[FL-3669] Expansion module protocol (#3250)

* ApiSymbols: add furi_record_destroy
* FuriHal: cleanup serial API, add logging configuration in RTC
* FuriHal: hide private part in _i header. Toolbox: cleanup value index. SystemSettings: logging device and baudrate.
* FuriHal: RTC logging method documentation
* Synchronize API Symbols
* Furi: mark HEAP_PRINT_DEBUG as broken
* FuriHal: furi_hal_serial, add custom IRQ func
* Fix PR review issues
* Implement basic external module detection and echo
* Update api symbols for f18
* Minimally working implementation (can create directory via rpc)
* Make expansion protocol parser a header-only library
* Rename a function
* Improve thread syncronisation
* Implement multi-packet transmissions
* Improve test application
* Clean up expansion worker code
* Send heartbeat when host is ready
* Update API symbols
* Add draft documentation
* Expansion worker: proper timeout and error handling
* Expansion worker: correct TX, do not disable expansion callback
* Expansion protocol: pc side test script
* PC side expansion test: trying to change baudrate
* Working comms between 2 flippers
* Cleaner exit from expansion worker thread
* Better checks
* Add debug logs
* Remove unneeded delays
* Use USART as default expansion port
* Refactor furi_hal_serial_control, fix crash
* Improve furi_hal abstraction, wait for stable rx pin
* Remove rogue include
* Set proper exit reason on RPC error
* Remove rogue comment
* Remove RX stability check as potentially problematic
* Improve expansion_test application
* Remove rogue define
* Give up on TODO
* Implement expansion protocol checksum support
* Update ExpansionModules.md
* RPC: reverse input
* Assets: sync protobuf
* Fix typos
* FuriHal: UART add reception DMA (#3220)
* FuriHal: add DMA serial rx mode
* usb_uart_bridge: switch to working with DMA
* Sync api symbol versions
* FuriHal: update serial docs and api
* FuriHal: Selial added similar API for simple reception mode as with DMA
* FuriHal: Update API target H18
* API: ver API H7
* FuriHal: Serial error processing
* FuriHal: fix furi_hal_serial set baudrate
* Sync api symbols
* FuriHal: cleanup serial isr and various flag handling procedures
* FuriHal: cleanup and simplify serial API
* Debug: update UART Echo serial related flags
* FuriHal: update serial API symbols naming
* Make expansion_test compile
* Remove unneeded file
* Make PVS-studio happy
* Optimise stack usage
* Optimise heap usage, improve api signature
* Fix typo
* Clean up code
* Update expansion_protocol.h
* Fix unit tests
* Add doxygen comments to expansion.h
* Update/add doxygen comments
* Update ExpansionModules.md
* Github: new global code owner
* FuriHal: naming in serial control
* Expansion: check mutex acquire return result

Co-authored-by: Aleksandr Kutuzov <alleteam@gmail.com>
Co-authored-by: hedger <hedger@users.noreply.github.com>
Co-authored-by: SkorP <skorpionm@yandex.ru>
Co-authored-by: SG <who.just.the.doctor@gmail.com>
Co-authored-by: Skorpionm <85568270+Skorpionm@users.noreply.github.com>

