From 8c025f78c0e3c3ba2d03f7d0912ffbd3cd172b46 Mon Sep 17 00:00:00 2001
From: Giovanni Di Sirio <gdisirio@gmail.com>
Date: Sun, 21 Aug 2022 06:10:28 +0000
Subject: [PATCH] SIO simplified. Added a "BufferedSIODriver" class that
 implements the behavior of the legacy Serial driver on top of a SIO
 implementation (buffering, events and all).

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@15727 27425a3e-05d8-49a3-a47f-9c15f0e5edd8
---
 demos/RP/RT-RP2040-PICO/c1_main.c             |   1 -
 os/hal/include/hal_buffered_serial.h          |   2 +-
 os/hal/include/hal_sio.h                      |  53 +++---
 .../complex/buffered_sio/hal_buffered_sio.c   |  15 +-
 os/hal/ports/RP/LLD/UARTv1/hal_sio_lld.c      |  39 +----
 os/hal/ports/RP/LLD/UARTv1/hal_sio_lld.h      |   2 -
 os/hal/ports/STM32/LLD/USARTv2/hal_sio_lld.c  |  46 ++----
 os/hal/ports/STM32/LLD/USARTv2/hal_sio_lld.h  |   2 -
 os/hal/ports/STM32/LLD/USARTv3/hal_sio_lld.c  |  50 ++----
 os/hal/ports/STM32/LLD/USARTv3/hal_sio_lld.h  |   2 -
 os/hal/src/hal_sio.c                          | 152 +++++-------------
 readme.txt                                    |   3 +
 testhal/STM32/multi/SIO/main.c                | 110 +++++++++++--
 .../multi/SIO/make/stm32g474re_nucleo64.make  |   8 +-
 .../multi/SIO/make/stm32l476vg_discovery.make |   8 +-
 15 files changed, 202 insertions(+), 291 deletions(-)

diff --git a/demos/RP/RT-RP2040-PICO/c1_main.c b/demos/RP/RT-RP2040-PICO/c1_main.c
index 20364b1b4..027b391dd 100644
--- a/demos/RP/RT-RP2040-PICO/c1_main.c
+++ b/demos/RP/RT-RP2040-PICO/c1_main.c
@@ -73,7 +73,6 @@ void c1_main(void) {
    * Activates the UART0 SIO driver using the default configuration.
    */
   sioStart(&SIOD0, NULL);
-  sioStartOperation(&SIOD0, NULL);
 
   /*
    * Creates the timer thread.
diff --git a/os/hal/include/hal_buffered_serial.h b/os/hal/include/hal_buffered_serial.h
index 78f451b94..a1fc5bbbc 100644
--- a/os/hal/include/hal_buffered_serial.h
+++ b/os/hal/include/hal_buffered_serial.h
@@ -161,7 +161,7 @@ static inline void __buffered_serial_objinit_impl(void *ip, const void *vmt,
                                                   qnotify_t onotify, void *oarg) {
   BufferedSerial *bsp = (BufferedSerial *)ip;
 
-  bsp->vmt = (const struct BufferedSerialVMT *)&vmt;  /* TODO use new obj model.*/
+  bsp->vmt = (const struct BufferedSerialVMT *)vmt;  /* TODO use new obj model.*/
   osalEventObjectInit(&bsp->event);  /* TODO super class should do this.*/
   bsp->state = BS_STOP;
   iqObjectInit(&bsp->iqueue, ib, ibsize, inotify, iarg);
diff --git a/os/hal/include/hal_sio.h b/os/hal/include/hal_sio.h
index 46ba2f8e9..c32d185e0 100644
--- a/os/hal/include/hal_sio.h
+++ b/os/hal/include/hal_sio.h
@@ -194,11 +194,6 @@ typedef struct hal_sio_driver SIODriver;
  */
 typedef struct hal_sio_config SIOConfig;
 
-/**
- * @brief   Type of structure representing a SIO operation.
- */
-typedef struct hal_sio_operation SIOOperation;
-
 /**
  * @brief   Generic SIO notification callback type.
  *
@@ -213,7 +208,6 @@ typedef enum {
   SIO_UNINIT = 0,                   /**< Not initialized.                   */
   SIO_STOP = 1,                     /**< Stopped.                           */
   SIO_READY = 2,                    /**< Ready.                             */
-  SIO_ACTIVE = 3                    /**< Operation ongoing.                 */
 } siostate_t;
 
 #include "hal_sio_lld.h"
@@ -271,9 +265,10 @@ struct hal_sio_driver {
    */
   sioflags_t                enabled;
   /**
-   * @brief   Current configuration data.
+   * @brief   Events callback.
+   * @note    Can be @p NULL.
    */
-  const SIOOperation        *operation;
+  siocb_t                   cb;
   /**
    * @brief   User argument to the operation.
    * @note    Can be retrieved through the @p siop argument of the callback.
@@ -304,24 +299,18 @@ struct hal_sio_driver {
   sio_lld_driver_fields;
 };
 
