Contradictory SVD contents regarding CHAN_ABORT

[jannic]

With version 2.0.0, the access specification of CHAN_ABORT was changed to write-only in RP2040.svd:

            <register>
                <name>CHAN_ABORT</name>
                <addressOffset>0x00000444</addressOffset>
                <description>Abort an in-progress transfer sequence on one or more channels</description>
                <resetValue>0x00000000</resetValue>
                <fields>
                    <field>
                        <name>CHAN_ABORT</name>
                        <description>Each bit corresponds to a channel. Writing a 1 aborts whatever transfer sequence is in progress on that channel. The bit will remain high until any in-flight transfers have been flushed through the address and data FIFOs.

                            After writing, this register must be polled until it returns all-zero. Until this point, it is unsafe to restart the channel.</description>
                        <bitRange>[15:0]</bitRange>
                        <access>write-only</access>
                    </field>
                </fields>
            </register>

I guess this was done because of RP2040-E13 and one should poll BUSY instead of CHAN_ABORT.

However, the description still says "After writing, this register must be polled until it returns all-zero." This can't be done on a write-only register.

[lurch]

ping @matiasilva

[kilograham]

ping @matiasilva @Wren6991

[Wren6991]

@matiasilva I checked the upstream sources and this field (one-field register) is correctly marked as sc. Is something going wrong in the new header export?

Seems possible it's getting incorrectly mapped as write-only in the SVD conversion, and we just haven't noticed because sc is usually in a register with other types which are readable.

[matiasilva]

2.1.1 should have this fixed. The access type is reverted to read-write for any write/set clear fields but at the same time I've also added <modifiedWriteValues>oneToClear</modifiedWriteValues> to help tooling see that writing 1 does have special effects.

[kilograham]

fix merged into develop