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debugfs: add tools to printk 32-bit registers

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Some debugfs file I deal with are mostly blocks of registers,
i.e. lines of the form "<name> = 0x<value>". Some files are only
registers, some include registers blocks among other material.  This
patch introduces data structures and functions to deal with both
cases.  I expect more users of this over time.

Signed-off-by: Alessandro Rubini <rubini@gnudd.com>
Acked-by: Giancarlo Asnaghi <giancarlo.asnaghi@st.com>
Cc: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alessandro Rubini 2011-11-18 14:50:21 +01:00 committed by Greg Kroah-Hartman
parent fe7484834b
commit 1a087c6ad9
3 changed files with 147 additions and 1 deletions
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32
Documentation/filesystems/debugfs.txt
View File

@ -97,7 +97,8 @@ A read on the resulting file will yield either Y (for non-zero values) or
N, followed by a newline. If written to, it will accept either upper- or
lower-case values, or 1 or 0. Any other input will be silently ignored.
Finally, a block of arbitrary binary data can be exported with:
Another option is exporting a block of arbitrary binary data, with
this structure and function:
struct debugfs_blob_wrapper {
void *data;
@ -115,6 +116,35 @@ can be used to export binary information, but there does not appear to be
any code which does so in the mainline. Note that all files created with
debugfs_create_blob() are read-only.
If you want to dump a block of registers (something that happens quite
often during development, even if little such code reaches mainline.
Debugfs offers two functions: one to make a registers-only file, and
another to insert a register block in the middle of another sequential
file.
struct debugfs_reg32 {
char *name;
unsigned long offset;
};
struct debugfs_regset32 {
struct debugfs_reg32 *regs;
int nregs;
void __iomem *base;
};
struct dentry *debugfs_create_regset32(const char *name, mode_t mode,
struct dentry *parent,
struct debugfs_regset32 *regset);
int debugfs_print_regs32(struct seq_file *s, struct debugfs_reg32 *regs,
int nregs, void __iomem *base, char *prefix);
The "base" argument may be 0, but you may want to build the reg32 array
using __stringify, and a number of register names (macros) are actually
byte offsets over a base for the register block.
There are a couple of other directory-oriented helper functions:
struct dentry *debugfs_rename(struct dentry *old_dir,

90
fs/debugfs/file.c
View File

@ -15,6 +15,7 @@
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/pagemap.h>
#include <linux/namei.h>
#include <linux/debugfs.h>
@ -525,3 +526,92 @@ struct dentry *debugfs_create_blob(const char *name, mode_t mode,
return debugfs_create_file(name, mode, parent, blob, &fops_blob);
}
EXPORT_SYMBOL_GPL(debugfs_create_blob);
/*
* The regset32 stuff is used to print 32-bit registers using the
* seq_file utilities. We offer printing a register set in an already-opened
* sequential file or create a debugfs file that only prints a regset32.
*/
/**
* debugfs_print_regs32 - use seq_print to describe a set of registers
* @s: the seq_file structure being used to generate output
* @regs: an array if struct debugfs_reg32 structures
* @mregs: the length of the above array
* @base: the base address to be used in reading the registers
* @prefix: a string to be prefixed to every output line
*
* This function outputs a text block describing the current values of
* some 32-bit hardware registers. It is meant to be used within debugfs
* files based on seq_file that need to show registers, intermixed with other
* information. The prefix argument may be used to specify a leading string,
* because some peripherals have several blocks of identical registers,
* for example configuration of dma channels
*/
int debugfs_print_regs32(struct seq_file *s, struct debugfs_reg32 *regs,
int nregs, void __iomem *base, char *prefix)
{
int i, ret = 0;
for (i = 0; i < nregs; i++, regs++) {
if (prefix)
ret += seq_printf(s, "%s", prefix);
ret += seq_printf(s, "%s = 0x%08x\n", regs->name,
readl((void *)(base + regs->offset)));
}
return ret;
}
EXPORT_SYMBOL_GPL(debugfs_print_regs32);
static int debugfs_show_regset32(struct seq_file *s, void *data)
{
struct debugfs_regset32 *regset = s->private;
debugfs_print_regs32(s, regset->regs, regset->nregs, regset->base, "");
return 0;
}
static int debugfs_open_regset32(struct inode *inode, struct file *file)
{
return single_open(file, debugfs_show_regset32, inode->i_private);
}
static const struct file_operations fops_regset32 = {
.open = debugfs_open_regset32,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
/**
* debugfs_create_regset32 - create a debugfs file that returns register values
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @regset: a pointer to a struct debugfs_regset32, which contains a pointer
* to an array of register definitions, the array size and the base
* address where the register bank is to be found.
*
* This function creates a file in debugfs with the given name that reports
* the names and values of a set of 32-bit registers. If the @mode variable
* is so set it can be read from. Writing is not supported.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned. It is not wise to check for this value, but rather, check for
* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
* code.
*/
struct dentry *debugfs_create_regset32(const char *name, mode_t mode,
struct dentry *parent,
struct debugfs_regset32 *regset)
{
return debugfs_create_file(name, mode, parent, regset, &fops_regset32);
}
EXPORT_SYMBOL_GPL(debugfs_create_regset32);

26
include/linux/debugfs.h
View File

@ -16,6 +16,7 @@
#define _DEBUGFS_H_
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/types.h>
@ -26,6 +27,17 @@ struct debugfs_blob_wrapper {
unsigned long size;
};
struct debugfs_reg32 {
char *name;
unsigned long offset;
};
struct debugfs_regset32 {
struct debugfs_reg32 *regs;
int nregs;
void __iomem *base;
};
extern struct dentry *arch_debugfs_dir;
#if defined(CONFIG_DEBUG_FS)
@ -74,6 +86,13 @@ struct dentry *debugfs_create_blob(const char *name, mode_t mode,
struct dentry *parent,
struct debugfs_blob_wrapper *blob);
struct dentry *debugfs_create_regset32(const char *name, mode_t mode,
struct dentry *parent,
struct debugfs_regset32 *regset);
int debugfs_print_regs32(struct seq_file *s, struct debugfs_reg32 *regs,
int nregs, void __iomem *base, char *prefix);
bool debugfs_initialized(void);
#else
@ -188,6 +207,13 @@ static inline struct dentry *debugfs_create_blob(const char *name, mode_t mode,
return ERR_PTR(-ENODEV);
}
static inline struct dentry *debugfs_create_regset32(const char *name,
mode_t mode, struct dentry *parent,
struct debugfs_regset32 *regset)
{
return ERR_PTR(-ENODEV);
}
static inline bool debugfs_initialized(void)
{
return false;