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Sat, 26 Sep 2026 17:20:46 -0700 (PDT) Received: from tcmichals-5759.lan ([2607:fb91:3584:35a9:66f8:2cb5:aa80:21fd]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-6d8828e1ea0sm838989eaf.6.2026.09.26.17.20.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 26 Sep 2026 17:20:45 -0700 (PDT) From: Tim Michals To: linux-sunxi@lists.linux.dev, linux-remoteproc@vger.kernel.org Cc: devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, wens@kernel.org, jernej.skrabec@gmail.com, samuel@sholland.org, andersson@kernel.org, mathieu.poirier@linaro.org, jassisinghbrar@gmail.com, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, Tim Michals Subject: [PATCH v2 0/7] remoteproc: sunxi: Add Allwinner XuanTie E907 RemoteProc and Message Box support Date: Sat, 26 Sep 2026 19:20:09 -0500 Message-ID: <20260927002021.797069-1-tcmichals@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260922034711.190253-1-tcmichals@gmail.com> References: <20260922034711.190253-1-tcmichals@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260926_172047_806348_91933646 X-CRM114-Status: GOOD ( 15.61 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This patch series (v2) introduces mainline Linux support for the Alibaba T-Head XuanTie E907 (RV32IMAFCX @ 200 MHz) RISC-V auxiliary co-processor integrated into Allwinner A523, A527, and T527 (sun55i) SoCs. The series adds a standalone 4-port hardware Message Box driver, the XuanTie RemoteProc driver, the associated Devicetree binding schemas, in-kernel KUnit unit test suites (68 total tests, 100% pass rate), and DT node enablement. Hardware Architecture & Memory Map ================================== Allwinner sun55i SoCs integrate an octa-core ARM Cortex-A55 cluster alongside an auxiliary XuanTie E907 RISC-V co-processor. The co-processor boots from on-chip dedicated SRAM Space 0 (Host PA 0x07280000 / Core DA 0x3FFC0000, 256 KB), can access secondary switchable SRAM Space 1 (Host PA 0x072C0000 / Core DA 0x40000000, 256 KB), and interacts with external DDR DRAM across the SoC's internal AXI bus. Inter-processor communication (IPC) is coordinated via a 4-port hardware Message Box controller (CPUX_MSGBOX at 0x03003000). The mailbox acts as a star crossbar connecting four processors on the silicon die: - Port 0: ARM Cortex-A55 host cluster - Port 1: Cadence Tensilica HiFi4 Audio DSP - Port 2: Power Management Unit (CPUS) - Port 3: XuanTie E907 RISC-V co-processor The Cortex-A55 exposes 12 logical channels (4 per remote processor), where Channels 8..11 route directly to the XuanTie E907. Changes from RFC v1 to v2 & Responses to Reviewer Feedback ========================================================== 1. Device Tree Binding Schemas (Krzysztof Kozlowski & Rob Herring): - allwinner,sun55i-rproc.yaml: * Constrained 'compatible' from an enum to a single 'const' string: 'allwinner,sun55i-a523-rproc', as A523, A527, and T527 share the same silicon die (per upstream policy). * Replaced inline enum arrays in 'reg-names', 'clock-names', and 'reset-names' with explicit, positional '- const:' lists. * Dropped redundant 'minItems: 2' on 'mboxes' (maxItems: 2 is sufficient). * Replaced '$ref: types.yaml' on 'firmware-name' with 'maxItems: 1'. * Defined 'memory-region' and 'memory-region-names' with explicit items instead of freeform text description. * Dropped redundant 'status: true' (inherited from base schema). * Dropped '|' block literal markers on single-line descriptions. * Replaced symbolic CCU clock/reset macro constants in example with raw hex values so schema validation succeeds in standalone CI trees. - allwinner,sun55i-a523-msgbox.yaml: * Dropped redundant 'minItems: 4' on 'reg'. * Dropped redundant one-line descriptions on 'clocks' and 'resets'. * Clarified 'interrupts': added 'interrupt-names' and explained in description that Port 0 (ARM host) interrupt is mandatory for reception, while remote port interrupts (DSP, CPUS, RV) are optional depending on board routing. - sun55i-a523.dtsi: * Replaced two-string compatible with single const 'allwinner,sun55i-a523-rproc'. * Maintained strictly sorted unit address order for msgbox@3003000 and rproc@7130000. 2. RemoteProc Lifecycle & Teardown Hardening (Bjorn Andersson & Mathieu Poirier): - Moved INIT_WORK(&priv->vq_work) before mbox_request_channel_byname() to eliminate race conditions executing or cancelling uninitialized work structs on early interrupt or probe deferral. - Masked crash IRQ with disable_irq() at the start of sunxi_rproc_remove() to prevent crash interrupts against deleted rproc instances. - Switched async mailbox sends to struct member 'priv->kick_msg' to eliminate stack pointer escape and use-after-free hazards. - In sunxi_rproc_start(), ensured STA_ADD_REG boot vector is written while core execution reset (rst_core) is asserted, guaranteeing deterministic entry at bootaddr upon reset release. - Added integer overflow checking ('len == 0 || da > U64_MAX - len') and defensive memory boundary guards in sunxi_rproc_da_to_va(). - Configured 32-bit DMA coherent mask via dma_set_coherent_mask(). 