EEPROM: Don't erase if we don't have to. Adding eeprom_driver_format abstraction. (#18332)

drivers/eeprom/eeprom_custom.c-template

@@ -23,6 +23,17 @@ void eeprom_driver_init(void) {
     /* Any initialisation code */
  }
 
+void eeprom_driver_format(bool erase) {
+    /* If erase=false, then only do the absolute minimum initialisation necessary
+       to make sure that the eeprom driver is usable. It doesn't need to guarantee
+       that the content of the eeprom is reset to any particular value. For many
+       eeprom drivers this may be a no-op.
+
+       If erase=true, then in addition to making sure the eeprom driver is in a
+       usable state, also make sure that it is erased.
+     */
+}
+
 void eeprom_driver_erase(void) {
     /* Wipe out the EEPROM, setting values to zero */
 }

drivers/eeprom/eeprom_driver.c

@@ -77,3 +77,9 @@ void eeprom_update_dword(uint32_t *addr, uint32_t value) {
         eeprom_write_dword(addr, value);
     }
 }
+
+void eeprom_driver_format(bool erase) __attribute__((weak));
+void eeprom_driver_format(bool erase) {
+    (void)erase; /* The default implementation assumes that the eeprom must be erased in order to be usable. */
+    eeprom_driver_erase();
+}

drivers/eeprom/eeprom_driver.h

@@ -16,7 +16,9 @@
 
 #pragma once
 
+#include <stdbool.h>
 #include "eeprom.h"
 
 void eeprom_driver_init(void);
+void eeprom_driver_format(bool erase);
 void eeprom_driver_erase(void);

drivers/eeprom/eeprom_i2c.c

@@ -36,6 +36,7 @@
 #include "wait.h"
 #include "i2c_master.h"
 #include "eeprom.h"
+#include "eeprom_driver.h"
 #include "eeprom_i2c.h"
 
 // #define DEBUG_EEPROM_OUTPUT
@@ -62,6 +63,13 @@ void eeprom_driver_init(void) {
 #endif
 }
 
+void eeprom_driver_format(bool erase) {
+    /* i2c eeproms do not need to be formatted before use */
+    if (erase) {
+        eeprom_driver_erase();
+    }
+}
+
 void eeprom_driver_erase(void) {
 #if defined(CONSOLE_ENABLE) && defined(DEBUG_EEPROM_OUTPUT)
     uint32_t start = timer_read32();

drivers/eeprom/eeprom_spi.c

@@ -35,6 +35,7 @@
 #include "timer.h"
 #include "spi_master.h"
 #include "eeprom.h"
+#include "eeprom_driver.h"
 #include "eeprom_spi.h"
 
 #define CMD_WREN 6
@@ -92,6 +93,13 @@ void eeprom_driver_init(void) {
     spi_init();
 }
 
+void eeprom_driver_format(bool erase) {
+    /* spi eeproms do not need to be formatted before use */
+    if (erase) {
+        eeprom_driver_erase();
+    }
+}
+
 void eeprom_driver_erase(void) {
 #if defined(CONSOLE_ENABLE) && defined(DEBUG_EEPROM_OUTPUT)
     uint32_t start = timer_read32();

drivers/eeprom/eeprom_transient.c

@@ -30,8 +30,13 @@ size_t clamp_length(intptr_t offset, size_t len) {
     return len;
 }
 
-void eeprom_driver_init(void) {
-    eeprom_driver_erase();
+void eeprom_driver_init(void) {}
+
+void eeprom_driver_format(bool erase) {
+    /* The transient eeprom driver doesn't necessarily need to be formatted before use, and it always starts up filled with zeros, due to placement in the .bss section */
+    if (erase) {
+        eeprom_driver_erase();
+    }
 }
 
 void eeprom_driver_erase(void) {

drivers/eeprom/eeprom_wear_leveling.c

@@ -10,6 +10,12 @@ void eeprom_driver_init(void) {
     wear_leveling_init();
 }
 
+void eeprom_driver_format(bool erase) {
+    /* wear leveling requires the write log data structures to be erased before use. */
+    (void)erase;
+    eeprom_driver_erase();
+}
+
 void eeprom_driver_erase(void) {
     wear_leveling_erase();
 }