-/**
- * @brief   Structure representing a SIO operation.
- */
-struct hal_sio_operation {
-  /**
-   * @brief   Events callback.
-   * @note    Can be @p NULL.
-   */
-  siocb_t                   cb;
-#if defined(SIO_OPERATION_EXT_FIELS)
-  SIO_OPERATION_EXT_FIELS
-#endif
-};
-
 /*===========================================================================*/
 /* Driver macros.                                                            */
 /*===========================================================================*/
 
+/**
+ * @brief   Associates a callback to te SIO instance.
+ *
+ * @param[in] siop      pointer to the @p SIODriver object
+ * @param[in] f         callback to be associated
+ */
+#define sioSetCallbackX(siop, f) (siop)->cb = (f)
+
 /**
  * @brief   Determines the state of the RX FIFO.
  *
@@ -384,10 +373,10 @@ struct hal_sio_operation {
 #define sioIsTXOngoingX(siop) sio_lld_is_tx_ongoing(siop)
 
 /**
- * @brief   Writes the condition flags mask.
+ * @brief   Writes the enabled events mask.
  *
  * @param[in] siop      pointer to the @p SIODriver object
- * @param[in] flags     flags mask to be written
+ * @param[in] flags     enabled events mask to be written
  *
  * @iclass
  */
@@ -397,10 +386,10 @@ struct hal_sio_operation {
 } while (false)
 
 /**
- * @brief   Enables flags to the condition flags mask.
+ * @brief   Sets flags into the enabled events flags mask.
  *
  * @param[in] siop      pointer to the @p SIODriver object
- * @param[in] flags     flags mask to be enabled
+ * @param[in] flags     enabled events mask to be set
  *
  * @iclass
  */
@@ -410,10 +399,10 @@ struct hal_sio_operation {
 } while (false)
 
 /**
- * @brief   Disables flags from the condition flags mask.
+ * @brief   Clears flags from the enabled events flags mask.
  *
  * @param[in] siop      pointer to the @p SIODriver object
- * @param[in] flags     flags mask to be disabled
+ * @param[in] flags     enabled events mask to be cleared
  *
  * @iclass
  */
@@ -533,8 +522,8 @@ struct hal_sio_operation {
  * @notapi
  */
 #define __sio_callback(siop) do {                                           \
-  if ((siop)->operation->cb != NULL) {                                      \
-    (siop)->operation->cb(siop);                                            \
+  if ((siop)->cb != NULL) {                                                 \
+    (siop)->cb(siop);                                                       \
   }                                                                         \
 } while (false)
 
@@ -634,10 +623,6 @@ extern "C" {
   void sioObjectInit(SIODriver *siop);
   msg_t sioStart(SIODriver *siop, const SIOConfig *config);
   void sioStop(SIODriver *siop);
-  void sioStartOperationI(SIODriver *siop, const SIOOperation *operation);
-  void sioStartOperation(SIODriver *siop, const SIOOperation *operation);
-  void sioStopOperationI(SIODriver *siop);
-  void sioStopOperation(SIODriver *siop);
   void sioWriteEnableFlags(SIODriver *siop, sioflags_t flags);
   void sioSetEnableFlags(SIODriver *siop, sioflags_t flags);
   void sioClearEnableFlags(SIODriver *siop, sioflags_t flags);
diff --git a/os/hal/lib/complex/buffered_sio/hal_buffered_sio.c b/os/hal/lib/complex/buffered_sio/hal_buffered_sio.c
index 40f500783..5c4246008 100644
--- a/os/hal/lib/complex/buffered_sio/hal_buffered_sio.c
+++ b/os/hal/lib/complex/buffered_sio/hal_buffered_sio.c
@@ -40,11 +40,6 @@
 /* Driver local variables and types.                                         */
 /*===========================================================================*/
 
-static void __bsio_default_cb(SIODriver *siop);
-static const SIOOperation __bsio_default_operation = {
-  .cb = __bsio_default_cb
-};
-
 /*===========================================================================*/
 /* Driver local functions.                                                   */
 /*===========================================================================*/
@@ -208,15 +203,10 @@ msg_t bsioStart(BufferedSIODriver *bsiop, const BufferedSIOConfig *config) {
   osalDbgAssert((bsiop->state == BS_STOP) || (bsiop->state == BS_READY),
                 "invalid state");
 
