irq commit: this large commit gets interrupts working
Signed-off-by: Sean Cross <sean@xobs.io>
This commit is contained in:
351
xous-kernel-riscv-rt/src/lib.rs
Normal file
351
xous-kernel-riscv-rt/src/lib.rs
Normal file
@ -0,0 +1,351 @@
|
||||
//! Minimal startup / runtime for RISC-V CPU's
|
||||
//!
|
||||
//! # Minimum Supported Rust Version (MSRV)
|
||||
//!
|
||||
//! This crate is guaranteed to compile on stable Rust 1.31 and up. It *might*
|
||||
//! compile with older versions but that may change in any new patch release.
|
||||
//!
|
||||
//! # Features
|
||||
//!
|
||||
//! This crate provides
|
||||
//!
|
||||
//! - Before main initialization of the `.bss` and `.data` sections.
|
||||
//!
|
||||
//! - `#[entry]` to declare the entry point of the program
|
||||
//! - `#[pre_init]` to run code *before* `static` variables are initialized
|
||||
//!
|
||||
//! - A linker script that encodes the memory layout of a generic RISC-V
|
||||
//! microcontroller. This linker script is missing some information that must
|
||||
//! be supplied through a `memory.x` file (see example below). This file
|
||||
//! must be supplied using rustflags and listed *before* `link.x`. Arbitrary
|
||||
//! filename can be use instead of `memory.x`.
|
||||
//!
|
||||
//! - A `_sheap` symbol at whose address you can locate a heap.
|
||||
//!
|
||||
//! ``` text
|
||||
//! $ cargo new --bin app && cd $_
|
||||
//!
|
||||
//! $ # add this crate as a dependency
|
||||
//! $ edit Cargo.toml && cat $_
|
||||
//! [dependencies]
|
||||
//! riscv-rt = "0.6.1"
|
||||
//! panic-halt = "0.2.0"
|
||||
//!
|
||||
//! $ # memory layout of the device
|
||||
//! $ edit memory.x && cat $_
|
||||
//! MEMORY
|
||||
//! {
|
||||
//! RAM : ORIGIN = 0x80000000, LENGTH = 16K
|
||||
//! FLASH : ORIGIN = 0x20000000, LENGTH = 16M
|
||||
//! }
|
||||
//!
|
||||
//! REGION_ALIAS("REGION_TEXT", FLASH);
|
||||
//! REGION_ALIAS("REGION_RODATA", FLASH);
|
||||
//! REGION_ALIAS("REGION_DATA", RAM);
|
||||
//! REGION_ALIAS("REGION_BSS", RAM);
|
||||
//! REGION_ALIAS("REGION_HEAP", RAM);
|
||||
//! REGION_ALIAS("REGION_STACK", RAM);
|
||||
//!
|
||||
//! $ edit src/main.rs && cat $_
|
||||
//! ```
|
||||
//!
|
||||
//! ``` ignore,no_run
|
||||
//! #![no_std]
|
||||
//! #![no_main]
|
||||
//!
|
||||
//! extern crate panic_halt;
|
||||
//!
|
||||
//! use riscv_rt::entry;
|
||||
//!
|
||||
//! // use `main` as the entry point of this application
|
||||
//! // `main` is not allowed to return
|
||||
//! #[entry]
|
||||
//! fn main() -> ! {
|
||||
//! // do something here
|
||||
//! loop { }
|
||||
//! }
|
||||
//! ```
|
||||
//!
|
||||
//! ``` text
|
||||
//! $ mkdir .cargo && edit .cargo/config && cat $_
|
||||
//! [target.riscv32imac-unknown-none-elf]
|
||||
//! rustflags = [
|
||||
//! "-C", "link-arg=-Tmemory.x",
|
||||
//! "-C", "link-arg=-Tlink.x",
|
||||
//! ]
|
||||
//!
|
||||
//! [build]
|
||||
//! target = "riscv32imac-unknown-none-elf"
|
||||
//! $ edit build.rs && cat $_
|
||||
//! ```
|
||||
//!
