[PATCH rtems-docs] user/bsps: Update ZynqMP for hardware BSPs

[Kinsey Moore]

Update the ZynqMP documentation for the new hardware BSP variants
including information about booting, boot image generation, and
networking.
---
 user/bsps/aarch64/xilinx-zynqmp.rst | 56 ++++++++++++++++++++++++-----
 1 file changed, 48 insertions(+), 8 deletions(-)

diff --git a/user/bsps/aarch64/xilinx-zynqmp.rst b/user/bsps/aarch64/xilinx-zynqmp.rst
index 7401e84..333ce8e 100644
--- a/user/bsps/aarch64/xilinx-zynqmp.rst
+++ b/user/bsps/aarch64/xilinx-zynqmp.rst
@@ -4,19 +4,45 @@
 
 .. _BSP_aarch64_qemu_xilinx_zynqmp_ilp32_qemu:
 .. _BSP_aarch64_qemu_xilinx_zynqmp_lp64_qemu:
+.. _BSP_aarch64_qemu_xilinx_zynqmp_ilp32_zu3eg:
+.. _BSP_aarch64_qemu_xilinx_zynqmp_lp64_zu3eg:
 
 Qemu Xilinx ZynqMP
 ==================
 
-This BSP supports two variants, `xilinx-zynqmp-ilp32-qemu` and
-`xilinx-zynqmp-lp64-qemu`. The basic hardware initialization is performed by the
-BSP. These BSPs support the GICv2 interrupt controller present in all ZynqMP
-systems.
+This BSP supports four variants: `xilinx-zynqmp-ilp32-qemu`,
+`xilinx-zynqmp-lp64-qemu`, `xilinx-zynqmp-ilp32-zu3eg`, and
+`xilinx-zynqmp-lp64-zu3eg`. The basic hardware initialization is performed by
+the BSP. These BSPs support the GICv2 interrupt controller present in all ZynqMP
+systems. The zu3eg BSPs have also been tested to be fully functional on zu2cg
+boards and should also work on any other ZynqMP chip variant since the
+Processing Subsystem (PS) does not vary among chip variants other than the
+number of CPU cores available.
 
-Boot via ELF
+Boot on QEMU
 ------------
 The executable image is booted by Qemu in ELF format.
 
+Boot on ZynqMP Hardware
+-----------------------
+
+On ZynqMP hardware, RTEMS can be started at EL1, EL2, or EL3 by u-boot or
+directly as part of BOOT.bin. Regardless of the exception level at boot, RTEMS
+will drop to EL1 for execution. For quick turnaround during testing, it is
+recommended to use the u-boot BOOT.bin that comes with the PetaLinux prebuilts
+for the board in question.
+
+Hardware Boot Image Generation
+------------------------------
+
+RTEMS expects basic hardware initialization to be performed by ARM Trusted
+Firmware (ATF) as well as the services it provides, so this must be included
+when generating a direct-boot RTEMS BOOT.bin.
+
+When booting via u-boot, RTEMS must be packaged into a u-boot image or booted
+as a raw binary since u-boot does not currently support ELF64 which is required
+for AArch64 ELF binaries.
+
 Clock Driver
 ------------
 
@@ -25,10 +51,24 @@ The clock driver uses the `ARM Generic Timer`.
 Console Driver
 --------------
 
-The console driver supports the default Qemu emulated ARM PL011 PrimeCell UART.
+The console driver supports the default Qemu emulated ARM PL011 PrimeCell UART
+as well as the physical ARM PL011 PrimeCell UART in the ZynqMP hardware.
+
+Network Configuration
+---------------------
+
+When used with LibBSD, these BSP variants support networking via the four
+Cadence GEM instances present on all ZynqMP hardware variants. These are enabled
+using config.inc in LibBSD by setting any of the following constants to 1:
+NET_CFG_ZYNQMP_USE_CGEM0 = 1
+NET_CFG_ZYNQMP_USE_CGEM1 = 1
+NET_CFG_ZYNQMP_USE_CGEM2 = 1
+NET_CFG_ZYNQMP_USE_CGEM3 = 1
+
+Most ZynqMP dev boards use CGEM3. None of the interfaces are enabled by default.
 
-Running Executables
--------------------
+Running Executables on QEMU
+---------------------------
 
 Executables generated by these BSPs can be run using the following command::
 
-- 
2.20.1