targets/f18/api_symbols.csv

@@ -1,10 +1,11 @@
 entry,status,name,type,params
-Version,+,51.0,,
+Version,+,52.0,,
 Header,+,applications/services/bt/bt_service/bt.h,,
 Header,+,applications/services/cli/cli.h,,
 Header,+,applications/services/cli/cli_vcp.h,,
 Header,+,applications/services/dialogs/dialogs.h,,
 Header,+,applications/services/dolphin/dolphin.h,,
+Header,+,applications/services/expansion/expansion.h,,
 Header,+,applications/services/gui/elements.h,,
 Header,+,applications/services/gui/gui.h,,
 Header,+,applications/services/gui/icon_i.h,,
@@ -788,6 +789,8 @@ Function,-,exp10f,float,float
 Function,-,exp2,double,double
 Function,-,exp2f,float,float
 Function,-,exp2l,long double,long double
+Function,+,expansion_disable,void,Expansion*
+Function,+,expansion_enable,void,"Expansion*, FuriHalSerialId"
 Function,-,expf,float,float
 Function,-,expl,long double,long double
 Function,-,explicit_bzero,void,"void*, size_t"
@@ -1268,22 +1271,27 @@ Function,+,furi_hal_sd_max_mount_retry_count,uint8_t,
 Function,+,furi_hal_sd_presence_init,void,
 Function,+,furi_hal_sd_read_blocks,FuriStatus,"uint32_t*, uint32_t, uint32_t"
 Function,+,furi_hal_sd_write_blocks,FuriStatus,"const uint32_t*, uint32_t, uint32_t"
+Function,+,furi_hal_serial_async_rx,uint8_t,FuriHalSerialHandle*
+Function,+,furi_hal_serial_async_rx_start,void,"FuriHalSerialHandle*, FuriHalSerialAsyncRxCallback, void*, _Bool"
+Function,+,furi_hal_serial_async_rx_stop,void,FuriHalSerialHandle*
 Function,+,furi_hal_serial_control_acquire,FuriHalSerialHandle*,FuriHalSerialId
 Function,+,furi_hal_serial_control_deinit,void,
 Function,+,furi_hal_serial_control_init,void,
 Function,+,furi_hal_serial_control_release,void,FuriHalSerialHandle*
 Function,+,furi_hal_serial_control_resume,void,
+Function,+,furi_hal_serial_control_set_expansion_callback,void,"FuriHalSerialId, FuriHalSerialControlExpansionCallback, void*"
 Function,+,furi_hal_serial_control_set_logging_config,void,"FuriHalSerialId, uint32_t"
 Function,+,furi_hal_serial_control_suspend,void,
 Function,+,furi_hal_serial_deinit,void,FuriHalSerialHandle*
+Function,+,furi_hal_serial_disable_direction,void,"FuriHalSerialHandle*, FuriHalSerialDirection"
 Function,+,furi_hal_serial_dma_rx,size_t,"FuriHalSerialHandle*, uint8_t*, size_t"
 Function,+,furi_hal_serial_dma_rx_start,void,"FuriHalSerialHandle*, FuriHalSerialDmaRxCallback, void*, _Bool"
 Function,+,furi_hal_serial_dma_rx_stop,void,FuriHalSerialHandle*
+Function,+,furi_hal_serial_enable_direction,void,"FuriHalSerialHandle*, FuriHalSerialDirection"
+Function,+,furi_hal_serial_get_gpio_pin,const GpioPin*,"FuriHalSerialHandle*, FuriHalSerialDirection"
 Function,+,furi_hal_serial_init,void,"FuriHalSerialHandle*, uint32_t"
+Function,+,furi_hal_serial_is_baud_rate_supported,_Bool,"FuriHalSerialHandle*, uint32_t"
 Function,+,furi_hal_serial_resume,void,FuriHalSerialHandle*
-Function,+,furi_hal_serial_async_rx,uint8_t,FuriHalSerialHandle*
-Function,+,furi_hal_serial_async_rx_start,void,"FuriHalSerialHandle*, FuriHalSerialAsyncRxCallback, void*, _Bool"
-Function,+,furi_hal_serial_async_rx_stop,void,FuriHalSerialHandle*
 Function,+,furi_hal_serial_set_br,void,"FuriHalSerialHandle*, uint32_t"
 Function,+,furi_hal_serial_suspend,void,FuriHalSerialHandle*
 Function,+,furi_hal_serial_tx,void,"FuriHalSerialHandle*, const uint8_t*, size_t"
@@ -2098,7 +2106,7 @@ Function,-,round,double,double
 Function,+,roundf,float,float
 Function,-,roundl,long double,long double
 Function,+,rpc_session_close,void,RpcSession*
-Function,+,rpc_session_feed,size_t,"RpcSession*, uint8_t*, size_t, uint32_t"
+Function,+,rpc_session_feed,size_t,"RpcSession*, const uint8_t*, size_t, uint32_t"
 Function,+,rpc_session_get_available_size,size_t,RpcSession*
 Function,+,rpc_session_get_owner,RpcOwner,RpcSession*
 Function,+,rpc_session_open,RpcSession*,"Rpc*, RpcOwner"