|
||||
//! ``` ignore,no_run
|
||||
//! use std::env;
|
||||
//! use std::fs::File;
|
||||
//! use std::io::Write;
|
||||
//! use std::path::Path;
|
||||
//!
|
||||
//! /// Put the linker script somewhere the linker can find it.
|
||||
//! fn main() {
|
||||
//! let out_dir = env::var("OUT_DIR").expect("No out dir");
|
||||
//! let dest_path = Path::new(&out_dir);
|
||||
//! let mut f = File::create(&dest_path.join("memory.x"))
|
||||
//! .expect("Could not create file");
|
||||
//!
|
||||
//! f.write_all(include_bytes!("memory.x"))
|
||||
//! .expect("Could not write file");
|
||||
//!
|
||||
//! println!("cargo:rustc-link-search={}", dest_path.display());
|
||||
//!
|
||||
//! println!("cargo:rerun-if-changed=memory.x");
|
||||
//! println!("cargo:rerun-if-changed=build.rs");
|
||||
//! }
|
||||
//! ```
|
||||
//!
|
||||
//! ``` text
|
||||
//! $ cargo build
|
||||
//!
|
||||
//! $ riscv32-unknown-elf-objdump -Cd $(find target -name app) | head
|
||||
//!
|
||||
//! Disassembly of section .text:
|
||||
//!
|
||||
//! 20000000 <_start>:
|
||||
//! 20000000: 800011b7 lui gp,0x80001
|
||||
//! 20000004: 80018193 addi gp,gp,-2048 # 80000800 <_stack_start+0xffffc800>
|
||||
//! 20000008: 80004137 lui sp,0x80004
|
||||
//! ```
|
||||
//!
|
||||
//! # Symbol interfaces
|
||||
//!
|
||||
//! This crate makes heavy use of symbols, linker sections and linker scripts to
|
||||
//! provide most of its functionality. Below are described the main symbol
|
||||
//! interfaces.
|
||||
//!
|
||||
//! ## `memory.x`
|
||||
//!
|
||||
//! This file supplies the information about the device to the linker.
|
||||
//!
|
||||
//! ### `MEMORY`
|
||||
//!
|
||||
//! The main information that this file must provide is the memory layout of
|
||||
//! the device in the form of the `MEMORY` command. The command is documented
|
||||
//! [here][2], but at a minimum you'll want to create at least one memory region.
|
||||
//!
|
||||
//! [2]: https://sourceware.org/binutils/docs/ld/MEMORY.html
|
||||
//!
|
||||
//! To support different relocation models (RAM-only, FLASH+RAM) multiple regions are used:
|
||||
//!
|
||||
//! - `REGION_TEXT` - for `.init`, `.trap` and `.text` sections
|
||||
//! - `REGION_RODATA` - for `.rodata` section and storing initial values for `.data` section
|
||||
//! - `REGION_DATA` - for `.data` section
|
||||
//! - `REGION_BSS` - for `.bss` section
|
||||
//! - `REGION_HEAP` - for the heap area
|
||||
//! - `REGION_STACK` - for hart stacks
|
||||
//!
|
||||
//! Specific aliases for these regions must be defined in `memory.x` file (see example below).
|
||||
//!
|
||||
//! ### `_stext`
|
||||
//!
|
||||
//! This symbol provides the loading address of `.text` section. This value can be changed
|
||||
//! to override the loading address of the firmware (for example, in case of bootloader present).
|
||||
//!
|
||||
//! If omitted this symbol value will default to `ORIGIN(REGION_TEXT)`.
|
||||
//!
|
||||
//! ### `_stack_start`
|
||||
//!
|
||||
//! This symbol provides the address at which the call stack will be allocated.
|
||||
//! The call stack grows downwards so this address is usually set to the highest
|
||||
//! valid RAM address plus one (this *is* an invalid address but the processor
|
||||
//! will decrement the stack pointer *before* using its value as an address).
|
||||
//!
|
||||
//! In case of multiple harts present, this address defines the initial stack pointer for hart 0.
