rust: cpufreq: Ensure C ABI compatibility in all unsafe

Update all `unsafe extern "C"` callback functions in the cpufreq module to
use `kernel::ffi` types (`c_int`, `c_uint`, etc.) instead of Rust-native
types like `i32`, `u32`, or `usize`.

This change ensures that all Rust callbacks have signatures that are
ABI-compatible with their corresponding C counterparts, which is critical
for FFI correctness and safety.

Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Link: Rust-for-Linux#1170
Signed-off-by: Abhinav Ananthu <abhinav.ogl@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Author: Herculoxz

rust/kernel/cpufreq.rs

@@ -1207,8 +1207,8 @@ impl<T: Driver> Registration<T> {
     /// - The pointer arguments must be valid pointers.
     unsafe extern "C" fn target_callback(
         ptr: *mut bindings::cpufreq_policy,
-        target_freq: u32,
-        relation: u32,
+        target_freq: c_uint,
+        relation: c_uint,
     ) -> kernel::ffi::c_int {
         from_result(|| {
             // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
@@ -1226,7 +1226,7 @@ impl<T: Driver> Registration<T> {
     /// - The pointer arguments must be valid pointers.
     unsafe extern "C" fn target_index_callback(
         ptr: *mut bindings::cpufreq_policy,
-        index: u32,
+        index: c_uint,
     ) -> kernel::ffi::c_int {
         from_result(|| {
             // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
@@ -1249,7 +1249,7 @@ impl<T: Driver> Registration<T> {
     /// - The pointer arguments must be valid pointers.
     unsafe extern "C" fn fast_switch_callback(
         ptr: *mut bindings::cpufreq_policy,
-        target_freq: u32,
+        target_freq: c_uint,
     ) -> kernel::ffi::c_uint {
         // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
         // lifetime of `policy`.
@@ -1263,10 +1263,10 @@ impl<T: Driver> Registration<T> {
     ///
     /// - This function may only be called from the cpufreq C infrastructure.
     unsafe extern "C" fn adjust_perf_callback(
-        cpu: u32,
-        min_perf: usize,
-        target_perf: usize,
-        capacity: usize,
+        cpu: c_uint,
+        min_perf: c_ulong,
+        target_perf: c_ulong,
+        capacity: c_ulong,
     ) {
         // SAFETY: The C API guarantees that `cpu` refers to a valid CPU number.
         let cpu_id = unsafe { CpuId::from_u32_unchecked(cpu) };
@@ -1284,7 +1284,7 @@ impl<T: Driver> Registration<T> {
     /// - The pointer arguments must be valid pointers.
     unsafe extern "C" fn get_intermediate_callback(
         ptr: *mut bindings::cpufreq_policy,
-        index: u32,
+        index: c_uint,
     ) -> kernel::ffi::c_uint {
         // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
         // lifetime of `policy`.
@@ -1305,7 +1305,7 @@ impl<T: Driver> Registration<T> {
     /// - The pointer arguments must be valid pointers.
     unsafe extern "C" fn target_intermediate_callback(
         ptr: *mut bindings::cpufreq_policy,
-        index: u32,
+        index: c_uint,
     ) -> kernel::ffi::c_int {
         from_result(|| {
             // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
@@ -1325,7 +1325,7 @@ impl<T: Driver> Registration<T> {
     /// # Safety
     ///
     /// - This function may only be called from the cpufreq C infrastructure.
-    unsafe extern "C" fn get_callback(cpu: u32) -> kernel::ffi::c_uint {
+    unsafe extern "C" fn get_callback(cpu: c_uint) -> kernel::ffi::c_uint {
         // SAFETY: The C API guarantees that `cpu` refers to a valid CPU number.
         let cpu_id = unsafe { CpuId::from_u32_unchecked(cpu) };
 
@@ -1351,7 +1351,7 @@ impl<T: Driver> Registration<T> {
     ///
     /// - This function may only be called from the cpufreq C infrastructure.
     /// - The pointer arguments must be valid pointers.
-    unsafe extern "C" fn bios_limit_callback(cpu: i32, limit: *mut u32) -> kernel::ffi::c_int {
+    unsafe extern "C" fn bios_limit_callback(cpu: c_int, limit: *mut c_uint) -> kernel::ffi::c_int {
         // SAFETY: The C API guarantees that `cpu` refers to a valid CPU number.
         let cpu_id = unsafe { CpuId::from_i32_unchecked(cpu) };
 
@@ -1371,7 +1371,7 @@ impl<T: Driver> Registration<T> {
     /// - The pointer arguments must be valid pointers.
     unsafe extern "C" fn set_boost_callback(
         ptr: *mut bindings::cpufreq_policy,
-        state: i32,
+        state: c_int,
     ) -> kernel::ffi::c_int {
         from_result(|| {
             // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the