-  /* Stopping current operation, if any.*/
-  if (bsiop->siop->state == SIO_ACTIVE) {
-    sioStopOperation(bsiop->siop);
-  }
-
   msg = sioStart(bsiop->siop, config);
   if (msg == HAL_RET_SUCCESS) {
     osalSysLock();
-    sioStartOperationI(bsiop->siop, &__bsio_default_operation);
+    sioSetCallbackX(bsiop->siop, &__bsio_default_cb);
     sioWriteEnableFlagsI(bsiop->siop, SIO_FL_ALL);
     bsiop->state = BS_READY;
     osalSysUnlock();
@@ -244,9 +234,6 @@ void bsioStop(BufferedSIODriver *bsiop) {
   osalDbgAssert((bsiop->state == BS_STOP) || (bsiop->state == BS_READY),
                 "invalid state");
 
-  /* Stopping current operation, if any.*/
-  sioStopOperation(bsiop->siop);
-
   /* Stopping undelying SIO driver.*/
   sioStop(bsiop->siop);
 
diff --git a/os/hal/ports/RP/LLD/UARTv1/hal_sio_lld.c b/os/hal/ports/RP/LLD/UARTv1/hal_sio_lld.c
index a324673a2..6673a2f9c 100644
--- a/os/hal/ports/RP/LLD/UARTv1/hal_sio_lld.c
+++ b/os/hal/ports/RP/LLD/UARTv1/hal_sio_lld.c
@@ -126,6 +126,11 @@ __STATIC_INLINE void uart_init(SIODriver *siop) {
   /* Registers settings, the LCR_H write also latches dividers values.*/
   siop->uart->UARTLCR_H = siop->config->UARTLCR_H & ~UART_LCRH_CFG_FORBIDDEN;
   siop->uart->UARTCR    = siop->config->UARTCR    & ~UART_CR_CFG_FORBIDDEN;
+
+  /* Setting up the operation.*/
+  siop->uart->UARTICR   = siop->uart->UARTRIS;
+  siop->uart->UARTCR    = siop->config->UARTCR |
+                          UART_UARTCR_RXE | UART_UARTCR_TXE | UART_UARTCR_UARTEN;
 }
 
 /*===========================================================================*/
@@ -240,35 +245,6 @@ void sio_lld_stop(SIODriver *siop) {
   }
 }
 
-/**
- * @brief   Starts a SIO operation.
- *
- * @param[in] siop          pointer to an @p SIODriver structure
- *
- * @api
- */
-void sio_lld_start_operation(SIODriver *siop) {
-
-  /* Setting up the operation.*/
-  siop->uart->UARTICR   = siop->uart->UARTRIS;
-  siop->uart->UARTCR    = siop->config->UARTCR |
-                          UART_UARTCR_RXE | UART_UARTCR_TXE | UART_UARTCR_UARTEN;
-}
-
-/**
- * @brief   Stops an ongoing SIO operation, if any.
- *
- * @param[in] siop      pointer to an @p SIODriver structure
- *
- * @api
- */
-void sio_lld_stop_operation(SIODriver *siop) {
-
-  /* Stop operation.*/
-  siop->uart->UARTIMSC = 0U;
-  siop->uart->UARTCR   = siop->config->UARTCR & ~UART_CR_CFG_FORBIDDEN;
-}
-
 /**
  * @brief   Enable flags change notification.
  *
@@ -513,7 +489,7 @@ void sio_lld_serve_interrupt(SIODriver *siop) {
   UART_TypeDef *u = siop->uart;
   uint32_t mis, imsc;
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   /* Note, ISR flags are just read but not cleared, ISR sources are
      disabled instead.*/
@@ -589,10 +565,9 @@ void sio_lld_serve_interrupt(SIODriver *siop) {
 
     /* The callback is invoked.*/
     __sio_callback(siop);
-
   }
   else {
-    osalDbgAssert(false, "spurious interrupt");
+//    osalDbgAssert(false, "spurious interrupt");
   }
 }
 
