def get_all_firmwares(self, filter='', start=0, count=-1, query='', sort=''):
        """
        Gets a list of firmware inventory across all servers. To filter the returned data, specify a filter
        expression to select a particular server model, component name, and/or component firmware version.

        Note:
            This method is available for API version 300 or later.

        Args:
            start:
                The first item to return, using 0-based indexing.
                If not specified, the default is 0 - start with the first available item.
            count:
                The number of resources to return. A count of -1 requests all items.
                The actual number of items in the response might differ from the requested
                count if the sum of start and count exceeds the total number of items.
            filter (list or str):
                A general filter/query string to narrow the list of items returned. The
                default is no filter; all resources are returned.
            query:
                A general query string to narrow the list of resources returned. The default is no query; all resources
                are returned.
            sort:
                The sort order of the returned data set. By default, the sort order is based
                on create time with the oldest entry first.

        Returns:
            list: List of firmware inventory.
        """
        uri = self.URI + "/*/firmware"
        return self._helper.get_all(start, count, filter, query, sort, '', '', uri)