flash: Add fns to store data in flash

- Writing to the wrong flash sector can cause MCU to stall
- Only 16KiB out of 128KiB in the sector is used to save RAM for compacting

Cargo.lock

@@ -8,7 +8,19 @@ version = "0.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "80a21b9440a626c7fc8573a9e3d3a06b75c7c97754c2949bc7857b90353ca655"
 dependencies = [
- "as-slice",
+ "as-slice 0.2.1",
+]
+
+[[package]]
+name = "as-slice"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "45403b49e3954a4b8428a0ac21a4b7afadccf92bfd96273f1a58cd4812496ae0"
+dependencies = [
+ "generic-array 0.12.4",
+ "generic-array 0.13.3",
+ "generic-array 0.14.7",
+ "stable_deref_trait",
 ]
 
 [[package]]
@@ -222,7 +234,7 @@ version = "0.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "db9efecb57ab54fa918730f2874d7d37647169c50fa1357fecb81abee840b113"
 dependencies = [
- "heapless",
+ "heapless 0.7.17",
  "nb 1.1.0",
  "no-std-net",
 ]
@@ -267,6 +279,43 @@ version = "2.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1d758ba1b47b00caf47f24925c0074ecb20d6dfcffe7f6d53395c0465674841a"
 
+[[package]]
+name = "generic-array"
+version = "0.12.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ffdf9f34f1447443d37393cc6c2b8313aebddcd96906caf34e54c68d8e57d7bd"
+dependencies = [
+ "typenum",
+]
+
+[[package]]
+name = "generic-array"
+version = "0.13.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f797e67af32588215eaaab8327027ee8e71b9dd0b2b26996aedf20c030fce309"
+dependencies = [
+ "typenum",
+]
+
+[[package]]
+name = "generic-array"
+version = "0.14.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85649ca51fd72272d7821adaf274ad91c288277713d9c18820d8499a7ff69e9a"
+dependencies = [
+ "typenum",
+ "version_check",
+]
+
+[[package]]
+name = "hash32"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d4041af86e63ac4298ce40e5cca669066e75b6f1aa3390fe2561ffa5e1d9f4cc"
+dependencies = [
+ "byteorder",
+]
+
 [[package]]
 name = "hash32"
 version = "0.2.1"
@@ -276,6 +325,19 @@ dependencies = [
  "byteorder",
 ]
 
+[[package]]
+name = "heapless"
+version = "0.5.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "74911a68a1658cfcfb61bc0ccfbd536e3b6e906f8c2f7883ee50157e3e2184f1"
+dependencies = [
+ "as-slice 0.1.5",
+ "generic-array 0.13.3",
+ "hash32 0.1.1",
+ "serde",
+ "stable_deref_trait",
+]
+
 [[package]]
 name = "heapless"
 version = "0.7.17"
@@ -283,7 +345,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cdc6457c0eb62c71aac4bc17216026d8410337c4126773b9c5daba343f17964f"
 dependencies = [
  "atomic-polyfill",
- "hash32",
+ "hash32 0.2.1",
  "rustc_version 0.4.0",
  "serde",
  "spin",
@@ -316,6 +378,7 @@ dependencies = [
  "panic-halt",
  "rtt-target",
  "serde",
+ "sfkv",
  "smoltcp",
  "stm32-eth",
  "stm32f4xx-hal",
@@ -358,7 +421,7 @@ version = "0.6.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "07df30ef660fa32d54836743fbdf8208747a559fc4296ec07dc12b6df65343b2"
 dependencies = [
- "heapless",
+ "heapless 0.7.17",
  "log",
  "miniconf_derive",
  "minimq",
@@ -387,7 +450,7 @@ dependencies = [
  "bit_field",
  "embedded-nal",
  "embedded-time",
- "heapless",
+ "heapless 0.7.17",
  "num_enum",
  "serde",
  "smlang",
@@ -505,6 +568,23 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "de96540e0ebde571dc55c73d60ef407c653844e6f9a1e2fdbd40c07b9252d812"
 
