[RFC PATCH 07/11] rust: add `dev_*` print macros.

[Danilo Krummrich]

From: Wedson Almeida Filho <wedsonaf@xxxxxxxxxx>

Implement `dev_*` print macros for `device::Device`.

They behave like the macros with the same names in C, i.e., they print
messages to the kernel ring buffer with the given level, prefixing the
messages with corresponding device information.

Signed-off-by: Wedson Almeida Filho <wedsonaf@xxxxxxxxxx>
Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
---
 rust/kernel/device.rs  | 321 +++++++++++++++++++++++++++++++++++++++++
 rust/kernel/prelude.rs |   2 +
 2 files changed, 323 insertions(+)

diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index b1c3f7a0d623..2988aeb4e040 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -18,11 +18,15 @@
     types::{ARef, Opaque},
 };
 use core::{
+    fmt,
     ops::{Deref, DerefMut},
     pin::Pin,
     ptr,
 };
 
+#[cfg(CONFIG_PRINTK)]
+use crate::c_str;
+
 /// A ref-counted device.
 ///
 /// # Invariants
@@ -66,6 +70,110 @@ pub unsafe fn as_ref<'a>(ptr: *mut bindings::device) -> &'a Self {
         // SAFETY: Guaranteed by the safety requirements of the function.
         unsafe { &*ptr.cast() }
     }
+
+    /// Prints an emergency-level message (level 0) prefixed with device information.
+    ///
+    /// More details are available from [`dev_emerg`].
+    ///
+    /// [`dev_emerg`]: crate::dev_emerg
+    pub fn pr_emerg(&self, args: fmt::Arguments<'_>) {
+        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.
+        unsafe { self.printk(bindings::KERN_EMERG, args) };
+    }
+
+    /// Prints an alert-level message (level 1) prefixed with device information.
+    ///
+    /// More details are available from [`dev_alert`].
+    ///
+    /// [`dev_alert`]: crate::dev_alert
+    pub fn pr_alert(&self, args: fmt::Arguments<'_>) {
+        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.
+        unsafe { self.printk(bindings::KERN_ALERT, args) };
+    }
+
+    /// Prints a critical-level message (level 2) prefixed with device information.
+    ///
+    /// More details are available from [`dev_crit`].
+    ///
+    /// [`dev_crit`]: crate::dev_crit
+    pub fn pr_crit(&self, args: fmt::Arguments<'_>) {
+        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.
+        unsafe { self.printk(bindings::KERN_CRIT, args) };
+    }
+
+    /// Prints an error-level message (level 3) prefixed with device information.
+    ///
+    /// More details are available from [`dev_err`].
+    ///
+    /// [`dev_err`]: crate::dev_err
+    pub fn pr_err(&self, args: fmt::Arguments<'_>) {
+        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.
+        unsafe { self.printk(bindings::KERN_ERR, args) };
+    }
+
+    /// Prints a warning-level message (level 4) prefixed with device information.
+    ///
+    /// More details are available from [`dev_warn`].
+    ///
+    /// [`dev_warn`]: crate::dev_warn
+    pub fn pr_warn(&self, args: fmt::Arguments<'_>) {
+        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.
+        unsafe { self.printk(bindings::KERN_WARNING, args) };
+    }
+
+    /// Prints a notice-level message (level 5) prefixed with device information.
+    ///
+    /// More details are available from [`dev_notice`].
+    ///
+    /// [`dev_notice`]: crate::dev_notice
+    pub fn pr_notice(&self, args: fmt::Arguments<'_>) {
+        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.
+        unsafe { self.printk(bindings::KERN_NOTICE, args) };
+    }
+
+    /// Prints an info-level message (level 6) prefixed with device information.
+    ///
+    /// More details are available from [`dev_info`].
+    ///
+    /// [`dev_info`]: crate::dev_info
+    pub fn pr_info(&self, args: fmt::Arguments<'_>) {
+        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.
+        unsafe { self.printk(bindings::KERN_INFO, args) };
+    }
+
+    /// Prints a debug-level message (level 7) prefixed with device information.
+    ///
+    /// More details are available from [`dev_dbg`].
+    ///
+    /// [`dev_dbg`]: crate::dev_dbg
+    pub fn pr_dbg(&self, args: fmt::Arguments<'_>) {
+        if cfg!(debug_assertions) {
+            // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.
+            unsafe { self.printk(bindings::KERN_DEBUG, args) };
+        }
+    }
+
+    /// Prints the provided message to the console.
+    ///
+    /// # Safety
+    ///
+    /// Callers must ensure that `klevel` is null-terminated; in particular, one of the
+    /// `KERN_*`constants, for example, `KERN_CRIT`, `KERN_ALERT`, etc.
+    #[cfg_attr(not(CONFIG_PRINTK), allow(unused_variables))]
+    unsafe fn printk(&self, klevel: &[u8], msg: fmt::Arguments<'_>) {
+        // SAFETY: `klevel` is null-terminated and one of the kernel constants. `self.as_raw`
+        // is valid because `self` is valid. The "%pA" format string expects a pointer to
+        // `fmt::Arguments`, which is what we're passing as the last argument.
+        #[cfg(CONFIG_PRINTK)]
+        unsafe {
+            bindings::_dev_printk(
+                klevel as *const _ as *const core::ffi::c_char,
+                self.as_raw(),
+                c_str!("%pA").as_char_ptr(),
+                &msg as *const _ as *const core::ffi::c_void,
+            )
+        };
+    }
 }
 
