Skip to content
Projects
Groups
Snippets
Help
Loading...
Help
Support
Keyboard shortcuts
?
Submit feedback
Contribute to GitLab
Sign in
Toggle navigation
L
linux-davinci
Project overview
Project overview
Details
Activity
Releases
Repository
Repository
Files
Commits
Branches
Tags
Contributors
Graph
Compare
Issues
0
Issues
0
List
Boards
Labels
Milestones
Redmine
Redmine
Merge Requests
0
Merge Requests
0
CI / CD
CI / CD
Pipelines
Jobs
Schedules
Operations
Operations
Metrics
Environments
Analytics
Analytics
CI / CD
Repository
Value Stream
Wiki
Wiki
Snippets
Snippets
Members
Members
Collapse sidebar
Close sidebar
Activity
Graph
Create a new issue
Jobs
Commits
Issue Boards
Open sidebar
linux
linux-davinci
Commits
1fc22fad
Commit
1fc22fad
authored
Dec 16, 2009
by
Len Brown
Browse files
Options
Browse Files
Download
Plain Diff
Merge branch 'debug-aml' into release
parents
8033c314
4bab30a0
Changes
2
Hide whitespace changes
Inline
Side-by-side
Showing
2 changed files
with
149 additions
and
1 deletion
+149
-1
Documentation/acpi/method-customizing.txt
Documentation/acpi/method-customizing.txt
+66
-0
drivers/acpi/debug.c
drivers/acpi/debug.c
+83
-1
No files found.
Documentation/acpi/method-customizing.txt
0 → 100644
View file @
1fc22fad
Linux ACPI Custom Control Method How To
=======================================
Written by Zhang Rui <rui.zhang@intel.com>
Linux supports customizing ACPI control methods at runtime.
Users can use this to
1. override an existing method which may not work correctly,
or just for debugging purposes.
2. insert a completely new method in order to create a missing
method such as _OFF, _ON, _STA, _INI, etc.
For these cases, it is far simpler to dynamically install a single
control method rather than override the entire DSDT, because kernel
rebuild/reboot is not needed and test result can be got in minutes.
Note: Only ACPI METHOD can be overridden, any other object types like
"Device", "OperationRegion", are not recognized.
Note: The same ACPI control method can be overridden for many times,
and it's always the latest one that used by Linux/kernel.
1. override an existing method
a) get the ACPI table via ACPI sysfs I/F. e.g. to get the DSDT,
just run "cat /sys/firmware/acpi/tables/DSDT > /tmp/dsdt.dat"
b) disassemble the table by running "iasl -d dsdt.dat".
c) rewrite the ASL code of the method and save it in a new file,
d) package the new file (psr.asl) to an ACPI table format.
Here is an example of a customized \_SB._AC._PSR method,
DefinitionBlock ("", "SSDT", 1, "", "", 0x20080715)
{
External (ACON)
Method (\_SB_.AC._PSR, 0, NotSerialized)
{
Store ("In AC _PSR", Debug)
Return (ACON)
}
}
Note that the full pathname of the method in ACPI namespace
should be used.
And remember to use "External" to declare external objects.
e) assemble the file to generate the AML code of the method.
e.g. "iasl psr.asl" (psr.aml is generated as a result)
f) mount debugfs by "mount -t debugfs none /sys/kernel/debug"
g) override the old method via the debugfs by running
"cat /tmp/psr.aml > /sys/kernel/debug/acpi/custom_method"
2. insert a new method
This is easier than overriding an existing method.
We just need to create the ASL code of the method we want to
insert and then follow the step c) ~ g) in section 1.
3. undo your changes
The "undo" operation is not supported for a new inserted method
right now, i.e. we can not remove a method currently.
For an overrided method, in order to undo your changes, please
save a copy of the method original ASL code in step c) section 1,
and redo step c) ~ g) to override the method with the original one.
