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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 9 | mjames | 1 | /* |
| 2 | * nvram.c |
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| 3 | * |
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| 4 | * Created on: 4 Jun 2017 |
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| 5 | * Converted to use two 1K pages of STM32L1 Block Erasable Flash memory |
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| 6 | * instead of 4k of genuine word erasable NVRAM |
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| 7 | * on 1 Mar 2023 |
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| 8 | * Author: Mike |
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| 9 | */ |
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| 10 | |||
| 11 | /* Includes ------------------------------------------------------------------*/ |
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| 12 | #include "stm32f1xx_hal.h" |
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| 13 | |||
| 14 | #include "nvram.h" |
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| 15 | |||
| 16 | // erase page size on STM32F103 is 1kbytes |
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| 17 | #define NVRAM_PAGESIZE (1024 / sizeof(nvram_info_t)) |
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| 18 | |||
| 19 | // decided to allocate 2 pages of Flash as NVRAM |
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| 20 | #define NVRAM_WORDS (2 * NVRAM_PAGESIZE) |
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| 21 | |||
| 10 | mjames | 22 | // Flash hardware erases to all 0 |
| 23 | nvram_info_t const HARDWARE_ERASED = {.u16 = (uint16_t)~0U}; |
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| 9 | mjames | 24 | // Marked as erased change to all 1 |
| 10 | mjames | 25 | nvram_info_t const MARKED_ERASED = {.u16 = (uint16_t)0U}; |
| 9 | mjames | 26 | |
| 27 | // allocate the memory for storing the NVRAM data |
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| 10 | mjames | 28 | nvram_info_t NVRAM_Base[NVRAM_WORDS] __attribute__((section(".nvram"))) = { [0 ... NVRAM_WORDS-1].u16 = (uint16_t)~0U}; // set by linker |
| 9 | mjames | 29 | |
| 30 | static void |
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| 31 | WriteNVRAM(nvram_info_t *Address, nvram_info_t data) |
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| 32 | { |
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| 33 | HAL_FLASH_Unlock(); |
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| 34 | HAL_FLASH_Program(FLASH_TYPEPROGRAM_HALFWORD, (uint32_t)Address, data.u16); |
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| 35 | HAL_FLASH_Lock(); |
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| 36 | } |
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| 37 | |||
| 38 | static void |
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| 39 | EraseNVRAM(nvram_info_t *Address) |
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| 40 | { |
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| 10 | mjames | 41 | FLASH_EraseInitTypeDef erase = {.TypeErase = FLASH_TYPEERASE_PAGES, .PageAddress = (uint32_t)Address, .NbPages = 1}; |
| 9 | mjames | 42 | uint32_t err; |
| 43 | HAL_FLASH_Unlock(); |
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| 44 | HAL_FLASHEx_Erase(&erase, &err); |
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| 45 | HAL_FLASH_Lock(); |
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| 46 | } |
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| 47 | |||
| 48 | // returns true if page crossed , used to trigger erasure of |
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| 49 | // the other page after copying out all data from other page to new page |
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| 50 | |||
| 51 | static uint8_t _write_nvram_data(nvram_info_t data, int *pIndex) |
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| 52 | { |
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| 53 | int base = *pIndex; |
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| 54 | uint8_t pageCrossed = 0; |
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| 55 | |||
| 10 | mjames | 56 | // search for correct data |
| 9 | mjames | 57 | for (int ptr = 0; ptr < NVRAM_WORDS; ptr++) |
| 58 | { |
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| 59 | int index = (ptr + base) % NVRAM_WORDS; |
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| 60 | // erase the entry just found |
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| 61 | if (NVRAM_Base[index].data.tag == data.data.tag) |
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| 62 | { |
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| 10 | mjames | 63 | // is this the same data as we are writing ? if so return immediately |
| 64 | if(NVRAM_Base[index].u16 == data.u16) |
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| 65 | return 0; |
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| 66 | // different data |
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| 9 | mjames | 67 | // erase previous data |
| 68 | WriteNVRAM(&NVRAM_Base[index], MARKED_ERASED); |
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| 10 | mjames | 69 | base = index+1; // look at next element |
| 9 | mjames | 70 | break; |
| 71 | } |
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| 72 | } |
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| 10 | mjames | 73 | // search forward for next hardware erased element, use it |
| 74 | for (int offset = 0; offset < NVRAM_WORDS; offset++) |
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| 9 | mjames | 75 | { |
| 76 | int index = (base + offset) % NVRAM_WORDS; |
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| 77 | |||
| 78 | if (NVRAM_Base[index].u16 == HARDWARE_ERASED.u16) |
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| 79 | { |
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| 80 | // if we cross a page by incrementing into it need action |
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| 81 | if (index % NVRAM_PAGESIZE == 0) |
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| 82 | pageCrossed = 1; |
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| 83 | |||
| 84 | WriteNVRAM(&NVRAM_Base[index], data); |
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| 85 | // now check to see if it actually wrote correctly |
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| 86 | if (NVRAM_Base[index].u16 != data.u16) |
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| 87 | { |
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| 10 | mjames | 88 | WriteNVRAM(&NVRAM_Base[index], MARKED_ERASED); // Set to all erased if the data did not write properly |
| 9 | mjames | 89 | continue; |
| 90 | } |
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| 91 | // record where the data was written |
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| 92 | *pIndex = index; |
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| 93 | return pageCrossed; |
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| 94 | } |
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| 95 | } |
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| 96 | // if it gets here, failure. |
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| 97 | return 0; |
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| 98 | } |
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| 99 | |||
| 100 | void write_nvram_data(nvram_info_t data) |
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| 101 | { |
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| 102 | int index = 0; |
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| 103 | // try the easy case - returns 0 , no further action |
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| 104 | if (!_write_nvram_data(data, &index)) |
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| 105 | return; |
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| 106 | // Returns 1, crossed page boundary with write of new data. |
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| 107 | // Now have the index pointing into the page where we need to copy the data to |
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| 108 | // for any data in the other page, copy it to the new page |
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| 109 | int oldPageBase = index >= NVRAM_PAGESIZE ? 0 : NVRAM_PAGESIZE; |
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| 110 | for (int i = oldPageBase; i < oldPageBase + NVRAM_WORDS; i++) |
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| 111 | { |
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| 112 | if (NVRAM_Base[i].u16 != HARDWARE_ERASED.u16 && NVRAM_Base[i].u16 != MARKED_ERASED.u16) |
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| 113 | { |
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| 114 | int base = i; |
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| 115 | // copy data forwards |
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| 116 | _write_nvram_data(NVRAM_Base[i], &base); |
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| 117 | } |
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| 118 | // erase the page we just copied out of |
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| 119 | } |
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| 10 | mjames | 120 | EraseNVRAM(&NVRAM_Base[oldPageBase]); |
| 9 | mjames | 121 | } |
| 122 | |||
| 123 | nvram_info_t *find_nvram_data(uint8_t searchTag) |
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| 124 | { |
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| 125 | for (int ptr = 0; ptr < NVRAM_WORDS; ptr++) |
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| 126 | { |
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| 127 | if (NVRAM_Base[ptr].data.tag == searchTag) |
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| 128 | return &NVRAM_Base[ptr]; |
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| 129 | } |
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| 130 | return NULL; |
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| 131 | } |