 // SAFETY: Instances of `Device` are always ref-counted.
@@ -175,3 +283,216 @@ fn deref_mut(&mut self) -> &mut U {
         &mut self.general
     }
 }
+
+#[doc(hidden)]
+#[macro_export]
+macro_rules! dev_printk {
+    ($method:ident, $dev:expr, $($f:tt)*) => {
+        {
+            // We have an explicity `use` statement here so that callers of this macro are not
+            // required to explicitly use the `RawDevice` trait to use its functions.
+            use $crate::device::Device;
+            ($dev).$method(core::format_args!($($f)*));
+        }
+    }
+}
+
+/// Prints an emergency-level message (level 0) prefixed with device information.
+///
+/// This level should be used if the system is unusable.
+///
+/// Equivalent to the kernel's `dev_emerg` macro.
+///
+/// Mimics the interface of [`std::print!`]. More information about the syntax is available from
+/// [`core::fmt`] and [`alloc::format!`].
+///
+/// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::device::Device;
+///
+/// fn example(dev: &Device) {
+///     dev_emerg!(dev, "hello {}\n", "there");
+/// }
+/// ```
+#[macro_export]
+macro_rules! dev_emerg {
+    ($($f:tt)*) => { $crate::dev_printk!(pr_emerg, $($f)*); }
+}
+
+/// Prints an alert-level message (level 1) prefixed with device information.
+///
+/// This level should be used if action must be taken immediately.
+///
+/// Equivalent to the kernel's `dev_alert` macro.
+///
+/// Mimics the interface of [`std::print!`]. More information about the syntax is available from
+/// [`core::fmt`] and [`alloc::format!`].
+///
+/// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::device::Device;
+///
+/// fn example(dev: &Device) {
+///     dev_alert!(dev, "hello {}\n", "there");
+/// }
+/// ```
+#[macro_export]
+macro_rules! dev_alert {
+    ($($f:tt)*) => { $crate::dev_printk!(pr_alert, $($f)*); }
+}
+
+/// Prints a critical-level message (level 2) prefixed with device information.
+///
+/// This level should be used in critical conditions.
+///
+/// Equivalent to the kernel's `dev_crit` macro.
+///
+/// Mimics the interface of [`std::print!`]. More information about the syntax is available from
+/// [`core::fmt`] and [`alloc::format!`].
+///
+/// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::device::Device;
+///
+/// fn example(dev: &Device) {
+///     dev_crit!(dev, "hello {}\n", "there");
+/// }
+/// ```
+#[macro_export]
+macro_rules! dev_crit {
+    ($($f:tt)*) => { $crate::dev_printk!(pr_crit, $($f)*); }
+}
+
+/// Prints an error-level message (level 3) prefixed with device information.
+///
+/// This level should be used in error conditions.
+///
+/// Equivalent to the kernel's `dev_err` macro.
+///
+/// Mimics the interface of [`std::print!`]. More information about the syntax is available from
+/// [`core::fmt`] and [`alloc::format!`].
+///
+/// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::device::Device;
+///
+/// fn example(dev: &Device) {
+///     dev_err!(dev, "hello {}\n", "there");
+/// }
+/// ```
+#[macro_export]
+macro_rules! dev_err {
+    ($($f:tt)*) => { $crate::dev_printk!(pr_err, $($f)*); }
+}
+
