rust: since rust 1.64, bindgen can use the c types from core

diff --git a/src/rust/bitbox02-rust-c/src/alloc.rs b/src/rust/bitbox02-rust-c/src/alloc.rs
index 3b3698d..14d1b19 100644
--- a/src/rust/bitbox02-rust-c/src/alloc.rs
+++ b/src/rust/bitbox02-rust-c/src/alloc.rs
@@ -15,8 +15,8 @@
 struct BB02Allocator;
 
 extern "C" {
-    pub fn malloc(size: usize) -> *mut util::c_types::c_void;
-    pub fn free(p: *mut util::c_types::c_void);
+    pub fn malloc(size: usize) -> *mut core::ffi::c_void;
+    pub fn free(p: *mut core::ffi::c_void);
 }
 
 unsafe impl core::alloc::GlobalAlloc for BB02Allocator {
diff --git a/src/rust/bitbox02-rust-c/src/lib.rs b/src/rust/bitbox02-rust-c/src/lib.rs
index b08b349..5883022 100644
--- a/src/rust/bitbox02-rust-c/src/lib.rs
+++ b/src/rust/bitbox02-rust-c/src/lib.rs
@@ -71,7 +71,7 @@ pub extern "C" fn rust_rtt_flush() {
 /// The pointer `ptr` must point to a null terminated string
 #[no_mangle]
 #[cfg_attr(not(all(feature = "rtt", target_os = "none")), allow(unused))]
-pub unsafe extern "C" fn rust_log(ptr: *const ::util::c_types::c_char) {
+pub unsafe extern "C" fn rust_log(ptr: *const core::ffi::c_char) {
     #[cfg(all(feature = "rtt", target_os = "none"))]
     {
         if ptr.is_null() {
diff --git a/src/rust/bitbox02-rust-c/src/sha2.rs b/src/rust/bitbox02-rust-c/src/sha2.rs
index ddd2c5f..9e81f61 100644
--- a/src/rust/bitbox02-rust-c/src/sha2.rs
+++ b/src/rust/bitbox02-rust-c/src/sha2.rs
@@ -15,9 +15,9 @@
 extern crate alloc;
 
 use alloc::boxed::Box;
+use core::ffi::{c_uchar, c_void};
 use sha2::Digest;
 use sha2::Sha256;
-use util::c_types::{c_uchar, c_void};
 
 /// Result must be freed by calling `rust_sha256_finish()` or `rust_sha256_free()`.
 #[no_mangle]
diff --git a/src/rust/bitbox02-rust-c/src/util.rs b/src/rust/bitbox02-rust-c/src/util.rs
index eb28075..5b3b3cc 100644
--- a/src/rust/bitbox02-rust-c/src/util.rs
+++ b/src/rust/bitbox02-rust-c/src/util.rs
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use util::c_types::c_uchar;
+use core::ffi::c_uchar;
 
