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platform: Add generic FDT based platform support

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We add generic FDT based platform support which provides platform
specific functionality based on the FDT passed by previous booting
stage.

By default, the generic FDT platform makes following assumptions:
1. platform FW_TEXT_START is 0x80000000
2. platform features are default
3. platform stack size is default
4. platform has no quirks or work-arounds

The above assumptions (except 1) can be overridden by adding special
platform callbacks which will be called based on the FDT root node
compatible string.

By default, we compile OpenSBI generic platform as follows:
$ make PLATFORM=generic

For a non-standard FW_TEXT_START, we can compile OpenSBI generic
platform as follows:
$ make PLATFORM=generic FW_TEXT_START=<non_standard_text_start>

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
This commit is contained in:
Anup Patel
2020-04-28 09:23:30 +05:30
committed by Anup Patel
parent 4d063538f0
commit f1aa9e54e0
6 changed files with 333 additions and 0 deletions
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42
docs/platform/generic.md Normal file
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@@ -0,0 +1,42 @@
Generic Platform
================
The **Generic** platform is a flattened device tree (FDT) based platform
where all platform specific functionality is provided based on FDT passed
by previous booting stage. The **Generic** platform allows us to use same
OpenSBI firmware binaries on various emulators, simulators, FPGAs, and
boards.
By default, the generic FDT platform makes following assumptions:
1. platform FW_TEXT_START is 0x80000000
2. platform features are default
3. platform stack size is default
4. platform has no quirks or work-arounds
The above assumptions (except 1) can be overridden by adding special platform
callbacks which will be called based on FDT root node compatible string.
Users of the generic FDT platform will have to ensure that:
1. Various FDT based drivers under lib/utils directory are upto date
based on their platform requirements
2. The FDT passed by previous booting stage has DT compatible strings and
DT properties in sync with the FDT based drivers under lib/utils directory
To build the platform-specific library and firmware images, provide the
*PLATFORM=generic* parameter to the top level `make` command.
For custom FW_TEXT_START, we can build the platform-specific library and
firmware images by passing *PLATFORM=generic FW_TEXT_START=<custom_text_start>*
parameter to the top level `make` command.
Platform Options
----------------
The *Generic* platform does not have any platform-specific options.
RISC-V Platforms Using Generic Platform
---------------------------------------
To be added later.

6
docs/platform/platform.md
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@@ -3,6 +3,11 @@ OpenSBI Supported Platforms
OpenSBI currently supports the following virtual and hardware platforms:
* **Generic**: Flattened device tree (FDT) based platform where platform
specific functionality is provided based on the FDT passed by previous
booting stage. More details on this platform can be found in the file
*[generic.md]*.
* **QEMU RISC-V Virt Machine**: Platform support for the QEMU *virt* virtual
RISC-V machine. This virtual machine is intended for RISC-V software
development and tests. More details on this platform can be found in the
@@ -34,6 +39,7 @@ template files for implementing support for a new platform. The *object.mk*,
*config.mk* and *platform.c* template files provides enough comments to
facilitate the implementation.
[generic.md]: generic.md
[qemu_virt.md]: qemu_virt.md
[sifive_fu540.md]: sifive_fu540.md
[fpga-ariane.md]: fpga-ariane.md