torvalds/linux

What:           /sys/kernel/debug/dcc/.../ready
Date:           December 2022
Contact:        Souradeep Chowdhury <quic_schowdhu@quicinc.com>
Description:
        This file is used to check the status of the dcc
        hardware if it's ready to receive user configurations.
        A 'Y' here indicates dcc is ready.

What:           /sys/kernel/debug/dcc/.../trigger
Date:           December 2022
Contact:        Souradeep Chowdhury <quic_schowdhu@quicinc.com>
Description:
        This is the debugfs interface for manual software
        triggers. The trigger can be invoked by writing '1'
        to the file.

What:           /sys/kernel/debug/dcc/.../config_reset
Date:           December 2022
Contact:        Souradeep Chowdhury <quic_schowdhu@quicinc.com>
Description:
        This file is used to reset the configuration of
        a dcc driver to the default configuration. When '1'
        is written to the file, all the previous addresses
        stored in the driver gets removed and users need to
        reconfigure addresses again.

What:           /sys/kernel/debug/dcc/.../[list-number]/config
Date:         December 2022
Contact:        Souradeep Chowdhury <quic_schowdhu@quicinc.com>
Description:
        This stores the addresses of the registers which
        can be read in case of a hardware crash or manual
        software triggers. The input addresses type
        can be one of following dcc instructions: read,
        write, read-write, and loop type. The lists need to
        be configured sequentially and not in a overlapping
        manner; e.g. users can jump to list x only after
        list y is configured and enabled. The input format for
        each type is as follows:

            i) Read instruction

           ::

             echo R <addr> <n> <bus> >/sys/kernel/debug/dcc/../[list-number]/config

           where:

           <addr>
            The address to be read.

           <n>
            The addresses word count, starting from address <1>.
            Each word is 32 bits (4 bytes). If omitted, defaulted
            to 1.

           <bus type>
            The bus type, which can be either 'apb' or 'ahb'.
            The default is 'ahb' if leaved out.

        ii) Write instruction

            ::

              echo W <addr> <n> <bus type> > /sys/kernel/debug/dcc/../[list-number]/config

            where:

            <addr>
            The address to be written.

            <n>
            The value to be written at <addr>.

            <bus type>
            The bus type, which can be either 'apb' or 'ahb'.

            iii) Read-write instruction

             ::

               echo RW <addr> <n> <mask> > /sys/kernel/debug/dcc/../[list-number]/config

             where:

             <addr>
            The address to be read and written.

             <n>
                The value to be written at <addr>.

             <mask>
            The value mask.

        iv) Loop instruction

            ::

              echo L <loop count> <address count> <address>... > /sys/kernel/debug/dcc/../[list-number]/config

            where:

            <loop count>
            Number of iterations

            <address count>
            total number of addresses to be written

            <address>
            Space-separated list of addresses.

What:           /sys/kernel/debug/dcc/.../[list-number]/enable
Date:           December 2022
Contact:        Souradeep Chowdhury <quic_schowdhu@quicinc.com>
Description:
        This debugfs interface is used for enabling the
        the dcc hardware. A file named "enable" is in the
        directory list number where users can enable/disable
        the specific list by writing boolean (1 or 0) to the
        file.

        On enabling the dcc, all the addresses specified
        by the user for the corresponding list is written
        into dcc sram which is read by the dcc hardware
        on manual or crash induced triggers. Lists must
        be configured and enabled sequentially, e.g. list
        2 can only be enabled when list 1 have so.