5 files changed, 76 insertions, 0 deletions

diff --git a/docs/feature_split_keyboard.md b/docs/feature_split_keyboard.md
index 0b475cc63d..eaef975fb7 100644
--- a/docs/feature_split_keyboard.md
+++ b/docs/feature_split_keyboard.md
@@ -286,6 +286,12 @@ This enables transmitting the pointing device status to the master side of the s
 
 !> There is additional required configuration for `SPLIT_POINTING_ENABLE` outlined in the [pointing device documentation](feature_pointing_device.md?id=split-keyboard-configuration).
 
+```c
+#define SPLIT_HAPTIC_ENABLE
+```
+
+This enables triggering of haptic feedback on the slave side of the split keyboard. For DRV2605L this will send the mode, but for solenoids it is expected that the desired mode is already set up on the slave.
+
 ### Custom data sync between sides :id=custom-data-sync
 
 QMK's split transport allows for arbitrary data transactions at both the keyboard and user levels. This is modelled on a remote procedure call, with the master invoking a function on the slave side, with the ability to send data from master to slave, process it slave side, and send data back from slave to master.
diff --git a/quantum/haptic.c b/quantum/haptic.c
index ad64fe2cc7..c151547fca 100644
--- a/quantum/haptic.c
+++ b/quantum/haptic.c
@@ -25,6 +25,9 @@
 #ifdef SOLENOID_ENABLE
 #    include "solenoid.h"
 #endif
+#if defined(SPLIT_KEYBOARD) && defined(SPLIT_HAPTIC_ENABLE)
+extern uint8_t split_haptic_play;
+#endif
 
 haptic_config_t haptic_config;
 
@@ -319,9 +322,15 @@ void haptic_play(void) {
     uint8_t play_eff = 0;
     play_eff         = haptic_config.mode;
     DRV_pulse(play_eff);
+#    if defined(SPLIT_KEYBOARD) && defined(SPLIT_HAPTIC_ENABLE)
+    split_haptic_play = haptic_config.mode;
+#    endif
 #endif
 #ifdef SOLENOID_ENABLE
     solenoid_fire_handler();
+#    if defined(SPLIT_KEYBOARD) && defined(SPLIT_HAPTIC_ENABLE)
+    split_haptic_play = 1;
+#    endif
 #endif
 }
 
diff --git a/quantum/split_common/transaction_id_define.h b/quantum/split_common/transaction_id_define.h
index 8c19948107..18d3826b83 100644
--- a/quantum/split_common/transaction_id_define.h
+++ b/quantum/split_common/transaction_id_define.h
@@ -88,6 +88,10 @@ enum serial_transaction_id {
     PUT_WATCHDOG,
 #endif // defined(SPLIT_WATCHDOG_ENABLE)
 
+#if defined(HAPTIC_ENABLE) && defined(SPLIT_HAPTIC_ENABLE)
+    PUT_HAPTIC,
+#endif // defined(HAPTIC_ENABLE) && defined(SPLIT_HAPTIC_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 527b2f4caf..8e1961b586 100644
--- a/quantum/split_common/transactions.c
+++ b/quantum/split_common/transactions.c
@@ -748,6 +748,48 @@ static void watchdog_handlers_slave(matrix_row_t master_matrix[], matrix_row_t s
 
 #endif // defined(SPLIT_WATCHDOG_ENABLE)
 
