Currently the `Io` trait exposes a bunch of untyped IO accesses, but if the
`Io` region itself is typed, then it might be weird to have
let io: Mmio<u32> = /* ... */;
io.read8(1);
while not unsound, it is surely strange. Thus, restrict the untyped methods
and also the register macro to `Region` type only.
Implement it by adding a generic type to `IoLoc` indicating allowed base
types. This also paves the way to add typed register blocks in the future;
for example, we could use this mechanism to block driver A's `register!()`
generated macro from being used on driver B's MMIO. The same mechanism
could be used for relative IO registers. These are future opportunities,
and for now restrict everything to require `IoLoc<Region<SIZE>, _>`.
Suggested-by: Alexandre Courbot <[email protected]>
Link:
https://lore.kernel.org/rust-for-linux/[email protected]/
Signed-off-by: Gary Guo <[email protected]>
---
rust/kernel/io.rs | 49 +++++++++++++++++++++++++++++++---------------
rust/kernel/io/register.rs | 21 +++++++++++---------
2 files changed, 45 insertions(+), 25 deletions(-)
diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs
index fa9ae39ad9d2..38281636b4da 100644
--- a/rust/kernel/io.rs
+++ b/rust/kernel/io.rs
@@ -244,15 +244,16 @@ pub trait IoCapable<T> {
/// (for primitive types like [`u32`]) and typed ones (like those generated by
the [`register!`]
/// macro).
///
-/// An `IoLoc<T>` carries three pieces of information:
+/// An `IoLoc<Base, T>` carries the following pieces of information:
///
+/// - The valid `Base` to operate on. For most registers, this should be
[`Region`].
/// - The offset to access (returned by [`IoLoc::offset`]),
/// - The width of the access (determined by [`IoLoc::IoType`]),
/// - The type `T` in which the raw data is returned or provided.
///
/// `T` and `IoLoc::IoType` may differ: for instance, a typed register has `T`
= the register type
/// with its bitfields, and `IoType` = its backing primitive (e.g. `u32`).
-pub trait IoLoc<T> {
+pub trait IoLoc<Base: ?Sized, T> {
/// Size ([`u8`], [`u16`], etc) of the I/O performed on the returned
[`offset`](IoLoc::offset).
type IoType: Into<T> + From<T>;
@@ -260,12 +261,12 @@ pub trait IoLoc<T> {
fn offset(self) -> usize;
}
-/// Implements [`IoLoc<$ty>`] for [`usize`], allowing [`usize`] to be used as
a parameter of
-/// [`Io::read`] and [`Io::write`].
+/// Implements [`IoLoc<Region<SIZE>, $ty>`] for [`usize`], allowing [`usize`]
to be used as a
+/// parameter of [`Io::read`] and [`Io::write`].
macro_rules! impl_usize_ioloc {
($($ty:ty),*) => {
$(
- impl IoLoc<$ty> for usize {
+ impl<const SIZE: usize> IoLoc<Region<SIZE>, $ty> for usize {
type IoType = $ty;
#[inline(always)]
@@ -339,6 +340,7 @@ fn io_addr<U>(&self, offset: usize) -> Result<usize> {
#[inline(always)]
fn try_read8(&self, offset: usize) -> Result<u8>
where
+ usize: IoLoc<Self::Target, u8, IoType = u8>,
Self: IoCapable<u8>,
{
self.try_read(offset)
@@ -348,6 +350,7 @@ fn try_read8(&self, offset: usize) -> Result<u8>
#[inline(always)]
fn try_read16(&self, offset: usize) -> Result<u16>
where
+ usize: IoLoc<Self::Target, u16, IoType = u16>,
Self: IoCapable<u16>,
{
self.try_read(offset)
@@ -357,6 +360,7 @@ fn try_read16(&self, offset: usize) -> Result<u16>
#[inline(always)]
fn try_read32(&self, offset: usize) -> Result<u32>
where
+ usize: IoLoc<Self::Target, u32, IoType = u32>,
Self: IoCapable<u32>,
{
self.try_read(offset)
@@ -366,6 +370,7 @@ fn try_read32(&self, offset: usize) -> Result<u32>
#[inline(always)]
fn try_read64(&self, offset: usize) -> Result<u64>
where
+ usize: IoLoc<Self::Target, u64, IoType = u64>,
Self: IoCapable<u64>,
{
self.try_read(offset)
@@ -375,6 +380,7 @@ fn try_read64(&self, offset: usize) -> Result<u64>
#[inline(always)]
fn try_write8(&self, value: u8, offset: usize) -> Result
where
+ usize: IoLoc<Self::Target, u8, IoType = u8>,
Self: IoCapable<u8>,
