Journalling Flash File System Version 2 (JFFS2) Support

Mount options for the Journalling Flash File System, Version 2 (JFFS2). More...

Data Structures
struct	rtems_jffs2_flash_control
	JFFS2 flash device control. More...
struct	rtems_jffs2_compressor_control
	JFFS2 compressor control. More...
struct	rtems_jffs2_compressor_zlib_control
	ZLIB compressor control structure. More...
struct	rtems_jffs2_mount_data
	JFFS2 mount options. More...
struct	rtems_jffs2_info
	JFFS2 filesystem instance information. More...

Macros
#define	RTEMS_JFFS2_GET_INFO   _IOR('F', 1, rtems_jffs2_info)
	IO control to get the JFFS2 filesystem instance information. More...
#define	RTEMS_JFFS2_ON_DEMAND_GARBAGE_COLLECTION   _IO('F', 2)
	IO control to perform an on demand garbage collection in a JFFS2 filesystem instance. More...
#define	RTEMS_JFFS2_FORCE_GARBAGE_COLLECTION   _IO('F', 3)
	IO control to force a garbage collection in a JFFS2 filesystem instance. More...

Typedefs
typedef int(*	rtems_jffs2_flash_read) (rtems_jffs2_flash_control *self, uint32_t offset, unsigned char *buffer, size_t size_of_buffer)
	Read from flash operation. More...
typedef int(*	rtems_jffs2_flash_write) (rtems_jffs2_flash_control *self, uint32_t offset, const unsigned char *buffer, size_t size_of_buffer)
	Write to flash operation. More...
typedef int(*	rtems_jffs2_flash_erase) (rtems_jffs2_flash_control *self, uint32_t offset)
	Flash erase operation. More...
typedef void(*	rtems_jffs2_flash_destroy) (rtems_jffs2_flash_control *self)
	Flash destroy operation. More...
typedef void(*	rtems_jffs2_trigger_garbage_collection) (rtems_jffs2_flash_control *self)
	Trigger garbage collection operation. More...
typedef struct rtems_jffs2_compressor_control	rtems_jffs2_compressor_control
typedef uint16_t(*	rtems_jffs2_compressor_compress) (rtems_jffs2_compressor_control *self, unsigned char *data_in, unsigned char *cdata_out, uint32_t *datalen, uint32_t *cdatalen)
	Compress operation. More...
typedef int(*	rtems_jffs2_compressor_decompress) (rtems_jffs2_compressor_control *self, uint16_t comprtype, unsigned char *cdata_in, unsigned char *data_out, uint32_t cdatalen, uint32_t datalen)
	Decompress operation. More...
typedef void(*	rtems_jffs2_compressor_destroy) (rtems_jffs2_compressor_control *self)
	Compressor destroy operation. More...

Functions
uint16_t	rtems_jffs2_compressor_rtime_compress (rtems_jffs2_compressor_control *self, unsigned char *data_in, unsigned char *cdata_out, uint32_t *datalen, uint32_t *cdatalen)
	RTIME compressor compress operation.
int	rtems_jffs2_compressor_rtime_decompress (rtems_jffs2_compressor_control *self, uint16_t comprtype, unsigned char *cdata_in, unsigned char *data_out, uint32_t cdatalen, uint32_t datalen)
	RTIME compressor decompress operation.
uint16_t	rtems_jffs2_compressor_zlib_compress (rtems_jffs2_compressor_control *self, unsigned char *data_in, unsigned char *cdata_out, uint32_t *datalen, uint32_t *cdatalen)
	ZLIB compressor compress operation.
int	rtems_jffs2_compressor_zlib_decompress (rtems_jffs2_compressor_control *self, uint16_t comprtype, unsigned char *cdata_in, unsigned char *data_out, uint32_t cdatalen, uint32_t datalen)
	ZLIB compressor decompress operation.
int	rtems_jffs2_initialize (rtems_filesystem_mount_table_entry_t *mt_entry, const void *data)
	Initialization handler of the JFFS2 file system. More...

Detailed Description

Mount options for the Journalling Flash File System, Version 2 (JFFS2).

The application must provide flash device geometry information and flash device operations in the flash control structure rtems_jffs2_flash_control.

The application can optionally provide a compressor control structure to enable data compression using the selected compression algorithm.