 /// Zero a buffer using volatile writes. Accepts null-ptr and 0-length buffers and does nothing.
 ///
diff --git a/src/rust/bitbox02-sys/build.rs b/src/rust/bitbox02-sys/build.rs
index 95101de..b18b0fb 100644
--- a/src/rust/bitbox02-sys/build.rs
+++ b/src/rust/bitbox02-sys/build.rs
@@ -262,7 +262,6 @@ pub fn main() -> Result<(), &'static str> {
         .args(["--output", &out_path])
         .arg("--use-core")
         .arg("--with-derive-default")
-        .args(["--ctypes-prefix", "util::c_types"])
         .args(
             ALLOWLIST_FNS
                 .iter()
diff --git a/src/rust/bitbox02/src/keystore.rs b/src/rust/bitbox02/src/keystore.rs
index b8f4f4b..cb1c289 100644
--- a/src/rust/bitbox02/src/keystore.rs
+++ b/src/rust/bitbox02/src/keystore.rs
@@ -66,7 +66,10 @@ pub fn unlock(password: &str) -> Result<(), Error> {
     let mut securechip_result: i32 = 0;
     match unsafe {
         bitbox02_sys::keystore_unlock(
-            crate::util::str_to_cstr_vec(password).unwrap().as_ptr(),
+            crate::util::str_to_cstr_vec(password)
+                .unwrap()
+                .as_ptr()
+                .cast(),
             &mut remaining_attempts,
             &mut securechip_result,
         )
@@ -89,7 +92,8 @@ pub fn unlock_bip39(mnemonic_passphrase: &str) -> Result<(), Error> {
         bitbox02_sys::keystore_unlock_bip39(
             crate::util::str_to_cstr_vec(mnemonic_passphrase)
                 .unwrap()
-                .as_ptr(),
+                .as_ptr()
+                .cast(),
         )
     } {
         Ok(())
@@ -101,7 +105,10 @@ pub fn unlock_bip39(mnemonic_passphrase: &str) -> Result<(), Error> {
 pub fn create_and_store_seed(password: &str, host_entropy: &[u8]) -> Result<(), Error> {
     match unsafe {
         bitbox02_sys::keystore_create_and_store_seed(
-            crate::util::str_to_cstr_vec(password).unwrap().as_ptr(),
+            crate::util::str_to_cstr_vec(password)
+                .unwrap()
+                .as_ptr()
+                .cast(),
             host_entropy.as_ptr(),
             host_entropy.len() as _,
         )
@@ -147,7 +154,7 @@ pub fn secp256k1_sign(
     host_nonce: &[u8; 32],
 ) -> Result<SignResult, ()> {
     let mut signature = [0u8; 64];
-    let mut recid: util::c_types::c_int = 0;
+    let mut recid: core::ffi::c_int = 0;
     match unsafe {
         bitbox02_sys::keystore_secp256k1_sign(
             private_key.as_ptr(),
@@ -196,7 +203,10 @@ pub fn encrypt_and_store_seed(seed: &[u8], password: &str) -> Result<(), Error>
         bitbox02_sys::keystore_encrypt_and_store_seed(
             seed.as_ptr(),
             seed.len(),
-            crate::util::str_to_cstr_vec(password).unwrap().as_ptr(),
+            crate::util::str_to_cstr_vec(password)
+                .unwrap()
+                .as_ptr()
+                .cast(),
         )
     } {
         keystore_error_t::KEYSTORE_OK => Ok(()),
diff --git a/src/rust/bitbox02/src/lib.rs b/src/rust/bitbox02/src/lib.rs
index c383a59..f06255e 100644
--- a/src/rust/bitbox02/src/lib.rs
+++ b/src/rust/bitbox02/src/lib.rs
@@ -43,7 +43,7 @@ pub mod securechip;
 pub mod spi_mem;
 pub mod ui;
 
-use ::util::c_types::c_int;
+use core::ffi::c_int;
 use core::time::Duration;
 
 pub use bitbox02_sys::buffer_t;
@@ -56,7 +56,7 @@ pub fn ug_put_string(x: i16, y: i16, input: &str, inverted: bool) {
         bitbox02_sys::UG_PutString(
             x,
             y,
-            crate::util::str_to_cstr_vec(input).unwrap().as_ptr(),
+            crate::util::str_to_cstr_vec(input).unwrap().as_ptr().cast(),
             inverted,
         );
     }
@@ -102,7 +102,7 @@ pub fn delay(duration: Duration) {
 pub fn screen_print_debug(msg: &str, duration: i32) {
     unsafe {
         bitbox02_sys::screen_print_debug(
-            crate::util::str_to_cstr_vec(msg).unwrap().as_ptr(),
+            crate::util::str_to_cstr_vec(msg).unwrap().as_ptr().cast(),
             duration,
         )
     }
@@ -229,15 +229,15 @@ pub fn reboot_to_bootloader() -> ! {
 #[cfg(any(feature = "testing", feature = "c-unit-testing"))]
 pub fn print_stdout(msg: &str) {
     unsafe {
-        bitbox02_sys::printf(crate::util::str_to_cstr_vec(msg).unwrap().as_ptr());
+        bitbox02_sys::printf(crate::util::str_to_cstr_vec(msg).unwrap().as_ptr().cast());
     }
 }
 
 #[cfg(any(feature = "testing", feature = "c-unit-testing"))]
 pub fn println_stdout(msg: &str) {
     unsafe {
-        bitbox02_sys::printf(crate::util::str_to_cstr_vec(msg).unwrap().as_ptr());
-        bitbox02_sys::printf(crate::util::str_to_cstr_vec("\n").unwrap().as_ptr());
+        bitbox02_sys::printf(crate::util::str_to_cstr_vec(msg).unwrap().as_ptr().cast());
+        bitbox02_sys::printf(crate::util::str_to_cstr_vec("\n").unwrap().as_ptr().cast());
     }
 }
 
diff --git a/src/rust/bitbox02/src/memory.rs b/src/rust/bitbox02/src/memory.rs
index fd39381..1a0d3d7 100644
--- a/src/rust/bitbox02/src/memory.rs
+++ b/src/rust/bitbox02/src/memory.rs
@@ -31,7 +31,7 @@ pub struct Error;
 