diff --git a/os/hal/ports/RP/LLD/UARTv1/hal_sio_lld.h b/os/hal/ports/RP/LLD/UARTv1/hal_sio_lld.h
index 229a383a4..f5e7fa871 100644
--- a/os/hal/ports/RP/LLD/UARTv1/hal_sio_lld.h
+++ b/os/hal/ports/RP/LLD/UARTv1/hal_sio_lld.h
@@ -211,8 +211,6 @@ extern "C" {
   void sio_lld_init(void);
   msg_t  sio_lld_start(SIODriver *siop);
   void sio_lld_stop(SIODriver *siop);
-  void sio_lld_start_operation(SIODriver *siop);
-  void sio_lld_stop_operation(SIODriver *siop);
   void sio_lld_update_enable_flags(SIODriver *siop);
   sioevents_t sio_lld_get_and_clear_errors(SIODriver *siop);
   sioevents_t sio_lld_get_and_clear_events(SIODriver *siop);
diff --git a/os/hal/ports/STM32/LLD/USARTv2/hal_sio_lld.c b/os/hal/ports/STM32/LLD/USARTv2/hal_sio_lld.c
index df02c87b0..57ae4af9e 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/hal_sio_lld.c
+++ b/os/hal/ports/STM32/LLD/USARTv2/hal_sio_lld.c
@@ -214,6 +214,10 @@ __STATIC_INLINE void usart_init(SIODriver *siop) {
   u->CR1   = siop->config->cr1 & ~USART_CR1_CFG_FORBIDDEN;
   u->CR2   = siop->config->cr2 & ~USART_CR2_CFG_FORBIDDEN;
   u->CR3   = siop->config->cr3 & ~USART_CR3_CFG_FORBIDDEN;
+
+  /* Starting operations.*/
+  u->ICR   = u->ISR;
+  u->CR1  |= USART_CR1_UE | USART_CR1_TE | USART_CR1_RE;
 }
 
 /*===========================================================================*/
@@ -447,35 +451,6 @@ void sio_lld_stop(SIODriver *siop) {
   }
 }
 
-/**
- * @brief   Starts a SIO operation.
- *
- * @param[in] siop          pointer to an @p SIODriver structure
- *
- * @api
- */
-void sio_lld_start_operation(SIODriver *siop) {
-
-  /* Setting up the operation.*/
-  siop->usart->ICR  = siop->usart->ISR;
-  siop->usart->CR1 |= USART_CR1_UE | USART_CR1_TE | USART_CR1_RE;
-}
-
-/**
- * @brief   Stops an ongoing SIO operation, if any.
- *
- * @param[in] siop      pointer to an @p SIODriver structure
- *
- * @api
- */
-void sio_lld_stop_operation(SIODriver *siop) {
-
-  /* Stop operation.*/
-  siop->usart->CR1 &= ~USART_CR1_CFG_FORBIDDEN;
-  siop->usart->CR2 &= ~USART_CR2_CFG_FORBIDDEN;
-  siop->usart->CR3 &= ~USART_CR3_CFG_FORBIDDEN;
-}
-
 /**
  * @brief   Enable flags change notification.
  *
@@ -559,7 +534,7 @@ sioevents_t sio_lld_get_and_clear_events(SIODriver *siop) {
                             USART_ISR_RXNE        |
                             USART_ISR_IDLE        |
                             USART_ISR_TXE         |
-							USART_ISR_TC);
+                            USART_ISR_TC);
 
   /* Clearing captured events.*/
   siop->usart->ICR = isr;
@@ -736,7 +711,7 @@ void sio_lld_serve_interrupt(SIODriver *siop) {
   uint32_t isr, isrmask;
   uint32_t cr1, cr2, cr3;
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   /* Read on control registers.*/
   cr1 = u->CR1;
@@ -758,7 +733,8 @@ void sio_lld_serve_interrupt(SIODriver *siop) {
 
   /* Note, ISR flags are just read but not cleared, ISR sources are
      disabled instead.*/
-  isr = u->ISR & isrmask;
+  isr = u->ISR;
+  isr = isr & isrmask;
   if (isr != 0U) {
 
     /* Error events handled as a group, except ORE.*/
@@ -768,7 +744,7 @@ void sio_lld_serve_interrupt(SIODriver *siop) {
 #if SIO_USE_SYNCHRONIZATION
       /* The idle flag is forcibly cleared when an RX error event is
          detected.*/
-      u->ICR = USART_ISR_IDLE;
+      u->ICR = USART_ICR_IDLECF;
 #endif
 
       /* Interrupt sources disabled.*/
@@ -796,7 +772,7 @@ void sio_lld_serve_interrupt(SIODriver *siop) {
 #if SIO_USE_SYNCHRONIZATION
       /* The idle flag is forcibly cleared when an RX data event is
          detected.*/
-      u->ICR = USART_ISR_IDLE;
+      u->ICR = USART_ICR_IDLECF;
 #endif
 