+/// Prints a warning-level message (level 4) prefixed with device information.
+///
+/// This level should be used in warning conditions.
+///
+/// Equivalent to the kernel's `dev_warn` macro.
+///
+/// Mimics the interface of [`std::print!`]. More information about the syntax is available from
+/// [`core::fmt`] and [`alloc::format!`].
+///
+/// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::device::Device;
+///
+/// fn example(dev: &Device) {
+///     dev_warn!(dev, "hello {}\n", "there");
+/// }
+/// ```
+#[macro_export]
+macro_rules! dev_warn {
+    ($($f:tt)*) => { $crate::dev_printk!(pr_warn, $($f)*); }
+}
+
+/// Prints a notice-level message (level 5) prefixed with device information.
+///
+/// This level should be used in normal but significant conditions.
+///
+/// Equivalent to the kernel's `dev_notice` macro.
+///
+/// Mimics the interface of [`std::print!`]. More information about the syntax is available from
+/// [`core::fmt`] and [`alloc::format!`].
+///
+/// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::device::Device;
+///
+/// fn example(dev: &Device) {
+///     dev_notice!(dev, "hello {}\n", "there");
+/// }
+/// ```
+#[macro_export]
+macro_rules! dev_notice {
+    ($($f:tt)*) => { $crate::dev_printk!(pr_notice, $($f)*); }
+}
+
+/// Prints an info-level message (level 6) prefixed with device information.
+///
+/// This level should be used for informational messages.
+///
+/// Equivalent to the kernel's `dev_info` macro.
+///
+/// Mimics the interface of [`std::print!`]. More information about the syntax is available from
+/// [`core::fmt`] and [`alloc::format!`].
+///
+/// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::device::Device;
+///
+/// fn example(dev: &Device) {
+///     dev_info!(dev, "hello {}\n", "there");
+/// }
+/// ```
+#[macro_export]
+macro_rules! dev_info {
+    ($($f:tt)*) => { $crate::dev_printk!(pr_info, $($f)*); }
+}
+
+/// Prints a debug-level message (level 7) prefixed with device information.
+///
+/// This level should be used for debug messages.
+///
+/// Equivalent to the kernel's `dev_dbg` macro, except that it doesn't support dynamic debug yet.
+///
+/// Mimics the interface of [`std::print!`]. More information about the syntax is available from
+/// [`core::fmt`] and [`alloc::format!`].
+///
+/// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::device::Device;
+///
+/// fn example(dev: &Device) {
+///     dev_dbg!(dev, "hello {}\n", "there");
+/// }
+/// ```
+#[macro_export]
+macro_rules! dev_dbg {
+    ($($f:tt)*) => { $crate::dev_printk!(pr_dbg, $($f)*); }
+}
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index b37a0b3180fb..c5765ab863d6 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -27,6 +27,8 @@
 // `super::std_vendor` is hidden, which makes the macro inline for some reason.
 #[doc(no_inline)]
 pub use super::dbg;
+pub use super::fmt;
+pub use super::{dev_alert, dev_crit, dev_dbg, dev_emerg, dev_err, dev_info, dev_notice, dev_warn};
 pub use super::{pr_alert, pr_crit, pr_debug, pr_emerg, pr_err, pr_info, pr_notice, pr_warn};
 
 pub use super::{init, pin_init, try_init, try_pin_init};
-- 
2.45.1