targets/f7/api_symbols.csv

@@ -1,11 +1,12 @@
 entry,status,name,type,params
-Version,+,51.0,,
+Version,+,52.0,,
 Header,+,applications/drivers/subghz/cc1101_ext/cc1101_ext_interconnect.h,,
 Header,+,applications/services/bt/bt_service/bt.h,,
 Header,+,applications/services/cli/cli.h,,
 Header,+,applications/services/cli/cli_vcp.h,,
 Header,+,applications/services/dialogs/dialogs.h,,
 Header,+,applications/services/dolphin/dolphin.h,,
+Header,+,applications/services/expansion/expansion.h,,
 Header,+,applications/services/gui/elements.h,,
 Header,+,applications/services/gui/gui.h,,
 Header,+,applications/services/gui/icon_i.h,,
@@ -877,6 +878,8 @@ Function,-,exp10f,float,float
 Function,-,exp2,double,double
 Function,-,exp2f,float,float
 Function,-,exp2l,long double,long double
+Function,+,expansion_disable,void,Expansion*
+Function,+,expansion_enable,void,"Expansion*, FuriHalSerialId"
 Function,-,expf,float,float
 Function,-,expl,long double,long double
 Function,-,explicit_bzero,void,"void*, size_t"
@@ -1434,22 +1437,27 @@ Function,+,furi_hal_sd_max_mount_retry_count,uint8_t,
 Function,+,furi_hal_sd_presence_init,void,
 Function,+,furi_hal_sd_read_blocks,FuriStatus,"uint32_t*, uint32_t, uint32_t"
 Function,+,furi_hal_sd_write_blocks,FuriStatus,"const uint32_t*, uint32_t, uint32_t"
+Function,+,furi_hal_serial_async_rx,uint8_t,FuriHalSerialHandle*
+Function,+,furi_hal_serial_async_rx_start,void,"FuriHalSerialHandle*, FuriHalSerialAsyncRxCallback, void*, _Bool"
+Function,+,furi_hal_serial_async_rx_stop,void,FuriHalSerialHandle*
 Function,+,furi_hal_serial_control_acquire,FuriHalSerialHandle*,FuriHalSerialId
 Function,+,furi_hal_serial_control_deinit,void,
 Function,+,furi_hal_serial_control_init,void,
 Function,+,furi_hal_serial_control_release,void,FuriHalSerialHandle*
 Function,+,furi_hal_serial_control_resume,void,
+Function,+,furi_hal_serial_control_set_expansion_callback,void,"FuriHalSerialId, FuriHalSerialControlExpansionCallback, void*"
 Function,+,furi_hal_serial_control_set_logging_config,void,"FuriHalSerialId, uint32_t"
 Function,+,furi_hal_serial_control_suspend,void,
 Function,+,furi_hal_serial_deinit,void,FuriHalSerialHandle*
+Function,+,furi_hal_serial_disable_direction,void,"FuriHalSerialHandle*, FuriHalSerialDirection"
 Function,+,furi_hal_serial_dma_rx,size_t,"FuriHalSerialHandle*, uint8_t*, size_t"
 Function,+,furi_hal_serial_dma_rx_start,void,"FuriHalSerialHandle*, FuriHalSerialDmaRxCallback, void*, _Bool"
 Function,+,furi_hal_serial_dma_rx_stop,void,FuriHalSerialHandle*
+Function,+,furi_hal_serial_enable_direction,void,"FuriHalSerialHandle*, FuriHalSerialDirection"
+Function,+,furi_hal_serial_get_gpio_pin,const GpioPin*,"FuriHalSerialHandle*, FuriHalSerialDirection"
 Function,+,furi_hal_serial_init,void,"FuriHalSerialHandle*, uint32_t"
+Function,+,furi_hal_serial_is_baud_rate_supported,_Bool,"FuriHalSerialHandle*, uint32_t"
 Function,+,furi_hal_serial_resume,void,FuriHalSerialHandle*
-Function,+,furi_hal_serial_async_rx,uint8_t,FuriHalSerialHandle*
-Function,+,furi_hal_serial_async_rx_start,void,"FuriHalSerialHandle*, FuriHalSerialAsyncRxCallback, void*, _Bool"
-Function,+,furi_hal_serial_async_rx_stop,void,FuriHalSerialHandle*
 Function,+,furi_hal_serial_set_br,void,"FuriHalSerialHandle*, uint32_t"
 Function,+,furi_hal_serial_suspend,void,FuriHalSerialHandle*
 Function,+,furi_hal_serial_tx,void,"FuriHalSerialHandle*, const uint8_t*, size_t"
@@ -2682,7 +2690,7 @@ Function,-,round,double,double
 Function,+,roundf,float,float
 Function,-,roundl,long double,long double
 Function,+,rpc_session_close,void,RpcSession*
-Function,+,rpc_session_feed,size_t,"RpcSession*, uint8_t*, size_t, uint32_t"
+Function,+,rpc_session_feed,size_t,"RpcSession*, const uint8_t*, size_t, uint32_t"
 Function,+,rpc_session_get_available_size,size_t,RpcSession*
 Function,+,rpc_session_get_owner,RpcOwner,RpcSession*
 Function,+,rpc_session_open,RpcSession*,"Rpc*, RpcOwner"

targets/f7/furi_hal/furi_hal_serial.c

@@ -31,6 +31,59 @@ typedef struct {
     void* context;
 } FuriHalSerial;
 