{
self.try_write(offset, value)
@@ -384,6 +390,7 @@ fn try_write8(&self, value: u8, offset: usize) -> Result
#[inline(always)]
fn try_write16(&self, value: u16, offset: usize) -> Result
where
+ usize: IoLoc<Self::Target, u16, IoType = u16>,
Self: IoCapable<u16>,
{
self.try_write(offset, value)
@@ -393,6 +400,7 @@ fn try_write16(&self, value: u16, offset: usize) -> Result
#[inline(always)]
fn try_write32(&self, value: u32, offset: usize) -> Result
where
+ usize: IoLoc<Self::Target, u32, IoType = u32>,
Self: IoCapable<u32>,
{
self.try_write(offset, value)
@@ -402,6 +410,7 @@ fn try_write32(&self, value: u32, offset: usize) -> Result
#[inline(always)]
fn try_write64(&self, value: u64, offset: usize) -> Result
where
+ usize: IoLoc<Self::Target, u64, IoType = u64>,
Self: IoCapable<u64>,
{
self.try_write(offset, value)
@@ -411,6 +420,7 @@ fn try_write64(&self, value: u64, offset: usize) -> Result
#[inline(always)]
fn read8(&self, offset: usize) -> u8
where
+ usize: IoLoc<Self::Target, u8, IoType = u8>,
Self: IoCapable<u8>,
{
self.read(offset)
@@ -420,6 +430,7 @@ fn read8(&self, offset: usize) -> u8
#[inline(always)]
fn read16(&self, offset: usize) -> u16
where
+ usize: IoLoc<Self::Target, u16, IoType = u16>,
Self: IoCapable<u16>,
{
self.read(offset)
@@ -429,6 +440,7 @@ fn read16(&self, offset: usize) -> u16
#[inline(always)]
fn read32(&self, offset: usize) -> u32
where
+ usize: IoLoc<Self::Target, u32, IoType = u32>,
Self: IoCapable<u32>,
{
self.read(offset)
@@ -438,6 +450,7 @@ fn read32(&self, offset: usize) -> u32
#[inline(always)]
fn read64(&self, offset: usize) -> u64
where
+ usize: IoLoc<Self::Target, u64, IoType = u64>,
Self: IoCapable<u64>,
{
self.read(offset)
@@ -447,6 +460,7 @@ fn read64(&self, offset: usize) -> u64
#[inline(always)]
fn write8(&self, value: u8, offset: usize)
where
+ usize: IoLoc<Self::Target, u8, IoType = u8>,
Self: IoCapable<u8>,
{
self.write(offset, value)
@@ -456,6 +470,7 @@ fn write8(&self, value: u8, offset: usize)
#[inline(always)]
fn write16(&self, value: u16, offset: usize)
where
+ usize: IoLoc<Self::Target, u16, IoType = u16>,
Self: IoCapable<u16>,
{
self.write(offset, value)
@@ -465,6 +480,7 @@ fn write16(&self, value: u16, offset: usize)
#[inline(always)]
fn write32(&self, value: u32, offset: usize)
where
+ usize: IoLoc<Self::Target, u32, IoType = u32>,
Self: IoCapable<u32>,
{
self.write(offset, value)
@@ -474,6 +490,7 @@ fn write32(&self, value: u32, offset: usize)
#[inline(always)]
fn write64(&self, value: u64, offset: usize)
where
+ usize: IoLoc<Self::Target, u64, IoType = u64>,
Self: IoCapable<u64>,
{
self.write(offset, value)
@@ -504,7 +521,7 @@ fn write64(&self, value: u64, offset: usize)
#[inline(always)]
fn try_read<T, L>(&self, location: L) -> Result<T>
where
- L: IoLoc<T>,
+ L: IoLoc<Self::Target, T>,
Self: IoCapable<L::IoType>,
{
let address = self.io_addr::<L::IoType>(location.offset())?;
@@ -538,7 +555,7 @@ fn try_read<T, L>(&self, location: L) -> Result<T>
#[inline(always)]
fn try_write<T, L>(&self, location: L, value: T) -> Result
where
- L: IoLoc<T>,
+ L: IoLoc<Self::Target, T>,
Self: IoCapable<L::IoType>,
{
let address = self.io_addr::<L::IoType>(location.offset())?;
@@ -584,8 +601,8 @@ fn try_write<T, L>(&self, location: L, value: T) -> Result
#[inline(always)]
fn try_write_reg<T, L, V>(&self, value: V) -> Result
where
- L: IoLoc<T>,
- V: LocatedRegister<Location = L, Value = T>,
+ L: IoLoc<Self::Target, T>,
+ V: LocatedRegister<Self::Target, Location = L, Value = T>,
Self: IoCapable<L::IoType>,
{
let (location, value) = value.into_io_op();
@@ -617,7 +634,7 @@ fn try_write_reg<T, L, V>(&self, value: V) -> Result
#[inline(always)]
fn try_update<T, L, F>(&self, location: L, f: F) -> Result
where
- L: IoLoc<T>,
+ L: IoLoc<Self::Target, T>,
Self: IoCapable<L::IoType>,
F: FnOnce(T) -> T,
{
@@ -656,7 +673,7 @@ fn try_update<T, L, F>(&self, location: L, f: F) -> Result