 pub fn get_device_name() -> String {
     let mut name = [0u8; DEVICE_NAME_MAX_LEN + 1];
-    unsafe { bitbox02_sys::memory_get_device_name(name.as_mut_ptr()) }
+    unsafe { bitbox02_sys::memory_get_device_name(name.as_mut_ptr().cast()) }
     crate::util::str_from_null_terminated(&name[..])
         .unwrap()
         .into()
@@ -40,7 +40,10 @@ pub fn get_device_name() -> String {
 pub fn set_device_name(name: &str) -> Result<(), Error> {
     match unsafe {
         bitbox02_sys::memory_set_device_name(
-            crate::util::str_to_cstr_vec(name).or(Err(Error))?.as_ptr(),
+            crate::util::str_to_cstr_vec(name)
+                .or(Err(Error))?
+                .as_ptr()
+                .cast(),
         )
     } {
         true => Ok(()),
@@ -155,7 +158,8 @@ pub fn multisig_set_by_hash(hash: &[u8], name: &str) -> Result<(), MemoryError>
             hash.as_ptr(),
             crate::util::str_to_cstr_vec(name)
                 .or(Err(MemoryError::MEMORY_ERR_INVALID_INPUT))?
-                .as_ptr(),
+                .as_ptr()
+                .cast(),
         )
     } {
         MemoryError::MEMORY_OK => Ok(()),
@@ -165,7 +169,9 @@ pub fn multisig_set_by_hash(hash: &[u8], name: &str) -> Result<(), MemoryError>
 
 pub fn multisig_get_by_hash(hash: &[u8]) -> Option<String> {
     let mut name = [0u8; MULTISIG_NAME_MAX_LEN + 1];
-    match unsafe { bitbox02_sys::memory_multisig_get_by_hash(hash.as_ptr(), name.as_mut_ptr()) } {
+    match unsafe {
+        bitbox02_sys::memory_multisig_get_by_hash(hash.as_ptr(), name.as_mut_ptr().cast())
+    } {
         true => Some(
             crate::util::str_from_null_terminated(&name[..])
                 .unwrap()
diff --git a/src/rust/bitbox02/src/random.rs b/src/rust/bitbox02/src/random.rs
index 7c72987..2284d97 100644
--- a/src/rust/bitbox02/src/random.rs
+++ b/src/rust/bitbox02/src/random.rs
@@ -20,7 +20,7 @@ pub fn mcu_32_bytes(out: &mut [u8; 32]) {
 #[cfg(not(target_arch = "arm"))]
 pub fn mcu_32_bytes(out: &mut [u8; 32]) {
     extern "C" {
-        fn rand() -> util::c_types::c_int;
+        fn rand() -> core::ffi::c_int;
     }
 
     for elem in out.iter_mut() {
diff --git a/src/rust/bitbox02/src/sd.rs b/src/rust/bitbox02/src/sd.rs
index 22dae2f..6815731 100644
--- a/src/rust/bitbox02/src/sd.rs
+++ b/src/rust/bitbox02/src/sd.rs
@@ -41,7 +41,7 @@ pub fn list_subdir(subdir: Option<&str>) -> Result<Vec<String>, ()> {
         bitbox02_sys::sd_list_subdir(
             &mut list.0,
             match c_subdir.as_ref() {
-                Some(s) => s.as_ptr(),
+                Some(s) => s.as_ptr().cast(),
                 None => core::ptr::null(),
             },
         )
@@ -59,8 +59,8 @@ pub fn list_subdir(subdir: Option<&str>) -> Result<Vec<String>, ()> {
 pub fn erase_file_in_subdir(filename: &str, dir: &str) -> Result<(), ()> {
     match unsafe {
         bitbox02_sys::sd_erase_file_in_subdir(
-            str_to_cstr_vec(filename).unwrap().as_ptr(),
-            str_to_cstr_vec(dir).unwrap().as_ptr(),
+            str_to_cstr_vec(filename).unwrap().as_ptr().cast(),
+            str_to_cstr_vec(dir).unwrap().as_ptr().cast(),
         )
     } {
         true => Ok(()),
@@ -73,8 +73,8 @@ pub fn load_bin(filename: &str, dir: &str) -> Result<zeroize::Zeroizing<Vec<u8>>
     let mut contents_len: usize = 0;
     match unsafe {
         bitbox02_sys::sd_load_bin(
-            str_to_cstr_vec(filename).unwrap().as_ptr(),
-            str_to_cstr_vec(dir).unwrap().as_ptr(),
+            str_to_cstr_vec(filename).unwrap().as_ptr().cast(),
+            str_to_cstr_vec(dir).unwrap().as_ptr().cast(),
             contents.as_mut_ptr(),
             &mut contents_len,
         )
@@ -87,8 +87,8 @@ pub fn load_bin(filename: &str, dir: &str) -> Result<zeroize::Zeroizing<Vec<u8>>
 pub fn write_bin(filename: &str, dir: &str, data: &[u8]) -> Result<(), ()> {
     match unsafe {
         bitbox02_sys::sd_write_bin(
-            str_to_cstr_vec(filename).unwrap().as_ptr(),
-            str_to_cstr_vec(dir).unwrap().as_ptr(),
+            str_to_cstr_vec(filename).unwrap().as_ptr().cast(),
+            str_to_cstr_vec(dir).unwrap().as_ptr().cast(),
             data.as_ptr(),
             data.len() as _,
             true,
diff --git a/src/rust/bitbox02/src/ui/types.rs b/src/rust/bitbox02/src/ui/types.rs
index 02a460e..324ab4a 100644
--- a/src/rust/bitbox02/src/ui/types.rs
+++ b/src/rust/bitbox02/src/ui/types.rs
@@ -83,9 +83,9 @@ impl<'a> ConfirmParams<'a> {
             crate::util::str_to_cstr_vec(crate::util::truncate_str(self.body, TRUNCATE_SIZE))
                 .unwrap();
         Survive::new(bitbox02_sys::confirm_params_t {
-            title: title_scatch.as_ptr(),
+            title: title_scatch.as_ptr().cast(),
             title_autowrap: self.title_autowrap,
-            body: body_scratch.as_ptr(),
+            body: body_scratch.as_ptr().cast(),
             font: self.font.as_ptr(),
             scrollable: self.scrollable,
             longtouch: self.longtouch,
@@ -125,7 +125,7 @@ impl<'a> TrinaryInputStringParams<'a> {
                 .unwrap();
 
