[PATCH 4/5] docs/system: Document the various MPS2 models

[Peter Maydell <peter.maydell@linaro.org>]

Add basic documentation of the MPS2 board models.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 docs/system/arm/mps2.rst   | 29 +++++++++++++++++++++++++++++
 docs/system/target-arm.rst |  1 +
 MAINTAINERS                |  1 +
 3 files changed, 31 insertions(+)
 create mode 100644 docs/system/arm/mps2.rst

diff --git a/docs/system/arm/mps2.rst b/docs/system/arm/mps2.rst
new file mode 100644
index 00000000000..3a98cb59b0d
--- /dev/null
+++ b/docs/system/arm/mps2.rst
@@ -0,0 +1,29 @@
+Arm MPS2 boards (``mps2-an385``, ``mps2-an505``, ``mps2-an511``, ``mps2-an521``)
+================================================================================
+
+These board models all use Arm M-profile CPUs.
+
+The Arm MPS2 and MPS2+ dev boards are FPGA based (the 2+ has a bigger
+FPGA but is otherwise the same as the 2). Since the CPU itself
+and most of the devices are in the FPGA, the details of the board
+as seen by the guest depend significantly on the FPGA image.
+
+QEMU models the following FPGA images:
+
+``mps2-an385``
+  Cortex-M3 as documented in ARM Application Note AN385
+``mps2-an511``
+  Cortex-M3 'DesignStart' as documented in AN511
+``mps2-an505``
+  Cortex-M33 as documented in ARM Application Note AN505
+``mps2-an521``
+  Dual Cortex-M33 as documented in Application Note AN521
+
+Differences between QEMU and real hardware:
+
+- AN385 remapping of low 16K of memory to either ZBT SSRAM1 or to
+  block RAM is unimplemented (QEMU always maps this to ZBT SSRAM1, as
+  if zbt_boot_ctrl is always zero)
+- QEMU provides a LAN9118 ethernet rather than LAN9220; the only guest
+  visible difference is that the LAN9118 doesn't support checksum
+  offloading
diff --git a/docs/system/target-arm.rst b/docs/system/target-arm.rst
index 4779293d731..15bcf9f81f0 100644
--- a/docs/system/target-arm.rst
+++ b/docs/system/target-arm.rst
@@ -71,6 +71,7 @@ undocumented; you can get a complete list by running
    :maxdepth: 1
 
    arm/integratorcp
+   arm/mps2
    arm/realview
    arm/versatile
    arm/vexpress
diff --git a/MAINTAINERS b/MAINTAINERS
index 74cff1c3818..ea7bdd359e0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -699,6 +699,7 @@ F: hw/misc/armsse-cpuid.c
 F: include/hw/misc/armsse-cpuid.h
 F: hw/misc/armsse-mhu.c
 F: include/hw/misc/armsse-mhu.h
+F: docs/system/arm/mps2.rst
 
 Musca
 M: Peter Maydell <peter.maydell@linaro.org>
-- 
2.20.1