Embedded HAL Traits #24

nnarain · 2022-07-31T05:11:14Z

This MR builds off of @fpagliughi 's netlink-update branch (#20).

I have implemented the following:

Embedded HAL blocking and non-blocking traits for CAN
Added examples for blocking read/write
Moved some code around into dedicated modules
Moved integration tests into tests/ folder

Could probably use some advice on the best way to map the errors.

fpagliughi · 2022-11-23T16:24:10Z

Hi @nnarain! I have a bunch of questions about this:

Is the goal to make this crate portable to other (non-Linux) systems? Or to make application source code that would be easier to port to other embedded crates?
- Would this be possible given the dependence on so many Linux and std crates (nix, etc)
What is the argument for doing this considering that none of the other Embedded Linux crates (gpio-cdev, i2cdev, spidev, etc) support embedded-hal interfaces?
Would we essentially get the embedded-hal compatibility "for free" or would we need to make tradeoffs with full Linux SocketCAN support? Meaning: Would it make implementing the full Linux capabilities more difficult to keep it compatible?
- Would this make supporting async/await (tokio, async-std, smol, etc) more difficult?
Assuming we do want to merge this, it seems there is a bunch of refactoring in this PR that might make merging a bunch of the older/stale PR's and forks more difficult. Should we try to merge those first and then rebase this? Or what would you suggest?

nnarain · 2022-11-23T22:53:10Z

No this is not really related to cross platform support
The advantage of embedded-hal is being able to build platform agnostic drivers.
a. If I write a embedded-hal i2c IMU driver, for example, I can use that driver on ESP, NRF and STM32 devices that implement embedded-hal
b. It does look like there is a linux implementation in the same github org: https://github.com/rust-embedded/linux-embedded-hal
c. For CAN specifically I've started writing some CANopen related libraries (https://github.com/nnarain/can-rs). That can could work on Linux or embedded devices). Also platform agnostic CAN tools (candump, cansend, etc).
No trade off I'm aware of. The can::Frame trait is implemented on the type. Other socketcan specific data could be stored in the struct if necessary
a. I have a fork of tokio-socketcan for async support https://github.com/nnarain/tokio-socketcan
I'd suggest merging other MRs first and I'd rebase my branch.

marcelbuesing · 2022-11-24T09:58:02Z

I think regarding 2b. the alternative would implementing the can traits in the linux-embedded-hal crate and reference the socketcan crate for that. I just did that for the current socketcan master branch here in a prototype. It's basically just a wrapper around socketcan, based on the current master branch. That's also the way it's done e.g. for the spi implementation, inverting the crate dependency relationship.

I noticed that on the master branch and latest alpha of embedded-hal 1.0.0-alpha.9 they seem to have moved the CAN module again into a separate crate called embedded-can. But I guess that makes little difference in the end. They also seem to have started splitting the async and blocking part.

nnarain · 2022-11-25T02:32:27Z

That seems like a reasonable approach to me

marcelbuesing · 2022-11-25T07:57:21Z

I just went through your implementation and it looks very good, would you maybe copy those to a PR for the linux-embedded-hal crate or should I do that? I think it's kind of bad timing right now because either you update the linux-embedded-hal crate to embedded-hal alpha.9 / master which will not work because there seem to be some stuff missing or you implement it for alpha.8 which will never become stable and already changed ;)... In the example I went with alpha.8 because it at least that way it compiles...

nnarain · 2022-11-26T15:55:11Z

@marcelbuesing seems like you've already done the work, so perhaps you can put up a PR? Or is there still something you need to implement on your branch?

fpagliughi · 2022-12-03T13:58:49Z

Cargo.toml

 [dependencies]
+embedded-hal = "1.0.0-alpha.8"


Their release appears to be a moving target. The alpha.9 has breaking changes incompatible with this PR. If you want to keep this as-is, you would need to pin this exact version:

embedded-hal = "=1.0.0-alpha.8"

fpagliughi · 2022-12-03T14:02:43Z

@nnarain , this should be a quick/clean rebase over master right now. Can you do that and push it? That way I can get started on the review while we wait for the other stuff. Maybe even pull this in first, as the other fixes might be easy enough to merge on top of this.

fpagliughi

Overall this looks really good. A lot of updates I would have done anyway. If you don't have time to make the requested changes, let me know. I can accept this as-is and then make the mods along with a bunch of other cleanup.

fpagliughi · 2022-12-04T01:20:29Z

src/constants.rs

@@ -0,0 +1,55 @@
+//
+// constants.rs


In general, I don't think a bunch of constants warrant their own module. These should probably stay in lib.rs.

But, for that matter, all of these constants and more are now available from the libc crate. We should probably import and re-export all of the ones related to CAN, like:

// lib.rs pub use libc::{ AF_CAN, PF_CAN, ... };

fpagliughi · 2022-12-04T01:37:21Z

src/frame.rs

+
+impl Frame for CanFrame {
+    /// Create a new frame
+    fn new(id: impl Into<Id>, data: &[u8]) -> Option<Self> {


If this can fail with an error, it should return a Result<>, not an Option.

fpagliughi · 2022-12-04T01:40:20Z

src/frame.rs

+impl Frame for CanFrame {
+    /// Create a new frame
+    fn new(id: impl Into<Id>, data: &[u8]) -> Option<Self> {
+        let raw_id = hal_id_to_raw(id.into());


You don't appear to be properly handling when someone passes in an ExtendedId with a value <= SFF_MASK.

