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Wysocki" Cc: linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, Fiona Behrens , Daniel Almeida X-Mailer: b4 0.14.2 X-ZohoMailClient: External In preparation for ioremap support, add a Rust abstraction for struct resource. A future commit will introduce the Rust API to ioremap a resource from a platform device. The current abstraction, therefore, adds only the minimum API needed to get that done. Co-developed-by: Fiona Behrens Signed-off-by: Fiona Behrens Signed-off-by: Daniel Almeida --- rust/bindings/bindings_helper.h | 1 + rust/helpers/io.c | 36 +++++++ rust/kernel/io.rs | 2 + rust/kernel/io/resource.rs | 222 ++++++++++++++++++++++++++++++++++++= ++++ 4 files changed, 261 insertions(+) diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helpe= r.h index ae39fc18a8bf07be385e383e5ee0a2e30c6922b4..89a2a17841b55b31afd385bda35= 66a8eb08b4f7e 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include diff --git a/rust/helpers/io.c b/rust/helpers/io.c index 4c2401ccd72078af4e6901f4cd95f9070522f396..939ab38ca61dac4cf884677a20e= dc760094d5812 100644 --- a/rust/helpers/io.c +++ b/rust/helpers/io.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 =20 #include +#include =20 void __iomem *rust_helper_ioremap(phys_addr_t offset, size_t size) { @@ -99,3 +100,38 @@ void rust_helper_writeq_relaxed(u64 value, volatile voi= d __iomem *addr) writeq_relaxed(value, addr); } #endif + +resource_size_t rust_helper_resource_size(struct resource *res) +{ + return resource_size(res); +} + +struct resource *rust_helper_request_mem_region(resource_size_t start, + resource_size_t n, + const char *name) +{ + return request_mem_region(start, n, name); +} + +void rust_helper_release_mem_region(resource_size_t start, resource_size_t= n) +{ + release_mem_region(start, n); +} + +struct resource *rust_helper_request_region(resource_size_t start, + resource_size_t n, const char *name) +{ + return request_region(start, n, name); +} + +struct resource *rust_helper_request_muxed_region(resource_size_t start, + resource_size_t n, + const char *name) +{ + return request_muxed_region(start, n, name); +} + +void rust_helper_release_region(resource_size_t start, resource_size_t n) +{ + release_region(start, n); +} diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs index d4a73e52e3ee68f7b558749ed0108acde92ae5fe..566d8b177e01ada5b184d4250dc= 24caba6492e49 100644 --- a/rust/kernel/io.rs +++ b/rust/kernel/io.rs @@ -7,6 +7,8 @@ use crate::error::{code::EINVAL, Result}; use crate::{bindings, build_assert}; =20 +pub mod resource; + /// Raw representation of an MMIO region. /// /// By itself, the existence of an instance of this structure does not pro= vide any guarantees that diff --git a/rust/kernel/io/resource.rs b/rust/kernel/io/resource.rs new file mode 100644 index 0000000000000000000000000000000000000000..3eb5c8ef585078398551fe8189f= d96c1b6c1eeff --- /dev/null +++ b/rust/kernel/io/resource.rs @@ -0,0 +1,222 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Abstraction for system resources. +//! +//! C header: [`include/linux/ioport.h`](srctree/include/linux/ioport.h) + +use core::ops::Deref; +use core::ptr::NonNull; + +use crate::str::CStr; +use crate::types::Opaque; + +#[cfg(CONFIG_HAS_IOPORT)] +/// Returns a reference to the global `ioport_resource` variable. +pub fn ioport_resource() -> &'static Resource { + // SAFETY: `bindings::ioport_resoure` has global lifetime and is of ty= pe Resource. + unsafe { Resource::from_ptr(core::ptr::addr_of_mut!