|
||||
//! Stack pointer for hart `N` is calculated as `_stack_start - N * _hart_stack_size`.
|
||||
//!
|
||||
//! If omitted this symbol value will default to `ORIGIN(REGION_STACK) + LENGTH(REGION_STACK)`.
|
||||
//!
|
||||
//! #### Example
|
||||
//!
|
||||
//! Allocating the call stack on a different RAM region.
|
||||
//!
|
||||
//! ``` text
|
||||
//! MEMORY
|
||||
//! {
|
||||
//! L2_LIM : ORIGIN = 0x08000000, LENGTH = 1M
|
||||
//! RAM : ORIGIN = 0x80000000, LENGTH = 16K
|
||||
//! FLASH : ORIGIN = 0x20000000, LENGTH = 16M
|
||||
//! }
|
||||
//!
|
||||
//! REGION_ALIAS("REGION_TEXT", FLASH);
|
||||
//! REGION_ALIAS("REGION_RODATA", FLASH);
|
||||
//! REGION_ALIAS("REGION_DATA", RAM);
|
||||
//! REGION_ALIAS("REGION_BSS", RAM);
|
||||
//! REGION_ALIAS("REGION_HEAP", RAM);
|
||||
//! REGION_ALIAS("REGION_STACK", L2_LIM);
|
||||
//!
|
||||
//! _stack_start = ORIGIN(L2_LIM) + LENGTH(L2_LIM);
|
||||
//! ```
|
||||
//!
|
||||
//! ### `_max_hart_id`
|
||||
//!
|
||||
//! This symbol defines the maximum hart id suppoted. All harts with id
|
||||
//! greater than `_max_hart_id` will be redirected to `abort()`.
|
||||
//!
|
||||
//! This symbol is supposed to be redefined in platform support crates for
|
||||
//! multi-core targets.
|
||||
//!
|
||||
//! If omitted this symbol value will default to 0 (single core).
|
||||
//!
|
||||
//! ### `_hart_stack_size`
|
||||
//!
|
||||
//! This symbol defines stack area size for *one* hart.
|
||||
//!
|
||||
//! If omitted this symbol value will default to 2K.
|
||||
//!
|
||||
//! ### `_heap_size`
|
||||
//!
|
||||
//! This symbol provides the size of a heap region. The default value is 0. You can set `_heap_size`
|
||||
//! to a non-zero value if you are planning to use heap allocations.
|
||||
//!
|
||||
//! ### `_sheap`
|
||||
//!
|
||||
//! This symbol is located in RAM right after the `.bss` and `.data` sections.
|
||||
//! You can use the address of this symbol as the start address of a heap
|
||||
//! region. This symbol is 4 byte aligned so that address will be a multiple of 4.
|
||||
//!
|
||||
//! #### Example
|
||||
//!
|
||||
//! ``` no_run
|
||||
//! extern crate some_allocator;
|
||||
//!
|
||||
//! extern "C" {
|
||||
//! static _sheap: u8;
|
||||
//! static _heap_size: u8;
|
||||
//! }
|
||||
//!
|
||||
//! fn main() {
|
||||
//! unsafe {
|
||||
//! let heap_bottom = &_sheap as *const u8 as usize;
|
||||
//! let heap_size = &_heap_size as *const u8 as usize;
|
||||
//! some_allocator::initialize(heap_bottom, heap_size);
|
||||
//! }
|
||||
//! }
|
||||
//! ```
|
||||
//!
|
||||
//! ### `_mp_hook`
|
||||
//!
|
||||
//! This function is called from all the harts and must return true only for one hart,
|
||||
//! which will perform memory initialization. For other harts it must return false
|
||||
//! and implement wake-up in platform-dependent way (e.g. after waiting for a user interrupt).
|
||||
//!
|
||||
//! This function can be redefined in the following way:
|
||||
//!
|
||||
//! ``` no_run
|
||||
//! #[export_name = "_mp_hook"]
|
||||
//! pub extern "Rust" fn mp_hook() -> bool {
|
||||
//! // ...
