rajamesandClaude Opus 5.5
0e2c60dac3
boards/BRINGUP.md R2/R3, FABRIC-3 SXXXIX. The entry stub cleans the cache over the image, builds an identity map (the image's GiB Normal, the rest Device) and enables MMU and caches at EL2 (or EL1); rpi5_mmu.c makes the devicetree's RAM Normal and the framebuffer uncached. Mailbox waits give up after one second; the buffer is cleaned around the exchange; the framebuffer address goes through dma-ranges, not a Pi 4 mask. New rpi5-rehearsal target runs the native image on QEMU virt at EL2. It found three more that would each have stopped the board: the PL011 shift (mine, c9519173; the host test asserted it), the GIC address not carried through /soc's ranges (new fdt_reg_address(), checked against the real Pi 5 DTB), and no timer IRQ at EL2 (HCR_EL2.IMO/FMO/AMO). Rehearsal: POST 1052 passed, same parity hash as UEFI. Standard acceptance on three ISAs: POST 1052, hash 0x82f4ae7cb2e2d424. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
218 lines
9.7 KiB
C
218 lines
9.7 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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* fdt.h - Minimal flattened-devicetree reader
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*
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* Just enough of the Devicetree Specification v0.4 §5 to pull values out of
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* the blob the UEFI firmware publishes under EFI_DTB_TABLE_GUID, or that a
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* native (non-UEFI) boot entry passes directly. Read-only, no allocation, no
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* tree construction — it walks the structure block each call, which is fine
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* for the handful of boot-time lookups the kernel needs.
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*
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* Deliberately not a general devicetree library. Added for punch-list item
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* 0.3 (riscv64 timebase-frequency); extended (FABRIC-3.md §IV.3/§V.3,
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* 2026-09-04) with node-scoped lookup, for exactly the case this header
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* originally flagged as a future need (item 0.6's aarch64 GIC) plus its
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* real, concrete consumers as of this pass: the Raspberry Pi 5's UART/
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* mailbox register addresses (native boot, no ACPI) and the Milk-V Mars's
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* real PLIC base address (currently hardcoded to QEMU-virt's own value,
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* `arch/riscv64/plic.c`'s own doc comment already warned this isn't
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* assumed stable across configurations).
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*/
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#ifndef STARKERNEL_FDT_H
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#define STARKERNEL_FDT_H
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#include <stdint.h>
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/**
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* @brief Test whether @p fdt points at a valid flattened devicetree.
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*
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* Checks the 0xd00dfeed magic and that the structure and strings blocks lie
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* inside totalsize. Does not validate the token stream.
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*
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* @param fdt Candidate blob; NULL is safe and returns 0.
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* @return 1 if the header is usable, 0 otherwise.
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*/
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int fdt_valid(const void* fdt);
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/**
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* @brief Find the first property with @p name anywhere in the tree.
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*
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* Scans the structure block in document order and returns the first match
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* regardless of which node it belongs to. That is sufficient for properties
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* which are uniform across a machine (timebase-frequency being the case this
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* was written for) and is *not* sufficient for anything node-scoped.
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*
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* @param fdt Blob, already checked with @c fdt_valid().
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* @param name Property name, NUL-terminated.
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* @param len_out Receives the property length in bytes; may be NULL.
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* @return Pointer to the property value inside @p fdt, or NULL if not found.
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* The value is big-endian as stored in the blob.
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*/
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const void* fdt_find_prop(const void* fdt, const char* name, uint32_t* len_out);
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/**
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* @brief Read a single-cell (32-bit) property by name.
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*
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* Convenience over @c fdt_find_prop() that also handles the big-endian
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* conversion. Fails if the property is absent or not exactly 4 bytes.
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*
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* @param fdt Blob, already checked with @c fdt_valid().
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* @param name Property name, NUL-terminated.
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* @param out Receives the host-order value on success; untouched on failure.
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* @return 1 on success, 0 on failure.
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*/
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int fdt_prop_u32(const void* fdt, const char* name, uint32_t* out);
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/**
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* @brief Find the first node whose "compatible" property matches @p compatible.
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*
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* "compatible" is a NUL-separated list of strings (DT spec §2.3.1) — matches
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* if @p compatible equals any one entry in the list, not just the whole
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* property verbatim. Scans the whole tree in document order; the first
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* matching node wins if more than one exists.
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*
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* @param fdt Blob, already checked with @c fdt_valid().
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* @param compatible Compatible string to match, NUL-terminated.
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* @return An opaque handle to the matched node, for use with
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* @c fdt_find_prop_in_node() only (not a raw offset or a pointer
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* to anything else meaningful) — or NULL if no node matches.
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*/
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const void* fdt_find_node_by_compatible(const void* fdt, const char* compatible);
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/**
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* @brief Find the first node whose "device_type" property equals @p type.
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*
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* Some standard nodes (`/memory` per DT spec §3.4) are identified by
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* `device_type`, not `compatible` — unlike `compatible`, `device_type` is a
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* single NUL-terminated string, not a list, so this matches the whole
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* property value rather than scanning entries within it. Scans the whole
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* tree in document order; the first matching node wins if more than one
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* exists.
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*
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* @param fdt Blob, already checked with @c fdt_valid().
