fs/fat: Improve help of Kconfig options for FAT

config FS_FATFS_READ_ONLY

	bool "Read-only support for all volumes"

	help

	  The option excludes write code from ELM FAT file system driver;

	  when selected, it no longer will be possible to write data on

	  the FAT FS.

	  If write support is not needed, enabling this flag will slightly

	  reduce application size.

	  This option translates to _FS_READONLY within ELM FAT file system

	  driver; it enables exclusion, from compilation, of write supporting

	  code.

	  Excludes write code from ELM FAT file system driver.

	  Select this when using FAT for read-only access to slightly

	  reduce code size.

	  This option affects FF_FS_READONLY defined in ffconf.h, inside

	  ELM FAT module.

config FS_FATFS_MKFS

	bool

	help

	  This option translates to _USE_MKFS within ELM FAT file system

	  driver; it enables additional code that is required for formatting

	  volumes to ELM FAT.

	  Adds code for creating disks with FAT file system.

	  This option affects FF_USE_MKFS defined in ffconf.h, inside

	  ELM FAT module.

config FS_FATFS_MOUNT_MKFS

	bool "Allow formatting volume when mounting fails"

	  a volume if no file system is found.

	  If formatting is not needed, disabling this flag will slightly

	  reduce application size.

	  Note: This option is destructive to data and will automatically

	  destroy your disk, if mount attempt fails. In case when your

	  disk can be detached from a device and recovered using other

	  system, it may be worth disabling this option.

	  When this option is disabled, disk needs to be FAT formatted

	  prior to connecting to a device, otherwise it will not be

	  mountable.

if FS_FATFS_MOUNT_MKFS

config FS_FATFS_NUM_FILES

	int "Maximum number of opened files"

	default 4

	help

	  Affects how many file objects area available for parallel

	  use by FAT driver. Each object is of size sizeof(FIL), where

	  FIL is defined in ff.h of ELM FAT driver, and is pre-allocated

	  at compile-time.

	  This affects use of fs_open on FAT type mounted file systems.

config FS_FATFS_NUM_DIRS

	int "Maximum number of opened directories"

	default 4

	help

	  Affects how many directory objects area available for parallel

	  use by FAT driver. Each object is of size sizeof(DIR), where

	  DIR is defined in ff.h of ELM FAT driver, and is pre-allocated

	  at compile-time.

	  This affects use of fs_opendir on FAT type mounted file systems.

config FS_FATFS_LFN

	bool "Long filenames (LFN)"

	bool "Static buffer"

	help

	  Enable LFN with static working buffer on the BSS. Always NOT thread-safe.

	  This option affects FF_USE_LFN defined in ffconf.h, inside

	  ELM FAT module, by setting its value to 1.

config FS_FATFS_LFN_MODE_STACK

	bool "Stack buffer"

	help

	  Enable LFN with dynamic working buffer on the STACK.

	  This option affects FF_USE_LFN defined in ffconf.h, inside

	  ELM FAT module, by setting its value to 2.

config FS_FATFS_LFN_MODE_HEAP

	bool "Heap buffer"

	depends on HEAP_MEM_POOL_SIZE > 0

	help

	  Enable LFN with dynamic working buffer on the HEAP.

	  This option affects FF_USE_LFN defined in ffconf.h, inside

	  ELM FAT module, by setting its value to 3.

endchoice

	   936 - Simplified Chinese (DBCS)

	   949 - Korean (DBCS)

	   950 - Traditional Chinese (DBCS)

	   0 - Include all supported code pages

	  This option affects FF_CODE_PAGE defined in ffconf.h, inside

	  ELM FAT module.

config FS_FATFS_MAX_SS

	int "Maximum supported sector size"

	range 512 4096

	default 512

	help

	  Value set here will be used as maximum supported read/write

	  sector size, with 512 being minimum value.

	  Option affects write/read granularity and will increase

	  size of buffers used by FAT driver, which in practice affects

	  how much RAM each FATFS object, used with FAT mount point,

	  requires, which is this value plus some constant amount,

	  independent from this setting.

	  This will affect your compile time RAM allocation, when

	  mount point is defined as static/global life time variable,

	  or stack.

	  When this value is set to 512, all mount points will use

	  512 as sector size, all other values will cause FAT driver

	  to query device for sector size on mount.

	  This option affects FF_MAX_SS defined in ffconf.h, inside

	  ELM FAT module.

config FS_FATFS_MIN_SS

	int "Minimum expected sector size"

	  sector size, to have slight reduction in code in FAT FS driver.

	  The reduction comes from the fact that FAT FS does not have to

	  query every connected device for sector size.

	  This option affects FF_MAX_SS defined in ffconf.h, inside

	  ELM FAT module

	  This option affects FF_MIN_SS defined in ffconf.h, inside

	  ELM FAT module.

config FS_FATFS_WINDOW_ALIGNMENT

	int "Memory alignment for the member \"win\" in FATFS"

	  provided here is used as such alignment. Note that the window

	  buffer is internal element of FATFS structure, which means

	  that, in worst scenario, value provided here may cause FATFS

	  structure to have size of twice the value

	  structure to have size of twice the value.

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