That was a known bug with the previous implementation. See #15.

We should be able to pass a unit test like:

let frame = CanFrame::new(ExtendedId::new(0x50), &[]).unwrap(); assert!(frame.is_extended());

fpagliughi · 2022-12-04T01:49:50Z

src/socket.rs

+
+impl CanFilter {
+    /// Construct a new CAN filter.
+    pub fn new(id: u32, mask: u32) -> Result<CanFilter, ConstructionError> {


Shouldn't this now be defined with the StandardId and ExtendedId types to be consistent? Or would that make things unnecessarily complicated?

Previously, I was thinking to add a From<(u32,u32)> (from a u32 tuple) for this to make it easier to create a list of filters. Maybe do both?

fpagliughi · 2022-12-04T13:16:44Z

src/lib.rs

-
-        Ok(CanSocket { fd: sock_fd })
-    }
+impl embedded_hal::can::nb::Can for CanSocket {


Why are these sitting out here, rather than in the socket module? Is this the stuff that would be moved upstream into the embedded-hal/can crate?

fpagliughi · 2022-12-04T13:20:34Z

src/frame.rs

@@ -0,0 +1,163 @@
+use crate::err::{ConstructionError, CanError, CanErrorDecodingFailure};


Perhaps put a small doc comment at the start of each new module describing it?

fpagliughi · 2022-12-04T14:17:28Z

src/util.rs

@@ -79,3 +79,10 @@ pub fn duration_from_timeval(ts: timespec) -> Duration {
 pub fn system_time_from_timespec(ts: timespec) -> SystemTime {
    UNIX_EPOCH + duration_from_timeval(ts)
 }
+
+pub fn hal_id_to_raw(id: Id) -> u32 {


I wonder if this isn't something we could push upstream to the embedded-hal/can crate?

impl Id { pub fn as_raw(&self) -> u32 { match self { Id::Standard(id) => id.as_raw() as u32, Id::Extended(id) => id.as_raw(), } } }

I threw a PR at them. Let's see how it goes.
rust-embedded/embedded-hal#428

fpagliughi · 2022-12-05T15:51:26Z

@nnarain The other big PR for CAN FD is actually branched off of the old v1.x line. So I will drop this into master now and then start working to manually merge that one in. If you have time to answer some of my PR questions, that might help us clean up down the road. But master will be a WIP for a few weeks, so feel free to send in any small PR's to do some cleanup after it has landed.

nnarain · 2022-12-06T01:19:07Z

I'll try to get to addressing the PR comments soon.

fpagliughi mentioned this pull request Nov 23, 2022

Unmaintained? #11

Closed

marcelbuesing mentioned this pull request Nov 29, 2022

Standard/extended identifier implementation incorrect? #15

Closed

This was referenced Nov 29, 2022

Ideas for v2.0 #28

Closed

Add CAN FD support #16

Merged

socketcan2-rs #29

Closed

fpagliughi reviewed Dec 3, 2022

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nnarain added 10 commits December 3, 2022 16:13

Initial implementation with embedded-hal CAN traits

b923058

embedded-hal 1.0.0 alpha traits

0290584

Use correct write function for blocking

21d4606

Map some errors into CAN HAL errors

0fe7820

Added example

c92bff8

Move CanFrame to itself own module

481f7b4

Move CanSocket to its own module

19d6a8b

Fix some tests. Move integration tests to folder

a3891bc

Implement embedded-hal non-blocking trait

7861e34

Export CAN filter

ab89ebe

nnarain force-pushed the embedded-hal branch from dc21dd3 to ab89ebe Compare December 3, 2022 16:14

fpagliughi requested changes Dec 4, 2022

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fpagliughi reviewed Dec 4, 2022

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fpagliughi added this to the v2.0 milestone Dec 4, 2022

fpagliughi approved these changes Dec 5, 2022

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fpagliughi merged commit d882020 into socketcan-rs:master Dec 5, 2022

fpagliughi mentioned this pull request Apr 1, 2023

2.0 ? #37

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Embedded HAL Traits #24

Embedded HAL Traits #24

nnarain commented Jul 31, 2022

fpagliughi commented Nov 23, 2022 •

edited

nnarain commented Nov 23, 2022 •

edited

marcelbuesing commented Nov 24, 2022

nnarain commented Nov 25, 2022

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nnarain commented Nov 26, 2022

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nnarain commented Dec 6, 2022

		@@ -0,0 +1,163 @@
		use crate::err::{ConstructionError, CanError, CanErrorDecodingFailure};

Embedded HAL Traits #24

Embedded HAL Traits #24

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nnarain commented Jul 31, 2022

fpagliughi commented Nov 23, 2022 • edited

nnarain commented Nov 23, 2022 • edited

marcelbuesing commented Nov 24, 2022

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fpagliughi commented Dec 5, 2022

nnarain commented Dec 6, 2022

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nnarain commented Nov 23, 2022 •

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fpagliughi commented Dec 3, 2022 •

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