5 files changed, 88 insertions, 0 deletions
diff --git a/quantum/split_common/split_util.c b/quantum/split_common/split_util.c
index 0b3338ed6f..9f57c7b9fc 100644
--- a/quantum/split_common/split_util.c
+++ b/quantum/split_common/split_util.c
@@ -74,6 +74,46 @@ static inline bool usbIsActive(void) {
 }
 #endif
 
+#if defined(SPLIT_WATCHDOG_ENABLE)
+#    if !defined(SPLIT_WATCHDOG_TIMEOUT)
+#        if defined(SPLIT_USB_TIMEOUT)
+#            define SPLIT_WATCHDOG_TIMEOUT (SPLIT_USB_TIMEOUT + 100)
+#        else
+#            define SPLIT_WATCHDOG_TIMEOUT 3000
+#        endif
+#    endif
+#    if defined(SPLIT_USB_DETECT)
+_Static_assert(SPLIT_USB_TIMEOUT < SPLIT_WATCHDOG_TIMEOUT, "SPLIT_WATCHDOG_TIMEOUT should not be below SPLIT_USB_TIMEOUT.");
+#    endif
+_Static_assert(SPLIT_MAX_CONNECTION_ERRORS > 0, "SPLIT_WATCHDOG_ENABLE requires SPLIT_MAX_CONNECTION_ERRORS be above 0 for a functioning disconnection check.");
+
+static uint32_t split_watchdog_started = 0;
+static bool     split_watchdog_done    = false;
+
+void split_watchdog_init(void) {
+    split_watchdog_started = timer_read32();
+}
+
+void split_watchdog_update(bool done) {
+    split_watchdog_done = done;
+}
+
+bool split_watchdog_check(void) {
+    if (!is_transport_connected()) {
+        split_watchdog_done = false;
+    }
+    return split_watchdog_done;
+}
+
+void split_watchdog_task(void) {
+    if (!split_watchdog_done && !is_keyboard_master()) {
+        if (timer_elapsed32(split_watchdog_started) > SPLIT_WATCHDOG_TIMEOUT) {
+            mcu_reset();
+        }
+    }
+}
+#endif // defined(SPLIT_WATCHDOG_ENABLE)
+
 #ifdef SPLIT_HAND_MATRIX_GRID
 void matrix_io_delay(void);
 
@@ -179,6 +219,9 @@ void split_pre_init(void) {
 void split_post_init(void) {
     if (!is_keyboard_master()) {
         transport_slave_init();
+#if defined(SPLIT_WATCHDOG_ENABLE)
+        split_watchdog_init();
+#endif
     }
 }
 
diff --git a/quantum/split_common/split_util.h b/quantum/split_common/split_util.h
index c7eabea233..5c9a260a14 100644
--- a/quantum/split_common/split_util.h
+++ b/quantum/split_common/split_util.h
@@ -14,3 +14,7 @@ void split_post_init(void);
 
 bool transport_master_if_connected(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]);
 bool is_transport_connected(void);
+
+void split_watchdog_update(bool done);
+void split_watchdog_task(void);
+bool split_watchdog_check(void);
+\ No newline at end of file
diff --git a/quantum/split_common/transaction_id_define.h b/quantum/split_common/transaction_id_define.h
index 761a8884f4..8c19948107 100644
--- a/quantum/split_common/transaction_id_define.h
+++ b/quantum/split_common/transaction_id_define.h
@@ -84,6 +84,10 @@ enum serial_transaction_id {
     PUT_POINTING_CPI,
 #endif // defined(POINTING_DEVICE_ENABLE) && defined(SPLIT_POINTING_ENABLE)
 