       /* Interrupt source disabled.*/
@@ -835,7 +811,7 @@ void sio_lld_serve_interrupt(SIODriver *siop) {
     __sio_callback(siop);
   }
   else {
-    osalDbgAssert(false, "spurious interrupt");
+//    osalDbgAssert(false, "spurious interrupt");
   }
 }
 
diff --git a/os/hal/ports/STM32/LLD/USARTv2/hal_sio_lld.h b/os/hal/ports/STM32/LLD/USARTv2/hal_sio_lld.h
index 8d7ba7624..b7fe1bdb0 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/hal_sio_lld.h
+++ b/os/hal/ports/STM32/LLD/USARTv2/hal_sio_lld.h
@@ -396,8 +396,6 @@ extern "C" {
   void sio_lld_init(void);
   msg_t  sio_lld_start(SIODriver *siop);
   void sio_lld_stop(SIODriver *siop);
-  void sio_lld_start_operation(SIODriver *siop);
-  void sio_lld_stop_operation(SIODriver *siop);
   void sio_lld_update_enable_flags(SIODriver *siop);
   sioevents_t sio_lld_get_and_clear_errors(SIODriver *siop);
   sioevents_t sio_lld_get_and_clear_events(SIODriver *siop);
diff --git a/os/hal/ports/STM32/LLD/USARTv3/hal_sio_lld.c b/os/hal/ports/STM32/LLD/USARTv3/hal_sio_lld.c
index 092c5e1fc..1f0f871d9 100644
--- a/os/hal/ports/STM32/LLD/USARTv3/hal_sio_lld.c
+++ b/os/hal/ports/STM32/LLD/USARTv3/hal_sio_lld.c
@@ -147,7 +147,7 @@ static const SIOConfig default_config = {
   .presc = USART_PRESC1,
   .cr1   = USART_CR1_DATA8 | USART_CR1_OVER16,
   .cr2   = USART_CR2_STOP1_BITS,
-  .cr3   = USART_CR3_TXFTCFG_1H | USART_CR3_RXFTCFG_NONEMPTY
+  .cr3   = USART_CR3_TXFTCFG_NONFULL | USART_CR3_RXFTCFG_NONEMPTY
 };
 
 /*===========================================================================*/
@@ -234,6 +234,10 @@ __STATIC_INLINE void usart_init(SIODriver *siop) {
   u->CR1   = (siop->config->cr1 & ~USART_CR1_CFG_FORBIDDEN) | USART_CR1_FIFOEN;
   u->CR2   = siop->config->cr2 & ~USART_CR2_CFG_FORBIDDEN;
   u->CR3   = siop->config->cr3 & ~USART_CR3_CFG_FORBIDDEN;
+
+  /* Starting operations.*/
+  u->ICR   = u->ISR;
+  u->CR1  |= USART_CR1_UE | USART_CR1_TE | USART_CR1_RE;
 }
 
 /*===========================================================================*/
@@ -501,35 +505,6 @@ void sio_lld_stop(SIODriver *siop) {
   }
 }
 
-/**
- * @brief   Starts a SIO operation.
- *
- * @param[in] siop          pointer to an @p SIODriver structure
- *
- * @api
- */
-void sio_lld_start_operation(SIODriver *siop) {
-
-  /* Setting up the operation.*/
-  siop->usart->ICR  = siop->usart->ISR;
-  siop->usart->CR1 |= USART_CR1_UE | USART_CR1_TE | USART_CR1_RE;
-}
-
-/**
- * @brief   Stops an ongoing SIO operation, if any.
- *
- * @param[in] siop      pointer to an @p SIODriver structure
- *
- * @api
- */
-void sio_lld_stop_operation(SIODriver *siop) {
-
-  /* Stop operation.*/
-  siop->usart->CR1 &= ~USART_CR1_CFG_FORBIDDEN;
-  siop->usart->CR2 &= ~USART_CR2_CFG_FORBIDDEN;
-  siop->usart->CR3 &= ~USART_CR3_CFG_FORBIDDEN;
-}
-
 /**
  * @brief   Enable flags change notification.
  *
@@ -608,10 +583,10 @@ sioevents_t sio_lld_get_and_clear_events(SIODriver *siop) {
            some scientist decided to use different positions for some
            of them.*/
   isr = siop->usart->ISR & (SIO_LLD_ISR_RX_ERRORS |
-							USART_ISR_RXNE_RXFNE  |
+                            USART_ISR_RXNE_RXFNE  |
                             USART_ISR_IDLE        |
                             USART_ISR_TXE_TXFNF   |
-							USART_ISR_TC);
+                            USART_ISR_TC);
 
   /* Clearing captured events.*/
   siop->usart->ICR = isr;
@@ -788,7 +763,7 @@ void sio_lld_serve_interrupt(SIODriver *siop) {
   uint32_t isr, isrmask;
   uint32_t cr1, cr2, cr3;
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   /* Read on control registers.*/
   cr1 = u->CR1;
@@ -810,7 +785,8 @@ void sio_lld_serve_interrupt(SIODriver *siop) {
 
   /* Note, ISR flags are just read but not cleared, ISR sources are
      disabled instead.*/
-  isr = u->ISR & isrmask;
+  isr = u->ISR;
+  isr = isr & isrmask;
   if (isr != 0U) {
 