(bindings::ioport_r= esource)) } +} + +#[cfg(CONFIG_HAS_IOMEM)] +/// Returns a reference to the global `iomem_resource` variable. +pub fn iomem_resource() -> &'static Resource { + // SAFETY: `bindings::iomem_resoure` has global lifetime and is of typ= e Resource. + unsafe { Resource::from_ptr(core::ptr::addr_of_mut!(bindings::iomem_re= source)) } +} + +/// Resource Size type. +/// +/// This is a type alias to `u64` depending on the config option +/// `CONFIG_PHYS_ADDR_T_64BIT`. +#[cfg(CONFIG_PHYS_ADDR_T_64BIT)] +pub type ResourceSize =3D u64; + +/// Resource Size type. +/// +/// This is a type alias to `u32` depending on the config option +/// `CONFIG_PHYS_ADDR_T_64BIT`. +#[cfg(not(CONFIG_PHYS_ADDR_T_64BIT))] +pub type ResourceSize =3D u32; + +/// A region allocated from a parent resource. +/// +/// # Invariants +/// +/// - `self.0` points to a valid `bindings::resource` that was obtained th= rough +/// `__request_region`. +pub struct Region(NonNull); + +impl Deref for Region { + type Target =3D Resource; + + fn deref(&self) -> &Self::Target { + // SAFETY: Safe as per the invariant of `Region` + unsafe { Resource::from_ptr(self.0.as_ptr()) } + } +} + +impl Drop for Region { + fn drop(&mut self) { + // SAFETY: Safe as per the invariant of `Region` + let res =3D unsafe { Resource::from_ptr(self.0.as_ptr()) }; + let flags =3D res.flags(); + + let release_fn =3D if flags.contains(flags::IORESOURCE_MEM) { + bindings::release_mem_region + } else { + bindings::release_region + }; + + // SAFETY: Safe as per the invariant of `Region` + unsafe { release_fn(res.start(), res.size()) }; + } +} + +// SAFETY: `Region` only holds a pointer to a C `struct resource`, which i= s safe to be used from +// any thread. +unsafe impl Send for Region {} + +// SAFETY: `Region` only holds a pointer to a C `struct resource`, referen= ces to which are +// safe to be used from any thread. +unsafe impl Sync for Region {} + +/// A resource abstraction. +/// +/// # Invariants +/// +/// `Resource` is a transparent wrapper around a valid `bindings::resource= `. +#[repr(transparent)] +pub struct Resource(Opaque); + +impl Resource { + /// Creates a reference to a [`Resource`] from a valid pointer. + /// + /// # Safety + /// + /// The caller must ensure that for the duration of 'a, the pointer wi= ll + /// point at a valid `bindings::resource` + /// + /// The caller must also ensure that the `Resource` is only accessed v= ia the + /// returned reference for the duration of 'a. + pub(crate) const unsafe fn from_ptr<'a>(ptr: *mut bindings::resource) = -> &'a Self { + // SAFETY: Self is a transparent wrapper around `Opaque`. + unsafe { &*ptr.cast() } + } + + /// Requests a resource region. + /// + /// Exclusive access will be given and the region will be marked as bu= sy. + /// Further calls to `request_region` will return `None` if the region= , or a + /// part of it, is already in use. + pub fn request_region( + &self, + start: ResourceSize, + size: ResourceSize, + name: &'static CStr, + flags: Flags, + ) -> Option { + // SAFETY: Safe as per the invariant of `Resource` + let region =3D unsafe { + bindings::__request_region( + self.0.get(), + start, + size, + name.as_char_ptr(), + flags.0 as i32, + ) + }; + + Some(Region(NonNull::new(region)?)) + } + + /// Returns the size of the resource. + pub fn size(&self) -> ResourceSize { + let inner =3D self.0.get(); + // SAFETY: safe as per the invariants of `Resource` + unsafe { bindings::resource_size(inner) } + } + + /// Returns the start