+#if defined(SPLIT_WATCHDOG_ENABLE)
+    PUT_WATCHDOG,
+#endif // defined(SPLIT_WATCHDOG_ENABLE)
+
 #if defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
     PUT_RPC_INFO,
     PUT_RPC_REQ_DATA,
diff --git a/quantum/split_common/transactions.c b/quantum/split_common/transactions.c
index 67986e4340..527b2f4caf 100644
--- a/quantum/split_common/transactions.c
+++ b/quantum/split_common/transactions.c
@@ -719,6 +719,36 @@ static void pointing_handlers_slave(matrix_row_t master_matrix[], matrix_row_t s
 #endif // defined(POINTING_DEVICE_ENABLE) && defined(SPLIT_POINTING_ENABLE)
 
 ////////////////////////////////////////////////////
+// WATCHDOG
+
+#if defined(SPLIT_WATCHDOG_ENABLE)
+
+static bool watchdog_handlers_master(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) {
+    bool okay = true;
+    if (!split_watchdog_check()) {
+        okay = transport_write(PUT_WATCHDOG, &okay, sizeof(okay));
+        split_watchdog_update(okay);
+    }
+    return okay;
+}
+
+static void watchdog_handlers_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) {
+    split_watchdog_update(split_shmem->watchdog_pinged);
+}
+
+#    define TRANSACTIONS_WATCHDOG_MASTER() TRANSACTION_HANDLER_MASTER(watchdog)
+#    define TRANSACTIONS_WATCHDOG_SLAVE() TRANSACTION_HANDLER_SLAVE_AUTOLOCK(watchdog)
+#    define TRANSACTIONS_WATCHDOG_REGISTRATIONS [PUT_WATCHDOG] = trans_initiator2target_initializer(watchdog_pinged),
+
+#else // defined(SPLIT_WATCHDOG_ENABLE)
+
+#    define TRANSACTIONS_WATCHDOG_MASTER()
+#    define TRANSACTIONS_WATCHDOG_SLAVE()
+#    define TRANSACTIONS_WATCHDOG_REGISTRATIONS
+
+#endif // defined(SPLIT_WATCHDOG_ENABLE)
+
+////////////////////////////////////////////////////
 
 split_transaction_desc_t split_transaction_table[NUM_TOTAL_TRANSACTIONS] = {
     // Set defaults
@@ -744,6 +774,7 @@ split_transaction_desc_t split_transaction_table[NUM_TOTAL_TRANSACTIONS] = {
     TRANSACTIONS_OLED_REGISTRATIONS
     TRANSACTIONS_ST7565_REGISTRATIONS
     TRANSACTIONS_POINTING_REGISTRATIONS
+    TRANSACTIONS_WATCHDOG_REGISTRATIONS
 // clang-format on
 
 #if defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
@@ -770,6 +801,7 @@ bool transactions_master(matrix_row_t master_matrix[], matrix_row_t slave_matrix
     TRANSACTIONS_OLED_MASTER();
     TRANSACTIONS_ST7565_MASTER();
     TRANSACTIONS_POINTING_MASTER();
+    TRANSACTIONS_WATCHDOG_MASTER();
     return true;
 }
 
@@ -789,6 +821,7 @@ void transactions_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[
     TRANSACTIONS_OLED_SLAVE();
     TRANSACTIONS_ST7565_SLAVE();
     TRANSACTIONS_POINTING_SLAVE();
+    TRANSACTIONS_WATCHDOG_SLAVE();
 }
 
 #if defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
diff --git a/quantum/split_common/transport.h b/quantum/split_common/transport.h
index 06778ad14a..833633edc2 100644
--- a/quantum/split_common/transport.h
+++ b/quantum/split_common/transport.h
@@ -188,6 +188,10 @@ typedef struct _split_shared_memory_t {
     split_slave_pointing_sync_t pointing;
 #endif // defined(POINTING_DEVICE_ENABLE) && defined(SPLIT_POINTING_ENABLE)
 
+#if defined(SPLIT_WATCHDOG_ENABLE)
+    bool watchdog_pinged;
+#endif // defined(SPLIT_WATCHDOG_ENABLE)
+
 #if defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
     rpc_sync_info_t rpc_info;
     uint8_t         rpc_m2s_buffer[RPC_M2S_BUFFER_SIZE];