The description of dcc sysfs files is somewhat confusing and not effective.
Rewrite it to be clear.
While at it, also use literal code block for config sysfs examples and
remove redundant examples that are obvious.
Signed-off-by: Bagas Sanjaya <bagasdotme@xxxxxxxxx>
---
Documentation/ABI/testing/debugfs-driver-dcc | 142 ++++++++++---------
1 file changed, 76 insertions(+), 66 deletions(-)
diff --git a/Documentation/ABI/testing/debugfs-driver-dcc b/Documentation/ABI/testing/debugfs-driver-dcc
index a00f4502885b58..27ed5919d21b9c 100644
--- a/Documentation/ABI/testing/debugfs-driver-dcc
+++ b/Documentation/ABI/testing/debugfs-driver-dcc
@@ -3,115 +3,125 @@ Date: December 2022
Contact: Souradeep Chowdhury <quic_schowdhu@xxxxxxxxxxx>
Description:
This file is used to check the status of the dcc
- hardware if it's ready to take the inputs. A 'Y'
- here indicates dcc is in a ready condition.
- Example:
- cat /sys/kernel/debug/dcc/.../ready
+ 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@xxxxxxxxxxx>
Description:
This is the debugfs interface for manual software
- triggers. The user can simply enter a 1 against
- the debugfs file and enable a manual trigger.
- Example:
- echo 1 > /sys/kernel/debug/dcc/.../trigger
+ 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@xxxxxxxxxxx>
Description:
This file is used to reset the configuration of
- a dcc driver to the default configuration. This
- means that all the previous addresses stored in
- the driver gets removed and user needs to enter
- the address values from the start.
- Example:
- echo 1 > /sys/kernel/debug/dcc/../config_reset
+ 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@xxxxxxxxxxx>
Description:
This stores the addresses of the registers which
- should be read in case of a hardware crash or
- manual software triggers. The addresses entered here
- are considered under all the 4 types of dcc
- instructions Read type, Write type, Read Modify Write
- type and Loop type. The lists need to be configured
- sequentially and not in a overlapping manner. As an
- example user can jump to list x only after list y is
- configured and enabled. The format for entering all
- types of instructions are explained in examples as
- follows:
+ 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 Type Instruction
+ i) Read instruction
- echo R <1> <2> <3> >/sys/kernel/debug/dcc/../[list-number]/config
+ ::
- 1->Address to be considered for reading the value.
+ echo R <addr> <n> <bus> >/sys/kernel/debug/dcc/../[list-number]/config
- 2->The word count of the addresses, read n words
- starting from address <1>. Each word is of 32 bits.
- If not entered 1 is considered.
+ where:
- 3->Can be 'apb' or 'ahb' which indicates if it is apb or ahb
- bus respectively. If not entered ahb is considered.
+ <addr>
+ The address to be read.
- ii) Write Type Instruction
+ <n>
+ The addresses word count, starting from address <1>.
+ Each word is 32 bits (4 bytes). If omitted, defaulted
+ to 1.
- echo W <1> <2> <3> > /sys/kernel/debug/dcc/../[list-number]/config
+ <bus type>
+ The bus type, which can be either 'apb' or 'ahb'.
+ The default is 'ahb' if leaved out.
- 1->Address to be considered for writing the value.
+ ii) Write instruction
- 2->The value that needs to be written at the location.
+ ::
- 3->Can be a 'apb' or 'ahb' which indicates if it is apb or ahb
- but respectively.
+ echo W <addr> <n> <bus type> > /sys/kernel/debug/dcc/../[list-number]/config
- iii) Read Modify Write type instruction
+ where:
- echo RW <1> <2> <3> > /sys/kernel/debug/dcc/../[list-number]/config
+ <addr>
+ The address to be written.
- 1->The address which needs to be considered for read then write.
+ <n>
+ The value to be written at <addr>.
- 2->The value that needs to be written on the address.
+ <bus type>
+ The bus type, which can be either 'apb' or 'ahb'.
- 3->The mask of the value to be written.
+ iii) Read-write instruction
- iv) Loop Type Instruction
+ ::
- echo L <1> <2> <3> > /sys/kernel/debug/dcc/../[list-number]/config
+ echo RW <addr> <n> <mask> > /sys/kernel/debug/dcc/../[list-number]/config
- 1->The loop count, the number of times the value of the addresses will be
- captured.
+ where:
- 2->The address count, total number of addresses to be entered in this
- instruction.
+ <addr>
+ The address to be read and written.
- 3->The series of addresses to be entered separated by a space like <addr1>
- <addr2>... and so on.
+ <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@xxxxxxxxxxx>
Description:
This debugfs interface is used for enabling the
- the dcc hardware. Enable file is kept under the
- directory list number for which the user wants
- to enable it. For example if the user wants to
- enable list 1, then he should go for
- echo 1 > /sys/kernel/debug/dcc/.../1/enable.
- On enabling the dcc, all the addresses entered
+ 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 should
- be enabled sequentially.For example after configuring
- addresses for list 1 and enabling it, a user can
- proceed to enable list 2 or vice versa.
- Example:
- echo 0 > /sys/kernel/debug/dcc/.../[list-number]/enable
- (disable dcc for the corresponding list number)
- echo 1 > /sys/kernel/debug/dcc/.../[list-number]/enable
- (enable dcc for the corresponding list number)
+ 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.
