path: root/drivers/gpu/nova-core/vbios.rs

// SPDX-License-Identifier: GPL-2.0

//! VBIOS extraction and parsing.

use core::convert::TryFrom;

use kernel::{
    device,
    prelude::*,
    ptr::{
        Alignable,
        Alignment, //
    },
    transmute::FromBytes,
    types::ARef,
};

use crate::{
    driver::Bar0,
    firmware::{
        fwsec::Bcrt30Rsa3kSignature,
        FalconUCodeDescV3, //
    },
    num::FromSafeCast,
};

/// The offset of the VBIOS ROM in the BAR0 space.
const ROM_OFFSET: usize = 0x300000;
/// The maximum length of the VBIOS ROM to scan into.
const BIOS_MAX_SCAN_LEN: usize = 0x100000;
/// The size to read ahead when parsing initial BIOS image headers.
const BIOS_READ_AHEAD_SIZE: usize = 1024;
/// The bit in the last image indicator byte for the PCI Data Structure that
/// indicates the last image. Bit 0-6 are reserved, bit 7 is last image bit.
const LAST_IMAGE_BIT_MASK: u8 = 0x80;

/// BIOS Image Type from PCI Data Structure code_type field.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u8)]
enum BiosImageType {
    /// PC-AT compatible BIOS image (x86 legacy)
    PciAt = 0x00,
    /// EFI (Extensible Firmware Interface) BIOS image
    Efi = 0x03,
    /// NBSI (Notebook System Information) BIOS image
    Nbsi = 0x70,
    /// FwSec (Firmware Security) BIOS image
    FwSec = 0xE0,
}

impl TryFrom<u8> for BiosImageType {
    type Error = Error;

    fn try_from(code: u8) -> Result<Self> {
        match code {
            0x00 => Ok(Self::PciAt),
            0x03 => Ok(Self::Efi),
            0x70 => Ok(Self::Nbsi),
            0xE0 => Ok(Self::FwSec),
            _ => Err(EINVAL),
        }
    }
}

// PMU lookup table entry types. Used to locate PMU table entries
// in the Fwsec image, corresponding to falcon ucodes.
#[expect(dead_code)]
const FALCON_UCODE_ENTRY_APPID_FIRMWARE_SEC_LIC: u8 = 0x05;
#[expect(dead_code)]
const FALCON_UCODE_ENTRY_APPID_FWSEC_DBG: u8 = 0x45;
const FALCON_UCODE_ENTRY_APPID_FWSEC_PROD: u8 = 0x85;

/// Vbios Reader for constructing the VBIOS data.
struct VbiosIterator<'a> {
    dev: &'a device::Device,
    bar0: &'a Bar0,
    /// VBIOS data vector: As BIOS images are scanned, they are added to this vector for reference
    /// or copying into other data structures. It is the entire scanned contents of the VBIOS which
    /// progressively extends. It is used so that we do not re-read any contents that are already
    /// read as we use the cumulative length read so far, and re-read any gaps as we extend the
    /// length.
    data: KVec<u8>,
    /// Current offset of the [`Iterator`].
    current_offset: usize,
    /// Indicate whether the last image has been found.
    last_found: bool,
}

impl<'a> VbiosIterator<'a> {
    fn new(dev: &'a device::Device, bar0: &'a Bar0) -> Result<Self> {
        Ok(Self {
            dev,
            bar0,
            data: KVec::new(),
            current_offset: 0,
            last_found: false,
        })
    }

    /// Read bytes from the ROM at the current end of the data vector.
    fn read_more(&mut self, len: usize) -> Result {
        let current_len = self.data.len();
        let start = ROM_OFFSET + current_len;

        // Ensure length is a multiple of 4 for 32-bit reads
        if len % core::mem::size_of::<u32>() != 0 {
            dev_err!(
                self.dev,
                "VBIOS read length {} is not a multiple of 4\n",
                len
            );
            return Err(EINVAL);
        }

        self.data.reserve(len, GFP_KERNEL)?;
        // Read ROM data bytes and push directly to `data`.
        for addr in (start..start + len).step_by(core::mem::size_of::<u32>()) {
            // Read 32-bit word from the VBIOS ROM
            let word = self.bar0.try_read32(addr)?;

            // Convert the `u32` to a 4 byte array and push each byte.
            word.to_ne_bytes()
                .