address of the resource. + pub fn start(&self) -> u64 { + let inner =3D self.0.get(); + // SAFETY: safe as per the invariants of `Resource` + unsafe { *inner }.start + } + + /// Returns the name of the resource. + pub fn name(&self) -> &'static CStr { + let inner =3D self.0.get(); + // SAFETY: safe as per the invariants of `Resource` + unsafe { CStr::from_char_ptr((*inner).name) } + } + + /// Returns the flags associated with the resource. + pub fn flags(&self) -> Flags { + let inner =3D self.0.get(); + // SAFETY: safe as per the invariants of `Resource` + let flags =3D unsafe { *inner }.flags; + + Flags(flags) + } +} + +// SAFETY: `Resource` only holds a pointer to a C `struct resource`, which= is safe to be used from +// any thead. +unsafe impl Send for Resource {} + +// SAFETY: `Resource` only holds a pointer to a C `struct resource`, refer= ences to which are +// safe to be used from any thead. +unsafe impl Sync for Resource {} + +/// Resource flags as stored in the C `struct resource::flags` field. +/// +/// They can be combined with the operators `|`, `&`, and `!`. +/// +/// Values can be used from the [`flags`] module. +#[derive(Clone, Copy, PartialEq)] +pub struct Flags(usize); + +impl Flags { + /// Check whether `flags` is contained in `self`. + pub fn contains(self, flags: Flags) -> bool { + (self & flags) =3D=3D flags + } +} + +impl core::ops::BitOr for Flags { + type Output =3D Self; + fn bitor(self, rhs: Self) -> Self::Output { + Self(self.0 | rhs.0) + } +} + +impl core::ops::BitAnd for Flags { + type Output =3D Self; + fn bitand(self, rhs: Self) -> Self::Output { + Self(self.0 & rhs.0) + } +} + +impl core::ops::Not for Flags { + type Output =3D Self; + fn not(self) -> Self::Output { + Self(!self.0) + } +} + +/// Resource flags as stored in the `struct resource::flags` field. +pub mod flags { + use super::Flags; + + /// PCI/ISA I/O ports. + pub const IORESOURCE_IO: Flags =3D Flags(bindings::IORESOURCE_IO as us= ize); + + /// Resource is software muxed. + pub const IORESOURCE_MUXED: Flags =3D Flags(bindings::IORESOURCE_MUXED= as usize); + + /// Resource represents a memory region. + pub const IORESOURCE_MEM: Flags =3D Flags(bindings::IORESOURCE_MEM as = usize); 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bh=kKEHgAo6DqLhhO69tVzjvTC5yJIdhYIgJuG19wNPJFM=; b=ArlGzV8iPbCH5SsjluxCT7Upr/5Oe5S3ufVJZI89pDMK5kAdkKESSEm0x4Fu3bYX CVFKiqbXnsFWx5x+ARm/fCb5jDP2V8mYisJL0/FqOdeMJbxACajFA5LJhuN1utiCeSB PfxT8u4oKGbJw3xZ/IOl9dgzD2ci17WBWBK/gzLo= Received: by mx.zohomail.com with SMTPS id 1742318462871321.5770885997749; Tue, 18 Mar 2025 10:21:02 -0700 (PDT) From: Daniel Almeida Date: Tue, 18 Mar 2025 14:20:42 -0300 Subject: [PATCH v7 2/3] rust: io: mem: add a generic iomem abstraction Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250318-topics-tyr-platform_iomem-v7-2-7438691d9ef7@collabora.com> References: <20250318-topics-tyr-platform_iomem-v7-0-7438691d9ef7@collabora.com> In-Reply-To: <20250318-topics-tyr-platform_iomem-v7-0-7438691d9ef7@collabora.com> To: Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Greg Kroah-Hartman , "Rafael J. Wysocki" Cc: linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, Daniel Almeida X-Mailer: b4 0.14.2 X-ZohoMailClient: External Add a generic iomem abstraction to safely read and write ioremapped regions. The reads and writes are done through IoRaw, and are thus checked either at compile-time, if the size of the region is known at that point, or at runtime otherwise. Non-exclusive access to the underlying memory region