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Carlo Caione c13d23a43e riscv: Add support for hardware stacking / unstacking
Some RISC-V SoCs implement a mechanism for hardware supported stacking /
unstacking of registers during ISR / exceptions. What happens is that on
ISR / exception entry part of the context is automatically saved by the
hardware on the stack without software intervention, and the same part
of the context is restored by the hardware usually on mret.

This is currently not yet supported by Zephyr, where the full context
must be saved by software in the full fledged ESF. This patcheset is
trying to address exactly this case.

At least three things are needed to support in a general fashion this
problem: (1) a way to store in software only the part of the ESF not
already stacked by hardware, (2) a way to restore in software only the
part of the context that is not going to be restored by hardware and (3)
a way to define a custom ESF.

Point (3) is important because the full ESF frame is now composed by a
custom part depending on the hardware (that can choose which register to
stack / unstack and the order they are saved onto the stack) and a part
defined in software for the remaining part of the context.

In this patch a new CONFIG_RISCV_SOC_HAS_ISR_STACKING is introduced that
enables the code path supporting the three points by the mean of three
macros that must be implemented by the user in a soc_stacking.h file:
SOC_ISR_SW_STACKING, SOC_ISR_SW_UNSTACKING and SOC_ISR_STACKING_ESF
(refer to the symbol help for more details).

This is an example of soc_isr_stacking.h for an hardware that doesn't do
any hardware stacking / unstacking but everything is managed in
software:

    #ifndef __SOC_ISR_STACKING
    #define __SOC_ISR_STACKING

    #if !defined(_ASMLANGUAGE)

    #define SOC_ISR_STACKING_ESF_DECLARE \
    	struct __esf { \
    		unsigned long ra; \
    		unsigned long t0; \
    		unsigned long t1; \
    		unsigned long t2; \
    		unsigned long t3; \
    		unsigned long t4; \
    		unsigned long t5; \
    		unsigned long t6; \
    		unsigned long a0; \
    		unsigned long a1; \
    		unsigned long a2; \
    		unsigned long a3; \
    		unsigned long a4; \
    		unsigned long a5; \
    		unsigned long a6; \
    		unsigned long a7; \
    		unsigned long mepc; \
    		unsigned long mstatus; \
    		unsigned long s0; \
    	} __aligned(16)
    #else

    #define SOC_ISR_SW_STACKING \
    	addi sp, sp, -__z_arch_esf_t_SIZEOF; \
    	DO_CALLER_SAVED(sr);

    #define SOC_ISR_SW_UNSTACKING \
    	DO_CALLER_SAVED(lr);

    #endif /* _ASMLANGUAGE */
    #endif /* __SOC_ISR_STACKING */

Signed-off-by: Carlo Caione <ccaione@baylibre.com>
2023-01-09 10:15:07 +01:00
.github scripts: compliance: add support for YAMLLint 2023-01-04 17:29:23 +01:00
arch riscv: Add support for hardware stacking / unstacking 2023-01-09 10:15:07 +01:00
boards boards: arm: b_l072z_lrwan1: Use LSE for RTC source clock 2023-01-09 10:14:35 +01:00
cmake cmake: armfvp: allow for extra arguments 2022-12-29 10:12:33 +01:00
doc doc: application development: adjust creation section hierarchy 2023-01-08 19:51:47 +01:00
drivers drivers: counter: Properly deprecate Kconfig symbols in STM32 RTC driver 2023-01-09 10:14:35 +01:00
dts ITE: dts: it8xxx2: Separate device nodes from it8xxx2.dtsi 2023-01-09 10:14:21 +01:00
include/zephyr riscv: Add support for hardware stacking / unstacking 2023-01-09 10:15:07 +01:00
kernel kernel: resolve static analysis false positives 2023-01-05 18:23:04 +00:00
lib posix: clock: fix seconds calculation 2023-01-04 21:12:58 +01:00
misc misc: generated: update configs.c template with <zephyr/...> prefix 2022-05-09 12:45:29 -04:00
modules modules: hal_nordic: nrf_802154: RNG xor-shift algorithm 2023-01-04 11:44:07 +00:00
samples samples: drivers: adc: add support for RT595 2023-01-08 19:48:54 +01:00
scripts scripts: compliance: add support for YAMLLint 2023-01-04 17:29:23 +01:00
share sysbuild: shared cache variable instead of local scope variable 2022-12-27 12:44:19 +01:00
soc soc: nxp: Add Power Management support for RT5xx 2023-01-04 11:03:42 -06:00
submanifests
subsys Bluetooth: controller: consider host ctrl feature bits in feat exchange 2023-01-08 19:48:38 +01:00
tests tests: drivers: counter: counter_basic_api: src: Fix STM32 RTC device 2023-01-09 10:14:06 +01:00
.checkpatch.conf checkpatch: Remove ext/ from excludes 2022-11-30 12:06:55 -05:00
.clang-format clang-format: enable SpaceBeforeParens option 2022-12-22 15:51:01 +00:00
.codecov.yml yamllint: fix all yamllint comments errors 2023-01-04 01:16:45 +09:00
.editorconfig editorconfig: Improve verbosity 2022-04-28 08:55:39 -04:00
.gitattributes
.gitignore scripts: compliance: Use consistent naming convention 2022-11-21 11:02:39 -05:00
.gitlint
.mailmap
.yamllint scripts: compliance: add support for YAMLLint 2023-01-04 17:29:23 +01:00
CMakeLists.txt linker: kobject: Handle literal section 2023-01-02 11:05:06 +01:00
CODE_OF_CONDUCT.md
CODEOWNERS scripts/utils/migrate_mcumgr_kconfigs.py: Script for migrating MCUmgr 2022-12-22 12:36:34 +01:00
CONTRIBUTING.rst
Kconfig
Kconfig.zephyr Kconfig.zephyr: Update UF2 ID for STM32F4 series 2022-12-22 10:57:49 +01:00
LICENSE
MAINTAINERS.yml MAINTAINERS: add collborators to intel adsp area 2023-01-04 12:16:15 -05:00
README.rst readme: Add support for light/dark modes in the logo 2022-11-18 08:58:59 +01:00
VERSION VERSION: bump to 3.2.99 2022-09-30 13:06:22 -05:00
version.h.in
west.yml manifest: Update TF-M to use upstream patch for MBedTLS build warnings 2023-01-06 22:33:37 +09:00
zephyr-env.cmd
zephyr-env.sh

