rust: module: introduce `authors` key

In the `module!` macro, the `author` field is currently of type `String`.

Since modules can have multiple authors, this limitation prevents
specifying more than one.

Add an `authors` field as `Option<Vec<String>>` to allow creating
modules with multiple authors, and change the documentation and all
current users to use it. Eventually, the single `author` field may
be removed.

[ The `modinfo` key needs to still be `author`; otherwise, tooling
may not work properly, e.g.:

$ modinfo --author samples/rust/rust_print.ko
Rust for Linux Contributors

I have also kept the original `author` field (undocumented), so
that we can drop it more easily in a kernel cycle or two.

- Miguel ]

Suggested-by: Miguel Ojeda <[e-mail]>
Link: https://github.com/Rust-for-Linux/linux/issues/244
Reviewed-by: Charalampos Mitrodimas <[e-mail]>
Reviewed-by: Alice Ryhl <[e-mail]>
Reviewed-by: Andreas Hindborg <[e-mail]>
Signed-off-by: Guilherme Giacomo Simoes <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
[ Fixed `modinfo` key. Kept `author` field. Reworded message
accordingly. Updated my email. - Miguel ]
Signed-off-by: Miguel Ojeda <[e-mail]>

drivers/block/rnull.rs

···
 module! {
     type: NullBlkModule,
     name: "rnull_mod",
-    author: "Andreas Hindborg",
+    authors: ["Andreas Hindborg"],
     description: "Rust implementation of the C null block driver",
     license: "GPL v2",
 }

drivers/net/phy/ax88796b_rust.rs

···
         DeviceId::new_with_driver::<PhyAX88796B>()
     ],
     name: "rust_asix_phy",
-    author: "FUJITA Tomonori <[e-mail]>",
+    authors: ["FUJITA Tomonori <[e-mail]>"],
     description: "Rust Asix PHYs driver",
     license: "GPL",
 }

drivers/net/phy/qt2025.rs

···
         phy::DeviceId::new_with_driver::<PhyQT2025>(),
     ],
     name: "qt2025_phy",
-    author: "FUJITA Tomonori <[e-mail]>",
+    authors: ["FUJITA Tomonori <[e-mail]>"],
     description: "AMCC QT2025 PHY driver",
     license: "GPL",
     firmware: ["qt2025-2.0.3.3.fw"],

rust/kernel/net/phy.rs

···
 ///         DeviceId::new_with_driver::<PhySample>()
 ///     ],
 ///     name: "rust_sample_phy",
-///     author: "Rust for Linux Contributors",
+///     authors: ["Rust for Linux Contributors"],
 ///     description: "Rust sample PHYs driver",
 ///     license: "GPL",
 /// }
···
 /// module! {
 ///     type: Module,
 ///     name: "rust_sample_phy",
-///     author: "Rust for Linux Contributors",
+///     authors: ["Rust for Linux Contributors"],
 ///     description: "Rust sample PHYs driver",
 ///     license: "GPL",
 /// }

rust/kernel/pci.rs

···
 /// kernel::module_pci_driver! {
 ///     type: MyDriver,
 ///     name: "Module name",
-///     author: "Author name",
+///     authors: ["Author name"],
 ///     description: "Description",
 ///     license: "GPL v2",
 /// }

rust/kernel/platform.rs

···
 /// kernel::module_platform_driver! {
 ///     type: MyDriver,
 ///     name: "Module name",
-///     author: "Author name",
+///     authors: ["Author name"],
 ///     description: "Description",
 ///     license: "GPL v2",
 /// }

rust/macros/lib.rs

···
 /// module!{
 ///     type: MyModule,
 ///     name: "my_kernel_module",
-///     author: "Rust for Linux Contributors",
+///     authors: ["Rust for Linux Contributors"],
 ///     description: "My very own kernel module!",
 ///     license: "GPL",
 ///     alias: ["alternate_module_name"],
···
 /// module!{
 ///     type: MyDeviceDriverModule,
 ///     name: "my_device_driver_module",
-///     author: "Rust for Linux Contributors",
+///     authors: ["Rust for Linux Contributors"],
 ///     description: "My device driver requires firmware",
 ///     license: "GPL",
 ///     firmware: ["my_device_firmware1.bin", "my_device_firmware2.bin"],
···
 /// # Supported argument types
 ///   - `type`: type which implements the [`Module`] trait (required).
 ///   - `name`: ASCII string literal of the name of the kernel module (required).
-///   - `author`: string literal of the author of the kernel module.
+///   - `authors`: array of ASCII string literals of the authors of the kernel module.
 ///   - `description`: string literal of the description of the kernel module.
 ///   - `license`: ASCII string literal of the license of the kernel module (required).
 ///   - `alias`: array of ASCII string literals of the alias names of the kernel module.

rust/macros/module.rs

···
     license: String,
     name: String,
     author: Option<String>,
+    authors: Option<Vec<String>>,
     description: Option<String>,
     alias: Option<Vec<String>>,
     firmware: Option<Vec<String>>,
···
             "type",
             "name",
             "author",
+            "authors",
             "description",
             "license",
             "alias",
···
                 "type" => info.type_ = expect_ident(it),
                 "name" => info.name = expect_string_ascii(it),
                 "author" => info.author = Some(expect_string(it)),
+                "authors" => info.authors = Some(expect_string_array(it)),
                 "description" => info.description = Some(expect_string(it)),
                 "license" => info.license = expect_string_ascii(it),
                 "alias" => info.alias = Some(expect_string_array(it)),
···
     let mut modinfo = ModInfoBuilder::new(info.name.as_ref());
     if let Some(author) = info.author {
         modinfo.emit("author", &author);
+    }
+    if let Some(authors) = info.authors {
+        for author in authors {
+            modinfo.emit("author", &author);
+        }
     }
     if let Some(description) = info.description {
         modinfo.emit("description", &description);

samples/rust/rust_driver_faux.rs

···
 module! {
     type: SampleModule,
     name: "rust_faux_driver",
-    author: "Lyude Paul",
+    authors: ["Lyude Paul"],
     description: "Rust faux device sample",
     license: "GPL",
 }

samples/rust/rust_driver_pci.rs

···
 kernel::module_pci_driver! {
     type: SampleDriver,
     name: "rust_driver_pci",
-    author: "Danilo Krummrich",
+    authors: ["Danilo Krummrich"],
     description: "Rust PCI driver",
     license: "GPL v2",
 }

samples/rust/rust_driver_platform.rs

···
 kernel::module_platform_driver! {
     type: SampleDriver,
     name: "rust_driver_platform",
-    author: "Danilo Krummrich",
+    authors: ["Danilo Krummrich"],
     description: "Rust Platform driver",
     license: "GPL v2",
 }

samples/rust/rust_minimal.rs

···
 module! {
     type: RustMinimal,
     name: "rust_minimal",
-    author: "Rust for Linux Contributors",
+    authors: ["Rust for Linux Contributors"],
     description: "Rust minimal sample",
     license: "GPL",
 }

samples/rust/rust_misc_device.rs

···
 module! {
     type: RustMiscDeviceModule,
     name: "rust_misc_device",
-    author: "Lee Jones",
+    authors: ["Lee Jones"],
     description: "Rust misc device sample",
     license: "GPL",
 }

samples/rust/rust_print_main.rs

···
 module! {
     type: RustPrint,
     name: "rust_print",
-    author: "Rust for Linux Contributors",
+    authors: ["Rust for Linux Contributors"],
     description: "Rust printing macros sample",
     license: "GPL",
 }