Note: We can use a kernel with multiple custom ACPI method running,
But each individual write to debugfs can implement a SINGLE
method override. i.e. if we want to insert/override multiple
ACPI methods, we need to redo step c) ~ g) for multiple times.
drivers/acpi/debug.c
View file @
1fc22fad
...
...
@@ -8,6 +8,7 @@
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/moduleparam.h>
#include <linux/debugfs.h>
#include <asm/uaccess.h>
#include <acpi/acpi_drivers.h>
...
...
@@ -195,6 +196,80 @@ static int param_get_trace_state(char *buffer, struct kernel_param *kp)
module_param_call
(
trace_state
,
param_set_trace_state
,
param_get_trace_state
,
NULL
,
0644
);
/* --------------------------------------------------------------------------
DebugFS Interface
-------------------------------------------------------------------------- */
static
ssize_t
cm_write
(
struct
file
*
file
,
const
char
__user
*
user_buf
,
size_t
count
,
loff_t
*
ppos
)
{
static
char
*
buf
;
static
int
uncopied_bytes
;
struct
acpi_table_header
table
;
acpi_status
status
;
if
(
!
(
*
ppos
))
{
/* parse the table header to get the table length */
if
(
count
<=
sizeof
(
struct
acpi_table_header
))
return
-
EINVAL
;
if
(
copy_from_user
(
&
table
,
user_buf
,
sizeof
(
struct
acpi_table_header
)))
return
-
EFAULT
;
uncopied_bytes
=
table
.
length
;
buf
=
kzalloc
(
uncopied_bytes
,
GFP_KERNEL
);
if
(
!
buf
)
return
-
ENOMEM
;
}
if
(
uncopied_bytes
<
count
)
{
kfree
(
buf
);
return
-
EINVAL
;
}
if
(
copy_from_user
(
buf
+
(
*
ppos
),
user_buf
,
count
))
{
kfree
(
buf
);
return
-
EFAULT
;
}
uncopied_bytes
-=
count
;
*
ppos
+=
count
;
if
(
!
uncopied_bytes
)
{
status
=
acpi_install_method
(
buf
);
kfree
(
buf
);
if
(
ACPI_FAILURE
(
status
))
return
-
EINVAL
;
add_taint
(
TAINT_OVERRIDDEN_ACPI_TABLE
);
}
return
count
;
}
static
const
struct
file_operations
cm_fops
=
{
.
write
=
cm_write
,
};
static
int
acpi_debugfs_init
(
void
)
{
struct
dentry
*
acpi_dir
,
*
cm_dentry
;
acpi_dir
=
debugfs_create_dir
(
"acpi"
,
NULL
);
if
(
!
acpi_dir
)
goto
err
;
cm_dentry
=
debugfs_create_file
(
"custom_method"
,
S_IWUGO
,
acpi_dir
,
NULL
,
&
cm_fops
);
if
(
!
cm_dentry
)
goto
err
;
return
0
;
err:
if
(
acpi_dir
)
debugfs_remove
(
acpi_dir
);
return
-
EINVAL
;
}
/* --------------------------------------------------------------------------
FS Interface (/proc)
-------------------------------------------------------------------------- */
...
...
@@ -286,7 +361,7 @@ static const struct file_operations acpi_system_debug_proc_fops = {
};
#endif
int
__init
acpi_
debug
_init
(
void
)
int
__init
acpi_
procfs
_init
(
void
)
{
#ifdef CONFIG_ACPI_PROCFS
struct
proc_dir_entry
*
entry
;
...
...
@@ -321,3 +396,10 @@ int __init acpi_debug_init(void)
return
0
;
#endif
}
int
__init
acpi_debug_init
(
void
)
{
acpi_debugfs_init
();
acpi_procfs_init
();
return
0
;
}
Write
Preview
Markdown
is supported
0%
Try again
or
attach a new file
Attach a file
Cancel
You are about to add
0
people
to the discussion. Proceed with caution.
Finish editing this message first!
Cancel
Please
register
or
sign in
to comment