is made possible to cater to cases where overlapped regions are unavoidable. Signed-off-by: Daniel Almeida --- rust/helpers/io.c | 5 ++ rust/kernel/io.rs | 1 + rust/kernel/io/mem.rs | 141 ++++++++++++++++++++++++++++++++++++++++++++++= ++++ 3 files changed, 147 insertions(+) diff --git a/rust/helpers/io.c b/rust/helpers/io.c index 939ab38ca61dac4cf884677a20edc760094d5812..4fbd70ab60f64155bef835a43b3= c64d441aee7bf 100644 --- a/rust/helpers/io.c +++ b/rust/helpers/io.c @@ -8,6 +8,11 @@ void __iomem *rust_helper_ioremap(phys_addr_t offset, size= _t size) return ioremap(offset, size); } =20 +void __iomem *rust_helper_ioremap_np(phys_addr_t offset, size_t size) +{ + return ioremap_np(offset, size); +} + void rust_helper_iounmap(volatile void __iomem *addr) { iounmap(addr); diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs index 566d8b177e01ada5b184d4250dc24caba6492e49..9ce3482b5ecd9c9de4f46bf9499= 84bb54081f5a3 100644 --- a/rust/kernel/io.rs +++ b/rust/kernel/io.rs @@ -7,6 +7,7 @@ use crate::error::{code::EINVAL, Result}; use crate::{bindings, build_assert}; =20 +pub mod mem; pub mod resource; =20 /// Raw representation of an MMIO region. diff --git a/rust/kernel/io/mem.rs b/rust/kernel/io/mem.rs new file mode 100644 index 0000000000000000000000000000000000000000..3e7ef8b6f0ca8b5b195a94c7ed0= f94a9e6c72944 --- /dev/null +++ b/rust/kernel/io/mem.rs @@ -0,0 +1,141 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Generic memory-mapped IO. + +use core::ops::Deref; + +use crate::device::Device; +use crate::devres::Devres; +use crate::io; +use crate::io::resource::Region; +use crate::io::resource::Resource; +use crate::io::Io; +use crate::io::IoRaw; +use crate::prelude::*; + +/// An exclusive memory-mapped IO region. +/// +/// # Invariants +/// +/// - [`ExclusiveIoMem`] has exclusive access to the underlying `iomem`. +pub struct ExclusiveIoMem { + /// The region abstraction. This represents exclusive access to the + /// range represented by the underlying `iomem`. + /// + /// It's placed first to ensure that the region is released before it = is + /// unmapped as a result of the drop order. + /// + /// This field is needed for ownership of the region. + _region: Region, + /// The underlying `IoMem` instance. + iomem: IoMem, +} + +impl ExclusiveIoMem { + /// Creates a new `ExclusiveIoMem` instance. + pub(crate) fn ioremap(resource: &Resource) -> Result { + let iomem =3D IoMem::ioremap(resource)?; + + let start =3D resource.start(); + let size =3D resource.size(); + let name =3D resource.name(); + + let region =3D resource + .request_region(start, size, name, io::resource::flags::IORESO= URCE_MEM) + .ok_or(EBUSY)?; + + let iomem =3D ExclusiveIoMem { + iomem, + _region: region, + }; + + Ok(iomem) + } + + pub(crate) fn new(resource: &Resource, device: &Device) -> Result> { + let iomem =3D Self::ioremap(resource)?; + let devres =3D Devres::new(device, iomem, GFP_KERNEL)?; + + Ok(devres) + } +} + +impl Deref for ExclusiveIoMem { + type Target =3D Io; + + fn deref(&self) -> &Self::Target { + &self.iomem + } +} + +/// A generic memory-mapped IO region. +/// +/// Accesses to the underlying region is checked either at compile time, i= f the +/// region's size is known at that point, or at runtime otherwise. +/// +/// # Invariants +/// +/// `IoMem` always holds an `IoRaw` instance that holds a valid pointer to= the +/// start of the I/O memory mapped region. +pub struct IoMem { + io: IoRaw, +} + +impl IoMem { + fn ioremap(resource: &Resource) -> Result { + let size =3D