Robert Allan JamesandClaude Sonnet 5
a32b0ebcbe
New rpi5_mailbox_get_framebuffer() sends one property-tag request buffer (phys size, virt size, depth, pixel order, virtual offset, allocate-buffer, get-pitch) over the register layout rpi5_dtb.c already discovers, populating an Rpi5FramebufferInfo kept in exact field-for-field sync with uefi.h's FramebufferInfo so console.c/vt100.c/framebuffer.c need no downstream changes once this is wired into a real entry stub. Register offsets (+0x00/+0x18 MBOX0 read/status, +0x20/+0x38 MBOX1 write/status) confirmed against a Pi-5-specific bare-metal reference, independently cross-checked against this codebase's own rpi5_dtb.c translated base address. Caught and fixed a real buffer-overflow bug before compiling: the static request buffer was sized 32 words against an actual 35-word requirement for the 7-tag sequence, recomputed exactly rather than re-estimated; resized to 40 words. Two things flagged as genuinely unverified against real hardware (not guessed past the comment): the allocate-buffer tag's request-size field value, and whether its response address needs classic bus-alias masking on Pi 5 specifically. Compile-only-verified -- no caller yet (that's the still-open entry-stub/DTB constructor items). Verified 3-arch boot to ok>/zuse)ok>. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_019YcT3H2PQeyujrzjqS3Var
69 lines
2.9 KiB
C
69 lines
2.9 KiB
C
/*
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StarForth — Steady-State Virtual Machine Runtime
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Copyright (c) 2023–2025 Robert A. James. All rights reserved.
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Licensed under the StarForth License, Version 1.0.
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*/
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/**
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* rpi5_mailbox.h - VideoCore mailbox property-interface framebuffer
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* setup, for the native (non-UEFI) Raspberry Pi 5 boot path
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* (FABRIC-3.md §IV.3 item 3).
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*
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* Register layout, message/tag format, and property-tag IDs confirmed
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* against multiple sources before writing `rpi5_mailbox.c` — see that
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* file's own doc comment for exactly which, and what (if anything)
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* remains unverified against real hardware (not in hand until
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* 2026-09-17; this driver has never run on real silicon).
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*/
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#ifndef STARKERNEL_RPI5_MAILBOX_H
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#define STARKERNEL_RPI5_MAILBOX_H
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#include <stdint.h>
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/* Mirrors uefi.h's FramebufferInfo exactly -- populated by
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* rpi5_mailbox_get_framebuffer() the same shape UEFI GOP already
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* populates it, so console.c/vt100.c/framebuffer.c need no changes at
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* all for this path. Not #include-ing uefi.h here (that header is a
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* large UEFI-protocol grab-bag; this driver only needs this one
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* struct's shape) -- callers that already have a `FramebufferInfo*`
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* (from uefi.h) can pass it directly, since the two struct
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* definitions are kept in exact field-for-field sync by convention.
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*/
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typedef struct {
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void* base;
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uint64_t size;
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uint32_t width;
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uint32_t height;
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uint32_t pixels_per_scanline;
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uint32_t pixel_format; /* 0 = RGB, matches uefi.h's
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* PixelRedGreenBlueReserved8BitPerColor --
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* this driver always requests RGB pixel
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* order explicitly (tag 0x00048006), never
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* leaves it at hardware/firmware default. */
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} Rpi5FramebufferInfo;
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/**
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* @brief Request a framebuffer from the VideoCore firmware via the
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* mailbox property interface, at the requested resolution/depth.
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*
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* Sends one buffer with all six setup tags (physical size, virtual
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* size, depth, pixel order, virtual offset, allocate) plus a
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* get-pitch tag, in one request/response round trip.
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*
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* @param dtb Devicetree blob (passed to `rpi5_mailbox_base()`).
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* @param width Requested physical+virtual width, pixels.
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* @param height Requested physical+virtual height, pixels.
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* @param bpp Requested bits per pixel (32 is the only depth this
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* driver has been designed against; others are not
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* refused outright but are unverified).
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* @param out Populated on success; untouched on failure.
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* @return 0 on success, negative on failure (mailbox node not found
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* in the DTB, VC firmware rejected the request, or a response
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* tag came back with an unexpected size).
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*/
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int rpi5_mailbox_get_framebuffer(const void* dtb, uint32_t width, uint32_t height,
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uint32_t bpp, Rpi5FramebufferInfo* out);
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#endif /* STARKERNEL_RPI5_MAILBOX_H */
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