+typedef void (*FuriHalSerialControlFunc)(USART_TypeDef*);
+
+typedef struct {
+    USART_TypeDef* periph;
+    GpioAltFn alt_fn;
+    const GpioPin* gpio[FuriHalSerialDirectionMax];
+    FuriHalSerialControlFunc enable[FuriHalSerialDirectionMax];
+    FuriHalSerialControlFunc disable[FuriHalSerialDirectionMax];
+} FuriHalSerialConfig;
+
+static const FuriHalSerialConfig furi_hal_serial_config[FuriHalSerialIdMax] = {
+    [FuriHalSerialIdUsart] =
+        {
+            .periph = USART1,
+            .alt_fn = GpioAltFn7USART1,
+            .gpio =
+                {
+                    [FuriHalSerialDirectionTx] = &gpio_usart_tx,
+                    [FuriHalSerialDirectionRx] = &gpio_usart_rx,
+                },
+            .enable =
+                {
+                    [FuriHalSerialDirectionTx] = LL_USART_EnableDirectionTx,
+                    [FuriHalSerialDirectionRx] = LL_USART_EnableDirectionRx,
+                },
+            .disable =
+                {
+                    [FuriHalSerialDirectionTx] = LL_USART_DisableDirectionTx,
+                    [FuriHalSerialDirectionRx] = LL_USART_DisableDirectionRx,
+                },
+        },
+    [FuriHalSerialIdLpuart] =
+        {
+            .periph = LPUART1,
+            .alt_fn = GpioAltFn8LPUART1,
+            .gpio =
+                {
+                    [FuriHalSerialDirectionTx] = &gpio_ext_pc1,
+                    [FuriHalSerialDirectionRx] = &gpio_ext_pc0,
+                },
+            .enable =
+                {
+                    [FuriHalSerialDirectionTx] = LL_LPUART_EnableDirectionTx,
+                    [FuriHalSerialDirectionRx] = LL_LPUART_EnableDirectionRx,
+                },
+            .disable =
+                {
+                    [FuriHalSerialDirectionTx] = LL_LPUART_DisableDirectionTx,
+                    [FuriHalSerialDirectionRx] = LL_LPUART_DisableDirectionRx,
+                },
+        },
+};
+
 static FuriHalSerial furi_hal_serial[FuriHalSerialIdMax] = {0};
 
 static size_t furi_hal_serial_dma_bytes_available(FuriHalSerialId ch);
@@ -451,6 +504,11 @@ void furi_hal_serial_init(FuriHalSerialHandle* handle, uint32_t baud) {
     }
 }
 
+bool furi_hal_serial_is_baud_rate_supported(FuriHalSerialHandle* handle, uint32_t baud) {
+    furi_check(handle);
+    return baud >= 9600UL && baud <= 4000000UL;
+}
+
 static uint32_t furi_hal_serial_get_prescaler(FuriHalSerialHandle* handle, uint32_t baud) {
     uint32_t uartclk = LL_RCC_GetUSARTClockFreq(LL_RCC_USART1_CLKSOURCE);
     uint32_t divisor = (uartclk / baud);
@@ -836,3 +894,44 @@ void furi_hal_serial_dma_rx_stop(FuriHalSerialHandle* handle) {
     furi_hal_serial_event_deinit(handle);
     furi_hal_serial_dma_configure(handle, NULL, NULL);
 }
+
+void furi_hal_serial_enable_direction(
+    FuriHalSerialHandle* handle,
+    FuriHalSerialDirection direction) {
+    furi_check(handle);
+    furi_check(handle->id < FuriHalSerialIdMax);
+    furi_check(direction < FuriHalSerialDirectionMax);
+
+    USART_TypeDef* periph = furi_hal_serial_config[handle->id].periph;
+    furi_hal_serial_config[handle->id].enable[direction](periph);
+
+    const GpioPin* gpio = furi_hal_serial_config[handle->id].gpio[direction];
+    const GpioAltFn alt_fn = furi_hal_serial_config[handle->id].alt_fn;
+
+    furi_hal_gpio_init_ex(
+        gpio, GpioModeAltFunctionPushPull, GpioPullUp, GpioSpeedVeryHigh, alt_fn);
+}
+
+void furi_hal_serial_disable_direction(
+    FuriHalSerialHandle* handle,
+    FuriHalSerialDirection direction) {
+    furi_check(handle);
+    furi_check(handle->id < FuriHalSerialIdMax);
+    furi_check(direction < FuriHalSerialDirectionMax);
+
+    USART_TypeDef* periph = furi_hal_serial_config[handle->id].periph;
+    furi_hal_serial_config[handle->id].disable[direction](periph);
+
+    const GpioPin* gpio = furi_hal_serial_config[handle->id].gpio[direction];
+
+    furi_hal_gpio_init(gpio, GpioModeAnalog, GpioPullNo, GpioSpeedLow);
+}
+
+const GpioPin*
+    furi_hal_serial_get_gpio_pin(FuriHalSerialHandle* handle, FuriHalSerialDirection direction) {
+    furi_check(handle);
+    furi_check(handle->id < FuriHalSerialIdMax);
+    furi_check(direction < FuriHalSerialDirectionMax);
+
+    return furi_hal_serial_config[handle->id].gpio[direction];
+}