     /* Error events handled as a group, except ORE.*/
@@ -820,7 +796,7 @@ void sio_lld_serve_interrupt(SIODriver *siop) {
 #if SIO_USE_SYNCHRONIZATION
       /* The idle flag is forcibly cleared when an RX error event is
          detected.*/
-      u->ICR = USART_ISR_IDLE;
+      u->ICR = USART_ICR_IDLECF;
 #endif
 
       /* Interrupt sources disabled.*/
@@ -848,7 +824,7 @@ void sio_lld_serve_interrupt(SIODriver *siop) {
 #if SIO_USE_SYNCHRONIZATION
       /* The idle flag is forcibly cleared when an RX data event is
          detected.*/
-      u->ICR = USART_ISR_IDLE;
+      u->ICR = USART_ICR_IDLECF;
 #endif
 
       /* Interrupt source disabled.*/
@@ -887,7 +863,7 @@ void sio_lld_serve_interrupt(SIODriver *siop) {
     __sio_callback(siop);
   }
   else {
-    osalDbgAssert(false, "spurious interrupt");
+//    osalDbgAssert(false, "spurious interrupt");
   }
 }
 
diff --git a/os/hal/ports/STM32/LLD/USARTv3/hal_sio_lld.h b/os/hal/ports/STM32/LLD/USARTv3/hal_sio_lld.h
index 6e0501e80..a2fd7837c 100644
--- a/os/hal/ports/STM32/LLD/USARTv3/hal_sio_lld.h
+++ b/os/hal/ports/STM32/LLD/USARTv3/hal_sio_lld.h
@@ -451,8 +451,6 @@ extern "C" {
   void sio_lld_init(void);
   msg_t  sio_lld_start(SIODriver *siop);
   void sio_lld_stop(SIODriver *siop);
-  void sio_lld_start_operation(SIODriver *siop);
-  void sio_lld_stop_operation(SIODriver *siop);
   void sio_lld_update_enable_flags(SIODriver *siop);
   sioevents_t sio_lld_get_and_clear_errors(SIODriver *siop);
   sioevents_t sio_lld_get_and_clear_events(SIODriver *siop);
diff --git a/os/hal/src/hal_sio.c b/os/hal/src/hal_sio.c
index d461e260b..3240d4ba8 100644
--- a/os/hal/src/hal_sio.c
+++ b/os/hal/src/hal_sio.c
@@ -38,10 +38,6 @@
 /* Driver local variables and types.                                         */
 /*===========================================================================*/
 
-static const SIOOperation default_operation = {
-  .cb       = NULL
-};
-
 /*===========================================================================*/
 /* Driver local functions.                                                   */
 /*===========================================================================*/
@@ -59,6 +55,9 @@ static size_t sync_write(void *ip, const uint8_t *bp, size_t n,
 
     msg = sioSynchronizeTX(siop, timeout);
     if (msg != MSG_OK) {
+      if (msg != MSG_TIMEOUT) {
+        i = 0U;
+      }
       break;
     }
 
@@ -81,6 +80,9 @@ static size_t sync_read(void *ip, uint8_t *bp, size_t n,
 
     msg = sioSynchronizeRX(siop, timeout);
     if (msg != MSG_OK) {
+      if (msg != MSG_TIMEOUT) {
+        i = 0U;
+      }
       break;
     }
 
@@ -225,6 +227,7 @@ void sioObjectInit(SIODriver *siop) {
   siop->state       = SIO_STOP;
   siop->config      = NULL;
   siop->enabled     = (sioflags_t)0;
+  siop->cb          = NULL;
   siop->arg         = NULL;
 #if SIO_USE_SYNCHRONIZATION == TRUE
   siop->sync_rx     = NULL;
@@ -268,6 +271,14 @@ msg_t sioStart(SIODriver *siop, const SIOConfig *config) {
     siop->state = SIO_STOP;
   }
 
+#if SIO_USE_SYNCHRONIZATION == TRUE
+  /* If synchronization is enabled then all events by default.*/
+  sioWriteEnableFlagsI(siop, SIO_FL_ALL);
+#else
+  /* If synchronization is disabled then no events by default.*/
+  sioWriteEnableFlagsI(siop, SIO_FL_NONE);
+#endif
+
   osalSysUnlock();
 
   return msg;
@@ -290,119 +301,28 @@ void sioStop(SIODriver *siop) {
                 "invalid state");
 
   sio_lld_stop(siop);
-  siop->config  = NULL;
   siop->state   = SIO_STOP;
+  siop->config  = NULL;
+  siop->cb      = NULL;
+  siop->arg     = NULL;
 
