280 lines
12 KiB
C
280 lines
12 KiB
C
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/** @file hal/micro/cortexm3/nvm.h
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* @brief Cortex-M3 Non-Volatile Memory data storage system.
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* See @ref nvm for documentation.
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*
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* The functions in this file return an ::StStatus value.
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* See error-def.h for definitions of all ::StStatus return values.
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*
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* See hal/micro/cortexm3/nvm.h for source code.
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*
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* <!--(C) COPYRIGHT 2010 STMicroelectronics. All rights reserved. -->
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*/
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/** @addtogroup nvm
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* @brief Cortex-M3 Non-Volatile Memory data storage system.
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*
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* This header defines the API for NVM data storage. This header also
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* describes the algorithm behind the NVM data storage system with notes
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* on algorithm behavior.
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*
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* See hal/micro/cortexm3/nvm.h for source code.
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*
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* @note The algorithm description uses "page" to indicate an area of memory
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* that is a multiple of physical flash pages. There are two pages: LEFT
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* and RIGHT. The term "flash page" is used to refer to a page of
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* physical flash.
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*
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* NVM data storage works by alternating between two pages: LEFT and RIGHT.
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* The basic algorithm is driven by a call to halCommonSaveToNvm(). It will:
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* - erase the inactive page
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* - write the new data to the inactive page
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* - copy existing data from the active page to the inactive page
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* - mark the inactive page as the new active page
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* - mark the old active page as the new inactive page
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* To accomplish alternating between two pages and knowing which page has the
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* valid set of data, the algorithm uses 4 bytes of mgmt data that exists
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* at the top of both LEFT and RIGHT (the term "mgmt" is shorthand referring to
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* the management data). The management data is comprised of a Valid marker,
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* an Active marker, a Dead marker, and a Spare byte. Viewing the
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* management data as a single 32 bit quantity yields:
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* - Valid is mgmt[0]
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* - Active is mgmt[1]
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* - Dead is mgmt[2]
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* - Spare is mgmt[3]
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* The algorithm is based on a simple, circular state machine. The following
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* discussion details all of the possible mgmt bytes and the states they
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* correspond to. The "Reads from" line indicates which page a call to
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* halCommonReadFromNvm() will read from (an 'x' page will stuff the read
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* data with 0xFF). The vertical "erase" and "write" words indicate the
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* flash altering actions taken between those states. Invalid mgmt bytes
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* is equivalent to erased mgmt bytes (state 0) and will trigger an
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* erase of both LEFT and RIGHT. State 3 and state 7 are the only exit
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* states. When the algorithm is run, regardless of starting state, it
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* will advance to the next exit state. This means if the "Read from"
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* is LEFT then the state machine will advance until state 7 and then exit.
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* If "Read from" is RIGHT, then the state machine will advance until
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* state 3 and then exit.
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*
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* @code
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* Starting from erased or invalid mgmt, write to LEFT
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* State # 0 0 1 2 3
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* Reads from: x x e w L L L
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* Valid xx|xx FF|FF r r 00|FF 00|FF 00|00
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* Active xx|xx FF|FF a i 00|FF 00|FF 00|00
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* Dead xx|xx FF|FF s t FF|FF FF|00 FF|00
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* Spare xx|xx FF|FF e e FF|FF FF|FF FF|FF
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*
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*
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* Starting from LEFT page, transition to RIGHT page:
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* State # 3 4 5 6 7
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* Reads from: L e L w R R R
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* Valid 00|00 r 00|FF r 00|00 00|00 00|00
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* Active 00|00 a 00|FF i 00|FF 00|FF 00|00
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* Dead FF|00 s FF|FF t FF|FF 00|FF 00|FF
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* Spare FF|FF e FF|FF e FF|FF FF|FF FF|FF
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*
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*
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* Starting from RIGHT page, transition to LEFT page:
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* State # 7 8 9 10 3
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* Reads from: R e R w L L L
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* Valid 00|00 r FF|00 r 00|00 00|00 00|00
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* Active 00|00 a FF|00 i FF|00 FF|00 00|00
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* Dead 00|FF s FF|FF t FF|FF FF|00 FF|00
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* Spare FF|FF e FF|FF e FF|FF FF|FF FF|FF
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* @endcode
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*
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* Based on the 10 possible states, there are 5 valid 32bit mgmt words:
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* - 0xFFFFFFFF
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* - 0xFFFFFF00
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* - 0xFFFF0000
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* - 0xFF000000
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* - 0xFF00FFFF
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* The algorithm determines the current state by using these 5 mgmt words
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* with the 10 possible combinations of LEFT mgmt and RIGHT mgmt.
