This extends the cpufreq bindings with bindings for registering a
driver.
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
rust/kernel/cpufreq.rs | 478 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 476 insertions(+), 2 deletions(-)
diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index d58bb0bbaad4..2631dbb4865f 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -9,14 +9,17 @@
use crate::{
bindings, clk, cpumask,
device::Device,
- error::{code::*, from_err_ptr, to_result, Result, VTABLE_DEFAULT_ERROR},
+ devres::Devres,
+ error::{code::*, from_err_ptr, from_result, to_result, Result, VTABLE_DEFAULT_ERROR},
prelude::*,
types::ForeignOwnable,
};
use core::{
+ cell::UnsafeCell,
+ marker::PhantomData,
pin::Pin,
- ptr::self,
+ ptr::{self, addr_of_mut},
};
use macros::vtable;
@@ -563,3 +566,474 @@ fn register_em(_policy: &mut Policy) {
kernel::build_error(VTABLE_DEFAULT_ERROR)
}
}
+
+/// Registration of a cpufreq driver.
+pub struct Registration<T: Driver> {
+ drv: Box<UnsafeCell<bindings::cpufreq_driver>>,
+ _p: PhantomData<T>,
+}
+
+// SAFETY: `Registration` doesn't offer any methods or access to fields when shared between threads
+// or CPUs, so it is safe to share it.
+unsafe impl<T: Driver> Sync for Registration<T> {}
+
+// SAFETY: Registration with and unregistration from the cpufreq subsystem can happen from any thread.
+// Additionally, `T::Data` (which is dropped during unregistration) is `Send`, so it is okay to move
+// `Registration` to different threads.
+#[allow(clippy::non_send_fields_in_send_ty)]
+unsafe impl<T: Driver> Send for Registration<T> {}
+
+impl<T: Driver> Registration<T> {
+ /// Registers a cpufreq driver with the rest of the kernel.
+ pub fn new(name: &'static CStr, data: T::Data, flags: u16, boost: bool) -> Result<Self> {
+ let mut drv = Box::new(
+ UnsafeCell::new(bindings::cpufreq_driver::default()),
+ GFP_KERNEL,
+ )?;
+ let drv_ref = drv.get_mut();
+
+ // Account for the trailing null character.
+ let len = name.len() + 1;
+ if len > drv_ref.name.len() {
+ return Err(EINVAL);
+ };
+
+ // SAFETY: `name` is a valid Cstr, and we are copying it to an array of equal or larger
+ // size.
+ let name = unsafe { &*(name.as_bytes_with_nul() as *const [u8] as *const [i8]) };
+ drv_ref.name[..len].copy_from_slice(name);
+
+ drv_ref.boost_enabled = boost;
+ drv_ref.flags = flags;
+
+ // Allocate an array of 3 pointers to be passed to the C code.
+ let mut attr = Box::new([ptr::null_mut(); 3], GFP_KERNEL)?;
+ let mut next = 0;
+
+ // SAFETY: The C code returns a valid pointer here, which is again passed to the C code in
+ // an array.
+ attr[next] =
+ unsafe { addr_of_mut!(bindings::cpufreq_freq_attr_scaling_available_freqs) as *mut _ };
+ next += 1;
+
+ if boost {
+ // SAFETY: The C code returns a valid pointer here, which is again passed to the C code
+ // in an array.
+ attr[next] =
+ unsafe { addr_of_mut!(bindings::cpufreq_freq_attr_scaling_boost_freqs) as *mut _ };
+ next += 1;
+ }
+ attr[next] = ptr::null_mut();
+
+ // Pass the ownership of the memory block to the C code. This will be freed when
+ // the [`Registration`] object goes out of scope.
+ drv_ref.attr = Box::leak(attr) as *mut _;