[PATCH v6 1/2] drm/tyr: add TyrIrq threaded IRQ wrapper

[Laura Nao]

Introduce a generic TyrIrq threaded IRQ wrapper along with the
TyrIrqTrait trait describing the operations required to handle a
Tyr interrupt source.

Co-developed-by: Daniel Almeida <daniel.almeida@xxxxxxxxxxxxx>
Signed-off-by: Daniel Almeida <daniel.almeida@xxxxxxxxxxxxx>
Co-developed-by: Deborah Brouwer <deborah.brouwer@xxxxxxxxxxxxx>
Signed-off-by: Deborah Brouwer <deborah.brouwer@xxxxxxxxxxxxx>
Signed-off-by: Laura Nao <laura.nao@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/tyr/irq.rs | 115 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/tyr/tyr.rs |   1 +
 2 files changed, 116 insertions(+)

diff --git a/drivers/gpu/drm/tyr/irq.rs b/drivers/gpu/drm/tyr/irq.rs
new file mode 100644
index 000000000000..e6a739532daa
--- /dev/null
+++ b/drivers/gpu/drm/tyr/irq.rs
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0 or MIT
+
+//! Threaded IRQ wrapper shared by all Tyr interrupt sources.
+#![allow(dead_code)]
+use core::marker::PhantomPinned;
+
+use kernel::{
+    device::Bound,
+    irq::{
+        Flags,
+        IrqReturn,
+        ThreadedHandler,
+        ThreadedIrqReturn,
+        ThreadedRegistration, //
+    },
+    platform,
+    prelude::*, //
+};
+
+/// Trait describing the operations required to service a Tyr interrupt source.
+pub(crate) trait TyrIrqTrait: Sync {
+    /// Returns the masked interrupt status.
+    fn read_status(&self) -> u32;
+
+    /// Clears all bits in the mask register, disabling the interrupt sources.
+    fn clear_mask(&self);
+
+    /// Sets the mask register to re-enable the interrupt sources.
+    fn reenable_mask(&self);
+
+    /// Returns the raw interrupt status, regardless of the current mask.
+    fn read_raw_status(&self) -> u32;
+
+    /// Clears the given bits in the interrupt status register.
+    fn clear_status(&self, status: u32);
+
+    /// Returns the bitmask of interrupt sources handled by this instance.
+    fn mask(&self) -> u32;
+
+    /// Handles the given pending, unmasked interrupt bits.
+    fn handle(&self, status: u32);
+}
+
+/// A threaded IRQ wrapper shared by all Tyr interrupt sources.
+#[pin_data]
+pub(crate) struct TyrIrq<T: TyrIrqTrait> {
+    /// The interrupt source.
+    irq: T,
+    #[pin]
+    _pin: PhantomPinned,
+}
+
+impl<T: TyrIrqTrait> TyrIrq<T> {
+    /// Requests a threaded IRQ registration for `irq`, using `name` to look up the interrupt.
+    ///
+    /// # Safety
+    ///
+    /// Callers must not `mem::forget()` the resulting registration or otherwise prevent its
+    /// [`Drop`] implementation from running.
+    pub(crate) unsafe fn request<'a>(
+        pdev: &'a platform::Device<Bound>,
+        name: &'static CStr,
+        irq: T,
+    ) -> Result<impl PinInit<ThreadedRegistration<'a, Self>, Error> + 'a>
+    where
+        T: 'a,
+    {
+        let handler = try_pin_init!(Self {
+            irq,
+            _pin: PhantomPinned,
+        });
+
+        // SAFETY: The caller guarantees the resulting registration will not be leaked.
+        let registration =
+            unsafe { pdev.request_threaded_irq_by_name(Flags::SHARED, name, name, handler) };
+
+        // Clear the status and unmask once the handler has been
+        // successfully registered.
+        Ok(registration.pin_chain(|reg| {
+            let irq = &reg.handler().irq;
+            irq.clear_status(irq.mask());
+            irq.reenable_mask();
+            Ok(())
+        }))
+    }
+}
+
+impl<T: TyrIrqTrait> ThreadedHandler for TyrIrq<T> {
+    fn handle(&self) -> ThreadedIrqReturn {
+        let masked_status = self.irq.read_status();
+
+        if masked_status == 0 {
+            return ThreadedIrqReturn::None;
+        }
+        self.irq.clear_mask();
+        ThreadedIrqReturn::WakeThread
+    }
+
+    fn handle_threaded(&self) -> IrqReturn {
+        let mut ret = IrqReturn::None;
+
+        loop {
+            let raw_status = self.irq.read_raw_status() & self.irq.mask();
+            if raw_status == 0 {
+                break;
+            }
+            self.irq.clear_status(raw_status);
+            self.irq.handle(raw_status);
+            ret = IrqReturn::Handled;
+        }
+
+        self.irq.reenable_mask();
+        ret
+    }
+}
diff --git a/drivers/gpu/drm/tyr/tyr.rs b/drivers/gpu/drm/tyr/tyr.rs
index e7ec450bdc9c..31205e3bf0e7 100644
--- a/drivers/gpu/drm/tyr/tyr.rs
+++ b/drivers/gpu/drm/tyr/tyr.rs
@@ -12,6 +12,7 @@
 mod fw;
 mod gem;
 mod gpu;
+mod irq;
 mod mmu;
 mod regs;
 mod slot;

-- 
2.39.5