targets/f7/furi_hal/furi_hal_serial.h

@@ -48,6 +48,15 @@ void furi_hal_serial_suspend(FuriHalSerialHandle* handle);
  */
 void furi_hal_serial_resume(FuriHalSerialHandle* handle);
 
+/**
+ * @brief Determine whether a certain baud rate is supported
+ *
+ * @param      handle  Serial handle
+ * @param      baud baud rate to be checked
+ * @returns    true if baud rate is supported, false otherwise.
+ */
+bool furi_hal_serial_is_baud_rate_supported(FuriHalSerialHandle* handle, uint32_t baud);
+
 /** Changes baud rate
  *
  * @param      handle  Serial handle
@@ -152,6 +161,42 @@ typedef void (*FuriHalSerialDmaRxCallback)(
     size_t data_len,
     void* context);
 
+/**
+ * @brief Enable an input/output directon
+ *
+ * Takes over the respective pin by reconfiguring it to
+ * the appropriate alternative function.
+ *
+ * @param     handle        Serial handle
+ * @param     direction     Direction to enable
+ */
+void furi_hal_serial_enable_direction(
+    FuriHalSerialHandle* handle,
+    FuriHalSerialDirection direction);
+
+/**
+ * @brief Disable an input/output directon
+ *
+ * Releases the respective pin by reconfiguring it to
+ * initial state, making possible its use for other purposes.
+ *
+ * @param     handle        Serial handle
+ * @param     direction     Direction to disable
+ */
+void furi_hal_serial_disable_direction(
+    FuriHalSerialHandle* handle,
+    FuriHalSerialDirection direction);
+
+/**
+ * @brief Get the GPIO pin associated with a serial
+ *
+ * @param     handle        Serial handle
+ * @param     direction     Direction to query
+ * @returns   pointer to the respective pin instance
+ */
+const GpioPin*
+    furi_hal_serial_get_gpio_pin(FuriHalSerialHandle* handle, FuriHalSerialDirection direction);
+
 /** Start and sets Serial event callback receive DMA
  *
  * @param      handle         Serial handle

targets/f7/furi_hal/furi_hal_serial_control.c

@@ -14,6 +14,8 @@ typedef enum {
     FuriHalSerialControlMessageTypeAcquire,
     FuriHalSerialControlMessageTypeRelease,
     FuriHalSerialControlMessageTypeLogging,
+    FuriHalSerialControlMessageTypeExpansionSetCallback,
+    FuriHalSerialControlMessageTypeExpansionIrq,
 } FuriHalSerialControlMessageType;
 
 typedef struct {
@@ -28,6 +30,12 @@ typedef struct {
     const uint32_t baud_rate;
 } FuriHalSerialControlMessageInputLogging;
 
+typedef struct {
+    const FuriHalSerialId id;
+    const FuriHalSerialControlExpansionCallback callback;
+    void* context;
+} FuriHalSerialControlMessageExpCallback;
+
 typedef struct {
     FuriHalSerialHandle handles[FuriHalSerialIdMax];
     FuriMessageQueue* queue;
@@ -38,6 +46,10 @@ typedef struct {
     uint32_t log_config_serial_baud_rate;
     FuriLogHandler log_handler;
     FuriHalSerialHandle* log_serial;
+
+    // Expansion detection
+    FuriHalSerialControlExpansionCallback expansion_cb;
+    void* expansion_ctx;
 } FuriHalSerialControl;
 
 FuriHalSerialControl* furi_hal_serial_control = NULL;
@@ -65,6 +77,150 @@ static void furi_hal_serial_control_log_set_handle(FuriHalSerialHandle* handle)
     }
 }
 