3. Mailbox Driver Hardening (Jassi Brar): - Added synchronize_irq() across all registered interrupts in sun55i_msgbox_remove() before gating clocks and asserting reset to prevent concurrent bus aborts on unclocked MMIO during teardown. - Added defensive bounds checking in sun55i_chan_to_route() to safely clamp invalid channel indices (< 0 or >= 12). - Bounded all hardirq FIFO drain loops and startup/shutdown flush loops to SUN55I_FIFO_MAX (8 iterations) to eliminate CPU starvation or RCU stalls under coprocessor message flood conditions. - In sun55i_msgbox_irq(), cleared pending interrupt status before reading the message FIFO to seal a TOCTOU race. 4. PREEMPT_RT Real-Time Compliance: - When the E907 announces a new RPMsg channel via Name Service announcement, virtio_rpmsg_bus acquires sleeping mutexes (device_register, blocking_notifier_call_chain). Calling these from hardirq context triggers a fatal "scheduling while atomic" bug under PREEMPT_RT. - The driver implements a workqueue-deferred notification architecture (vq_work), which safely shifts vring processing to a preemptible kernel worker thread, ensuring 100% PREEMPT_RT compliance with zero jitter. 5. Comprehensive In-Kernel KUnit Test Suites (68 Tests): - Added sunxi_rproc_test.c (34 tests) covering da_to_va() translation across Space 0, Space 1, DRAM carveout, and trace buffers, integer wraparound guards, corrupted ELF segments, malformed resource tables, and lifecycle mocks. - Added sun55i_msgbox_test.c (34 tests) covering 12-channel routing formulas, register offset macros, mock MMIO FIFO send/read, bounded drain limits, burst interleaving, crosstalk isolation, and simultaneous 3-route concurrency. - Both test suites execute with 68/68 passed, 0 failed, 0 skipped. Physical Silicon Validation Evidence ==================================== The complete driver series has been rigorously validated on physical silicon using the Radxa Cubie A5E development board (Allwinner A527 / T527) running mainline Linux 7.1.0 PREEMPT_RT across three distinct hardware profiles: Profile 1: Standard Linux VirtIO RPMsg over DDR CMA Carveout - 1,000 pings: 100% success (0 timeouts, 0 corrupted packets). - Latency: 189.70 us avg RTT, 4.83 us jitter. - Throughput: 2,995.5 msgs/sec, 2.83 MB/s bidirectional bandwidth. - DRAM bulk transfer: 4,498.5 msgs/sec, 4.39 MB/sec. Profile 2: Pure On-Chip SRAM Space 1 VirtIO - Vrings and message buffers mapped directly to on-chip SRAM Space 1. - 1,000 pings: 100% success (0 corrupted packets). - Latency: 136.57 us avg RTT. - Throughput: 7,281.8 msgs/sec, 6.89 MB/s bidirectional bandwidth. Profile 3: Userspace UIO Direct Mailbox & Shared SRAM - Hardware mailbox bound to generic-uio with userspace doorbell. - 1,000 pings: 100% success. - Latency: 13.76 us avg RTT (50th percentile: 13.58 us). - Throughput: 65,986.6 msgs/sec, 64.44 MB/sec bidirectional bandwidth. All kernel dmesg logs across all profile reboots and stress benchmarks remained 100% clean of call traces, oopses, and bug warnings. Code Hygiene ============ All patches have been verified with scripts/checkpatch.pl --strict and pass with 0 errors and 0 warnings. Tim Michals (7): dt-bindings: mailbox: add Allwinner sun55i msgbox schema mailbox: sun55i: add Allwinner sun55i/sun60i 4-port Message Box driver mailbox: sun55i: add KUnit test suite for sun55i msgbox driver dt-bindings: remoteproc: add Allwinner sun55i-rproc schema remoteproc: sunxi: add Allwinner XuanTie RISC-V remoteproc driver remoteproc: sunxi: add KUnit test suite for sunxi remoteproc driver arm64: dts: allwinner: add a523 msgbox and remoteproc nodes .../mailbox/allwinner,sun55i-a523-msgbox.yaml | 102 ++ .../remoteproc/allwinner,sun55i-rproc.yaml | 146 +++ .../arm64/boot/dts/allwinner/sun55i-a523.dtsi | 39 + drivers/mailbox/Kconfig | 20 + drivers/mailbox/Makefile | 2 + drivers/mailbox/sun55i-msgbox.c | 375 +++++++ drivers/mailbox/sun55i-msgbox.h | 58 ++ drivers/mailbox/sun55i_msgbox_test.c | 823 ++++++++++++++++ drivers/remoteproc/Kconfig | 18 + drivers/remoteproc/Makefile | 2 + drivers/remoteproc/sunxi_rproc.c | 922 ++++++++++++++++++ drivers/remoteproc/sunxi_rproc.h | 116 +++ drivers/remoteproc/sunxi_rproc_test.c | 701 +++++++++++++ 13 files changed, 3324 insertions(+) create mode 100644 Documentation/devicetree/bindings/mailbox/allwinner,sun55i-a523-msgbox.yaml create mode 100644 Documentation/devicetree/bindings/remoteproc/allwinner,sun55i-rproc.yaml create mode 100644 drivers/mailbox/sun55i-msgbox.c create mode 100644 drivers/mailbox/sun55i-msgbox.h create mode 100644 drivers/mailbox/sun55i_msgbox_test.c create mode 100644 drivers/remoteproc/sunxi_rproc.c create mode 100644 drivers/remoteproc/sunxi_rproc.h create mode 100644 drivers/remoteproc/sunxi_rproc_test.c base-commit: 5c4d4169604b335c38bbc79bc1fc03042981fc6f -- 2.43.0