/fip.bin ../
+
+Those images cannot be used by itself (no semihosing support). Flash images are built by
+EDK2 build system, refer to edk2-platform repo for full build instructions.
+
+::
+
+ git clone https://github.com/tianocore/edk2-platforms.git
+ Platform/Qemu/SbsaQemu/Readme.md
+