support <access>read-writeOnce</access>

[japaric]

The code generated from the file STM32L063x.svd doesn't compile. Because the read-writeOnce access mode is not supported by svd2rust the DAC_SR register has no access methods:

# [ doc = "Digital-to-analog converter" ]
pub mod dac {
    // ..
    # [ doc = "status register" ]
    pub struct Sr {
        register: VolatileCell<u32>,
    }
    # [ doc = "status register" ]
    pub mod sr {
        impl super::Sr {}
    }
}

And you run into an unused field warning which becomes an error because of #![deny(warnings)].

[kjetilkjeka]

I will contribute to this issue instead of making a new since I suspect these issues are the same.

When using svd2rust on NXP S32K144 svd file i get:

svd2rust -i ~/Nedlastinger/S32K144.svd | rustfmt | tee src/s32k144.rs
thread 'main' panicked at 'unknown access variant: writeonce', 
/home/kjeka/.cargo/registry/src/github.com-1ecc6299db9ec823/svd-parser-0.5.1/src/lib.rs:286
note: Run with `RUST_BACKTRACE=1` for a backtrace.

and with RUST_BACKTRACE=1

RUST_BACKTRACE=1 svd2rust -i ~/Nedlastinger/S32K144.svd | rustfmt | tee src/s32k144.rs
thread 'main' panicked at 'unknown access variant: writeonce',         
/home/kjeka/.cargo/registry/src/github.com-1ecc6299db9ec823/svd-parser-0.5.1/src/lib.rs:286
stack backtrace:
   0: std::sys::imp::backtrace::tracing::imp::unwind_backtrace
             at /checkout/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::_print
             at /checkout/src/libstd/sys_common/backtrace.rs:71
   2: std::panicking::default_hook::{{closure}}
             at /checkout/src/libstd/sys_common/backtrace.rs:60
             at /checkout/src/libstd/panicking.rs:355
   3: std::panicking::default_hook
             at /checkout/src/libstd/panicking.rs:371
   4: std::panicking::rust_panic_with_hook
             at /checkout/src/libstd/panicking.rs:549
   5: std::panicking::begin_panic
             at /checkout/src/libstd/panicking.rs:511
   6: std::panicking::begin_panic_fmt
             at /checkout/src/libstd/panicking.rs:495
   7: <core::option::Option<T>>::map
   8: <core::iter::FilterMap<I, F> as core::iter::iterator::Iterator>::next
   9: svd_parser::Device::parse
  10: svd_parser::parse
  11: svd2rust::main
  12: __rust_maybe_catch_panic
             at /checkout/src/libpanic_unwind/lib.rs:98
  13: std::rt::lang_start
             at /checkout/src/libstd/panicking.rs:433
             at /checkout/src/libstd/panic.rs:361
             at /checkout/src/libstd/rt.rs:56
  14: __libc_start_main
  15: _start

I will attach the file in case you would like to test for yourself.
S32K144.svd.zip

[Emilgardis]

@kjetilkjeka Your error is not related, it comes from a miswritten svd file, the variant is called writeOnce, not writeonce. We could fix this in svd-parser, but I think we should strive to follow the SVD 1.0/1.1 schema as close as possible.

To fix your error and generate some code simply patch your svd to change all the writeonce into writeOnce.

[kjetilkjeka]

@Emilgardis You are of course right. It worked when replacing writeonce with writeOnce, thanks.

And for what it's worth I do agree with your view on forcing the svd to be up to spec rather than accepting badly written svd files.

[adamgreig]

Implemented by #322.