+[[package]]
+name = "postcard"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8a9ba0d1b66f31fb374fede892eb4b0818ea819d5e7bc587345ce50a6949e782"
+dependencies = [
+ "heapless 0.5.6",
+ "postcard-cobs",
+ "serde",
+]
+
+[[package]]
+name = "postcard-cobs"
+version = "0.1.5-pre"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7c68cb38ed13fd7bc9dd5db8f165b7c8d9c1a315104083a2b10f11354c2af97f"
+
 [[package]]
 name = "powerfmt"
 version = "0.2.0"
@@ -635,7 +715,7 @@ version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3c9e1ab533c0bc414c34920ec7e5f097101d126ed5eac1a1aac711222e0bbb33"
 dependencies = [
- "heapless",
+ "heapless 0.7.17",
  "ryu",
  "serde",
 ]
@@ -651,6 +731,17 @@ dependencies = [
  "syn 2.0.41",
 ]
 
+[[package]]
+name = "sfkv"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "25f5bfac3f66a7c10a6f37ee81aeaa471f4d35dc21665b59ad7c555adcb9e8aa"
+dependencies = [
+ "byteorder",
+ "postcard",
+ "serde",
+]
+
 [[package]]
 name = "smlang"
 version = "0.6.0"
@@ -680,7 +771,7 @@ dependencies = [
  "bitflags",
  "byteorder",
  "cfg-if",
- "heapless",
+ "heapless 0.7.17",
  "log",
  "managed",
 ]

Cargo.toml

@@ -33,7 +33,7 @@ fugit = "0.3.6"
 rtt-target = { version = "0.3.1", features = ["cortex-m"] }
 miniconf = "0.6.3"
 serde = { version = "1.0.158", features = ["derive"], default-features = false }
-
+sfkv = "0.1"
 [features]
 semihosting = ["cortex-m-log/semihosting"]
 RTT = []

src/device/flash_store.rs

@@ -0,0 +1,62 @@
+use log::error;
+use stm32f4xx_hal::{
+    flash::{Error, FlashExt},
+    pac::FLASH,
+};
+use sfkv::{Store, StoreBackend};
+
+// Last flash sector is used to avoid overwriting the code in flash.
+pub const FLASH_SECTOR: u8 = 11;
+pub const FLASH_SECTOR_11_OFFSET: u32 = 0xE0000;
+
+/// Only 16 KiB out of 128KiB in the Sector is used to save RAM
+pub const RESERVED_MEMORY: usize = 0x4000;
+static mut BACKUP_SPACE: [u8; RESERVED_MEMORY] = [0; RESERVED_MEMORY];
+
+pub struct FlashBackend {
+    flash: FLASH,
+}
+
+fn get_offset() -> usize {
+    FLASH_SECTOR_11_OFFSET as usize
+}
+
+impl StoreBackend for FlashBackend {
+    type Data = [u8];
+
+    fn data(&self) -> &Self::Data {
+        &self.flash.read()[get_offset()..(get_offset() + RESERVED_MEMORY)]
+    }
+
+    type Error = Error;
+    fn erase(&mut self) -> Result<(), Self::Error> {
+        self.flash.unlocked().erase(FLASH_SECTOR)
+    }
+
+    fn program(&mut self, offset: usize, payload: &[u8]) -> Result<(), Self::Error> {
+        self.flash.unlocked()
+            .program(get_offset() + offset, payload.iter())
+    }
+
+    fn backup_space(&self) -> &'static mut [u8] {
+        unsafe { &mut BACKUP_SPACE }
+    }
+}
+
+pub type FlashStore = Store<FlashBackend>;
+
+pub fn store(flash: FLASH) -> FlashStore {
+    let backend = FlashBackend { flash };
+    let mut store = FlashStore::new(backend);
+
+    match store.get_bytes_used() {
+        Ok(_) => {}
+        Err(e) => {
+            error!("corrupt store, erasing. error: {:?}", e);
+            let _ = store.erase()
+                .map_err(|e| error!("flash erase failed: {:?}", e));
+        }
+    }
+
+    store
+}

src/device/mod.rs

@@ -4,3 +4,4 @@ pub mod log_setup;
 pub mod rtt_logger;
 pub mod sys_timer;
 pub mod usb;
+pub mod flash_store;