rust: net::phy add module_phy_driver macro

This macro creates an array of kernel's `struct phy_driver` and
registers it. This also corresponds to the kernel's
`MODULE_DEVICE_TABLE` macro, which embeds the information for module
loading into the module binary file.

A PHY driver should use this macro.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>

rust/kernel/net/phy.rs

@@ -753,3 +753,149 @@ impl DeviceMask {
         }
     }
 }
+
+/// Declares a kernel module for PHYs drivers.
+///
+/// This creates a static array of kernel's `struct phy_driver` and registers it.
+/// This also corresponds to the kernel's `MODULE_DEVICE_TABLE` macro, which embeds the information
+/// for module loading into the module binary file. Every driver needs an entry in `device_table`.
+///
+/// # Examples
+///
+/// ```
+/// # mod module_phy_driver_sample {
+/// use kernel::c_str;
+/// use kernel::net::phy::{self, DeviceId};
+/// use kernel::prelude::*;
+///
+/// kernel::module_phy_driver! {
+///     drivers: [PhySample],
+///     device_table: [
+///         DeviceId::new_with_driver::<PhySample>()
+///     ],
+///     name: "rust_sample_phy",
+///     author: "Rust for Linux Contributors",
+///     description: "Rust sample PHYs driver",
+///     license: "GPL",
+/// }
+///
+/// struct PhySample;
+///
+/// #[vtable]
+/// impl phy::Driver for PhySample {
+///     const NAME: &'static CStr = c_str!("PhySample");
+///     const PHY_DEVICE_ID: phy::DeviceId = phy::DeviceId::new_with_exact_mask(0x00000001);
+/// }
+/// # }
+/// ```
+///
+/// This expands to the following code:
+///
+/// ```ignore
+/// use kernel::c_str;
+/// use kernel::net::phy::{self, DeviceId};
+/// use kernel::prelude::*;
+///
+/// struct Module {
+///     _reg: ::kernel::net::phy::Registration,
+/// }
+///
+/// module! {
+///     type: Module,
+///     name: "rust_sample_phy",
+///     author: "Rust for Linux Contributors",
+///     description: "Rust sample PHYs driver",
+///     license: "GPL",
+/// }
+///
+/// struct PhySample;
+///
+/// #[vtable]
+/// impl phy::Driver for PhySample {
+///     const NAME: &'static CStr = c_str!("PhySample");
+///     const PHY_DEVICE_ID: phy::DeviceId = phy::DeviceId::new_with_exact_mask(0x00000001);
+/// }
+///
+/// const _: () = {
+///     static mut DRIVERS: [::kernel::net::phy::DriverVTable; 1] =
+///         [::kernel::net::phy::create_phy_driver::<PhySample>()];
+///
+///     impl ::kernel::Module for Module {
+///         fn init(module: &'static ThisModule) -> Result<Self> {
+///             let drivers = unsafe { &mut DRIVERS };
+///             let mut reg = ::kernel::net::phy::Registration::register(
+///                 module,
+///                 ::core::pin::Pin::static_mut(drivers),
+///             )?;
+///             Ok(Module { _reg: reg })
+///         }
+///     }
+/// };
+///
+/// #[cfg(MODULE)]
+/// #[no_mangle]
+/// static __mod_mdio__phydev_device_table: [::kernel::bindings::mdio_device_id; 2] = [
+///     ::kernel::bindings::mdio_device_id {
+///         phy_id: 0x00000001,
+///         phy_id_mask: 0xffffffff,
+///     },
+///     ::kernel::bindings::mdio_device_id {
+///         phy_id: 0,
+///         phy_id_mask: 0,
+///     },
+/// ];
+/// ```
+#[macro_export]
+macro_rules! module_phy_driver {
+    (@replace_expr $_t:tt $sub:expr) => {$sub};
+
+    (@count_devices $($x:expr),*) => {
+        0usize $(+ $crate::module_phy_driver!(@replace_expr $x 1usize))*
+    };
+
+    (@device_table [$($dev:expr),+]) => {
+        // SAFETY: C will not read off the end of this constant since the last element is zero.
+        #[cfg(MODULE)]
+        #[no_mangle]
+        static __mod_mdio__phydev_device_table: [$crate::bindings::mdio_device_id;
+            $crate::module_phy_driver!(@count_devices $($dev),+) + 1] = [
+            $($dev.mdio_device_id()),+,
+            $crate::bindings::mdio_device_id {
+                phy_id: 0,
+                phy_id_mask: 0
+            }
+        ];
+    };
+
+    (drivers: [$($driver:ident),+ $(,)?], device_table: [$($dev:expr),+ $(,)?], $($f:tt)*) => {
+        struct Module {
+            _reg: $crate::net::phy::Registration,
+        }
+
+        $crate::prelude::module! {
+            type: Module,
+            $($f)*
+        }
+
+        const _: () = {
+            static mut DRIVERS: [$crate::net::phy::DriverVTable;
+                $crate::module_phy_driver!(@count_devices $($driver),+)] =
+                [$($crate::net::phy::create_phy_driver::<$driver>()),+];
+
+            impl $crate::Module for Module {
+                fn init(module: &'static ThisModule) -> Result<Self> {
+                    // SAFETY: The anonymous constant guarantees that nobody else can access
+                    // the `DRIVERS` static. The array is used only in the C side.
+                    let drivers = unsafe { &mut DRIVERS };
+                    let mut reg = $crate::net::phy::Registration::register(
+                        module,
+                        ::core::pin::Pin::static_mut(drivers),
+                    )?;
+                    Ok(Module { _reg: reg })
+                }
+            }
+        };
+
+        $crate::module_phy_driver!(@device_table [$($dev),+]);
+    }
+}