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Add init() to the Chip trait #4682

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Add init() to the Chip trait #4682

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695cb52
kernel: add `init()` to `Chip`
bradjc Dec 2, 2025
4feedb3
chips: nrf52: implement init()
bradjc Dec 2, 2025
dfb031a
boards: nrf52840dk: use ChipHw::init()
bradjc Dec 2, 2025
b41ddd9
nrf52: move deferred call init to the chip
bradjc Dec 2, 2025
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8 changes: 2 additions & 6 deletions boards/nordic/nrf52840dk/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,7 @@ use kernel::hil::led::LedLow;
use kernel::hil::time::Counter;
#[allow(unused_imports)]
use kernel::hil::usb::Client;
use kernel::platform::chip::Chip;
use kernel::platform::{KernelResources, SyscallDriverLookup};
use kernel::process::ProcessArray;
use kernel::scheduler::round_robin::RoundRobinSched;
Expand Down Expand Up @@ -404,12 +405,7 @@ pub unsafe fn start_no_pconsole() -> (
//--------------------------------------------------------------------------

// Apply errata fixes and enable interrupts.
nrf52840::init();

// Initialize deferred calls very early.
kernel::deferred_call::initialize_deferred_call_state::<
<ChipHw as kernel::platform::chip::Chip>::ThreadIdProvider,
>();
ChipHw::init();

// Set up peripheral drivers. Called in separate function to reduce stack
// usage.
Expand Down
21 changes: 21 additions & 0 deletions chips/nrf52/src/chip.rs
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Expand Up @@ -109,6 +109,27 @@ impl<'a, I: InterruptService + 'a> kernel::platform::chip::Chip for NRF52<'a, I>
type UserspaceKernelBoundary = cortexm4f::syscall::SysCall;
type ThreadIdProvider = cortexm4f::thread_id::CortexMThreadIdProvider;

fn init() {
// # Safety
//
// We are setting up the nRF52 chip, so these memory locations are valid
// on the nRF52 and this is OK to call.
unsafe {
crate::crt1::fix_errata();
}
crate::crt1::initialize_vector_table();

// # Safety
//
// Need to enable interrupts.
unsafe {
nvic::enable_all();
}

// Initialize deferred calls very early.
kernel::deferred_call::initialize_deferred_call_state::<Self::ThreadIdProvider>();
}

fn mpu(&self) -> &Self::MPU {
&self.mpu
}
Expand Down
40 changes: 26 additions & 14 deletions chips/nrf52/src/crt1.rs
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Expand Up @@ -2,9 +2,7 @@
// SPDX-License-Identifier: Apache-2.0 OR MIT
// Copyright Tock Contributors 2022.

use cortexm4f::{
initialize_ram_jump_to_main, nvic, scb, unhandled_interrupt, CortexM4F, CortexMVariant,
};
use cortexm4f::{initialize_ram_jump_to_main, scb, unhandled_interrupt, CortexM4F, CortexMVariant};

/*
* Adapted from crt1.c which was relicensed by the original author from
Expand Down Expand Up @@ -71,8 +69,13 @@ pub static BASE_VECTORS: [unsafe extern "C" fn(); 16] = [
#[cfg_attr(all(target_arch = "arm", target_os = "none"), used)]
pub static IRQS: [unsafe extern "C" fn(); 80] = [CortexM4F::GENERIC_ISR; 80];

#[no_mangle]
pub unsafe extern "C" fn init() {
/// Apply fixes for various nRF52 errata
///
/// # Safety
///
/// Fixing these errata requires writing to various memory locations. These
/// operations are safe as long as this is only run on an nRF52 MCU.
pub(crate) unsafe fn fix_errata() {
// Apply early initialization workarounds for anomalies documented on
// 2015-12-11 nRF52832 Errata v1.2
// http://infocenter.nordicsemi.com/pdf/nRF52832_Errata_v1.2.pdf
Expand Down Expand Up @@ -139,14 +142,23 @@ pub unsafe extern "C" fn init() {
// "RAM: RAM content cannot be trusted upon waking up from System ON Idle
// or System OFF mode" found at the Errata doc
*(0x40000ee4i32 as *mut u32) = *(0x10000258i32 as *mut u32) & 0x4fu32;
}

// Explicitly tell the core where Tock's vector table is located. If Tock is the
// only thing on the chip then this is effectively a no-op. If, however, there is
// a bootloader present then we want to ensure that the vector table is set
// correctly for Tock. The bootloader _may_ set this for us, but it may not
// so that any errors early in the Tock boot process trap back to the bootloader.
// To be safe we unconditionally set the vector table.
scb::set_vector_table_offset(BASE_VECTORS.as_ptr().cast::<()>());

nvic::enable_all();
/// Explicitly tell the core where Tock's vector table is located.
///
/// If Tock is the
/// only thing on the chip then this is effectively a no-op. If, however, there is
/// a bootloader present then we want to ensure that the vector table is set
/// correctly for Tock. The bootloader _may_ set this for us, but it may not
/// so that any errors early in the Tock boot process trap back to the bootloader.
/// To be safe we unconditionally set the vector table.
pub(crate) fn initialize_vector_table() {
// # Safety
//
// The vector table must setup function pointers for the thumb core
// correctly. Because `BASE_VECTORS` is the correct data type this is
// safe.
unsafe {
scb::set_vector_table_offset(BASE_VECTORS.as_ptr().cast::<()>());
}
}
1 change: 0 additions & 1 deletion chips/nrf52/src/lib.rs
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Expand Up @@ -23,7 +23,6 @@ pub mod uart;
pub mod uicr;
pub mod usbd;

pub use crate::crt1::init;
pub use nrf5x::{
aes, constants, gpio, peripheral_interrupts, pinmux, rtc, temperature, timer, trng,
};
4 changes: 2 additions & 2 deletions chips/nrf52840/src/lib.rs
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Expand Up @@ -4,8 +4,8 @@

#![no_std]
pub use nrf52::{
acomp, adc, aes, ble_radio, chip, clock, constants, crt1, ficr, i2c, ieee802154_radio, init,
nvmc, peripheral_interrupts as base_interrupts, pinmux, power, ppi, pwm, rtc, spi, temperature,
acomp, adc, aes, ble_radio, chip, clock, constants, crt1, ficr, i2c, ieee802154_radio, nvmc,
peripheral_interrupts as base_interrupts, pinmux, power, ppi, pwm, rtc, spi, temperature,
timer, trng, uart, uicr, usbd,
};
pub mod gpio;
Expand Down
11 changes: 11 additions & 0 deletions kernel/src/platform/chip.rs
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Expand Up @@ -28,6 +28,17 @@ pub trait Chip {
/// chips may have various custom requirements.
type UserspaceKernelBoundary: syscall::UserspaceKernelBoundary;

/// Run any necessary initialization for this chip.
///
/// This should be called first by the board in its `main()` function.
///
/// This should contain any necessary initialization steps, including:
///
/// - Any architecture-specific setup
/// - Any errata fixes
/// - Any configuration needed for the chip to continue booting the kernel
fn init();
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@alexandruradovici alexandruradovici Dec 16, 2025

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Is there any way to write a check that would panic if this function was not called by the board?

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@bradjc bradjc Dec 17, 2025

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I'm not entirely sure, be we could probably enforce a return type that is required to call the kernel loop if we wanted.


/// The kernel calls this function to tell the chip to check for all pending
/// interrupts and to correctly dispatch them to the peripheral drivers for
/// the chip.
Expand Down
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