resource.size(); + if size =3D=3D 0 { + return Err(EINVAL); + } + + let res_start =3D resource.start(); + + let addr =3D if resource + .flags() + .contains(io::resource::flags::IORESOURCE_MEM_NONPOSTED) + { + // SAFETY: + // - `res_start` and `size` are read from a presumably valid `= struct resource`. + // - `size` is known not to be zero at this point. + unsafe { bindings::ioremap_np(res_start, size as usize) } + } else { + // SAFETY: + // - `res_start` and `size` are read from a presumably valid `= struct resource`. + // - `size` is known not to be zero at this point. + unsafe { bindings::ioremap(res_start, size as usize) } + }; + + if addr.is_null() { + return Err(ENOMEM); + } + + let io =3D IoRaw::new(addr as usize, size as usize)?; + let io =3D IoMem { io }; + + Ok(io) + } + + /// Creates a new `IoMem` instance. + pub(crate) fn new(resource: &Resource, device: &Device) -> Result> { + let io =3D Self::ioremap(resource)?; + let devres =3D Devres::new(device, io, GFP_KERNEL)?; + + Ok(devres) + } +} + +impl Drop for IoMem { + fn drop(&mut self) { + // SAFETY: Safe as by the invariant of `Io`. + unsafe { bindings::iounmap(self.io.addr() as *mut core::ffi::c_voi= d) } + } +} + +impl Deref for IoMem { + type Target =3D Io; + + fn deref(&self) -> &Self::Target { + // SAFETY: Safe as by the invariant of `IoMem`. + unsafe { Io::from_raw(&self.io) } + } +} --=20 2.48.1 From nobody Thu Apr 3 23:45:05 2025 Received: from sender4-op-o12.zoho.com (sender4-op-o12.zoho.com [136.143.188.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 59E53212D6A; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250318-topics-tyr-platform_iomem-v7-3-7438691d9ef7@collabora.com> References: <20250318-topics-tyr-platform_iomem-v7-0-7438691d9ef7@collabora.com> In-Reply-To: <20250318-topics-tyr-platform_iomem-v7-0-7438691d9ef7@collabora.com> To: Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Greg Kroah-Hartman , "Rafael J. Wysocki" Cc: linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, Daniel Almeida X-Mailer: b4 0.14.2 X-ZohoMailClient: External The preceding patches added support for resources, and for a general IoMem abstraction, but thus far there is no way to access said IoMem from drivers, as its creation is unsafe and depends on a resource that must be acquired from some device first. Now, allow the ioremap of platform resources themselves, thereby making the IoMem available to platform drivers. Signed-off-by: Daniel Almeida --- rust/kernel/platform.rs | 123 ++++++++++++++++++++++++++++++++++++++++++++= +++- 1 file changed, 122 insertions(+), 1 deletion(-) diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs index 1297f5292ba9b7ca9784f84979efbeccb0768bd3..56f3d7c0d536d77082d7f8d2407= de17ee3e95ffa 100644 --- a/rust/kernel/platform.rs +++ b/rust/kernel/platform.rs @@ -5,8 +5,14 @@ //! C header: [`include/linux/platform_device.h`](srctree/include/linux/pl= atform_device.h) =20 use crate::{ - bindings, container_of, device, driver, + bindings, container_of, device, + devres::Devres, + driver, error::{to_result, Result}, + io::{ + mem::{ExclusiveIoMem, IoMem}, + resource::Resource, + }, of, prelude::*, str::CStr, @@ -191,6 +197,121 @@ fn as_raw(&self) -> *mut bindings::platform_device { // embedded in `struct platform_device`. unsafe { container_of!