|
||||
//! }
|
||||
//! ```
|
||||
//!
|
||||
//! Default implementation of this function wakes hart 0 and busy-loops all the other harts.
|
||||
|
||||
// NOTE: Adapted from cortex-m/src/lib.rs
|
||||
#![no_std]
|
||||
#![deny(missing_docs)]
|
||||
#![deny(warnings)]
|
||||
|
||||
extern crate xous_riscv;
|
||||
extern crate xous_kernel_riscv_rt_macros as macros;
|
||||
extern crate r0;
|
||||
|
||||
pub use macros::{xous_kernel_entry, pre_init};
|
||||
|
||||
use xous_riscv::register::mstatus;
|
||||
|
||||
#[export_name = "error: riscv-rt appears more than once in the dependency graph"]
|
||||
#[doc(hidden)]
|
||||
pub static __ONCE__: () = ();
|
||||
|
||||
extern "C" {
|
||||
// Boundaries of the .bss section
|
||||
static mut _ebss: u32;
|
||||
static mut _sbss: u32;
|
||||
|
||||
// Boundaries of the .data section
|
||||
static mut _edata: u32;
|
||||
static mut _sdata: u32;
|
||||
|
||||
// Initial values of the .data section (stored in Flash)
|
||||
static _sidata: u32;
|
||||
}
|
||||
|
||||
|
||||
/// Rust entry point (_start_rust)
|
||||
///
|
||||
/// Zeros bss section, initializes data section and calls main. This function
|
||||
/// never returns.
|
||||
#[link_section = ".init.rust"]
|
||||
#[export_name = "_start_rust"]
|
||||
pub unsafe extern "C" fn start_rust() -> ! {
|
||||
extern "Rust" {
|
||||
// This symbol will be provided by the kernel
|
||||
fn xous_kernel_main() -> !;
|
||||
|
||||
// This symbol will be provided by the user via `#[pre_init]`
|
||||
fn __pre_init();
|
||||
|
||||
fn _mp_hook() -> bool;
|
||||
}
|
||||
|
||||
if _mp_hook() {
|
||||
__pre_init();
|
||||
|
||||
r0::zero_bss(&mut _sbss, &mut _ebss);
|
||||
r0::init_data(&mut _sdata, &mut _edata, &_sidata);
|
||||
}
|
||||
|
||||
xous_kernel_main();
|
||||
}
|
||||
|
||||
|
||||
/// Trap entry point rust (_start_trap_rust)
|
||||
///
|
||||
/// mcause is read to determine the cause of the trap. XLEN-1 bit indicates
|
||||
/// if it's an interrupt or an exception. The result is converted to an element
|
||||
/// of the Interrupt or Exception enum and passed to handle_interrupt or
|
||||
/// handle_exception.
|
||||
#[link_section = ".trap.rust"]
|
||||
#[export_name = "_start_trap_rust"]
|
||||
pub extern "C" fn start_trap_rust() {
|
||||
extern "C" {
|
||||
fn trap_handler();
|
||||
}
|
||||
|
||||
unsafe {
|
||||
// dispatch trap to handler
|
||||
trap_handler();
|
||||
|
||||
// mstatus, remain in M-mode after mret
|
||||
mstatus::set_mpp(mstatus::MPP::Machine);
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
#[doc(hidden)]
|
||||
#[no_mangle]
|
||||
pub fn default_trap_handler() {}
|
||||
|
||||
#[doc(hidden)]
|
||||
#[no_mangle]
|
||||
pub unsafe extern "Rust" fn default_pre_init() {}
|
||||
|
||||
#[doc(hidden)]
|
||||
#[no_mangle]
|
||||
pub extern "Rust" fn default_mp_hook() -> bool {
|
||||
use xous_riscv::register::mhartid;
|
||||
match mhartid::read() {
|
||||
0 => true,
|
||||
_ => loop {
|
||||
unsafe { xous_riscv::asm::wfi() }
|
||||
},
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user