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*
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* Detailed State Description:
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* - State 0:
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* In this state the mgmt bytes do not conform to any of the other states
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* and therefore the entire NVM system, both the LEFT and RIGHT, is
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* invalid. Invalid could be as simple as both LEFT and RIGHT are erased
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* or as complex as serious memory corruption or a bug caused bad data to
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* be written to the NVM. By using a small set of very strict, precise,
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* valid states (versus other management systems such as a simple counter),
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* the algorithm/data gains some protection against not only corruption, but
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* also executing the NVM algorithm on a chip that previously did not
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* have the NVM system running on it.
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* - State 1, 4, 8
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* In these states, mgmt is saying that one page is valid and active, while
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* the other page is erased. This tells the algorithm which page to read
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* from and indicates that the other page has already been erased.
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* - State 2
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* This state is only necessary for transitioning from state 0. From state
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* 0, the goal is to arrive at state 3. Ideally, the RIGHT mgmt would
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* be written with 0xFF000000, but the flash library only permits 16 bit
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* writes. If a reset were to occur in the middle of this section of the
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* algorithm, we want to ensure that the mgmt is left in a known state,
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* state 2, so that the algorithm could continue from where it got
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* interrupted.
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* - State 5, 9
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* These states indicate that the other page has just become valid because
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* the new data has just been written. Once at these states, reading
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* from the NVM will now pull data from the other page.
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* - State 6, 10
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* These states indicate that the old page is now dead and not in use.
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* While the algorithm already knows to read from the new page, the Dead
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* mgmt byte is primarily used to indicate that the other page needs to
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* be erased. Conceptually, the Dead byte can also be considered a type
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* of "garbage collection" flag indicating the old page needs to be
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* destroyed and has not yet been erased.
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* - State 3, 7
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* These states are the final exit points of the circular state machine.
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* Once at these states, the current page is marked Valid and Active and
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* the old page is marked as Dead. The algorithm knows which page to
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* read from and which page needs to be erased on the next write to the NVM.
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*
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*
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* Notes on algorithm behavior:
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* - Refer to nvm-def.h for a list of offset/length that define the data
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* stored in NVM storage space.
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* - All writes to flash are 16bit granularity and therefore the internal
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* flash writes cast the data to int16u. Length is also required to be
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* a multiple of 16bits.
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* - Flash page erase uses a granularity of a single flash page. The size
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* of a flash page depends on the chip and is defined in memmap.h with
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* the define MFB_PAGE_SIZE_B.
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* - Erasing will only occur when halCommonSaveToNvm() is called.
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* - Erasing will always occur when halCommonSaveToNvm() is called unless the
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* page intended to be erased is already entirely 0xFFFF.
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* - When reading and management is invalid, the read will return 0xFF for data.
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* - Calling halCommonSaveToNvm() while in any state is always valid and the
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* new data will be written to flash.
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* - halCommonSaveToNvm() will always advance the state machine to 3 or 7.
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* - When writing and management is invalid, both LEFT and RIGHT will be erased
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* and the new data will be written to LEFT.
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* - Writing causes the new data being passed into halCommonSaveToNvm() to be
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* written to flash. The data already existing in the currently valid page
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* will be copied over to the new page.
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* - Reading or writing to an offset equal to or greater than NVM_DATA_SIZE_B is
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* illegal and will cause an assert.
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* - Offset and length must always be multiples of 16bits. If not, both a read
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* and a write will trigger an assert.
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* - Offset and length must be supplied in bytes.
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* - All data in NVM storage must exist above the mgmt bytes, denoted by
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* NVM_MGMT_SIZE_B.
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* - The bottom 64 bytes of NVM storage are allocated to radio calibration
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* values. These 64 bytes *must* exist for the radio to function.
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* - There is no error checking beyond checking for 16bit alignment. This
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* means it is possible to use data offset and size combinations that
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* exceed NVM storage space or overlap with other data. Be careful!