The application must enable JFFS2 support with rtems_filesystem_register() or CONFIGURE_FILESYSTEM_JFFS2 via <rtems/confdefs.h>.

An example mount with a simple memory based flash device simulation follows. The zlib is used for as the compressor.

#include <string.h>
 
#include <rtems/jffs2.h>
#include <rtems/libio.h>
 
#define BLOCK_SIZE (32UL * 1024UL)
 
#define FLASH_SIZE (32UL * BLOCK_SIZE)
 
typedef struct {
  rtems_jffs2_flash_control super;
  unsigned char area[FLASH_SIZE];
} flash_control;
 
static flash_control *get_flash_control(rtems_jffs2_flash_control *super)
{
  return (flash_control *) super;
}
 
static int flash_read(
  rtems_jffs2_flash_control *super,
  uint32_t offset,
  unsigned char *buffer,
  size_t size_of_buffer
)
{
  flash_control *self = get_flash_control(super);
  unsigned char *chunk = &self->area[offset];
 
  memcpy(buffer, chunk, size_of_buffer);
 
  return 0;
}
 
static int flash_write(
  rtems_jffs2_flash_control *super,
  uint32_t offset,
  const unsigned char *buffer,
  size_t size_of_buffer
)
{
  flash_control *self = get_flash_control(super);
  unsigned char *chunk = &self->area[offset];
  size_t i;
 
  for (i = 0; i < size_of_buffer; ++i) {
    chunk[i] &= buffer[i];
  }
 
  return 0;
}
 
static int flash_erase(
  rtems_jffs2_flash_control *super,
  uint32_t offset
)
{
  flash_control *self = get_flash_control(super);
  unsigned char *chunk = &self->area[offset];
 
  memset(chunk, 0xff, BLOCK_SIZE);
 
  return 0;
}
 
static flash_control flash_instance = {
  .super = {
    .block_size = BLOCK_SIZE,
    .flash_size = FLASH_SIZE,
    .read = flash_read,
    .write = flash_write,
    .erase = flash_erase,
    .device_identifier = 0xc01dc0fe
  }
};
 
static rtems_jffs2_compressor_zlib_control compressor_instance = {
  .super = {
    .compress = rtems_jffs2_compressor_zlib_compress,
    .decompress = rtems_jffs2_compressor_zlib_decompress
  }
};
 
static const rtems_jffs2_mount_data mount_data = {
  .flash_control = &flash_instance.super,
  .compressor_control = &compressor_instance.super
};
 
static void erase_all(void)
{
  memset(&flash_instance.area[0], 0xff, FLASH_SIZE);
}
 
void example_jffs2_mount(const char *mount_dir)
{
  int rv;
 
  erase_all();
 
  rv = mount_and_make_target_path(
    NULL,
    mount_dir,
    RTEMS_FILESYSTEM_TYPE_JFFS2,
    RTEMS_FILESYSTEM_READ_WRITE,
    &mount_data
  );
  assert(rv == 0);
}

Macro Definition Documentation

RTEMS_JFFS2_FORCE_GARBAGE_COLLECTION

#define RTEMS_JFFS2_FORCE_GARBAGE_COLLECTION   _IO('F', 3)

IO control to force a garbage collection in a JFFS2 filesystem instance.

Use this operation with care since it may wear out your flash.

RTEMS_JFFS2_GET_INFO

#define RTEMS_JFFS2_GET_INFO   _IOR('F', 1, rtems_jffs2_info)

IO control to get the JFFS2 filesystem instance information.

See also

rtems_jffs2_info.

RTEMS_JFFS2_ON_DEMAND_GARBAGE_COLLECTION

#define RTEMS_JFFS2_ON_DEMAND_GARBAGE_COLLECTION   _IO('F', 2)

IO control to perform an on demand garbage collection in a JFFS2 filesystem instance.

This operation is intended to be used by an optional garbage collection thread. See rtems_jffs2_flash_control::trigger_garbage_collection.

Typedef Documentation

rtems_jffs2_compressor_compress

typedef uint16_t(* rtems_jffs2_compressor_compress) (rtems_jffs2_compressor_control *self, unsigned char *data_in, unsigned char *cdata_out, uint32_t *datalen, uint32_t *cdatalen)

Compress operation.