-  osalSysUnlock();
-}
-
-/**
- * @brief   Starts a SIO operation.
- *
- * @param[in] siop          pointer to an @p SIODriver structure
- * @param[in] operation     pointer to an @p SIOOperation structure, can
- *                          be @p NULL if callbacks are not required
- *                          encoding the operation to be performed
- *
- * @iclass
- */
-void sioStartOperationI(SIODriver *siop, const SIOOperation *operation) {
-
-  osalDbgCheck(siop != NULL);
-  osalDbgCheckClassI();
-
-  osalDbgAssert((siop->state == SIO_READY) ||
-                (siop->state == SIO_ACTIVE), "invalid state");
-
-  /* The application can pass NULL if it is not interested in callbacks,
-     attaching a default operation structure.*/
-  if (operation != NULL) {
-    siop->operation = operation;
-  }
-  else {
-    siop->operation = &default_operation;
-  }
-
-  if (siop->state == SIO_READY) {
-    sio_lld_start_operation(siop);
-    siop->state = SIO_ACTIVE;
-
-#if SIO_USE_SYNCHRONIZATION == TRUE
-    /* If synchronization is enabled then all events.*/
-    sioWriteEnableFlagsI(siop, SIO_FL_ALL);
-#endif
-  }
-}
-
-/**
- * @brief   Starts a SIO operation.
- *
- * @param[in] siop          pointer to an @p SIODriver structure
- * @param[in] operation     pointer to an @p SIOOperation structure, can
- *                          be @p NULL if callbacks are not required
- *                          encoding the operation to be performed
- *
- * @api
- */
-void sioStartOperation(SIODriver *siop, const SIOOperation *operation) {
-
-  osalSysLock();
-  sioStartOperationI(siop, operation);
-  osalSysUnlock();
-}
-
-/**
- * @brief   Stops an ongoing SIO operation, if any.
- *
- * @param[in] siop      pointer to an @p SIODriver structure
- *
- * @iclass
- */
-void sioStopOperationI(SIODriver *siop) {
-
-  osalDbgCheck(siop != NULL);
-  osalDbgCheckClassI();
-
-  osalDbgAssert((siop->state == SIO_READY) ||
-                (siop->state == SIO_ACTIVE), "invalid state");
-
-  if (siop->state == SIO_ACTIVE) {
 #if SIO_USE_SYNCHRONIZATION == TRUE
     /* Informing waiting threads, if any.*/
     osalThreadResumeI(&siop->sync_rx, MSG_RESET);
     osalThreadResumeI(&siop->sync_rxidle, MSG_RESET);
     osalThreadResumeI(&siop->sync_tx, MSG_RESET);
     osalThreadResumeI(&siop->sync_txend, MSG_RESET);
+    osalOsRescheduleS();
 #endif
 
-    sio_lld_stop_operation(siop);
-
-    siop->operation = NULL;
-    siop->state     = SIO_READY;
-  }
-}
-
-/**
- * @brief   Stops an ongoing SIO operation, if any.
- *
- * @param[in] siop      pointer to an @p SIODriver structure
- *
- * @api
- */
-void sioStopOperation(SIODriver *siop) {
-
-  osalDbgCheck(siop != NULL);
-
-  osalSysLock();
-  sioStopOperationI(siop);
   osalSysUnlock();
 }
 
 /**
- * @brief   Writes the condition flags mask.
+ * @brief   Writes the enabled events flags mask.
  *
  * @param[in] siop      pointer to the @p SIODriver object
- * @param[in] flags     flags mask to be written
+ * @param[in] flags     enabled events mask to be written
  *
  * @api
  */
@@ -412,7 +332,7 @@ void sioWriteEnableFlags(SIODriver *siop, sioflags_t flags) {
 
   osalSysLock();
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   sioWriteEnableFlagsI(siop, flags);
 
@@ -420,10 +340,10 @@ void sioWriteEnableFlags(SIODriver *siop, sioflags_t flags) {
 }
 
 /**
- * @brief   Enables flags to the condition flags mask.
+ * @brief   Sets flags into the enabled events flags mask.
  *
  * @param[in] siop      pointer to the @p SIODriver object
- * @param[in] flags     flags mask to be enabled
+ * @param[in] flags     enabled events mask to be set
  *
  * @api
  */
@@ -433,7 +353,7 @@ void sioSetEnableFlags(SIODriver *siop, sioflags_t flags) {
 
   osalSysLock();
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   sioSetEnableFlagsI(siop, flags);
 
@@ -441,10 +361,10 @@ void sioSetEnableFlags(SIODriver *siop, sioflags_t flags) {
 }
 