+static void furi_hal_serial_control_expansion_irq_callback(void* context) {
+    UNUSED(context);
+
+    FuriHalSerialControlMessage message;
+    message.type = FuriHalSerialControlMessageTypeExpansionIrq;
+    message.api_lock = NULL;
+    furi_message_queue_put(furi_hal_serial_control->queue, &message, 0);
+}
+
+static bool furi_hal_serial_control_handler_stop(void* input, void* output) {
+    UNUSED(input);
+    UNUSED(output);
+    return false;
+}
+
+static bool furi_hal_serial_control_handler_suspend(void* input, void* output) {
+    UNUSED(input);
+    UNUSED(output);
+
+    for(size_t i = 0; i < FuriHalSerialIdMax; i++) {
+        furi_hal_serial_tx_wait_complete(&furi_hal_serial_control->handles[i]);
+        furi_hal_serial_suspend(&furi_hal_serial_control->handles[i]);
+    }
+
+    return true;
+}
+
+static bool furi_hal_serial_control_handler_resume(void* input, void* output) {
+    UNUSED(input);
+    UNUSED(output);
+
+    for(size_t i = 0; i < FuriHalSerialIdMax; i++) {
+        furi_hal_serial_resume(&furi_hal_serial_control->handles[i]);
+    }
+
+    return true;
+}
+
+static bool furi_hal_serial_control_handler_acquire(void* input, void* output) {
+    FuriHalSerialId serial_id = *(FuriHalSerialId*)input;
+    if(furi_hal_serial_control->handles[serial_id].in_use) {
+        *(FuriHalSerialHandle**)output = NULL;
+    } else {
+        // Logging
+        if(furi_hal_serial_control->log_config_serial_id == serial_id) {
+            furi_hal_serial_control_log_set_handle(NULL);
+        }
+        // Return handle
+        furi_hal_serial_control->handles[serial_id].in_use = true;
+        *(FuriHalSerialHandle**)output = &furi_hal_serial_control->handles[serial_id];
+    }
+
+    return true;
+}
+
+static bool furi_hal_serial_control_handler_release(void* input, void* output) {
+    UNUSED(output);
+
+    FuriHalSerialHandle* handle = *(FuriHalSerialHandle**)input;
+    furi_assert(handle->in_use);
+    furi_hal_serial_deinit(handle);
+    handle->in_use = false;
+
+    // Return back logging
+    if(furi_hal_serial_control->log_config_serial_id == handle->id) {
+        furi_hal_serial_control_log_set_handle(handle);
+    }
+
+    return true;
+}
+
+static bool furi_hal_serial_control_handler_logging(void* input, void* output) {
+    UNUSED(output);
+
+    // Set new configuration
+    FuriHalSerialControlMessageInputLogging* message_input = input;
+    furi_hal_serial_control->log_config_serial_id = message_input->id;
+    furi_hal_serial_control->log_config_serial_baud_rate = message_input->baud_rate;
+    // Apply new configuration
+    FuriHalSerialHandle* handle = NULL;
+    if(furi_hal_serial_control->log_config_serial_id < FuriHalSerialIdMax) {
+        if(!furi_hal_serial_control->handles[furi_hal_serial_control->log_config_serial_id].in_use) {
+            handle =
+                &furi_hal_serial_control->handles[furi_hal_serial_control->log_config_serial_id];
+        }
+    }
+
+    furi_hal_serial_control_log_set_handle(handle);
+
+    return true;
+}
+
+static bool furi_hal_serial_control_handler_expansion_set_callback(void* input, void* output) {
+    UNUSED(output);
+
+    FuriHalSerialControlMessageExpCallback* message_input = input;
+    FuriHalSerialHandle* handle = &furi_hal_serial_control->handles[message_input->id];
+    const GpioPin* gpio = furi_hal_serial_get_gpio_pin(handle, FuriHalSerialDirectionRx);
+
+    if(message_input->callback) {
+        furi_check(furi_hal_serial_control->expansion_cb == NULL);
+
+        furi_hal_serial_disable_direction(handle, FuriHalSerialDirectionRx);
+        furi_hal_gpio_add_int_callback(gpio, furi_hal_serial_control_expansion_irq_callback, NULL);
+        furi_hal_gpio_init(gpio, GpioModeInterruptFall, GpioPullUp, GpioSpeedLow);
+    } else {
+        furi_check(furi_hal_serial_control->expansion_cb != NULL);
+
+        furi_hal_gpio_remove_int_callback(gpio);
+        furi_hal_serial_enable_direction(handle, FuriHalSerialDirectionRx);
+    }
+
+    furi_hal_serial_control->expansion_cb = message_input->callback;
+    furi_hal_serial_control->expansion_ctx = message_input->context;
+
+    return true;
+}
+
+static bool furi_hal_serial_control_handler_expansion_irq(void* input, void* output) {
+    UNUSED(input);
+    UNUSED(output);
+
+    if(furi_hal_serial_control->expansion_cb) {
+        void* context = furi_hal_serial_control->expansion_ctx;
+        furi_hal_serial_control->expansion_cb(context);
+    }
+
+    return true;
+}
+
+typedef bool (*FuriHalSerialControlCommandHandler)(void* input, void* output);
+
+static const FuriHalSerialControlCommandHandler furi_hal_serial_control_handlers[] = {
+    [FuriHalSerialControlMessageTypeStop] = furi_hal_serial_control_handler_stop,
+    [FuriHalSerialControlMessageTypeSuspend] = furi_hal_serial_control_handler_suspend,
+    [FuriHalSerialControlMessageTypeResume] = furi_hal_serial_control_handler_resume,
+    [FuriHalSerialControlMessageTypeAcquire] = furi_hal_serial_control_handler_acquire,
+    [FuriHalSerialControlMessageTypeRelease] = furi_hal_serial_control_handler_release,
+    [FuriHalSerialControlMessageTypeLogging] = furi_hal_serial_control_handler_logging,
+    [FuriHalSerialControlMessageTypeExpansionSetCallback] =
+        furi_hal_serial_control_handler_expansion_set_callback,
+    [FuriHalSerialControlMessageTypeExpansionIrq] = furi_hal_serial_control_handler_expansion_irq,
+};
+
 static int32_t furi_hal_serial_control_thread(void* args) {
     UNUSED(args);
 
