rust/qdev: Support bit property in #property macro

Add BIT_INFO to QDevProp trait, so that bit related property info could
be bound to u32 & u64.

Then add "bit=*" field in #property attributes macro to allow device to
configure bit property.

In addtion, convert the #property field parsing from `if-else` pattern
to `match` pattern, to help readability. And note, the `bitnr` member of
`Property` struct is generated by manual TokenStream construction,
instead of conditional repetition (like #(bitnr: #bitnr,)?) since
`quote` doesn't support this.

In addtion, rename VALUE member of QDevProp trait to BASE_INFO.

And update the test cases about qdev property.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20250920160520.3699591-9-zhao1.liu@intel.com

2 files changed, 20 insertions, 6 deletions

diff --git a/rust/qemu-macros/src/lib.rs b/rust/qemu-macros/src/lib.rs
index 37e1b72..3e21b67 100644
--- a/rust/qemu-macros/src/lib.rs
+++ b/rust/qemu-macros/src/lib.rs
@@ -179,6 +179,7 @@ impl Parse for DevicePropertyName {
 #[derive(Default, Debug)]
 struct DeviceProperty {
     rename: Option<DevicePropertyName>,
+    bitnr: Option<syn::Expr>,
     defval: Option<syn::Expr>,
 }
 
@@ -187,6 +188,7 @@ impl DeviceProperty {
         use attrs::{set, with, Attrs};
         let mut parser = Attrs::new();
         parser.once("rename", with::eq(set::parse(&mut self.rename)));
+        parser.once("bit", with::eq(set::parse(&mut self.bitnr)));
         parser.once("default", with::eq(set::parse(&mut self.defval)));
         a.parse_args_with(&mut parser)
     }
@@ -222,7 +224,11 @@ fn derive_device_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream
     let mut properties_expanded = vec![];
 
     for (field, prop) in properties {
-        let DeviceProperty { rename, defval } = prop;
+        let DeviceProperty {
+            rename,
+            bitnr,
+            defval,
+        } = prop;
         let field_name = field.ident.unwrap();
         macro_rules! str_to_c_str {
             ($value:expr, $span:expr) => {{
@@ -252,14 +258,20 @@ fn derive_device_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStream
             },
         )?;
         let field_ty = field.ty.clone();
-        let qdev_prop = quote! { <#field_ty as ::hwcore::QDevProp>::VALUE };
+        let qdev_prop = if bitnr.is_none() {
+            quote! { <#field_ty as ::hwcore::QDevProp>::BASE_INFO }
+        } else {
+            quote! { <#field_ty as ::hwcore::QDevProp>::BIT_INFO }
+        };
+        let bitnr = bitnr.unwrap_or(syn::Expr::Verbatim(quote! { 0 }));
         let set_default = defval.is_some();
         let defval = defval.unwrap_or(syn::Expr::Verbatim(quote! { 0 }));
         properties_expanded.push(quote! {
             ::hwcore::bindings::Property {
                 name: ::std::ffi::CStr::as_ptr(#prop_name),
-                info: #qdev_prop ,
+                info: #qdev_prop,
                 offset: ::core::mem::offset_of!(#name, #field_name) as isize,
+                bitnr: #bitnr,
                 set_default: #set_default,
                 defval: ::hwcore::bindings::Property__bindgen_ty_1 { u: #defval as u64 },
                 ..::common::Zeroable::ZERO
diff --git a/rust/qemu-macros/src/tests.rs b/rust/qemu-macros/src/tests.rs
index 00a1066..ec13713 100644
--- a/rust/qemu-macros/src/tests.rs
+++ b/rust/qemu-macros/src/tests.rs
@@ -60,7 +60,7 @@ fn test_derive_device() {
                 migrate_clock: bool,
             }
         },
-        "Expected one of `default` or `rename`"
+        "Expected one of `bit`, `default` or `rename`"
     );
     // Check that repeated attributes are not allowed:
     derive_compile_fail!(
@@ -106,8 +106,9 @@ fn test_derive_device() {
                 const PROPERTIES: &'static [::hwcore::bindings::Property] = &[
                     ::hwcore::bindings::Property {
                         name: ::std::ffi::CStr::as_ptr(c"migrate_clock"),
-                        info: <bool as ::hwcore::QDevProp>::VALUE,
+                        info: <bool as ::hwcore::QDevProp>::BASE_INFO,
                         offset: ::core::mem::offset_of!(DummyState, migrate_clock) as isize,
+                        bitnr: 0,
                         set_default: true,
                         defval: ::hwcore::bindings::Property__bindgen_ty_1 { u: true as u64 },
                         ..::common::Zeroable::ZERO
@@ -133,8 +134,9 @@ fn test_derive_device() {
                 const PROPERTIES: &'static [::hwcore::bindings::Property] = &[
                     ::hwcore::bindings::Property {
                         name: ::std::ffi::CStr::as_ptr(c"migrate-clk"),
-                        info: <bool as ::hwcore::QDevProp>::VALUE,
+                        info: <bool as ::hwcore::QDevProp>::BASE_INFO,
                         offset: ::core::mem::offset_of!(DummyState, migrate_clock) as isize,
+                        bitnr: 0,
                         set_default: true,
                         defval: ::hwcore::bindings::Property__bindgen_ty_1 { u: true as u64 },
                         ..::common::Zeroable::ZERO