svdtools

svdtools is a Python package for modifying vendor-supplied, often buggy SVD files. It can be imported as a library for use in other applications, or run directly via the included svd CLI utility.

A common use case is patching vendor-supplied SVD files, then applying svd2rust to the resulting patched SVD.

Getting Started

Python 3.6 or newer is required to install and use svdtools. To install:

$ pip3 install --upgrade --user svdtools

Once installation has completed, the svd utility can be called from the command line.

An example is given in make example, which calls svd patch example/incomplete-stm32l4x2.yaml and generates a patched SVD file example/stm32l4x2.svd.patched.

See Device and Peripheral YAML Format for more information on creating patches.

Develop

To each their own, but the intended workflow is as follows:

1. Setup a virtual environment via make setup; this also installs the svd CLI
2. Activate the virtual environment by running source venv/bin/activate (or use direnv)
3. Iterate, running make check and make fix as necessary

Device and Peripheral YAML Format

The patch specifications are in YAML, and have the following general format:

# Path to the SVD file we're targeting. Relative to this file.
# This must be included only in the device YAML file.
_svd: "../svd/STM32F0x0.svd"

# Include other YAML files. Path relative to this file.
_include:
    - "../peripherals/gpio_v2.yaml"

# Alter top-level information and peripherals for this device
_modify:
    version: 1.1
    description: bla bla
    addressUnitBits: 8
    width: 32
    cpu:
        revision: r1p2
        mpuPresent: true
    # Peripherals can either live directly at this level (but other top-level
    # fields will name match first)
    C_ADC:
        name: ADC_Common
    # Or they can be inside a _peripherals block, to avoid name conflicts.
    _peripherals:
        FSMC:
            description: Flexible static memory controller

# Add whole new peripherals to this device.
# Incredibly this feature is required.
_add:
    ADC_Common:
        description: ADC Common registers
        groupName: ADC
        baseAddress: 0x40012300
        addressBlock:
            offset: 0x0
            size: 0x400
        registers:
            CSR:
                description: ADC Common status register
                addressOffset: 0x0
                access: read-only
                resetValue: 0x00000000
                fields:
                    OVR3:
                        description: Overrun flag of ADC3
                        bitOffset: 21
                        bitWidth: 1
        interrupts:
            ADC1_2:
                description: ADC global interrupt
                value: 18

# A whole new peripheral can also be created as derivedFrom another peripheral.
_add:
    USART3:
        derivedFrom: USART1
        baseAddress: "0x40004800"
        interrupts:
            USART3:
                description: USART3 global interrupt
                value: 39

# A new peripheral can have all its registers copied from another, in case
# it cannot quite be derivedFrom (e.g. some fields need different enumerated
# values) but it's otherwise almost exactly the same.
# The registers are copied but not name or address or interrupts.
_copy:
    ADC3:
        from: ADC2

# The new peripheral can also be copied from another svd file for a different
# device. This is useful when a peripheral is missing in a device but the exact
# same peripheral already exist in another device.
_copy:
    TIM1:
        from: ../svd/stm32f302.svd:TIM1

# Replace peripheral registers by a 'deriveFrom'.
# This is used when e.g. UART4 and UART5 are both independently defined,
# but you'd like to make UART5 be defined as derivedFrom UART4 instead.
_derive:
    # The KEY peripheral looses all its elements but 'interrupt', 'name',
    # and 'baseAddress', and it is derivedFrom the VALUE peripheral.
    # Peripherals that were 'deriveFrom="KEY"' are now 'deriveFrom="VALUE"'.
    UART5: UART4

# Reorder the hierarchy of peripherals with 'deriveFrom'.
# This is used when e.g. I2C1 is marked as derivedFrom I2C3,
# but you'd like to swap that so that I2C3 becomes derivedFrom I2C1.
_rebase:
    # The KEY peripheral steals everything but 'interrupt', 'name',
    # and 'baseAddress' elements from the VALUE peripheral.
    # Peripherals that were 'deriveFrom="VALUE"' are now 'deriveFrom="KEY"'.
    # The VALUE peripheral is marked as derivedFrom the updated KEY.
    I2C1: I2C3

# An STM32 peripheral, matches an SVD <peripheral> tag.
# Does not match any tag with derivedFrom attribute set.
"GPIO*":
    # We can include other YAML files inside this peripheral
    _include:
        - "path/to/file.yaml"

