QTechOS/kernel/common/dtb/dtb.cpp

#include "dtb/dtb.h"

#include <opensbi/extensions/legacy.h>
using drivers::opensbi::legacy::console_putchar;

extern void fmt(const char *f, ...);

namespace dtb {
    // TEMP
    void puts(const char *s) {
        while(*s)
            console_putchar(*s++);
    }

    namespace {
        template<typename T>
        inline T bswap(T value) {
            if constexpr(sizeof(T) == 1)
                return value;
            else if constexpr (sizeof(T) == 2)
                return __builtin_bswap16(value);
            else if constexpr (sizeof(T) == 4)
                return __builtin_bswap32(value);
            else if constexpr (sizeof(T) == 8)
                return __builtin_bswap64(value);
            else
                __builtin_trap();
        }

        template<typename T>
        struct big_endian {
            T value() {
                return bswap(m_value);
            }

        private:
            T m_value;
        };

        struct [[gnu::packed]] FdtHeader {
            big_endian<uint32_t> magic;
            big_endian<uint32_t> size;
            big_endian<uint32_t> struct_offset;
            big_endian<uint32_t> strings_offset;
            big_endian<uint32_t> reserved_map_offset;
            big_endian<uint32_t> version;
            big_endian<uint32_t> last_compatible_version;
            big_endian<uint32_t> boot_cpu_id;
            big_endian<uint32_t> strings_size;
            big_endian<uint32_t> struct_size;
        };

        struct [[gnu::packed]] FdtReserveEntry {
            big_endian<uint64_t> address;
            big_endian<uint64_t> size;
        };
    };

    int validate_and_parse_header(DeviceTree &dt, void *base) {
        auto header = reinterpret_cast<FdtHeader *>(base);

        // Make sure the base address is acutally valid
        if(header->magic.value() != 0xD00DFEED) {
            fmt("magic @ {}\n", header);
            fmt("magic is {}\n", header->magic.value());
            puts("Bad magic\n");
            return -1;
        }

        // TODO: I would rather copy all data to pointers we own so I
        // can be sure we have control over it and can remove this pointer
        dt.meta.base = base;

        // Copy metadata and fix it's endianness
        dt.meta.size = header->size.value();
        dt.meta.version = header->version.value();
        dt.meta.last_compatible_version = header->last_compatible_version.value();
        dt.meta.boot_cpu_id = header->boot_cpu_id.value();

        // Calculate other block pointers
        dt.memory_reservation_block =
            reinterpret_cast<char *>(base) + header->reserved_map_offset.value();
        dt.structure_block =
            reinterpret_cast<char *>(base) + header->struct_offset.value();
        dt.strings_block =
            reinterpret_cast<char *>(base) + header->strings_offset.value();

        return 0;
    }

    void print_reserved_regions(DeviceTree dt) {
        auto regions = reinterpret_cast<FdtReserveEntry *>(dt.memory_reservation_block);
        int i = 0;
        fmt("Print mem regions\n");
        while(true) {
            fmt("----- {}\n", i);
            auto region = regions[i++];
            if(region.address.value() == 0 && region.size.value() == 0)
                break;
            fmt("address {}\n", region.address.value());
            fmt("size {}\n", region.size.value());
        }
    }

    void print_structure_block(DeviceTree dt) {
        fmt("is start? {}\n", *(uint32_t *)dt.structure_block);
        puts("asdasd\n");
        puts(((char *)dt.structure_block+4));
        puts("asdasd\n");
        fmt("is start? {}\n", *(uint32_t *)((char *)dt.structure_block+8));
        fmt("is len? {}\n", *(uint32_t *)((char *)dt.structure_block+8+4));
        fmt("is off? {}\n", *(uint32_t *)((char *)dt.structure_block+8+8));
        puts(((char *)((char *)dt.strings_block+0x1d)));
        puts("\n");
    }

}  // End namespace dtb