(self.0.as_raw(), bindings::platform_device,= dev) }.cast_mut() } + + /// Maps a platform resource through ioremap() where the size is known= at + /// compile time. + /// + /// # Examples + /// + /// ```no_run + /// use kernel::{bindings, c_str, platform}; + /// + /// fn probe(pdev: &mut platform::Device, /* ... */) -> Result<()> { + /// let offset =3D 0; // Some offset. + /// + /// // If the size is known at compile time, use `ioremap_resource= _sized`. + /// // No runtime checks will apply when reading and writing. + /// let resource =3D pdev.resource(0).ok_or(ENODEV)?; + /// let iomem =3D pdev.ioremap_resource_sized::<42>(&resource)?; + /// + /// // Read and write a 32-bit value at `offset`. Calling `try_acc= ess()` on + /// // the `Devres` makes sure that the resource is still valid. + /// let data =3D iomem.try_access().ok_or(ENODEV)?.readl(offset); + /// + /// iomem.try_access().ok_or(ENODEV)?.writel(data, offset); + /// + /// # Ok::<(), Error>(()) + /// } + /// ``` + pub fn ioremap_resource_sized( + &self, + resource: &Resource, + ) -> Result>> { + IoMem::new(resource, self.as_ref()) + } + + /// Same as [`Self::ioremap_resource_sized`] but with exclusive access= to the + /// underlying region. + pub fn ioremap_resource_exclusive_sized( + &self, + resource: &Resource, + ) -> Result>> { + ExclusiveIoMem::new(resource, self.as_ref()) + } + + /// Maps a platform resource through ioremap(). + /// + /// # Examples + /// + /// ```no_run + /// # use kernel::{bindings, c_str, platform}; + /// + /// fn probe(pdev: &mut platform::Device, /* ... */) -> Result<()> { + /// let offset =3D 0; // Some offset. + /// + /// // Unlike `ioremap_resource_sized`, here the size of the memor= y region + /// // is not known at compile time, so only the `try_read*` and `= try_write*` + /// // family of functions should be used, leading to runtime chec= ks on every + /// // access. + /// let resource =3D pdev.resource(0).ok_or(ENODEV)?; + /// let iomem =3D pdev.ioremap_resource(&resource)?; + /// + /// let data =3D iomem.try_access().ok_or(ENODEV)?.try_readl(offse= t)?; + /// + /// iomem.try_access().ok_or(ENODEV)?.try_writel(data, offset)?; + /// + /// # Ok::<(), Error>(()) + /// } + /// ``` + pub fn ioremap_resource(&self, resource: &Resource) -> Result>> { + self.ioremap_resource_sized::<0>(resource) + } + + /// Same as [`Self::ioremap_resource`] but with exclusive access to th= e underlying + /// region. + pub fn ioremap_resource_exclusive( + &self, + resource: &Resource, + ) -> Result>> { + self.ioremap_resource_exclusive_sized::<0>(resource) + } + + /// Returns the resource at `index`, if any. + pub fn resource(&self, index: u32) -> Option<&Resource> { + // SAFETY: `self.as_raw()` returns a valid pointer to a `struct pl= atform_device`. + let resource =3D unsafe { + bindings::platform_get_resource(self.as_raw(), bindings::IORES= OURCE_MEM, index) + }; + + if resource.is_null() { + return None; + } + + // SAFETY: `resource` is a valid pointer to a `struct resource` as + // returned by `platform_get_resource`. + Some(unsafe { Resource::from_ptr(resource) }) + } + + /// Returns the resource with a given `name`, if any. + pub fn resource_by_name(&self, name: &CStr) -> Option<&Resource> { + // SAFETY: `self.as_raw()` returns a valid pointer to a `struct + // platform_device` and `name` points to a valid C string. + let resource =3D unsafe { + bindings::platform_get_resource_byname( + self.as_raw(), + bindings::IORESOURCE_MEM, + name.as_char_ptr(), + ) + }; + + if resource.is_null() { + return None; + } + + // SAFETY: `resource` is a valid pointer to a `struct resource` as + // returned by `platform_get_resource`. + Some(unsafe { Resource::from_ptr(resource) }) + } } =20 impl AsRef for Device { --=20 2.48.1