// SPDX-License-Identifier: GPL-2.0

//! Rust PCI driver sample (based on QEMU's `pci-testdev`).
//!
//! To make this driver probe, QEMU must be run with `-device pci-testdev`.

use kernel::{c_str, device::Core, devres::Devres, pci, prelude::*, sync::aref::ARef};

struct Regs;

impl Regs {
    const TEST: usize = 0x0;
    const OFFSET: usize = 0x4;
    const DATA: usize = 0x8;
    const COUNT: usize = 0xC;
    const END: usize = 0x10;
}

type Bar0 = pci::Bar<{ Regs::END }>;

#[derive(Copy, Clone, Debug)]
struct TestIndex(u8);

impl TestIndex {
    const NO_EVENTFD: Self = Self(0);
}

#[pin_data(PinnedDrop)]
struct SampleDriver {
    pdev: ARef<pci::Device>,
    #[pin]
    bar: Devres<Bar0>,
    index: TestIndex,
}

kernel::pci_device_table!(
    PCI_TABLE,
    MODULE_PCI_TABLE,
    <SampleDriver as pci::Driver>::IdInfo,
    [(
        pci::DeviceId::from_id(pci::Vendor::REDHAT, 0x5),
        TestIndex::NO_EVENTFD
    )]
);

impl SampleDriver {
    fn testdev(index: &TestIndex, bar: &Bar0) -> Result<u32> {
        // Select the test.
        bar.write8(index.0, Regs::TEST);

        let offset = bar.read32(Regs::OFFSET) as usize;
        let data = bar.read8(Regs::DATA);

        // Write `data` to `offset` to increase `count` by one.
        //
        // Note that we need `try_write8`, since `offset` can't be checked at compile-time.
        bar.try_write8(data, offset)?;

        Ok(bar.read32(Regs::COUNT))
    }
}

impl pci::Driver for SampleDriver {
    type IdInfo = TestIndex;

    const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;

    fn probe(pdev: &pci::Device<Core>, info: &Self::IdInfo) -> Result<Pin<KBox<Self>>> {
        let vendor = pdev.vendor_id();
        dev_dbg!(
            pdev.as_ref(),
            "Probe Rust PCI driver sample (PCI ID: {}, 0x{:x}).\n",
            vendor,
            pdev.device_id()
        );

        pdev.enable_device_mem()?;
        pdev.set_master();

        let drvdata = KBox::pin_init(
            try_pin_init!(Self {
                bar <- pdev.iomap_region_sized::<{ Regs::END }>(0, c_str!("rust_driver_pci")),
                pdev: pdev.into(),
                index: *info,
            }),
            GFP_KERNEL,
        )?;

        let bar = drvdata.bar.access(pdev.as_ref())?;
        dev_info!(
            pdev.as_ref(),
            "pci-testdev data-match count: {}\n",
            Self::testdev(info, bar)?
        );

        Ok(drvdata)
    }

    fn unbind(pdev: &pci::Device<Core>, this: Pin<&Self>) {
        if let Ok(bar) = this.bar.access(pdev.as_ref()) {
            // Reset pci-testdev by writing a new test index.
            bar.write8(this.index.0, Regs::TEST);
        }
    }
}

#[pinned_drop]
impl PinnedDrop for SampleDriver {
    fn drop(self: Pin<&mut Self>) {
        dev_dbg!(self.pdev.as_ref(), "Remove Rust PCI driver sample.\n");
    }
}

kernel::module_pci_driver! {
    type: SampleDriver,
    name: "rust_driver_pci",
    authors: ["Danilo Krummrich"],
    description: "Rust PCI driver",
    license: "GPL v2",
}