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The Zephyr Project is a scalable real-time operating system (RTOS) supporting
multiple hardware architectures, optimized for resource constrained devices,
and built with security in mind.

The Zephyr OS is based on a small-footprint kernel designed for use on
resource-constrained systems: from simple embedded environmental sensors and
LED wearables to sophisticated smart watches and IoT wireless gateways.

The Zephyr kernel supports multiple architectures, including ARM (Cortex-A,
Cortex-R, Cortex-M), Intel x86, ARC, Nios II, Tensilica Xtensa, and RISC-V,
SPARC, MIPS, and a large number of `supported boards`_.

.. below included in doc/introduction/introduction.rst


Getting Started
***************

Welcome to Zephyr! See the `Introduction to Zephyr`_ for a high-level overview,
and the documentation's `Getting Started Guide`_ to start developing.

.. start_include_here

Community Support
*****************

Community support is provided via mailing lists and Discord; see the Resources
below for details.

.. _project-resources:

Resources
*********

Here's a quick summary of resources to help you find your way around:

* **Help**: `Asking for Help Tips`_
* **Documentation**: http://docs.zephyrproject.org (`Getting Started Guide`_)
* **Source Code**: https://github.com/zephyrproject-rtos/zephyr is the main
  repository; https://elixir.bootlin.com/zephyr/latest/source contains a
  searchable index
* **Releases**: https://github.com/zephyrproject-rtos/zephyr/releases
* **Samples and example code**: see `Sample and Demo Code Examples`_
* **Mailing Lists**: users@lists.zephyrproject.org and
  devel@lists.zephyrproject.org are the main user and developer mailing lists,
  respectively. You can join the developer's list and search its archives at
  `Zephyr Development mailing list`_. The other `Zephyr mailing list
  subgroups`_ have their own archives and sign-up pages.
* **Nightly CI Build Status**: https://lists.zephyrproject.org/g/builds
  The builds@lists.zephyrproject.org mailing list archives the CI nightly build results.
* **Chat**: Real-time chat happens in Zephyr's Discord Server. Use
  this `Discord Invite`_ to register.
* **Contributing**: see the `Contribution Guide`_
* **Wiki**: `Zephyr GitHub wiki`_
* **Issues**: https://github.com/zephyrproject-rtos/zephyr/issues
* **Security Issues**: Email vulnerabilities@zephyrproject.org to report
  security issues; also see our `Security`_ documentation. Security issues are
  tracked separately at https://zephyrprojectsec.atlassian.net.
* **Zephyr Project Website**: https://zephyrproject.org

.. _Discord Invite: https://chat.zephyrproject.org
.. _supported boards: http://docs.zephyrproject.org/latest/boards/index.html
.. _Zephyr Documentation: http://docs.zephyrproject.org
.. _Introduction to Zephyr: http://docs.zephyrproject.org/latest/introduction/index.html
.. _Getting Started Guide: http://docs.zephyrproject.org/latest/develop/getting_started/index.html
.. _Contribution Guide: http://docs.zephyrproject.org/latest/contribute/index.html
.. _Zephyr GitHub wiki: https://github.com/zephyrproject-rtos/zephyr/wiki
.. _Zephyr Development mailing list: https://lists.zephyrproject.org/g/devel
.. _Zephyr mailing list subgroups: https://lists.zephyrproject.org/g/main/subgroups
.. _Sample and Demo Code Examples: http://docs.zephyrproject.org/latest/samples/index.html
.. _Security: http://docs.zephyrproject.org/latest/security/index.html
.. _Asking for Help Tips: https://docs.zephyrproject.org/latest/develop/getting_started/index.html#asking-for-help