// SPDX-License-Identifier: GPL-2.0

use kernel::{
    device, devres::Devres, error::code::*, firmware, fmt, pci, prelude::*, str::CString,
};

use crate::driver::Bar0;
use crate::regs;
use crate::util;
use core::fmt;

macro_rules! define_chipset {
    ({ $($variant:ident = $value:expr),* $(,)* }) =>
    {
        /// Enum representation of the GPU chipset.
        #[derive(fmt::Debug)]
        pub(crate) enum Chipset {
            $($variant = $value),*,
        }

        impl Chipset {
            pub(crate) const ALL: &'static [Chipset] = &[
                $( Chipset::$variant, )*
            ];

            pub(crate) const NAMES: [&'static str; Self::ALL.len()] = [
                $( util::const_bytes_to_str(
                        util::to_lowercase_bytes::<{ stringify!($variant).len() }>(
                            stringify!($variant)
                        ).as_slice()
                ), )*
            ];
        }

        // TODO replace with something like derive(FromPrimitive)
        impl TryFrom<u32> for Chipset {
            type Error = kernel::error::Error;

            fn try_from(value: u32) -> Result<Self, Self::Error> {
                match value {
                    $( $value => Ok(Chipset::$variant), )*
                    _ => Err(ENODEV),
                }
            }
        }
    }
}

define_chipset!({
    // Turing
    TU102 = 0x162,
    TU104 = 0x164,
    TU106 = 0x166,
    TU117 = 0x167,
    TU116 = 0x168,
    // Ampere
    GA102 = 0x172,
    GA103 = 0x173,
    GA104 = 0x174,
    GA106 = 0x176,
    GA107 = 0x177,
    // Ada
    AD102 = 0x192,
    AD103 = 0x193,
    AD104 = 0x194,
    AD106 = 0x196,
    AD107 = 0x197,
});

impl Chipset {
    pub(crate) fn arch(&self) -> Architecture {
        match self {
            Self::TU102 | Self::TU104 | Self::TU106 | Self::TU117 | Self::TU116 => {
                Architecture::Turing
            }
            Self::GA102 | Self::GA103 | Self::GA104 | Self::GA106 | Self::GA107 => {
                Architecture::Ampere
            }
            Self::AD102 | Self::AD103 | Self::AD104 | Self::AD106 | Self::AD107 => {
                Architecture::Ada
            }
        }
    }
}

// TODO
//
// The resulting strings are used to generate firmware paths, hence the
// generated strings have to be stable.
//
// Hence, replace with something like strum_macros derive(Display).
//
// For now, redirect to fmt::Debug for convenience.
impl fmt::Display for Chipset {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{:?}", self)
    }
}

/// Enum representation of the GPU generation.
#[derive(fmt::Debug)]
pub(crate) enum Architecture {
    Turing,
    Ampere,
    Ada,
}

pub(crate) struct Revision {
    major: u8,
    minor: u8,
}

impl Revision {
    fn from_boot0(boot0: regs::Boot0) -> Self {
        Self {
            major: boot0.major_rev(),
            minor: boot0.minor_rev(),
        }
    }
}

impl fmt::Display for Revision {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{:x}.{:x}", self.major, self.minor)
    }
}

/// Structure holding the metadata of the GPU.
pub(crate) struct Spec {
    chipset: Chipset,
    /// The revision of the chipset.
    revision: Revision,
}

impl Spec {
    fn new(bar: &Devres<Bar0>) -> Result<Spec> {
        let bar = bar.try_access().ok_or(ENXIO)?;
        let boot0 = regs::Boot0::read(&bar);

        Ok(Self {
            chipset: boot0.chipset().try_into()?,
            revision: Revision::from_boot0(boot0),
        })
    }
}

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

        let request = |name_| {
            CString::try_from_fmt(fmt!("nvidia/{}/gsp/{}-{}.bin", &*chip_name, name_, ver))
                .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 holding the resources required to operate the GPU.
#[pin_data]
pub(crate) struct Gpu {
    spec: Spec,
    /// MMIO mapping of PCI BAR 0
    bar: Devres<Bar0>,
    fw: Firmware,
}

impl Gpu {
    pub(crate) fn new(pdev: &pci::Device, bar: Devres<Bar0>) -> Result<impl PinInit<Self>> {
        let spec = Spec::new(&bar)?;
        let fw = Firmware::new(pdev.as_ref(), &spec, "535.113.01")?;

        dev_info!(
            pdev.as_ref(),
            "NVIDIA (Chipset: {}, Architecture: {:?}, Revision: {})\n",
            spec.chipset,
            spec.chipset.arch(),
            spec.revision
        );

        Ok(pin_init!(Self { spec, bar, fw }))
    }
}