@@ -74,61 +230,13 @@ static int32_t furi_hal_serial_control_thread(void* args) {
         FuriStatus status =
             furi_message_queue_get(furi_hal_serial_control->queue, &message, FuriWaitForever);
         furi_check(status == FuriStatusOk);
+        furi_check(message.type < COUNT_OF(furi_hal_serial_control_handlers));
 
-        if(message.type == FuriHalSerialControlMessageTypeStop) {
-            should_continue = false;
-        } else if(message.type == FuriHalSerialControlMessageTypeSuspend) {
-            for(size_t i = 0; i < FuriHalSerialIdMax; i++) {
-                furi_hal_serial_tx_wait_complete(&furi_hal_serial_control->handles[i]);
-                furi_hal_serial_suspend(&furi_hal_serial_control->handles[i]);
-            }
-            api_lock_unlock(message.api_lock);
-        } else if(message.type == FuriHalSerialControlMessageTypeResume) {
-            for(size_t i = 0; i < FuriHalSerialIdMax; i++) {
-                furi_hal_serial_resume(&furi_hal_serial_control->handles[i]);
-            }
-            api_lock_unlock(message.api_lock);
-        } else if(message.type == FuriHalSerialControlMessageTypeAcquire) {
-            FuriHalSerialId serial_id = *(FuriHalSerialId*)message.input;
-            if(furi_hal_serial_control->handles[serial_id].in_use) {
-                *(FuriHalSerialHandle**)message.output = NULL;
-            } else {
-                // Logging
-                if(furi_hal_serial_control->log_config_serial_id == serial_id) {
-                    furi_hal_serial_control_log_set_handle(NULL);
-                }
-                // Return handle
-                furi_hal_serial_control->handles[serial_id].in_use = true;
-                *(FuriHalSerialHandle**)message.output =
-                    &furi_hal_serial_control->handles[serial_id];
-            }
-            api_lock_unlock(message.api_lock);
-        } else if(message.type == FuriHalSerialControlMessageTypeRelease) {
-            FuriHalSerialHandle* handle = *(FuriHalSerialHandle**)message.input;
-            furi_assert(handle->in_use);
-            furi_hal_serial_deinit(handle);
-            handle->in_use = false;
+        should_continue =
+            furi_hal_serial_control_handlers[message.type](message.input, message.output);
 