         Survive::new(bitbox02_sys::trinary_input_string_params_t {
-            title: title_scratch.as_ptr(),
+            title: title_scratch.as_ptr().cast(),
             wordlist: match self.wordlist {
                 None => core::ptr::null(),
                 Some(wordlist) => wordlist.as_ptr(),
diff --git a/src/rust/bitbox02/src/ui/ui.rs b/src/rust/bitbox02/src/ui/ui.rs
index 79e93d3..6f16742 100644
--- a/src/rust/bitbox02/src/ui/ui.rs
+++ b/src/rust/bitbox02/src/ui/ui.rs
@@ -18,7 +18,7 @@ pub use super::types::{
     TrinaryChoiceCb, TrinaryInputStringParams,
 };
 
-use util::c_types::{c_char, c_void};
+use core::ffi::{c_char, c_void};
 
 extern crate alloc;
 use alloc::boxed::Box;
@@ -249,7 +249,7 @@ pub fn menu_create(params: MenuParams<'_>) -> Component<'_> {
         .collect();
     // Step two: collect pointers. This var also has to be valid until menu_create() finishes, or
     // the pointer will be invalid.
-    let c_words: Vec<*const util::c_types::c_char> =
+    let c_words: Vec<*const core::ffi::c_char> =
         words.iter().map(|word| word.as_ptr() as _).collect();
 
     let (select_word_cb, select_word_cb_param) = match params.select_word_cb {
diff --git a/src/rust/util/src/c_types.rs b/src/rust/util/src/c_types.rs
deleted file mode 100644
index 9e49ce7..0000000
--- a/src/rust/util/src/c_types.rs
+++ /dev/null
@@ -1,50 +0,0 @@
-// Copyright 2019 Shift Cryptosecurity AG
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#![allow(non_camel_case_types)]
-#[repr(u8)]
-pub enum c_void {
-    #[doc(hidden)]
-    __variant,
-}
-pub type c_char = u8;
-pub type c_schar = i8;
-pub type c_uchar = u8;
-pub type c_short = i16;
-pub type c_ushort = u16;
-pub type c_int = i32;
-
-#[cfg(target_arch = "x86_64")]
-pub type c_uint = u64;
-#[cfg(target_arch = "aarch64")]
-pub type c_uint = u64;
-#[cfg(target_arch = "arm")]
-pub type c_uint = u32;
-
-#[cfg(target_arch = "x86_64")]
-pub type c_long = i64;
-#[cfg(target_arch = "aarch64")]
-pub type c_long = i64;
-#[cfg(target_arch = "arm")]
-pub type c_long = i32;
-
-#[cfg(target_arch = "x86_64")]
-pub type c_ulong = u64;
-#[cfg(target_arch = "aarch64")]
-pub type c_ulong = u64;
-#[cfg(target_arch = "arm")]
-pub type c_ulong = u32;
-
-pub type c_longlong = i64;
-pub type c_ulonglong = u64;
diff --git a/src/rust/util/src/lib.rs b/src/rust/util/src/lib.rs
index 680fc57..5d7a2e7 100644
--- a/src/rust/util/src/lib.rs
+++ b/src/rust/util/src/lib.rs
@@ -15,7 +15,6 @@
 #![cfg_attr(not(test), no_std)]
 pub mod ascii;
 pub mod bip32;
-pub mod c_types;
 pub mod decimal;
 pub mod log;
 pub mod name;