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* @param type device_type value to match, NUL-terminated.
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* @return An opaque handle to the matched node, for use with
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* @c fdt_find_prop_in_node() only — or NULL if no node matches.
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*/
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const void* fdt_find_node_by_device_type(const void* fdt, const char* type);
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/**
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* @brief Find the first node whose own name matches @p name.
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*
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* Node names follow the DT spec §2.2.1 `name[@unit-address]` convention —
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* matches if @p name equals the node's name up to (not including) an `@`
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* suffix, or the whole name if there is none. For a singleton node with
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* no unit address (`/reserved-memory` being the concrete case this was
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* added for), this is an exact match. Scans the whole tree in document
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* order; the first matching node wins if more than one exists.
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*
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* @param fdt Blob, already checked with @c fdt_valid().
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* @param name Node name to match, NUL-terminated, no `@` suffix.
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* @return An opaque handle to the matched node, for use with
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* @c fdt_find_prop_in_node() / @c fdt_next_child_node() only —
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* or NULL if no node matches.
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*/
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const void* fdt_find_node_by_name(const void* fdt, const char* name);
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/**
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* @brief Iterate the direct children of one node.
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*
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* Pass @p prev_child as NULL to get the first child; pass a previous
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* result back in to get the next one. Stops (returns NULL) once there are
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* no more children. Skips over each child's own descendants correctly
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* (so a child with grandchildren doesn't confuse the scan), but does not
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* itself descend into them — only direct children of @p parent are ever
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* returned.
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*
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* @param fdt Blob, already checked with @c fdt_valid().
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* @param parent Handle from one of the `fdt_find_node_by_*()`
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* functions.
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* @param prev_child NULL for the first child, or a handle previously
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* returned by this function for @p parent to
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* continue from.
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* @return Handle to the next direct child, for use with
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* @c fdt_find_prop_in_node() / @c fdt_next_child_node() only —
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* or NULL once @p parent's children are exhausted.
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*/
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const void* fdt_next_child_node(const void* fdt, const void* parent,
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const void* prev_child);
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/**
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* @brief Find a property by name, scoped to one node.
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*
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* Like @c fdt_find_prop(), but scans only @p node's own direct properties
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* (as returned by @c fdt_find_node_by_compatible()) — stops at the first
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* child node or the end of @p node's property list, never descends into
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* children, never continues into a sibling. This is the difference that
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* matters for a property name like "reg", which is not unique across the
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* tree the way "timebase-frequency" (the whole reason @c fdt_find_prop()
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* was originally sufficient) happens to be.
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*
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* @param fdt Blob, already checked with @c fdt_valid().
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* @param node Handle from @c fdt_find_node_by_compatible(); NULL is
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* safe and returns NULL (propagates a failed node lookup
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* without a separate caller-side check).
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* @param name Property name, NUL-terminated.
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* @param len_out Receives the property length in bytes; may be NULL.
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* @return Pointer to the property value inside @p fdt, or NULL if not
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* found (or if @p node is NULL). The value is big-endian as
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* stored in the blob.
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*/
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const void* fdt_find_prop_in_node(const void* fdt, const void* node,
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const char* name, uint32_t* len_out);
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/**
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* @brief Is the structure block whole?
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* @c fdt_valid() checks the header; this checks also that the structure
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* block ends with its end token, as a blob that has not been cut short
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* does. A reader that takes a property's absence to mean its default
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* (a UART's "reg-shift") must not be handed half a tree.
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* @return 1 if @p fdt is valid and its structure block ends with FDT_END.
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*/
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int fdt_complete(const void* fdt);
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/**
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* @brief The root node.
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* @param fdt Blob; checked with @c fdt_valid().
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* @return Handle to the root node, for @c fdt_find_child() and
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* @c fdt_find_prop_in_node(), or NULL.
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*/
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const void* fdt_root_node(const void* fdt);
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/**
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* @brief Find a direct child of a node by its whole name.
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* The name is matched exactly, unit address included ("serial@10000000"
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* is not "serial"), and is given with its length so that one component of
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* a path can be passed without copying it. Only @p parent's own children
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* are looked at, never their descendants.
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* @param fdt Blob; checked with @c fdt_valid().
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* @param parent Node handle; NULL is safe and returns NULL.
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* @param name The child's name; need not be NUL-terminated.
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* @param name_len Its length in bytes.
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* @return Handle to the child, or NULL if @p parent has none of that name.
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*/
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const void* fdt_find_child(const void* fdt, const void* parent,
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const char* name, uint32_t name_len);
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/**
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* @brief The CPU's address for entry @p index of the `reg` of the first
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* enabled node compatible with @p compatible (2026-10-14).
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*
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* The entry is read in its parent's #address-cells/#size-cells and carried
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* up through every bus's `ranges` to the root -- an empty `ranges` keeps
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* the address, a bus with no `ranges` has no way up. The Pi 5's GIC, for
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* one, sits at 0x7fff9000 on /soc, which is 0x107fff9000 to the CPU.
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*
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* @return 1 and the address in @p out, or 0 if there is no such node,
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* entry or way up.
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*/
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int fdt_reg_address(const void* fdt, const char* compatible, uint32_t index, uint64_t* out);
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#endif /* STARKERNEL_FDT_H */
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