// SPDX-License-Identifier: GPL-2.0

//! Contains structures and functions dedicated to the parsing, building and patching of firmwares
//! to be loaded into a given execution unit.

use core::marker::PhantomData;

use kernel::device;
use kernel::firmware;
use kernel::prelude::*;
use kernel::str::CString;

use crate::dma::DmaObject;
use crate::falcon::FalconFirmware;
use crate::gpu;
use crate::gpu::Chipset;

pub(crate) mod fwsec;

pub(crate) const FIRMWARE_VERSION: &str = "535.113.01";

/// Structure encapsulating the firmware blobs required for the GPU to operate.
#[expect(dead_code)]
pub(crate) struct Firmware {
    booter_load: firmware::Firmware,
    booter_unload: firmware::Firmware,
    bootloader: firmware::Firmware,
    gsp: firmware::Firmware,
}

impl Firmware {
    pub(crate) fn new(dev: &device::Device, chipset: Chipset, ver: &str) -> Result<Firmware> {
        let mut chip_name = CString::try_from_fmt(fmt!("{chipset}"))?;
        chip_name.make_ascii_lowercase();
        let chip_name = &*chip_name;

        let request = |name_| {
            CString::try_from_fmt(fmt!("nvidia/{chip_name}/gsp/{name_}-{ver}.bin"))
                .and_then(|path| firmware::Firmware::request(&path, dev))
        };

        Ok(Firmware {
            booter_load: request("booter_load")?,
            booter_unload: request("booter_unload")?,
            bootloader: request("bootloader")?,
            gsp: request("gsp")?,
        })
    }
}

/// Structure used to describe some firmwares, notably FWSEC-FRTS.
#[repr(C)]
#[derive(Debug, Clone)]
pub(crate) struct FalconUCodeDescV3 {
    /// Header defined by `NV_BIT_FALCON_UCODE_DESC_HEADER_VDESC*` in OpenRM.
    hdr: u32,
    /// Stored size of the ucode after the header.
    stored_size: u32,
    /// Offset in `DMEM` at which the signature is expected to be found.
    pub(crate) pkc_data_offset: u32,
    /// Offset after the code segment at which the app headers are located.
    pub(crate) interface_offset: u32,
    /// Base address at which to load the code segment into `IMEM`.
    pub(crate) imem_phys_base: u32,
    /// Size in bytes of the code to copy into `IMEM`.
    pub(crate) imem_load_size: u32,
    /// Virtual `IMEM` address (i.e. `tag`) at which the code should start.
    pub(crate) imem_virt_base: u32,
    /// Base address at which to load the data segment into `DMEM`.
    pub(crate) dmem_phys_base: u32,
    /// Size in bytes of the data to copy into `DMEM`.
    pub(crate) dmem_load_size: u32,
    /// Mask of the falcon engines on which this firmware can run.
    pub(crate) engine_id_mask: u16,
    /// ID of the ucode used to infer a fuse register to validate the signature.
    pub(crate) ucode_id: u8,
    /// Number of signatures in this firmware.
    pub(crate) signature_count: u8,
    /// Versions of the signatures, used to infer a valid signature to use.
    pub(crate) signature_versions: u16,
    _reserved: u16,
}

impl FalconUCodeDescV3 {
    /// Returns the size in bytes of the header.
    pub(crate) fn size(&self) -> usize {
        const HDR_SIZE_SHIFT: u32 = 16;
        const HDR_SIZE_MASK: u32 = 0xffff0000;

        ((self.hdr & HDR_SIZE_MASK) >> HDR_SIZE_SHIFT) as usize
    }
}

/// Trait implemented by types defining the signed state of a firmware.
trait SignedState {}

/// Type indicating that the firmware must be signed before it can be used.
struct Unsigned;
impl SignedState for Unsigned {}

/// Type indicating that the firmware is signed and ready to be loaded.
struct Signed;
impl SignedState for Signed {}

/// A [`DmaObject`] containing a specific microcode ready to be loaded into a falcon.
///
/// This is module-local and meant for sub-modules to use internally.
///
/// After construction, a firmware is [`Unsigned`], and must generally be patched with a signature
/// before it can be loaded (with an exception for development hardware). The
/// [`Self::patch_signature`] and [`Self::no_patch_signature`] methods are used to transition the
/// firmware to its [`Signed`] state.
struct FirmwareDmaObject<F: FalconFirmware, S: SignedState>(DmaObject, PhantomData<(F, S)>);

/// Trait for signatures to be patched directly into a given firmware.
///
/// This is module-local and meant for sub-modules to use internally.
trait FirmwareSignature<F: FalconFirmware>: AsRef<[u8]> {}

impl<F: FalconFirmware> FirmwareDmaObject<F, Unsigned> {
    /// Patches the firmware at offset `sig_base_img` with `signature`.
    fn patch_signature<S: FirmwareSignature<F>>(
        mut self,
        signature: &S,
        sig_base_img: usize,
    ) -> Result<FirmwareDmaObject<F, Signed>> {
        let signature_bytes = signature.as_ref();
        if sig_base_img + signature_bytes.len() > self.0.size() {
            return Err(EINVAL);
        }

        // SAFETY: We are the only user of this object, so there cannot be any race.
        let dst = unsafe { self.0.start_ptr_mut().add(sig_base_img) };

        // SAFETY: `signature` and `dst` are valid, properly aligned, and do not overlap.
        unsafe {
            core::ptr::copy_nonoverlapping(signature_bytes.as_ptr(), dst, signature_bytes.len())
        };

        Ok(FirmwareDmaObject(self.0, PhantomData))
    }

    /// Mark the firmware as signed without patching it.
    ///
    /// This method is used to explicitly confirm that we do not need to sign the firmware, while
    /// allowing us to continue as if it was. This is typically only needed for development
    /// hardware.
    fn no_patch_signature(self) -> FirmwareDmaObject<F, Signed> {
        FirmwareDmaObject(self.0, PhantomData)
    }
}

pub(crate) struct ModInfoBuilder<const N: usize>(firmware::ModInfoBuilder<N>);

impl<const N: usize> ModInfoBuilder<N> {
    const fn make_entry_file(self, chipset: &str, fw: &str) -> Self {
        ModInfoBuilder(
            self.0
                .new_entry()
                .push("nvidia/")
                .push(chipset)
                .push("/gsp/")
                .push(fw)
                .push("-")
                .push(FIRMWARE_VERSION)
                .push(".bin"),
        )
    }

    const fn make_entry_chipset(self, chipset: &str) -> Self {
        self.make_entry_file(chipset, "booter_load")
            .make_entry_file(chipset, "booter_unload")
            .make_entry_file(chipset, "bootloader")
            .make_entry_file(chipset, "gsp")
    }

    pub(crate) const fn create(
        module_name: &'static kernel::str::CStr,
    ) -> firmware::ModInfoBuilder<N> {
        let mut this = Self(firmware::ModInfoBuilder::new(module_name));
        let mut i = 0;

        while i < gpu::Chipset::NAMES.len() {
            this = this.make_entry_chipset(gpu::Chipset::NAMES[i]);
            i += 1;
        }

        this.0
    }
}