Resolve reading Write-Only registers in peripheral register view

[promodkumar-ashling]

Description

The write-only registers(The access type information available in the peripheral register file) attempt to read values from UI when the peripheral register views are opened.

Steps to Reproduce

1. Run an Arm GDB Launch.
2. Enable the peripheral register view.
3. Keep a register with "access" as "write-only" in the SVD Register file. Eg:
4. Try to open the register with access write-only.

Expected behavior: [What you expected to happen] It shouldn't read the "write-only" register values.

Actual behavior: [What actually happened] The write-only registers attempt to read values from UI causing the target to go for an exception.

Versions

• EmbedCDT - 6.2.1
• Eclipse - 2022-03
• Java - 16
• Windows

[jonahgraham]

AFAICT @promodkumar-ashling the write-only has only been implemented to display a different background colour so far. SvdDMNode.getAccess()'s call hierarchy shows that when access is read only then IValueModification.supportsValueModification() will return false. But the write-only is not wired up to anything.

I hope that gives you enough guidance to start working on a patch. Let us know if you need more info.

[ilg-ul]

Can you provide more details on the SVD file you used, and what peripheral was that?

[promodkumar-ashling]

                    <register>
                <name>SMMU_SGFSR</name>
                <displayName>Secure Global Fault Status register</displayName>
                <description>Gives the fault status for each of the following possible faults.</description>
                <addressOffset>0x48</addressOffset>
                <size>32</size>
                <access>write-only</access>
                <resetValue>0x00000000</resetValue>
                <resetMask>0xffffffff</resetMask>   
                <fields>
                    <field>
                        <name>MULTI</name>
                        <lsb>31</lsb>
                        <msb>31</msb>
                        <access>write-only</access>
                        <modifiedWriteValues>modify</modifiedWriteValues>
                    </field>
                    <field>
                        <name>UUT</name>
                        <lsb>8</lsb>
                        <msb>8</msb>
                        <access>write-only</access>
                        <modifiedWriteValues>modify</modifiedWriteValues>
                    </field>
                    <field>
                        <name>PF</name>
                        <lsb>7</lsb>
                        <msb>7</msb>
                        <access>write-only</access>
                        <modifiedWriteValues>modify</modifiedWriteValues>
                    </field>
                    <field>
                        <name>EF</name>
                        <lsb>6</lsb>
                        <msb>6</msb>
                        <access>write-only</access>
                        <modifiedWriteValues>modify</modifiedWriteValues>
                    </field>
                    <field>
                        <name>CAF</name>
                        <lsb>5</lsb>
                        <msb>5</msb>
                        <access>write-only</access>
                        <modifiedWriteValues>modify</modifiedWriteValues>
                    </field>
                    <field>
                        <name>UCIF</name>
                        <lsb>4</lsb>
                        <msb>4</msb>
                        <access>write-only</access>
                        <modifiedWriteValues>modify</modifiedWriteValues>
                    </field>
                    <field>
                        <name>UCBF</name>
                        <lsb>3</lsb>
                        <msb>3</msb>
                        <access>write-only</access>
                        <modifiedWriteValues>modify</modifiedWriteValues>
                    </field>
                    <field>
                        <name>SMCF</name>
                        <lsb>2</lsb>
                        <msb>2</msb>
                        <access>write-only</access>
                        <modifiedWriteValues>modify</modifiedWriteValues>
                    </field>
                    <field>
                        <name>USF</name>
                        <lsb>1</lsb>
                        <msb>1</msb>
                        <access>write-only</access>
                        <modifiedWriteValues>modify</modifiedWriteValues>
                    </field>
                    <field>
                        <name>ICF</name>
                        <lsb>0</lsb>
                        <msb>0</msb>
                        <access>write-only</access>
                        <modifiedWriteValues>modify</modifiedWriteValues>
                    </field>
                </fields>
            </register>