Update PersistentStore api (#11538)

- Clean up the API to use a `static` class instance to adhere to Marlin convention
- Add `const` position data access for read/write
- Add Storage capacity to the interface

Marlin/src/HAL/HAL_LPC1768/include/Arduino.h

@@ -43,8 +43,6 @@
 #define FALLING      0x03
 #define RISING       0x04
 
-#define E2END 0xFFF // EEPROM end address
-
 typedef uint8_t byte;
 #define PROGMEM
 #define PSTR(v) (v)

Marlin/src/HAL/HAL_LPC1768/persistent_store_sdcard.cpp

@@ -27,19 +27,17 @@
 
 #include "../persistent_store_api.h"
 
-#include "chanfs/diskio.h"
-#include "chanfs/ff.h"
+#include <chanfs/diskio.h>
+#include <chanfs/ff.h>
 
 extern uint32_t MSC_Aquire_Lock();
 extern uint32_t MSC_Release_Lock();
 
-namespace HAL {
-namespace PersistentStore {
-
 FATFS fat_fs;
 FIL eeprom_file;
+bool eeprom_file_open = false;
 
-bool access_start() {
+bool PersistentStore::access_start() {
   const char eeprom_erase_value = 0xFF;
   MSC_Aquire_Lock();
   if (f_mount(&fat_fs, "", 1)) {
@@ -53,7 +51,7 @@ bool access_start() {
     UINT bytes_written;
     FSIZE_t file_size = f_size(&eeprom_file);
     f_lseek(&eeprom_file, file_size);
-    while (file_size <= E2END && res == FR_OK) {
+    while (file_size < capacity() && res == FR_OK) {
       res = f_write(&eeprom_file, &eeprom_erase_value, 1, &bytes_written);
       file_size++;
     }
@@ -61,14 +59,16 @@ bool access_start() {
   if (res == FR_OK) {
     f_lseek(&eeprom_file, 0);
     f_sync(&eeprom_file);
+    eeprom_file_open = true;
   }
   return res == FR_OK;
 }
 
-bool access_finish() {
+bool PersistentStore::access_finish() {
   f_close(&eeprom_file);
   f_unmount("");
   MSC_Release_Lock();
+  eeprom_file_open = false;
   return true;
 }
 
@@ -98,7 +98,8 @@ bool access_finish() {
 //    FR_INVALID_PARAMETER     /* (19) Given parameter is invalid */
 //  } FRESULT;
 
-bool write_data(int &pos, const uint8_t *value, uint16_t size, uint16_t *crc) {
+bool PersistentStore::write_data(int &pos, const uint8_t *value, size_t size, uint16_t *crc) {
+  if(!eeprom_file_open) return true;
   FRESULT s;
   UINT bytes_written = 0;
 
@@ -128,7 +129,8 @@ bool write_data(int &pos, const uint8_t *value, uint16_t size, uint16_t *crc) {
   return (bytes_written != size);  // return true for any error
 }
 
-bool read_data(int &pos, uint8_t* value, uint16_t size, uint16_t *crc, const bool writing/*=true*/) {
+bool PersistentStore::read_data(int &pos, uint8_t* value, size_t size, uint16_t *crc, const bool writing/*=true*/) {
+  if(!eeprom_file_open) return true;
   UINT bytes_read = 0;
   FRESULT s;
   s = f_lseek(&eeprom_file, pos);
@@ -163,8 +165,21 @@ bool read_data(int &pos, uint8_t* value, uint16_t size, uint16_t *crc, const boo
   return bytes_read != size;  // return true for any error
 }
 
-} // PersistentStore
-} // HAL
+bool PersistentStore::write_data(const int pos, uint8_t* value, size_t size) {
+  int data_pos = pos;
+  uint16_t crc = 0;
+  return write_data(data_pos, value, size, &crc);
+}
+
+bool PersistentStore::read_data(const int pos, uint8_t* value, size_t size) {
+  int data_pos = pos;
+  uint16_t crc = 0;
+  return read_data(data_pos, value, size, &crc);
+}
+
+const size_t PersistentStore::capacity() {
+  return 4096; //4KiB of Emulated EEPROM
+}
 
 #endif // EEPROM_SETTINGS
 #endif // TARGET_LPC1768