+#if defined(HAPTIC_ENABLE) && defined(SPLIT_HAPTIC_ENABLE)
+
+uint8_t                split_haptic_play = 0xFF;
+extern haptic_config_t haptic_config;
+
+static bool haptic_handlers_master(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) {
+    static uint32_t           last_update = 0;
+    split_slave_haptic_sync_t haptic_sync;
+
+    memcpy(&haptic_sync.haptic_config, &haptic_config, sizeof(haptic_config_t));
+    haptic_sync.haptic_play = split_haptic_play;
+
+    bool okay = send_if_data_mismatch(PUT_HAPTIC, &last_update, &haptic_sync, &split_shmem->haptic_sync, sizeof(haptic_sync));
+
+    split_haptic_play = 0xFF;
+
+    return okay;
+}
+
+static void haptic_handlers_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) {
+    memcpy(&haptic_config, &split_shmem->haptic_sync.haptic_config, sizeof(haptic_config_t));
+
+    if (split_shmem->haptic_sync.haptic_play != 0xFF) {
+        haptic_set_mode(split_shmem->haptic_sync.haptic_play);
+        haptic_play();
+    }
+}
+
+// clang-format off
+#    define TRANSACTIONS_HAPTIC_MASTER() TRANSACTION_HANDLER_MASTER(haptic)
+#    define TRANSACTIONS_HAPTIC_SLAVE() TRANSACTION_HANDLER_SLAVE(haptic)
+#    define TRANSACTIONS_HAPTIC_REGISTRATIONS [PUT_HAPTIC] = trans_initiator2target_initializer(haptic_sync),
+// clang-format on
+
+#else // defined(HAPTIC_ENABLE) && defined(SPLIT_HAPTIC_ENABLE)
+
+#    define TRANSACTIONS_HAPTIC_MASTER()
+#    define TRANSACTIONS_HAPTIC_SLAVE()
+#    define TRANSACTIONS_HAPTIC_REGISTRATIONS
+
+#endif // defined(HAPTIC_ENABLE) && defined(SPLIT_HAPTIC_ENABLE)
+
 ////////////////////////////////////////////////////
 
 split_transaction_desc_t split_transaction_table[NUM_TOTAL_TRANSACTIONS] = {
@@ -775,6 +817,7 @@ split_transaction_desc_t split_transaction_table[NUM_TOTAL_TRANSACTIONS] = {
     TRANSACTIONS_ST7565_REGISTRATIONS
     TRANSACTIONS_POINTING_REGISTRATIONS
     TRANSACTIONS_WATCHDOG_REGISTRATIONS
+    TRANSACTIONS_HAPTIC_REGISTRATIONS
 // clang-format on
 
 #if defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
@@ -802,6 +845,7 @@ bool transactions_master(matrix_row_t master_matrix[], matrix_row_t slave_matrix
     TRANSACTIONS_ST7565_MASTER();
     TRANSACTIONS_POINTING_MASTER();
     TRANSACTIONS_WATCHDOG_MASTER();
+    TRANSACTIONS_HAPTIC_MASTER();
     return true;
 }
 
@@ -822,6 +866,7 @@ void transactions_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[
     TRANSACTIONS_ST7565_SLAVE();
     TRANSACTIONS_POINTING_SLAVE();
     TRANSACTIONS_WATCHDOG_SLAVE();
+    TRANSACTIONS_HAPTIC_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 833633edc2..adee4470d2 100644
--- a/quantum/split_common/transport.h
+++ b/quantum/split_common/transport.h
@@ -114,6 +114,14 @@ typedef struct _split_slave_pointing_sync_t {
 } split_slave_pointing_sync_t;
 #endif // defined(POINTING_DEVICE_ENABLE) && defined(SPLIT_POINTING_ENABLE)
 
+#if defined(HAPTIC_ENABLE) && defined(SPLIT_HAPTIC_ENABLE)
+#    include "haptic.h"
+typedef struct _split_slave_haptic_sync_t {
+    haptic_config_t haptic_config;
+    uint8_t         haptic_play;
+} split_slave_haptic_sync_t;
+#endif // defined(HAPTIC_ENABLE) && defined(SPLIT_HAPTIC_ENABLE)
+
 #if defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
 typedef struct _rpc_sync_info_t {
     uint8_t checksum;
@@ -192,6 +200,10 @@ typedef struct _split_shared_memory_t {
     bool watchdog_pinged;
 #endif // defined(SPLIT_WATCHDOG_ENABLE)
 
+#if defined(HAPTIC_ENABLE)
+    split_slave_haptic_sync_t haptic_sync;
+#endif // defined(HAPTIC_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];