#[inline(always)]
fn read<T, L>(&self, location: L) -> T
where
- L: IoLoc<T>,
+ L: IoLoc<Self::Target, T>,
Self: IoCapable<L::IoType>,
{
let address = self.io_addr_assert::<L::IoType>(location.offset());
@@ -688,7 +705,7 @@ fn read<T, L>(&self, location: L) -> T
#[inline(always)]
fn write<T, L>(&self, location: L, value: T)
where
- L: IoLoc<T>,
+ L: IoLoc<Self::Target, T>,
Self: IoCapable<L::IoType>,
{
let address = self.io_addr_assert::<L::IoType>(location.offset());
@@ -731,8 +748,8 @@ fn write<T, L>(&self, location: L, value: T)
#[inline(always)]
fn write_reg<T, L, V>(&self, value: V)
where
- L: IoLoc<T>,
- V: LocatedRegister<Location = L, Value = T>,
+ L: IoLoc<Self::Target, T>,
+ V: LocatedRegister<Self::Target, Location = L, Value = T>,
Self: IoCapable<L::IoType>,
{
let (location, value) = value.into_io_op();
@@ -764,8 +781,8 @@ fn write_reg<T, L, V>(&self, value: V)
#[inline(always)]
fn update<T, L, F>(&self, location: L, f: F)
where
- L: IoLoc<T>,
- Self: IoCapable<L::IoType> + Sized,
+ L: IoLoc<Self::Target, T>,
+ Self: IoCapable<L::IoType>,
F: FnOnce(T) -> T,
{
let address = self.io_addr_assert::<L::IoType>(location.offset());
diff --git a/rust/kernel/io/register.rs b/rust/kernel/io/register.rs
index f924c7c7c1db..64fff9193a13 100644
--- a/rust/kernel/io/register.rs
+++ b/rust/kernel/io/register.rs
@@ -113,6 +113,8 @@
io::IoLoc, //
};
+use super::Region;
+
/// Trait implemented by all registers.
pub trait Register: Sized {
/// Backing primitive type of the register.
@@ -129,7 +131,7 @@ pub trait FixedRegister: Register {}
/// Allows `()` to be used as the `location` parameter of
[`Io::write`](super::Io::write) when
/// passing a [`FixedRegister`] value.
-impl<T> IoLoc<T> for ()
+impl<const SIZE: usize, T> IoLoc<Region<SIZE>, T> for ()
where
T: FixedRegister,
{
@@ -143,7 +145,7 @@ fn offset(self) -> usize {
/// A [`FixedRegister`] carries its location in its type. Thus `FixedRegister`
values can be used
/// as an [`IoLoc`].
-impl<T> IoLoc<T> for T
+impl<const SIZE: usize, T> IoLoc<Region<SIZE>, T> for T
where
T: FixedRegister,
{
@@ -168,7 +170,7 @@ pub const fn new() -> Self {
}
}
-impl<T> IoLoc<T> for FixedRegisterLoc<T>
+impl<const SIZE: usize, T> IoLoc<Region<SIZE>, T> for FixedRegisterLoc<T>
where
T: FixedRegister,
{
@@ -239,7 +241,8 @@ const fn offset(self) -> usize {
}
}
-impl<T, B> IoLoc<T> for RelativeRegisterLoc<T, B>
+// FIXME: Make use of `Base` type parameter of `Region` directly.
+impl<const SIZE: usize, T, B> IoLoc<Region<SIZE>, T> for
RelativeRegisterLoc<T, B>
where
T: RelativeRegister,
B: RegisterBase<T::BaseFamily> + ?Sized,
@@ -283,7 +286,7 @@ pub fn try_new(idx: usize) -> Option<Self> {
}
}
-impl<T> IoLoc<T> for RegisterArrayLoc<T>
+impl<const SIZE: usize, T> IoLoc<Region<SIZE>, T> for RegisterArrayLoc<T>
where
T: RegisterArray,
{
@@ -370,7 +373,7 @@ pub fn try_at(self, idx: usize) ->
Option<RelativeRegisterArrayLoc<T, B>> {
}
}
-impl<T, B> IoLoc<T> for RelativeRegisterArrayLoc<T, B>
+impl<const SIZE: usize, T, B> IoLoc<Region<SIZE>, T> for
RelativeRegisterArrayLoc<T, B>
where
T: RelativeRegisterArray,
B: RegisterBase<T::BaseFamily> + ?Sized,
@@ -387,18 +390,18 @@ fn offset(self) -> usize {
/// which to write it.
///
/// Implementors can be used with [`Io::write_reg`](super::Io::write_reg).
-pub trait LocatedRegister {
+pub trait LocatedRegister<Base: ?Sized> {
/// Register value to write.
type Value: Register;
/// Full location information at which to write the value.
- type Location: IoLoc<Self::Value>;
+ type Location: IoLoc<Base, Self::Value>;
/// Consumes `self` and returns a `(location, value)` tuple describing a
valid I/O write
/// operation.
fn into_io_op(self) -> (Self::Location, Self::Value);
}
-impl<T> LocatedRegister for T
+impl<const SIZE: usize, T> LocatedRegister<Region<SIZE>> for T
where
T: FixedRegister,
{
--
2.54.0