Parameters

[in,out]	self	The compressor control.
[in]	data_in	The uncompressed data.
[out]	cdata_out	Pointer to buffer with the compressed data.
[in,out]	datalen	On entry, the size in bytes of the uncompressed data. On exit, the size in bytes of uncompressed data which was actually compressed.
[in,out]	cdatalen	On entry, the size in bytes available for compressed data. On exit, the size in bytes of the actually compressed data.

Returns

The compressor type.

rtems_jffs2_compressor_decompress

typedef int(* rtems_jffs2_compressor_decompress) (rtems_jffs2_compressor_control *self, uint16_t comprtype, unsigned char *cdata_in, unsigned char *data_out, uint32_t cdatalen, uint32_t datalen)

Decompress operation.

Parameters

[in,out]	self	The compressor control.
[in]	comprtype	The compressor type.
[in]	cdata_in	The compressed data.
[out]	data_out	The uncompressed data.
[in]	cdatalen	The size in bytes of the compressed data.
[in]	datalen	The size in bytes of the uncompressed data.

Return values

0	Successful operation.
-EIO	An error occurred. Please note that the value is negative.
other	All other values are reserved and must not be used.

rtems_jffs2_compressor_destroy

typedef void(* rtems_jffs2_compressor_destroy) (rtems_jffs2_compressor_control *self)

Compressor destroy operation.

The compressor destroy operation is called during unmount of the file system instance. It can be used to free the resources associated with the now unused compressor operations.

Parameters

[in,out]

self

The compressor control.

rtems_jffs2_flash_destroy

typedef void(* rtems_jffs2_flash_destroy) (rtems_jffs2_flash_control *self)

Flash destroy operation.

The flash destroy operation is called during unmount of the file system instance. It can be used to free the resources associated with the now unused flash control

Parameters

[in,out]

self

The flash control.

rtems_jffs2_flash_erase

typedef int(* rtems_jffs2_flash_erase) (rtems_jffs2_flash_control *self, uint32_t offset)

Flash erase operation.

This operation must erase one block specified by the offset.

Parameters

[in,out]	self	The flash control.
[in]	offset	The offset to erase from the flash begin in bytes.

Return values

0	Successful operation.
-EIO	An error occurred. Please note that the value is negative.
other	All other values are reserved and must not be used.

rtems_jffs2_flash_read

typedef int(* rtems_jffs2_flash_read) (rtems_jffs2_flash_control *self, uint32_t offset, unsigned char *buffer, size_t size_of_buffer)

Read from flash operation.

Parameters

[in,out]	self	The flash control.
[in]	offset	The offset to read from the flash begin in bytes.
[out]	buffer	The buffer receiving the data.
[in]	size_of_buffer	The size of the buffer in bytes.

Return values

0	Successful operation.
-EIO	An error occurred. Please note that the value is negative.
other	All other values are reserved and must not be used.

rtems_jffs2_flash_write

typedef int(* rtems_jffs2_flash_write) (rtems_jffs2_flash_control *self, uint32_t offset, const unsigned char *buffer, size_t size_of_buffer)

Write to flash operation.

Parameters

[in,out]	self	The flash control.
[in]	offset	The offset to write from the flash begin in bytes.
[in]	buffer	The buffer containing the data to write.
[in]	size_of_buffer	The size of the buffer in bytes.

Return values

0	Successful operation.
-EIO	An error occurred. Please note that the value is negative.
other	All other values are reserved and must not be used.

rtems_jffs2_trigger_garbage_collection

typedef void(* rtems_jffs2_trigger_garbage_collection) (rtems_jffs2_flash_control *self)

Trigger garbage collection operation.

An optional garbage collection thread may perform now a garbage collection using the RTEMS_JFFS2_ON_DEMAND_GARBAGE_COLLECTION IO control.

The garbage collection must not run in the executing context.

Parameters

[in]

self

The flash control.

Function Documentation

rtems_jffs2_initialize()

int rtems_jffs2_initialize	(	rtems_filesystem_mount_table_entry_t *	mt_entry,
		const void *	data
	)

Initialization handler of the JFFS2 file system.

Parameters

[in,out]	mt_entry	The mount table entry.
[in]	data	The mount options are mandatory for JFFS2 and data must point to a valid rtems_jffs2_mount_data structure used for this file system instance.

Return values

0	Successful operation.
-1	An error occurred. The errno indicates the error.

See also

mount().