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*@{
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*/
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#ifndef __NVM_H__
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#define __NVM_H__
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//Pull in the MFB_ definitions.
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#include "hal/micro/cortexm3/memmap.h"
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//Pull in nvm-def.h so any code including nvm.h has access to the
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//offsets and sizes defining the NVM data.
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#include "hal/micro/cortexm3/nvm-def.h"
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//Necessary to define StStatus and codes.
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#include "error.h"
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/**
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* @brief Copy the NVM data from flash into the provided RAM location.
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* It is illegal for the offset to be greater than NVM_DATA_SIZE_B.
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*
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* @param data A (RAM) pointer to where the data should be copied.
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*
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* @param offset The location from which the data should be copied. Must be
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* 16bit aligned.
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*
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* @param length The length of the data in bytes. Must be 16bit aligned.
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*
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* @return An StStatus value indicating the success of the function.
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* - ST_SUCCESS if the read completed cleanly.
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* - ST_ERR_FATAL if the NVM storage management indicated an invalid
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* state. The function will return entirely 0xFF in the data parameter.
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*/
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StStatus halCommonReadFromNvm(void *data, int32u offset, int16u length);
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/**
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* @brief Return the address of the token in NVM
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*
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* @param offset The location offset from which the address should be returned
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*
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*
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* @return The address requested
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*/
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int16u *halCommonGetAddressFromNvm(int32u offset);
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/**
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* @brief Write the NVM data from the provided location RAM into flash.
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* It is illegal for the offset to be greater than NVM_DATA_SIZE_B.
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*
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* @param data A (RAM) pointer from where the data should be taken.
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*
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* @param offset The location to which the data should be written. Must be
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* 16bit aligned.
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*
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* @param length The length of the data in bytes. Must be 16bit aligned.
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*
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* @return An StStatus value indicating the success of the function.
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* - ST_SUCCESS if the write completed cleanly.
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* - Any other status value is an error code generated by the low level
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* flash erase and write API. Refer to flash.h for details.
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*/
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StStatus halCommonWriteToNvm(const void *data, int32u offset, int16u length);
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/**
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* @brief Define the number of physical flash pages that comprise a NVM page.
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* Since NVM_DATA_SIZE_B must be a multiple of MFB_PAGE_SIZE_B, increasing the
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* size of NVM storage should be done by modifying this define.
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*
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* @note The total flash area consumed by NVM storage is double this value.
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* This is due to the fact that there are two NVM pages, LEFT and RIGHT,
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* which the algorithm alternates between.
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*/
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#define NVM_FLASH_PAGE_COUNT (1)
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/**
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* @brief Define the total size of a NVM page, in bytes. This must be a
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* multiple of the memory map define MFB_PAGE_SIZE_B. Note that 4 bytes of
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* the total size of an NVM page are dedicated to page management.
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*
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* @note <b>DO NOT EDIT THIS DEFINE. Instead, edit NVM_FLASH_PAGE_COUNT.</b>
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*/
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#define NVM_DATA_SIZE_B (MFB_PAGE_SIZE_B*NVM_FLASH_PAGE_COUNT)
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#if ((NVM_DATA_SIZE_B%MFB_PAGE_SIZE_B) != 0)
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#error Illegal NVM data storage size. NVM_DATA_SIZE_B must be a multiple of MFB_PAGE_SIZE_B.
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#endif
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/**
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* @brief Define the absolute address of the LEFT page. LEFT page storage
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* is defined by nvmStorageLeft[NVM_DATA_SIZE_B] and placed by the linker
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* using the segment "NVM".
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*/
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#define NVM_LEFT_PAGE ((int32u)nvmStorageLeft)
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/**
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* @brief Define the absolute address of the RIGHT page. RIGHT page storage
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* is defined by nvmStorageRight[NVM_DATA_SIZE_B] and placed by the linker
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* using the segment "NVM".
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*/
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#define NVM_RIGHT_PAGE ((int32u)nvmStorageRight)
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/**
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* @brief Define the number of bytes that comprise the NVM management bytes.
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* All data must begin at an offset above the management bytes.
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*
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* @note This value <b>must not change</b>.
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*/
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#define NVM_MGMT_SIZE_B (4)
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/** @} END addtogroup */
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#endif // __NVM_H__
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