[dm][rpmsg] support Remote Processor Messaging (RPMSG)

[GuEe-GUI]

拉取/合并请求描述：(PR description)

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support Remote Processor Messaging, The virtio driver will support in QEMU

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当前拉取/合并请求的状态 Intent for your PR

必须选择一项 Choose one (Mandatory):

• 本拉取/合并请求是一个草稿版本 This PR is for a code-review and is intended to get feedback
• 本拉取/合并请求是一个成熟版本 This PR is mature, and ready to be integrated into the repo

代码质量 Code Quality：

我在这个拉取/合并请求中已经考虑了 As part of this pull request, I've considered the following:

• 已经仔细查看过代码改动的对比 Already check the difference between PR and old code
• 代码风格正确，包括缩进空格，命名及其他风格 Style guide is adhered to, including spacing, naming and other styles
• 没有垃圾代码，代码尽量精简，不包含#if 0代码，不包含已经被注释了的代码 All redundant code is removed and cleaned up
• 所有变更均有原因及合理的，并且不会影响到其他软件组件代码或BSP All modifications are justified and not affect other components or BSP
• 对难懂代码均提供对应的注释 I've commented appropriately where code is tricky
• 代码是高质量的 Code in this PR is of high quality
• 已经使用formatting 等源码格式化工具确保格式符合RT-Thread代码规范 This PR complies with RT-Thread code specification
• 如果是新增bsp, 已经添加ci检查到.github/ALL_BSP_COMPILE.json 详细请参考链接BSP自查

[github-actions]

📌 Code Review Assignment

🏷️ Tag: components

Reviewers: Maihuanyi

Changed Files (Click to expand)

• components/drivers/Kconfig
• components/drivers/include/drivers/rpmsg.h
• components/drivers/include/rtdevice.h
• components/drivers/rpmsg/Kconfig
• components/drivers/rpmsg/SConscript
• components/drivers/rpmsg/rpmsg.c
• components/drivers/rpmsg/rpmsg_char.c
• components/drivers/rpmsg/rpmsg_ns.c

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📊 Current Review Status (Last Updated: 2026-05-09 14:01 CST)

• ⌛ Maihuanyi Pending Review

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📝 Review Instructions

1. 维护者可以通过单击此处来刷新审查状态: 🔄 刷新状态
   Maintainers can refresh the review status by clicking here: 🔄 Refresh Status

2. 确认审核通过后评论 LGTM/lgtm
   Comment LGTM/lgtm after confirming approval

3. PR合并前需至少一位维护者确认
   PR must be confirmed by at least one maintainer before merging

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ℹ️ Refresh CI status operation requires repository Write permission.

[github-actions]

👋 感谢您对 RT-Thread 的贡献！Thank you for your contribution to RT-Thread!

为确保代码符合 RT-Thread 的编码规范，请在你的仓库中执行以下步骤运行代码格式化工作流（如果格式化CI运行失败）。
To ensure your code complies with RT-Thread's coding style, please run the code formatting workflow by following the steps below (If the formatting of CI fails to run).

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🛠 操作步骤 | Steps

1. 前往 Actions 页面 | Go to the Actions page
   点击进入工作流 → | Click to open workflow →

2. 点击 Run workflow | Click Run workflow

• 设置需排除的文件/目录（目录请以"/"结尾）
  Set files/directories to exclude (directories should end with "/")
• 将目标分支设置为 \ Set the target branch to：dm_rpmsg
• 设置PR number为 \ Set the PR number to：11303

3. 等待工作流完成 | Wait for the workflow to complete
   格式化后的代码将自动推送至你的分支。
   The formatted code will be automatically pushed to your branch.

完成后，提交将自动更新至 dm_rpmsg 分支，关联的 Pull Request 也会同步更新。
Once completed, commits will be pushed to the dm_rpmsg branch automatically, and the related Pull Request will be updated.

如有问题欢迎联系我们，再次感谢您的贡献！💐
If you have any questions, feel free to reach out. Thanks again for your contribution!

[Copilot]

Pull request overview

This PR introduces an RPMsg (Remote Processor Messaging) subsystem under RT-Thread’s driver model, aiming to provide endpoint management, name-service handling, and a character-device interface, with an intended VirtIO-based transport for QEMU.

Changes:

• Add RPMsg core bus/device/endpoint APIs (rpmsg.c) and public header (drivers/rpmsg.h).
• Add RPMsg name-service driver (rpmsg_ns.c) and RPMsg char/control device (rpmsg_char.c).
• Add build integration via components/drivers/rpmsg/{Kconfig,SConscript} and hook into components/drivers/Kconfig + rtdevice.h.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 12 comments.

Show a summary per file

File	Description
components/drivers/rpmsg/rpmsg.c	RPMsg bus registration and endpoint lifecycle + send APIs
components/drivers/rpmsg/rpmsg_char.c	RPMsg char/control device implementation with endpoint create/destroy
components/drivers/rpmsg/rpmsg_ns.c	RPMsg name-service message handling and driver registration
components/drivers/rpmsg/rpmsg-rt-thread-virtio.c	Intended VirtIO transport glue for RPMsg over mailbox/shared-memory
components/drivers/rpmsg/SConscript	Build group and source selection for RPMsg module
components/drivers/rpmsg/Kconfig	Kconfig options for enabling RPMsg + char limits + virtio option
components/drivers/include/drivers/rpmsg.h	Public RPMsg API/types exported to the system
components/drivers/include/rtdevice.h	Expose RPMsg header via rtdevice.h when enabled
components/drivers/Kconfig	Adds rpmsg Kconfig entry to drivers menu

[GuEe-GUI]

审核相关问题已经修复 @Rbb666