Merge pull request #60 from braun-embedded/flash

Add Flash API

Author: arkorobotics

Cargo.toml

@@ -111,6 +111,10 @@ required-features = ["rt"]
 name = "button_irq_rtfm"
 required-features = ["rt"]
 
+[[example]]
+name = "flash"
+required-features = ["rt","stm32l082"]
+
 [[example]]
 name = "i2c_dma"
 required-features = ["rt","stm32l0x2"]

build.rs

@@ -1,5 +1,5 @@
 use std::env;
-use std::fs::File;
+use std::fs::{self, File};
 use std::io::Write;
 use std::path::PathBuf;
 
@@ -48,4 +48,23 @@ fn main() {
     }
 
     println!("cargo:rerun-if-changed=build.rs");
+
+
+    // Copy the binary blog required by the Flash API somewhere the linker can
+    // find it, and tell Cargo to link it.
+
+    let blob_name = "flash";
+    let blob_file = format!("lib{}.a", blob_name);
+    let blob_path = format!("flash-code/{}", blob_file);
+
+    fs::copy(
+        &blob_path,
+        out.join(format!("{}", blob_file)),
+    )
+    .expect("Failed to copy binary blog for Flash API");
+
+    println!("cargo:rustc-link-lib=static={}", blob_name);
+    println!("cargo:rustc-link-search={}", out.display());
+
+    println!("cargo:rerun-if-changed={}", blob_path);
 }

examples/flash.rs

@@ -0,0 +1,83 @@
+#![no_main]
+#![no_std]
+
+
+extern crate panic_semihosting;
+
+
+use cortex_m_rt::entry;
+use stm32l0xx_hal::{
+    prelude::*,
+    flash::{
+        FLASH,
+        FLASH_START,
+        flash_size_in_kb,
+    },
+    pac,
+    rcc,
+};
+
+
+#[entry]
+fn main() -> ! {
+    let cp = cortex_m::Peripherals::take().unwrap();
+    let dp = pac::Peripherals::take().unwrap();
+
+    let mut rcc   = dp.RCC.freeze(rcc::Config::hsi16());
+    let mut flash = FLASH::new(dp.FLASH, &mut rcc);
+    let     gpiob = dp.GPIOB.split(&mut rcc);
+
+    let mut led = gpiob.pb2.into_push_pull_output();
+
+    // Get the delay provider.
+    let mut delay = cp.SYST.delay(rcc.clocks);
+
+    // This should be the first word in the second flash bank. Since this
+    // example should be quite small, we can be reasonably sure that it fully
+    // fits into the first flash bank. This means we won't overwrite our own
+    // code or stall execution.
+    //
+    // This example requires STM32L082, which has 2 banks.
+    let address = FLASH_START + flash_size_in_kb() / 2 * 1024;
+    let address = address as *mut u32;
+
+    flash.erase_flash_page(address)
+        .expect("Failed to erase Flash page (1)");
+    for i in 0 .. 32 {
+        let word = unsafe { *address.offset(i * 4) };
+        assert_eq!(word, 0);
+    }
+
+    flash.write_word(address, 0x12345678)
+        .expect("Failed to write word");
+    assert_eq!(unsafe { *address }, 0x12345678);
+
+    flash.erase_flash_page(address)
+        .expect("Failed to erase Flash page (2)");
+    for i in 0 .. 32 {
+        let word = unsafe { *address.offset(i * 4) };
+        assert_eq!(word, 0);
+    }
+
+    let words = [
+        0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7,
+        0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf,
+    ];
+
+    flash.write_flash_half_page(address, &words)
+        .expect("Failed to write Flash half-page");
+
+    for (i, &expected) in words.iter().enumerate() {
+        let actual = unsafe { *address.offset(i as isize) };
+        assert_eq!(expected, actual);
+    }
+
+    // Blink LED to indicate we haven't panicked.
+    loop {
+        led.set_high().unwrap();
+        delay.delay_ms(500_u16);
+
+        led.set_low().unwrap();
+        delay.delay_ms(500_u16);
+    }
+}

flash-code/.gitignore

@@ -0,0 +1,2 @@
+# C compiler output
+/*.o

flash-code/README.md

@@ -0,0 +1,3 @@
+C code used by the FLASH API to write half-pages. Contains both the source code, as well as a precompiled binary.
+
+The binary can be compiled using `compile.sh` in this directory. See `src/flash.rs` for an explanation of why this is necessary.

flash-code/compile.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+# Compiles `flash.c` using the GCC toolchain. `build.rs` makes sure that the
+# resulting library is linked.
+#
+# Since requiring all users of this HAL to have the GCC toolchain installed
+# would be inconvenient for many, the resulting library is checked into the
+# repository. After every change to `flash.c`, you need to call this script
+# manually and commit the updated binary.
+
+arm-none-eabi-gcc -march=armv6s-m -ffreestanding -O2 -c flash.c &&
+arm-none-eabi-ar r libflash.a flash.o

flash-code/flash.c

@@ -0,0 +1,13 @@
+#include <stdint.h>
+
+
+// Called from src/flash.rs. See comment there for an explanation of why a C
+// function is necessary.
+__attribute__((section(".data")))
+void write_half_page(uint32_t *address, uint32_t *words) {
+    uint32_t i = 0;
+    while (i < 16) {
+        *(address + i) = *(words + i);
+        i++;
+    }
+}