    # Alter fields on existing registers inside this peripheral
    _modify:
        # Rename this badly named register. Takes effect before anything else.
        # Don't use wildcard matches if you are changing the name!
        # We could have specified name or description or other tags to update.
        GPIOB_OSPEEDR:
          name: OSPEEDR
        # Equivalently the register could go in a '_registers' block
        _registers:
            GPIOB_OSPEEDR:
                name: OSPEEDR
        # Change the value of an interrupt in this peripheral
        _interrupts:
            EXTI0:
                value: 101


    # Add new registers and interrupts to this peripheral.
    # Entries are registers by default, which can also go inside a '_registers'
    # block, or interrupts go in an '_interrupts' block.
    _add:
        EXAMPLER:
            description: An example register
            addressOffset: 0x04
            access: read-write
            fields:
                EXR1:
                    description: Example field
                    bitOffset: 16
                    bitWidth: 4
        _registers:
            EXAMPLR2:
                description: Another example register
        _interrupts:
            EXAMPLEI:
                description: An example interrupt
                value: 100

    # Anywhere you can '_add' something, you can also '_delete' it.
    # Wildcards are supported. The value here can be a YAML list of registers
    # to delete (supported for backwards compatibility), or a YAML mapping
    # of lists of registers or interrupts.
    _delete:
        GPIO*_EXTRAR:
        _registers:
            - GPIO*_EXAMPLER
        _interrupts:
            - USART1

    # If registers have unnecessary common prefix,
    # you can clean it in all registers in peripheral by:
    _strip:
        - PREFIX_

    # You can collect several same registers into one register array
    # that will be represented with svd2rust as array or elements
    # with one type
    # Minimal version:
    _array:
        ARRAY*: {}

    # You can also use the modifiers shown below:
    _array:
        ARRAY*:
            name: NEW_NAME%s
            _modify:
                FIELD: [MINIMUM, MAXIMUM]
                FIELD:
                  description: NEWDESC
        OTHER_ARRAY*: {}

    # If you have registers that make up a group and can be repeated,
    # you can collect them into cluster like this:
    _cluster:
        CLUSTER%s:
            FIRST_REG: {}
            SECOND_REG: {}

    # A register on this peripheral, matches an SVD <register> tag
    MODER:
        # As in the peripheral scope, rename or redescribe a field.
        # Don't use wildcard matches if you are changing the name!
        _modify:
            FIELD:
              description: NEWDESC

        # Add new fields to this register
        _add:
            NEWFIELD:
              description: DESCRIPTION
              bitOffset: 12
              bitWidth: 4
              access: read-write

        # Often fields that should be one contiguous integer are specified
        # as a number of individual bits instead. This merges any matching
        # registers into a single field with the combined bitwidth and lowest
        # bit offset, and the shared description and access.
        _merge:
            - "FIELD*"

        # A field in this register, matches an SVD <field> tag
        FIELD:
            # By giving the field a dictionary we construct an enumerateValues
            VARIANT: [VALUE, DESCRIPTION]
            VARIANT: [VALUE, DESCRIPTION]

        # Another field. A list of two numbers gives a range writeConstraint.
        FIELD: [MINIMUM, MAXIMUM]

        # Another field with separate enumerated values for read and write
        FIELD:
            _read:
                VARIANT: [VALUE, DESCRIPTION]
                VARIANT: [VALUE, DESCRIPTION]
            _write:
                VARIANT: [VALUE, DESCRIPTION]
                VARIANT: [VALUE, DESCRIPTION]
        # Sometimes fields are to big so we need to split them into smaller fields
        EXTI:
          IMR:
            # This would split MR into MRi where i = 0 ... bitlength
            _split: [MR]

Name Matching

Peripheral, register, and field names can be specified:

• Directly (eg. the full name of the peripheral/register/field)
• Using ? and * for single- and multi- character wildcards
• Using [ABC] to give a list of possible matching characters
• Using commas to separate a list of possible matches

You must quote the name if using any special characters in YAML.

Style Guide

• Enumerated values should be named in the past tense (enabled, masked, etc.)
• Descriptions should start with capital letters and should not end with a period

License

svdtools is licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE)
• MIT License (LICENSE-MIT)

at your option.

Contribute

Pull requests are very welcome!

Please apply black and isort before committing. This can be accomplished by:

• running make fix
• running black svdtools/ and isort -y --recursive svdtools/
• installing an editor/IDE plugin

This avoids bikeshedding over formatting issues :)

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.