[PATCH v10 3/4] rust: platform: add resource accessors

[Daniel Almeida <daniel.almeida@collabora.com>]

A previous patch has exposed the abstractions struct resource.

Now make it possible to retrieve resources from platform devices in Rust
using either a name or an index.

Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
---
 rust/kernel/platform.rs | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index 5b21fa517e55348582622ec10471918919502959..0eedb8239fec31df7ab64dc68d220c9d965f1f21 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -7,6 +7,7 @@
 use crate::{
     bindings, container_of, device, driver,
     error::{to_result, Result},
+    io::Resource,
     of,
     prelude::*,
     str::CStr,
@@ -188,6 +189,43 @@ impl<Ctx: device::DeviceContext> Device<Ctx> {
     fn as_raw(&self) -> *mut bindings::platform_device {
         self.0.get()
     }
+
+    /// Returns the resource at `index`, if any.
+    pub fn resource_by_index(&self, index: u32) -> Option<&Resource> {
+        // SAFETY: `self.as_raw()` returns a valid pointer to a `struct platform_device`.
+        let resource = unsafe {
+            bindings::platform_get_resource(self.as_raw(), bindings::IORESOURCE_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::as_ref(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 = 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::as_ref(resource) })
+    }
 }
 
 // SAFETY: `Device` is a transparent wrapper of a type that doesn't depend on `Device`'s generic

-- 
2.50.0