Extensible split data sync (#11930)

* Extensible split data sync capability through transactions.

- Split common transport has been split up between the transport layer
  and data layer.
- Split "transactions" model used, with convergence between I2C and
  serial data definitions.
- Slave matrix "generation count" is used to determine if the full slave
  matrix needs to be retrieved.
- Encoders get the same "generation count" treatment.
- All other blocks of data are synchronised when a change is detected.
- All transmissions have a globally-configurable deadline before a
  transmission is forced (`FORCED_SYNC_THROTTLE_MS`, default 100ms).
- Added atomicity for all core-synced data, preventing partial updates
- Added retries to AVR i2c_master's i2c_start, to minimise the number of
  failed transactions when interrupts are disabled on the slave due to
  atomicity checks.
- Some keyboards have had slight modifications made in order to ensure
  that they still build due to firmware size restrictions.

* Fixup LED_MATRIX compile.

* Parameterise ERROR_DISCONNECT_COUNT.

1 files changed, 27 insertions, 2 deletions

diff --git a/drivers/avr/i2c_slave.c b/drivers/avr/i2c_slave.c
index 62a378165a..2907f164c0 100644
--- a/drivers/avr/i2c_slave.c
+++ b/drivers/avr/i2c_slave.c
@@ -17,6 +17,7 @@
  * GitHub repository: https://github.com/g4lvanix/I2C-slave-lib
  */
 
+#include <stddef.h>
 #include <avr/io.h>
 #include <util/twi.h>
 #include <avr/interrupt.h>
@@ -24,6 +25,12 @@
 
 #include "i2c_slave.h"
 
+#if defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
+#    include "transactions.h"
+
+static volatile bool is_callback_executor = false;
+#endif  // defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
+
 volatile uint8_t i2c_slave_reg[I2C_SLAVE_REG_COUNT];
 
 static volatile uint8_t buffer_address;
@@ -48,11 +55,14 @@ ISR(TWI_vect) {
         case TW_SR_SLA_ACK:
             // The device is now a slave receiver
             slave_has_register_set = false;
+#if defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
+            is_callback_executor = false;
+#endif  // defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
             break;
 
         case TW_SR_DATA_ACK:
             // This device is a slave receiver and has received data
-            // First byte is the location then the bytes will be writen in buffer with auto-incriment
+            // First byte is the location then the bytes will be writen in buffer with auto-increment
             if (!slave_has_register_set) {
                 buffer_address = TWDR;
 
@@ -60,10 +70,25 @@ ISR(TWI_vect) {
                     ack            = 0;
                     buffer_address = 0;
                 }
-                slave_has_register_set = true;  // address has been receaved now fill in buffer
+                slave_has_register_set = true;  // address has been received now fill in buffer
+
+#if defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
+                // Work out if we're attempting to execute a callback
+                is_callback_executor = buffer_address == split_transaction_table[I2C_EXECUTE_CALLBACK].initiator2target_offset;
+#endif  // defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
             } else {
                 i2c_slave_reg[buffer_address] = TWDR;
                 buffer_address++;
+
+#if defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
+                // If we're intending to execute a transaction callback, do so, as we've just received the transaction ID
+                if (is_callback_executor) {
+                    split_transaction_desc_t *trans = &split_transaction_table[split_shmem->transaction_id];
+                    if (trans->slave_callback) {
+                        trans->slave_callback(trans->initiator2target_buffer_size, split_trans_initiator2target_buffer(trans), trans->target2initiator_buffer_size, split_trans_target2initiator_buffer(trans));
+                    }
+                }
+#endif  // defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS)
             }
             break;