-            // Return back logging
-            if(furi_hal_serial_control->log_config_serial_id == handle->id) {
-                furi_hal_serial_control_log_set_handle(handle);
-            }
+        if(message.api_lock != NULL) {
             api_lock_unlock(message.api_lock);
-        } else if(message.type == FuriHalSerialControlMessageTypeLogging) {
-            // Set new configuration
-            FuriHalSerialControlMessageInputLogging* message_input = message.input;
-            furi_hal_serial_control->log_config_serial_id = message_input->id;
-            furi_hal_serial_control->log_config_serial_baud_rate = message_input->baud_rate;
-            // Apply new configuration
-            FuriHalSerialHandle* handle = NULL;
-            if(furi_hal_serial_control->log_config_serial_id < FuriHalSerialIdMax) {
-                handle = &furi_hal_serial_control
-                              ->handles[furi_hal_serial_control->log_config_serial_id];
-            }
-            furi_hal_serial_control_log_set_handle(handle);
-            api_lock_unlock(message.api_lock);
-        } else {
-            furi_crash("Invalid parameter");
         }
     }
 
@@ -157,6 +265,7 @@ void furi_hal_serial_control_deinit(void) {
     // Stop control plane thread
     FuriHalSerialControlMessage message;
     message.type = FuriHalSerialControlMessageTypeStop;
+    message.api_lock = NULL;
     furi_message_queue_put(furi_hal_serial_control->queue, &message, FuriWaitForever);
     furi_thread_join(furi_hal_serial_control->thread);
     // Release resources
@@ -220,6 +329,9 @@ void furi_hal_serial_control_set_logging_config(FuriHalSerialId serial_id, uint3
     // Very special case of updater, where RTC initialized before kernel start
     if(!furi_hal_serial_control) return;
 
+    furi_check(furi_hal_serial_is_baud_rate_supported(
+        &furi_hal_serial_control->handles[serial_id], baud_rate));
+
     FuriHalSerialControlMessageInputLogging message_input = {
         .id = serial_id,
         .baud_rate = baud_rate,
@@ -231,3 +343,23 @@ void furi_hal_serial_control_set_logging_config(FuriHalSerialId serial_id, uint3
     furi_message_queue_put(furi_hal_serial_control->queue, &message, FuriWaitForever);
     api_lock_wait_unlock_and_free(message.api_lock);
 }
+
+void furi_hal_serial_control_set_expansion_callback(
+    FuriHalSerialId serial_id,
+    FuriHalSerialControlExpansionCallback callback,
+    void* context) {
+    furi_check(serial_id <= FuriHalSerialIdMax);
+    furi_check(furi_hal_serial_control);
+
+    FuriHalSerialControlMessageExpCallback message_input = {
+        .id = serial_id,
+        .callback = callback,
+        .context = context,
+    };
+    FuriHalSerialControlMessage message;
+    message.type = FuriHalSerialControlMessageTypeExpansionSetCallback;
+    message.api_lock = api_lock_alloc_locked();
+    message.input = &message_input;
+    furi_message_queue_put(furi_hal_serial_control->queue, &message, FuriWaitForever);
+    api_lock_wait_unlock_and_free(message.api_lock);
+}

targets/f7/furi_hal/furi_hal_serial_control.h

@@ -41,6 +41,27 @@ void furi_hal_serial_control_release(FuriHalSerialHandle* handle);
  */
 void furi_hal_serial_control_set_logging_config(FuriHalSerialId serial_id, uint32_t baud_rate);
 
+/**
+ * @brief Expansion module detection callback type.
+ *
+ * @param[in,out] context Pointer to the user-defined context object.
+ */
+typedef void (*FuriHalSerialControlExpansionCallback)(void* context);
+
+/**
+ * @brief Enable expansion module detection for a given serial interface.
+ *
+ * Passing NULL as the callback parameter disables external module detection.
+ *
+ * @param[in] serial_id Identifier of the serial interface to be used.
+ * @param[in] callback Pointer to the callback function to be called upon module detection.
+ * @param[in,out] context Pointer to the user-defined context object. Will be passed to the callback function.
+ */
+void furi_hal_serial_control_set_expansion_callback(
+    FuriHalSerialId serial_id,
+    FuriHalSerialControlExpansionCallback callback,
+    void* context);
+
 #ifdef __cplusplus
 }
 #endif

targets/f7/furi_hal/furi_hal_serial_types.h

@@ -12,4 +12,11 @@ typedef enum {
     FuriHalSerialIdMax,
 } FuriHalSerialId;
 
+typedef enum {
+    FuriHalSerialDirectionTx,
+    FuriHalSerialDirectionRx,
+
+    FuriHalSerialDirectionMax,
+} FuriHalSerialDirection;
+
 typedef struct FuriHalSerialHandle FuriHalSerialHandle;