// SPDX-License-Identifier: GPL-2.0

use kernel::{device, devres::Devres, error::code::*, pci, prelude::*};

use crate::driver::Bar0;
use crate::firmware::{Firmware, FIRMWARE_VERSION};
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, Copy, Clone, PartialOrd, Ord, PartialEq, Eq)]
        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
    GA100 = 0x170,
    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::GA100 | 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 = 0x16,
    Ampere = 0x17,
    Ada = 0x19,
}

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

    fn try_from(value: u8) -> Result<Self> {
        match value {
            0x16 => Ok(Self::Turing),
            0x17 => Ok(Self::Ampere),
            0x19 => Ok(Self::Ada),
            _ => Err(ENODEV),
        }
    }
}

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

impl Revision {
    fn from_boot0(boot0: regs::NV_PMC_BOOT_0) -> Self {
        Self {
            major: boot0.major_revision(),
            minor: boot0.minor_revision(),
        }
    }
}

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: &Bar0) -> Result<Spec> {
        let boot0 = regs::NV_PMC_BOOT_0::read(bar);

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

/// 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<device::Bound>,
        devres_bar: Devres<Bar0>,
    ) -> Result<impl PinInit<Self>> {
        let bar = devres_bar.access(pdev.as_ref())?;
        let spec = Spec::new(bar)?;
        let fw = Firmware::new(pdev.as_ref(), spec.chipset, FIRMWARE_VERSION)?;

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

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