add support for a small filesystem on the watch

apps/eeprom-emulation-upgrade/app.c

@@ -0,0 +1,62 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <peripheral_clk_config.h>
+#include "watch.h"
+
+void app_init(void) {
+}
+
+void app_wake_from_backup(void) {
+}
+
+void app_setup(void) {
+    delay_ms(5000);
+    while (!(NVMCTRL->INTFLAG.reg & NVMCTRL_INTFLAG_READY));
+    uint32_t user_row = (*((uint32_t *)NVMCTRL_AUX0_ADDRESS));
+    uint8_t eeprom = (user_row >> NVMCTRL_FUSES_EEPROM_SIZE_Pos) & 7;
+    printf("User row read successfully: 0x%lx\n", user_row);
+
+    if (eeprom != 1) {
+        user_row &= ~NVMCTRL_FUSES_EEPROM_SIZE_Msk;
+        user_row |= NVMCTRL_FUSES_EEPROM_SIZE(1);
+        if (NVMCTRL->STATUS.reg & NVMCTRL_STATUS_SB) {
+            printf("Secured bit was set; cannot perform upgrade.\n");
+            return;
+        }
+        printf("EEPROM configuration was %d.\nApplying change...\n", eeprom);
+
+        uint32_t temp = NVMCTRL->CTRLB.reg;                                     // Backup settings
+        NVMCTRL->CTRLB.reg = temp | NVMCTRL_CTRLB_CACHEDIS;                     // Disable Cache
+        NVMCTRL->STATUS.reg |= NVMCTRL_STATUS_MASK;                             // Clear error flags
+        NVMCTRL->ADDR.reg = NVMCTRL_AUX0_ADDRESS / 2;                           // Set address, command will be issued elsewhere
+        NVMCTRL->CTRLA.reg = NVMCTRL_CTRLA_CMD_EAR | NVMCTRL_CTRLA_CMDEX_KEY;   // Erase the user page
+        while (!(NVMCTRL->INTFLAG.reg & NVMCTRL_INTFLAG_READY));                // Wait for NVM command to complete
+        NVMCTRL->STATUS.reg |= NVMCTRL_STATUS_MASK;                             // Clear error flags
+        NVMCTRL->ADDR.reg = NVMCTRL_AUX0_ADDRESS / 2;                           // Set address, command will be issued elsewhere
+        NVMCTRL->CTRLA.reg = NVMCTRL_CTRLA_CMD_PBC | NVMCTRL_CTRLA_CMDEX_KEY;   // Erase the page buffer before buffering new data
+        while (!(NVMCTRL->INTFLAG.reg & NVMCTRL_INTFLAG_READY));                // Wait for NVM command to complete
+        NVMCTRL->STATUS.reg |= NVMCTRL_STATUS_MASK;                             // Clear error flags
+        NVMCTRL->ADDR.reg = NVMCTRL_AUX0_ADDRESS / 2;                           // Set address, command will be issued elsewhere
+        *((uint32_t *)NVMCTRL_AUX0_ADDRESS) = user_row;                         // write the new fuse values to the memory buffer
+        NVMCTRL->CTRLA.reg = NVMCTRL_CTRLA_CMD_WAP | NVMCTRL_CTRLA_CMDEX_KEY;   // Write the user page
+        NVMCTRL->CTRLB.reg = temp;                                              // Restore settings
+
+        printf("Done! Resetting...\n");
+        delay_ms(1000);
+        NVIC_SystemReset();
+    } else {
+        printf("EEPROM configuration was %d (8192 bytes). Upgrade successful!\n", eeprom);
+    }
+    printf("%d %d\n", eeprom, NVMCTRL->PARAM.bit.RWWEEP);
+}
+
+void app_prepare_for_standby(void) {
+}
+
+void app_wake_from_standby(void) {
+}
+
+bool app_loop(void) {
+    return true;
+}