| Message ID | 20250304173555.2496-3-dakr@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Initial Nova Core series | expand |
On Tue, Mar 04, 2025 at 06:34:49PM +0100, Danilo Krummrich wrote: > The `firmware` field of the `module!` only accepts literal strings, > which is due to the fact that it is implemented as a proc macro. > > Some drivers require a lot of firmware files (such as nova-core) and > hence benefit from more flexibility composing firmware path strings. > > The `firmware::ModInfoBuilder` is a helper component to flexibly compose > firmware path strings for the .modinfo section in const context. > > It is meant to be used in combination with `kernel::module_firmware!`, > which is introduced in a subsequent patch. Ditto. > > Co-developed-by: Alice Ryhl <aliceryhl@google.com> > Signed-off-by: Alice Ryhl <aliceryhl@google.com> > Signed-off-by: Danilo Krummrich <dakr@kernel.org> > --- > rust/kernel/firmware.rs | 98 +++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 98 insertions(+) > > diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs > index c5162fdc95ff..6e6972d94597 100644 > --- a/rust/kernel/firmware.rs > +++ b/rust/kernel/firmware.rs > @@ -115,3 +115,101 @@ unsafe impl Send for Firmware {} > // SAFETY: `Firmware` only holds a pointer to a C `struct firmware`, references to which are safe to > // be used from any thread. > unsafe impl Sync for Firmware {} > + > +/// Builder for firmware module info. > +/// > +/// [`ModInfoBuilder`] is a helper component to flexibly compose firmware paths strings for the > +/// .modinfo section in const context. > +/// > +/// It is meant to be used in combination with [`kernel::module_firmware!`]. > +/// > +/// For more details and an example, see [`kernel::module_firmware!`]. > +pub struct ModInfoBuilder<const N: usize> { > + buf: [u8; N], > + n: usize, > + module_name: &'static CStr, > +} > + > +impl<const N: usize> ModInfoBuilder<N> { > + /// Create an empty builder instance. > + pub const fn new(module_name: &'static CStr) -> Self { > + Self { > + buf: [0; N], > + n: 0, > + module_name, > + } > + } > + > + const fn push_internal(mut self, bytes: &[u8]) -> Self { > + let mut j = 0; > + > + if N == 0 { > + self.n += bytes.len(); > + return self; > + } > + > + while j < bytes.len() { > + if self.n < N { > + self.buf[self.n] = bytes[j]; > + } > + self.n += 1; > + j += 1; > + } > + self > + } > + > + /// Push an additional path component. > + /// > + /// After a new [`ModInfoBuilder`] instance has been created, [`ModInfoBuilder::prepare`] must > + /// be called before adding path components. > + pub const fn push(self, s: &str) -> Self { > + if N != 0 && self.n == 0 { > + crate::build_error!("Must call prepare() before push()."); > + } > + > + self.push_internal(s.as_bytes()) > + } > + > + const fn prepare_module_name(self) -> Self { > + let mut this = self; > + let module_name = this.module_name; > + > + if !this.module_name.is_empty() { > + this = this.push_internal(module_name.as_bytes_with_nul()); > + > + if N != 0 { > + // Re-use the space taken by the NULL terminator and swap it with the '.' separator. > + this.buf[this.n - 1] = b'.'; > + } > + } > + > + this.push_internal(b"firmware=") > + } > + > + /// Prepare for the next module info entry. > + /// > + /// Must be called before [`ModInfoBuilder::push`] can be called. > + pub const fn prepare(self) -> Self { > + self.push_internal(b"\0").prepare_module_name() > + } > + > + /// Build the byte array. > + pub const fn build(self) -> [u8; N] { > + // Add the final NULL terminator. > + let this = self.push_internal(b"\0"); > + > + if this.n == N { > + this.buf > + } else { > + crate::build_error!("Length mismatch."); > + } > + } > +} > + > +impl ModInfoBuilder<0> { > + /// Return the length of the byte array to build. > + pub const fn build_length(self) -> usize { > + // Compensate for the NULL terminator added by `build`. > + self.n + 1 > + } > +} > -- > 2.48.1 > > BR, Jarkko
diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs index c5162fdc95ff..6e6972d94597 100644 --- a/rust/kernel/firmware.rs +++ b/rust/kernel/firmware.rs @@ -115,3 +115,101 @@ unsafe impl Send for Firmware {} // SAFETY: `Firmware` only holds a pointer to a C `struct firmware`, references to which are safe to // be used from any thread. unsafe impl Sync for Firmware {} + +/// Builder for firmware module info. +/// +/// [`ModInfoBuilder`] is a helper component to flexibly compose firmware paths strings for the +/// .modinfo section in const context. +/// +/// It is meant to be used in combination with [`kernel::module_firmware!`]. +/// +/// For more details and an example, see [`kernel::module_firmware!`]. +pub struct ModInfoBuilder<const N: usize> { + buf: [u8; N], + n: usize, + module_name: &'static CStr, +} + +impl<const N: usize> ModInfoBuilder<N> { + /// Create an empty builder instance. + pub const fn new(module_name: &'static CStr) -> Self { + Self { + buf: [0; N], + n: 0, + module_name, + } + } + + const fn push_internal(mut self, bytes: &[u8]) -> Self { + let mut j = 0; + + if N == 0 { + self.n += bytes.len(); + return self; + } + + while j < bytes.len() { + if self.n < N { + self.buf[self.n] = bytes[j]; + } + self.n += 1; + j += 1; + } + self + } + + /// Push an additional path component. + /// + /// After a new [`ModInfoBuilder`] instance has been created, [`ModInfoBuilder::prepare`] must + /// be called before adding path components. + pub const fn push(self, s: &str) -> Self { + if N != 0 && self.n == 0 { + crate::build_error!("Must call prepare() before push()."); + } + + self.push_internal(s.as_bytes()) + } + + const fn prepare_module_name(self) -> Self { + let mut this = self; + let module_name = this.module_name; + + if !this.module_name.is_empty() { + this = this.push_internal(module_name.as_bytes_with_nul()); + + if N != 0 { + // Re-use the space taken by the NULL terminator and swap it with the '.' separator. + this.buf[this.n - 1] = b'.'; + } + } + + this.push_internal(b"firmware=") + } + + /// Prepare for the next module info entry. + /// + /// Must be called before [`ModInfoBuilder::push`] can be called. + pub const fn prepare(self) -> Self { + self.push_internal(b"\0").prepare_module_name() + } + + /// Build the byte array. + pub const fn build(self) -> [u8; N] { + // Add the final NULL terminator. + let this = self.push_internal(b"\0"); + + if this.n == N { + this.buf + } else { + crate::build_error!("Length mismatch."); + } + } +} + +impl ModInfoBuilder<0> { + /// Return the length of the byte array to build. + pub const fn build_length(self) -> usize { + // Compensate for the NULL terminator added by `build`. + self.n + 1 + } +}