Add a basic timer device and exercise it during device probing. This
first draft is probably very questionable.
One point in particular which should IMHO receive attention: the generic
wait_on() method aims at providing similar functionality to Nouveau's
nvkm_[num]sec() macros. Since this method will be heavily used with
different conditions to test, I'd like to avoid monomorphizing it
entirely with each instance ; that's something that is achieved in
nvkm_xsec() using functions that the macros invoke.
I have tried achieving the same result in Rust using closures (kept
as-is in the current code), but they seem to be monomorphized as well.
Calling extra functions could work better, but looks also less elegant
to me, so I am really open to suggestions here.
Signed-off-by: Alexandre Courbot <acour...@nvidia.com>
---
drivers/gpu/nova-core/driver.rs | 4 +-
drivers/gpu/nova-core/gpu.rs | 55 +++++++++++++++-
drivers/gpu/nova-core/nova_core.rs | 1 +
drivers/gpu/nova-core/regs.rs | 11 ++++
drivers/gpu/nova-core/timer.rs | 132 +++++++++++++++++++++++++++++++++++++
5 files changed, 201 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index
63c19f140fbdd65d8fccf81669ac590807cc120f..0cd23aa306e4082405f480afc0530a41131485e7
100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -10,7 +10,7 @@ pub(crate) struct NovaCore {
pub(crate) gpu: Gpu,
}
-const BAR0_SIZE: usize = 8;
+const BAR0_SIZE: usize = 0x9500;
pub(crate) type Bar0 = pci::Bar<BAR0_SIZE>;
kernel::pci_device_table!(
@@ -42,6 +42,8 @@ fn probe(pdev: &mut pci::Device, _info: &Self::IdInfo) ->
Result<Pin<KBox<Self>>
GFP_KERNEL,
)?;
+ let _ = this.gpu.test_timer();
+
Ok(this)
}
}
diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index
d96901e5c8eace1e7c57c77da7def209e8149cd3..f010d3152530b1cec032ca620e59de51a2fc1a13
100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -6,8 +6,10 @@
use crate::driver::Bar0;
use crate::regs;
+use crate::timer::Timer;
use crate::util;
use core::fmt;
+use core::time::Duration;
macro_rules! define_chipset {
({ $($variant:ident = $value:expr),* $(,)* }) =>
@@ -179,6 +181,7 @@ pub(crate) struct Gpu {
/// MMIO mapping of PCI BAR 0
bar: Devres<Bar0>,
fw: Firmware,
+ timer: Timer,
}
impl Gpu {
@@ -194,6 +197,56 @@ pub(crate) fn new(pdev: &pci::Device, bar: Devres<Bar0>)
-> Result<impl PinInit<
spec.revision
);
- Ok(pin_init!(Self { spec, bar, fw }))
+ let timer = Timer::new();
+
+ Ok(pin_init!(Self {
+ spec,
+ bar,
+ fw,
+ timer,
+ }))
+ }
+
+ pub(crate) fn test_timer(&self) -> Result<()> {
+ pr_info!("testing timer subdev\n");
+ with_bar!(self.bar, |b| {
+ pr_info!("current timestamp: {}\n", self.timer.read(b))
+ })?;
+
+ if !matches!(
+ self.timer
+ .wait_on(&self.bar, Duration::from_millis(10), || Some(())),
+ Ok(())
+ ) {
+ pr_crit!("timer test failure\n");
+ }
+
+ let t1 = with_bar!(self.bar, |b| {
+ pr_info!("timestamp after immediate exit: {}\n",
self.timer.read(b));
+ self.timer.read(b)
+ })?;
+
+ if self
+ .timer
+ .wait_on(&self.bar, Duration::from_millis(10), ||
Option::<()>::None)
+ != Err(ETIMEDOUT)
+ {
+ pr_crit!("timer test 2 failure\n");
+ }
+
+ let t2 = with_bar!(self.bar, |b| self.timer.read(b))?;
+ if t2 - t1 < Duration::from_millis(10) {
+ pr_crit!("timer test 3 failure\n");
+ }
+
+ with_bar!(self.bar, |b| {
+ pr_info!(
+ "timestamp after timeout: {} ({:?})\n",
+ self.timer.read(b),
+ t2 - t1
+ );
+ })?;
+
+ Ok(())
}
}
diff --git a/drivers/gpu/nova-core/nova_core.rs
b/drivers/gpu/nova-core/nova_core.rs
index
94f4778c16f6a4d046c2f799129ed0cc68df6fd4..f54dcfc66490cb6b10090ef944ac14feca9f6972
100644
--- a/drivers/gpu/nova-core/nova_core.rs
+++ b/drivers/gpu/nova-core/nova_core.rs
@@ -18,6 +18,7 @@ macro_rules! with_bar {
mod firmware;
mod gpu;
mod regs;
+mod timer;
mod util;
kernel::module_pci_driver! {
diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs
index
7bfd2b575fe2184565d495012e55cd0829b0b1ad..0d06e09b1ba62d55688c633500f37d3fe1aeb30e
100644
--- a/drivers/gpu/nova-core/regs.rs
+++ b/drivers/gpu/nova-core/regs.rs
@@ -11,3 +11,14 @@
7:4 major_rev => as u8, "major revision of the chip";
28:20 chipset => try_into Chipset, "chipset model"
);
+
+/* PTIMER */
+
+register!(PtimerTime0@0x00009400;
+ 31:0 lo => as u32, "low 32-bits of the timer"
+);
+
+register!(PtimerTime1@0x00009410;
+ 31:0 hi => as u32, "high 32 bits of the timer"
+);
+
diff --git a/drivers/gpu/nova-core/timer.rs b/drivers/gpu/nova-core/timer.rs
new file mode 100644
index
0000000000000000000000000000000000000000..1361e4ad10d923ce114972889cdfcfa6e58a691b
--- /dev/null
+++ b/drivers/gpu/nova-core/timer.rs
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Nova Core Timer subdevice
+
+use core::fmt::Display;
+use core::ops::{Add, Sub};
+use core::time::Duration;
+
+use kernel::devres::Devres;
+use kernel::num::U64Ext;
+use kernel::prelude::*;
+
+use crate::driver::Bar0;
+use crate::regs;
+
+/// A timestamp with nanosecond granularity obtained from the GPU timer.
