diff options
| -rw-r--r-- | bsp-howto/index.rst | 1 | ||||
| -rw-r--r-- | bsp-howto/non_volatile_memory.rst | 217 |
2 files changed, 0 insertions, 218 deletions
diff --git a/bsp-howto/index.rst b/bsp-howto/index.rst index f99118d..d826369 100644 --- a/bsp-howto/index.rst +++ b/bsp-howto/index.rst @@ -53,7 +53,6 @@ to the Community Project hosted at http://www.rtems.org. real_time_clock ata ide_controller - non_volatile_memory networking shared_memory_support frame_buffer diff --git a/bsp-howto/non_volatile_memory.rst b/bsp-howto/non_volatile_memory.rst deleted file mode 100644 index e23c162..0000000 --- a/bsp-howto/non_volatile_memory.rst +++ /dev/null @@ -1,217 +0,0 @@ -.. comment SPDX-License-Identifier: CC-BY-SA-4.0 - -.. COMMENT: Written by Eric Norum -.. COMMENT: COPYRIGHT (c) 1988-2002. -.. COMMENT: On-Line Applications Research Corporation (OAR). -.. COMMENT: All rights reserved. - -Non-Volatile Memory Driver -************************** - -The Non-Volatile driver is responsible for providing an interface to various -types of non-volatile memory. These types of memory include, but are not -limited to, Flash, EEPROM, and battery backed RAM. The capabilities provided -by this class of device driver are: - -- Initialize the Non-Volatile Memory Driver - -- Optional Disable Read and Write Handlers - -- Open a Particular Memory Partition - -- Close a Particular Memory Partition - -- Read from a Particular Memory Partition - -- Write to a Particular Memory Partition - -- Erase the Non-Volatile Memory Area - -There is currently only one non-volatile device driver included in the RTEMS -source tree. The information provided in this chapter is based on drivers -developed for applications using RTEMS. It is hoped that this driver model -information can form the basis for a standard non-volatile memory driver model -that can be supported in future RTEMS distribution. - -Major and Minor Numbers -======================= - -The ``major`` number of a device driver is its index in the RTEMS Device -Address Table. - -A ``minor`` number is associated with each device instance managed by a -particular device driver. An RTEMS minor number is an ``unsigned32`` entity. -Convention calls dividing the bits in the minor number down into categories -that specify an area of non-volatile memory and a partition with that area. -This results in categories like the following: - -- ``area`` - indicates a block of non-volatile memory - -- ``partition`` - indicates a particular address range with an area - -From the above, it should be clear that a single device driver can support -multiple types of non-volatile memory in a single system. The minor number is -used to distinguish the types of memory and blocks of memory used for different -purposes. - -Non-Volatile Memory Driver Configuration -======================================== - -There is not a standard non-volatile driver configuration table but some fields -are common across different drivers. The non-volatile memory driver -configuration table is typically an array of structures with each structure -containing the information for a particular area of non-volatile memory. The -following is a list of the type of information normally required to configure -each area of non-volatile memory. - -``memory_type`` - is the type of memory device in this area. Choices are battery backed RAM, - EEPROM, Flash, or an optional user-supplied type. If the user-supplied - type is configured, then the user is responsible for providing a set of - routines to program the memory. - -``memory`` - is the base address of this memory area. - -``attributes`` - is a pointer to a memory type specific attribute block. Some of the fields - commonly contained in this memory type specific attribute structure area: - - ``use_protection_algorithm`` - is set to TRUE to indicate that the protection (i.e. locking) algorithm - should be used for this area of non-volatile memory. A particular type - of non-volatile memory may not have a protection algorithm. - - ``access`` - is an enumerated type to indicate the organization of the memory - devices in this memory area. The following is a list of the access - types supported by the current driver implementation: - - - simple unsigned8 - - simple unsigned16 - - simple unsigned32 - - simple unsigned64 - - single unsigned8 at offset 0 in an unsigned16 - - single unsigned8 at offset 1 in an unsigned16 - - single unsigned8 at offset 0 in an unsigned32 - - single unsigned8 at offset 1 in an unsigned32 - - single unsigned8 at offset 2 in an unsigned32 - - single unsigned8 at offset 3 in an unsigned32 - - ``depth`` - is the depth of the progamming FIFO on this particular chip. Some - chips, particularly EEPROMs, have the same programming algorithm but - vary in the depth of the amount of data that can be programmed in a - single block. - -``number_of_partitions`` - is the number of logical partitions within this area. - -``Partitions`` - is the address of the table that contains an entry to describe each - partition in this area. Fields within each element of this table are - defined as follows: - - ``offset`` - is the offset of this partition from the base address of this area. - - ``length`` - is the length of this partition. - -By dividing an area of memory into multiple partitions, it is possible to -easily divide the non-volatile memory for different purposes. - -Initialize the Non-Volatile Memory Driver -========================================= - -At system initialization, the non-volatile memory driver's initialization entry -point will be invoked. As part of initialization, the driver will perform -whatever initializatin is required on each non-volatile memory area. - -The discrete I/O driver may register device names for memory partitions of -particular interest to the system. Normally this will be restricted to the -device "/dev/nv_memory" to indicate the entire device driver. - -Disable Read and Write Handlers -=============================== - -Depending on the target's non-volatile memory configuration, it may be possible -to write to a status register and make the memory area completely inaccessible. -This is target dependent and beyond the standard capabilities of any memory -type. The user has the optional capability to provide handlers to disable and -enable access to a partiticular memory area. - -Open a Particular Memory Partition -================================== - -This is the driver open call. Usually this call does nothing other than -validate the minor number. - -With some drivers, it may be necessary to allocate memory when a particular -device is opened. If that is the case, then this is often the place to do this -operation. - -Close a Particular Memory Partition -=================================== - -This is the driver close call. Usually this call does nothing. - -With some drivers, it may be necessary to allocate memory when a particular -device is opened. If that is the case, then this is the place where that -memory should be deallocated. - -Read from a Particular Memory Partition -======================================= - -This corresponds to the driver read call. After validating the minor number -and arguments, this call enables reads from the specified memory area by -invoking the user supplied "enable reads handler" and then reads the indicated -memory area. When invoked the ``argument_block`` is actually a pointer to the -following structure type: - -.. code-block:: c - - typedef struct { - uint32_t offset; - void *buffer; - uint32_t length; - uint32_t status; - } Non_volatile_memory_Driver_arguments; - -The driver reads ``length`` bytes starting at ``offset`` into the partition and -places them at ``buffer``. The result is returned in ``status``. - -After the read operation is complete, the user supplied "disable reads handler" -is invoked to protect the memory area again. - -Write to a Particular Memory Partition -====================================== - -This corresponds to the driver write call. After validating the minor number -and arguments, this call enables writes to the specified memory area by -invoking the "enable writes handler", then unprotecting the memory area, and -finally actually writing to the indicated memory area. When invoked the -``argument_block`` is actually a pointer to the following structure type: - -.. code-block:: c - - typedef struct { - uint32_t offset; - void *buffer; - uint32_t length; - uint32_t status; - } Non_volatile_memory_Driver_arguments; - -The driver writes ``length`` bytes from ``buffer`` and writes them to the -non-volatile memory starting at ``offset`` into the partition. The result is -returned in ``status``. - -After the write operation is complete, the "disable writes handler" is invoked -to protect the memory area again. - -Erase the Non-Volatile Memory Area -================================== - -This is one of the IOCTL functions supported by the I/O control device driver -entry point. When this IOCTL function is invoked, the specified area of -non-volatile memory is erased. |