massdrop alt/ctrl: support saving into nvm

tmk_core/common/arm_atsam/eeprom.c

@@ -13,24 +13,110 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-
 #include "eeprom.h"
+#include "debug.h"
+#include "samd51j18a.h"
+#include "core_cm4.h"
+#include "component/nvmctrl.h"
 
 #ifndef EEPROM_SIZE
 #    include "eeconfig.h"
 #    define EEPROM_SIZE (((EECONFIG_SIZE + 3) / 4) * 4)  // based off eeconfig's current usage, aligned to 4-byte sizes, to deal with LTO
 #endif
 
-__attribute__((aligned(4))) static uint8_t buffer[EEPROM_SIZE];
+#ifndef MAX
+#    define MAX(X, Y) ((X) > (Y) ? (X) : (Y))
+#endif
+
+#ifndef BUSY_RETRIES
+#    define BUSY_RETRIES 10000
+#endif
+
+// #define DEBUG_EEPROM_OUTPUT
+
+/*
+ * Debug print utils
+ */
+#if defined(DEBUG_EEPROM_OUTPUT)
+#    define eeprom_printf(fmt, ...) xprintf(fmt, ##__VA_ARGS__);
+#else /* NO_DEBUG */
+#    define eeprom_printf(fmt, ...)
+#endif /* NO_DEBUG */
+
+__attribute__((aligned(4))) static uint8_t buffer[EEPROM_SIZE] = {0};
+volatile uint8_t *                         SmartEEPROM8        = (uint8_t *)SEEPROM_ADDR;
+
+static inline bool eeprom_is_busy(void) {
+    int timeout = BUSY_RETRIES;
+    while (NVMCTRL->SEESTAT.bit.BUSY && timeout-- > 0)
+        ;
+
+    return NVMCTRL->SEESTAT.bit.BUSY;
+}
+
+static uint32_t get_virtual_eeprom_size(void) {
+    // clang-format off
+    static const uint32_t VIRTUAL_EEPROM_MAP[11][8] = {
+    /*          4    8    16    32    64    128    256    512 */
+    /* 0*/ {   0,    0,    0,    0,    0,     0,     0,     0 },
+    /* 1*/ { 512, 1024, 2048, 4096, 4096,  4096,  4096,  4096 },
+    /* 2*/ { 512, 1024, 2048, 4096, 8192,  8192,  8192,  8192 },
+    /* 3*/ { 512, 1024, 2048, 4096, 8192, 16384, 16384, 16384 },
+    /* 4*/ { 512, 1024, 2048, 4096, 8192, 16384, 16384, 16384 },
+    /* 5*/ { 512, 1024, 2048, 4096, 8192, 16384, 32768, 32768 },
+    /* 6*/ { 512, 1024, 2048, 4096, 8192, 16384, 32768, 32768 },
+    /* 7*/ { 512, 1024, 2048, 4096, 8192, 16384, 32768, 32768 },
+    /* 8*/ { 512, 1024, 2048, 4096, 8192, 16384, 32768, 32768 },
+    /* 9*/ { 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536 },
+    /*10*/ { 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536 },
+    };
+    // clang-format on
+
+    static uint32_t virtual_eeprom_size = UINT32_MAX;
+    if (virtual_eeprom_size == UINT32_MAX) {
+        virtual_eeprom_size = VIRTUAL_EEPROM_MAP[NVMCTRL->SEESTAT.bit.PSZ][NVMCTRL->SEESTAT.bit.SBLK];
+    }
+    // eeprom_printf("get_virtual_eeprom_size:: %d:%d:%d\n", NVMCTRL->SEESTAT.bit.PSZ, NVMCTRL->SEESTAT.bit.SBLK, virtual_eeprom_size);
+    return virtual_eeprom_size;
+}
 
 uint8_t eeprom_read_byte(const uint8_t *addr) {
     uintptr_t offset = (uintptr_t)addr;
-    return buffer[offset];
+    if (offset >= MAX(EEPROM_SIZE, get_virtual_eeprom_size())) {
+        eeprom_printf("eeprom_read_byte:: out of bounds\n");
+        return 0x0;
+    }
+
+    if (get_virtual_eeprom_size() == 0) {
+        return buffer[offset];
+    }
+
+    if (eeprom_is_busy()) {
+        eeprom_printf("eeprom_write_byte:: timeout\n");
+        return 0x0;
+    }
+
+    return SmartEEPROM8[offset];
 }
 
 void eeprom_write_byte(uint8_t *addr, uint8_t value) {
     uintptr_t offset = (uintptr_t)addr;
-    buffer[offset]   = value;
+    if (offset >= MAX(EEPROM_SIZE, get_virtual_eeprom_size())) {
+        eeprom_printf("eeprom_write_byte:: out of bounds\n");
+        return;
+    }
+
+    if (get_virtual_eeprom_size() == 0) {
+        buffer[offset] = value;
+        return;
+    }
+
+    if (eeprom_is_busy()) {
+        eeprom_printf("eeprom_write_byte:: timeout\n");
+        return;
+    }
+
+    SmartEEPROM8[offset] = value;
 }
 
 uint16_t eeprom_read_word(const uint16_t *addr) {