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Merge pull request torvalds#593 from m-falkowski1/add_initial_common_…
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…clk_bindings

rust: add initial common clock framework bindings
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wedsonaf authored Jan 12, 2022
2 parents cd969b5 + 632ef86 commit c871b6d
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Showing 5 changed files with 113 additions and 1 deletion.
13 changes: 13 additions & 0 deletions rust/helpers.c
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Expand Up @@ -2,6 +2,7 @@

#include <linux/bug.h>
#include <linux/build_bug.h>
#include <linux/clk.h>
#include <linux/uaccess.h>
#include <linux/sched/signal.h>
#include <linux/gfp.h>
Expand All @@ -22,6 +23,18 @@ __noreturn void rust_helper_BUG(void)
BUG();
}

void rust_helper_clk_disable_unprepare(struct clk *clk)
{
return clk_disable_unprepare(clk);
}
EXPORT_SYMBOL_GPL(rust_helper_clk_disable_unprepare);

int rust_helper_clk_prepare_enable(struct clk *clk)
{
return clk_prepare_enable(clk);
}
EXPORT_SYMBOL_GPL(rust_helper_clk_prepare_enable);

unsigned long rust_helper_copy_from_user(void *to, const void __user *from, unsigned long n)
{
return copy_from_user(to, from, n);
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1 change: 1 addition & 0 deletions rust/kernel/bindings_helper.h
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@@ -1,6 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0 */

#include <linux/cdev.h>
#include <linux/clk.h>
#include <linux/errname.h>
#include <linux/fs.h>
#include <linux/module.h>
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75 changes: 75 additions & 0 deletions rust/kernel/clk.rs
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@@ -0,0 +1,75 @@
// SPDX-License-Identifier: GPL-2.0

//! Common clock framework.
//!
//! C header: [`include/linux/clk.h`](../../../../include/linux/clk.h)
use crate::{bindings, error::Result, to_result};
use core::mem::ManuallyDrop;

/// Represents `struct clk *`.
///
/// # Invariants
///
/// The pointer is valid.
pub struct Clk(*mut bindings::clk);

impl Clk {
/// Creates new clock structure from a raw pointer.
///
/// # Safety
///
/// The pointer must be valid.
pub unsafe fn new(clk: *mut bindings::clk) -> Self {
Self(clk)
}

/// Returns value of the rate field of `struct clk`.
pub fn get_rate(&self) -> usize {
// SAFETY: the pointer is valid by the type invariant.
unsafe { bindings::clk_get_rate(self.0) as usize }
}

/// Prepares and enables the underlying hardware clock.
///
/// This function should not be called in atomic context.
pub fn prepare_enable(self) -> Result<EnabledClk> {
// SAFETY: the pointer is valid by the type invariant.
to_result(|| unsafe { bindings::clk_prepare_enable(self.0) })?;
Ok(EnabledClk(self))
}
}

impl Drop for Clk {
fn drop(&mut self) {
// SAFETY: the pointer is valid by the type invariant.
unsafe { bindings::clk_put(self.0) };
}
}

/// A clock variant that is prepared and enabled.
pub struct EnabledClk(Clk);

impl EnabledClk {
/// Returns value of the rate field of `struct clk`.
pub fn get_rate(&self) -> usize {
self.0.get_rate()
}

/// Disables and later unprepares the underlying hardware clock prematurely.
///
/// This function should not be called in atomic context.
pub fn disable_unprepare(self) -> Clk {
let mut clk = ManuallyDrop::new(self);
// SAFETY: the pointer is valid by the type invariant.
unsafe { bindings::clk_disable_unprepare(clk.0 .0) };
core::mem::replace(&mut clk.0, Clk(core::ptr::null_mut()))
}
}

impl Drop for EnabledClk {
fn drop(&mut self) {
// SAFETY: the pointer is valid by the type invariant.
unsafe { bindings::clk_disable_unprepare(self.0 .0) };
}
}
23 changes: 22 additions & 1 deletion rust/kernel/device.rs
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,9 @@
//!
//! C header: [`include/linux/device.h`](../../../../include/linux/device.h)
#[cfg(CONFIG_COMMON_CLK)]
use crate::{clk::Clk, error::from_kernel_err_ptr};

use crate::{
bindings,
revocable::{Revocable, RevocableGuard},
Expand Down Expand Up @@ -43,6 +46,24 @@ pub unsafe trait RawDevice {
// by the compiler because of their lifetimes).
unsafe { CStr::from_char_ptr(name) }
}

/// Lookups a clock producer consumed by this device.
///
/// Returns a managed reference to the clock producer.
#[cfg(CONFIG_COMMON_CLK)]
fn clk_get(&self, id: Option<&CStr>) -> Result<Clk> {
let id_ptr = match id {
Some(cstr) => cstr.as_char_ptr(),
None => core::ptr::null(),
};

// SAFETY: id_ptr is optional and may be either a valid pointer
// from the type invariant or NULL otherwise.
let clk_ptr = unsafe { from_kernel_err_ptr(bindings::clk_get(self.raw_device(), id_ptr)) }?;

// SAFETY: clock is initialized with valid pointer returned from `bindings::clk_get` call.
unsafe { Ok(Clk::new(clk_ptr)) }
}
}

/// A ref-counted device.
Expand All @@ -62,7 +83,7 @@ impl Device {
///
/// Callers must ensure that `ptr` is valid, non-null, and has a non-zero reference count.
pub unsafe fn new(ptr: *mut bindings::device) -> Self {
// SAFETY: By the safety requiments, ptr is valid and its refcounted will be incremented.
// SAFETY: By the safety requirements, ptr is valid and its refcounted will be incremented.
unsafe { bindings::get_device(ptr) };
// INVARIANT: The safety requirements satisfy all but one invariant, which is that `self`
// owns a reference. This is satisfied by the call to `get_device` above.
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2 changes: 2 additions & 0 deletions rust/kernel/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,8 @@ pub mod amba;
pub mod buffer;
pub mod c_types;
pub mod chrdev;
#[cfg(CONFIG_COMMON_CLK)]
pub mod clk;
pub mod cred;
pub mod device;
pub mod driver;
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