+///
+/// A timestamp can also be substracted to another in order to obtain a
[`Duration`].
+///
+/// TODO: add Kunit tests!
+#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
+pub(crate) struct Timestamp(u64);
+
+impl Display for Timestamp {
+ fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+ write!(f, "{}", self.0)
+ }
+}
+
+impl Add<Duration> for Timestamp {
+ type Output = Self;
+
+ fn add(mut self, rhs: Duration) -> Self::Output {
+ let mut nanos = rhs.as_nanos();
+ while nanos > u64::MAX as u128 {
+ self.0 = self.0.wrapping_add(nanos as u64);
+ nanos -= u64::MAX as u128;
+ }
+
+ Timestamp(self.0.wrapping_add(nanos as u64))
+ }
+}
+
+impl Sub for Timestamp {
+ type Output = Duration;
+
+ fn sub(self, rhs: Self) -> Self::Output {
+ Duration::from_nanos(self.0.wrapping_sub(rhs.0))
+ }
+}
+
+pub(crate) struct Timer {}
+
+impl Timer {
+ pub(crate) fn new() -> Self {
+ Self {}
+ }
+
+ /// Read the current timer timestamp.
+ pub(crate) fn read(&self, bar: &Bar0) -> Timestamp {
+ loop {
+ let hi = regs::PtimerTime1::read(bar);
+ let lo = regs::PtimerTime0::read(bar);
+
+ if hi.hi() == regs::PtimerTime1::read(bar).hi() {
+ return Timestamp(u64::from_u32s(hi.hi(), lo.lo()));
+ }
+ }
+ }
+
+ #[allow(dead_code)]
+ pub(crate) fn time(bar: &Bar0, time: u64) {
+ regs::PtimerTime1::default()
+ .set_hi(time.upper_32_bits())
+ .write(bar);
+ regs::PtimerTime0::default()
+ .set_lo(time.lower_32_bits())
+ .write(bar);
+ }
+
+ /// Wait until `cond` is true or `timeout` elapsed, based on GPU time.
+ ///
+ /// When `cond` evaluates to `Some`, its return value is returned.
+ ///
+ /// `Err(ETIMEDOUT)` is returned if `timeout` has been reached without
`cond` evaluating to
+ /// `Some`, or if the timer device is stuck for some reason.
+ pub(crate) fn wait_on<R, F: Fn() -> Option<R>>(
+ &self,
+ bar: &Devres<Bar0>,
+ timeout: Duration,
+ cond: F,
+ ) -> Result<R> {
+ // Number of consecutive time reads after which we consider the timer
frozen if it hasn't
+ // moved forward.
+ const MAX_STALLED_READS: usize = 16;
+
+ let (mut cur_time, mut prev_time, deadline) = {
+ let cur_time = with_bar!(bar, |b| self.read(b))?;
+ let deadline = cur_time + timeout;
+
+ (cur_time, cur_time, deadline)
+ };
+ let mut num_reads = 0;
+
+ loop {
+ if let Some(ret) = cond() {
+ return Ok(ret);
+ }
+
+ (|| {
+ cur_time = with_bar!(bar, |b| self.read(b))?;
+
+ /* Check if the timer is frozen for some reason. */
+ if cur_time == prev_time {
+ if num_reads >= MAX_STALLED_READS {
+ return Err(ETIMEDOUT);
+ }
+ num_reads += 1;
+ } else {
+ if cur_time >= deadline {
+ return Err(ETIMEDOUT);
+ }
+
+ num_reads = 0;
+ prev_time = cur_time;
+ }
+
+ Ok(())
+ })()?;
+ }
+ }
+}
--
2.48.1
