Documentation/ABI/testing/debugfs-driver-dcc

   1 What:           /sys/kernel/debug/dcc/.../ready
   2 Date:           December 2022
   3 Contact:        Souradeep Chowdhury <quic_schowdhu@quicinc.com>
   4 Description:
   5                 This file is used to check the status of the dcc
   6                 hardware if it's ready to receive user configurations.
   7                 A 'Y' here indicates dcc is ready.
   8
   9 What:           /sys/kernel/debug/dcc/.../trigger
  10 Date:           December 2022
  11 Contact:        Souradeep Chowdhury <quic_schowdhu@quicinc.com>
  12 Description:
  13                 This is the debugfs interface for manual software
  14                 triggers. The trigger can be invoked by writing '1'
  15                 to the file.
  16
  17 What:           /sys/kernel/debug/dcc/.../config_reset
  18 Date:           December 2022
  19 Contact:        Souradeep Chowdhury <quic_schowdhu@quicinc.com>
  20 Description:
  21                 This file is used to reset the configuration of
  22                 a dcc driver to the default configuration. When '1'
  23                 is written to the file, all the previous addresses
  24                 stored in the driver gets removed and users need to
  25                 reconfigure addresses again.
  26
  27 What:           /sys/kernel/debug/dcc/.../[list-number]/config
  28 Date:            December 2022
  29 Contact:        Souradeep Chowdhury <quic_schowdhu@quicinc.com>
  30 Description:
  31                 This stores the addresses of the registers which
  32                 can be read in case of a hardware crash or manual
  33                 software triggers. The input addresses type
  34                 can be one of following dcc instructions: read,
  35                 write, read-write, and loop type. The lists need to
  36                 be configured sequentially and not in a overlapping
  37                 manner; e.g. users can jump to list x only after
  38                 list y is configured and enabled. The input format for
  39                 each type is as follows:
  40
  41                 i) Read instruction
  42
  43                    ::
  44
  45                      echo R <addr> <n> <bus> >/sys/kernel/debug/dcc/../[list-number]/config
  46
  47                    where:
  48
  49                    <addr>
  50                         The address to be read.
  51
  52                    <n>
  53                         The addresses word count, starting from address <1>.
  54                         Each word is 32 bits (4 bytes). If omitted, defaulted
  55                         to 1.
  56
  57                    <bus type>
  58                         The bus type, which can be either 'apb' or 'ahb'.
  59                         The default is 'ahb' if leaved out.
  60
  61                 ii) Write instruction
  62
  63                     ::
  64
  65                       echo W <addr> <n> <bus type> > /sys/kernel/debug/dcc/../[list-number]/config
  66
  67                     where:
  68
  69                     <addr>
  70                         The address to be written.
  71
  72                     <n>
  73                         The value to be written at <addr>.
  74
  75                     <bus type>
  76                         The bus type, which can be either 'apb' or 'ahb'.
  77
  78                 iii) Read-write instruction
  79
  80                      ::
  81
  82                        echo RW <addr> <n> <mask> > /sys/kernel/debug/dcc/../[list-number]/config
  83
  84                      where:
  85
  86                      <addr>
  87                         The address to be read and written.
  88
  89                      <n>
  90                         The value to be written at <addr>.
  91
  92                      <mask>
  93                         The value mask.
  94
  95                 iv) Loop instruction
  96
  97                     ::
  98
  99                       echo L <loop count> <address count> <address>... > /sys/kernel/debug/dcc/../[list-number]/config
 100
 101                     where:
 102
 103                     <loop count>
 104                         Number of iterations
 105
 106                     <address count>
 107                         total number of addresses to be written
 108
 109                     <address>
 110                         Space-separated list of addresses.
 111
 112 What:           /sys/kernel/debug/dcc/.../[list-number]/enable
 113 Date:           December 2022
 114 Contact:        Souradeep Chowdhury <quic_schowdhu@quicinc.com>
 115 Description:
 116                 This debugfs interface is used for enabling the
 117                 the dcc hardware. A file named "enable" is in the
 118                 directory list number where users can enable/disable
 119                 the specific list by writing boolean (1 or 0) to the
 120                 file.
 121
 122                 On enabling the dcc, all the addresses specified
 123                 by the user for the corresponding list is written
 124                 into dcc sram which is read by the dcc hardware
 125                 on manual or crash induced triggers. Lists must
 126                 be configured and enabled sequentially, e.g. list
 127                 2 can only be enabled when list 1 have so.