 /**
- * @brief   Disables flags from the condition flags mask.
+ * @brief   Clears flags from the enabled events flags mask.
  *
  * @param[in] siop      pointer to the @p SIODriver object
- * @param[in] flags     flags mask to be disabled
+ * @param[in] flags     enabled events mask to be cleared
  *
  * @api
  */
@@ -454,7 +374,7 @@ void sioClearEnableFlags(SIODriver *siop, sioflags_t flags) {
 
   osalSysLock();
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   sioClearEnableFlagsI(siop, flags);
 
@@ -476,7 +396,7 @@ sioevents_t sioGetAndClearErrors(SIODriver *siop) {
 
   osalSysLock();
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   errors = sioGetAndClearErrorsI(siop);
 
@@ -500,7 +420,7 @@ sioevents_t sioGetAndClearEvents(SIODriver *siop) {
 
   osalSysLock();
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   events = sioGetAndClearEventsI(siop);
 
@@ -529,7 +449,7 @@ size_t sioAsyncRead(SIODriver *siop, uint8_t *buffer, size_t n) {
 
   osalSysLock();
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   n = sioAsyncReadI(siop, buffer, n);
 
@@ -558,7 +478,7 @@ size_t sioAsyncWrite(SIODriver *siop, const uint8_t *buffer, size_t n) {
 
   osalSysLock();
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   n = sioAsyncWriteI(siop, buffer, n);
 
@@ -591,7 +511,7 @@ msg_t sioSynchronizeRX(SIODriver *siop, sysinterval_t timeout) {
 
   osalSysLock();
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   /* Checking for errors before going to sleep.*/
   if (((siop->enabled & SIO_FL_ALL_ERRORS) != 0U) && sioHasRXErrorsX(siop)) {
@@ -636,7 +556,7 @@ msg_t sioSynchronizeRXIdle(SIODriver *siop, sysinterval_t timeout) {
 
   osalSysLock();
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   /* Checking for errors before going to sleep.*/
   if (((siop->enabled & SIO_FL_ALL_ERRORS) != 0U) && sioHasRXErrorsX(siop)) {
@@ -683,7 +603,7 @@ msg_t sioSynchronizeTX(SIODriver *siop, sysinterval_t timeout) {
 
   osalSysLock();
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   msg = MSG_OK;
   /*lint -save -e506 -e681 [2.1] Silencing this error because it is
@@ -721,7 +641,7 @@ msg_t sioSynchronizeTXEnd(SIODriver *siop, sysinterval_t timeout) {
 
   osalSysLock();
 
-  osalDbgAssert(siop->state == SIO_ACTIVE, "invalid state");
+  osalDbgAssert(siop->state == SIO_READY, "invalid state");
 
   /*lint -save -e506 -e774 [2.1, 14.3] Silencing this error because
     it is tested with a template implementation of sio_lld_is_tx_ongoing()
diff --git a/readme.txt b/readme.txt
index b31852e6c..ec4068e2e 100644
--- a/readme.txt
+++ b/readme.txt
@@ -74,6 +74,9 @@
 *****************************************************************************
 
 *** Next ***
+- NEW: Added a "BufferedSIODriver" class that implements the behavior of the
+       legacy Serial driver on top of a SIO implementation (buffering, events
+       and all).
 - NEW: Added __CH_OWNEROF() macro to RT.
 - NEW; Now hal.h includes cc_portab.h by default making it mandatory.
 - NEW: Moved HAL serial error flags into asynchronous channels interface
diff --git a/testhal/STM32/multi/SIO/main.c b/testhal/STM32/multi/SIO/main.c
index b1db61cac..5dfb04811 100644
--- a/testhal/STM32/multi/SIO/main.c
+++ b/testhal/STM32/multi/SIO/main.c
@@ -20,6 +20,73 @@
 
 #include "portab.h"
 
+#include "chprintf.h"
+#include "shell.h"
+
+static BufferedSIODriver bsio1;
+static uint8_t rxbuf[32];
+static uint8_t txbuf[32];
+
+/*===========================================================================*/
+/* Command line related.                                                     */
+/*===========================================================================*/
+
+#define SHELL_WA_SIZE   THD_WORKING_AREA_SIZE(2048)
+
+/* Can be measured using dd if=/dev/xxxx of=/dev/null bs=512 count=10000.*/
+static void cmd_write(BaseSequentialStream *chp, int argc, char *argv[]) {
+  static uint8_t buf[] =
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
+
+  (void)argv;
+  if (argc > 0) {
+    chprintf(chp, "Usage: write\r\n");
+    return;
+  }
+
+  while (chnGetTimeout((BaseChannel *)chp, TIME_IMMEDIATE) == Q_TIMEOUT) {
+#if 1
+    /* Writing in channel mode.*/
+    chnWrite(&bsio1, buf, sizeof buf - 1);
+#else
+    /* Writing in buffer mode.*/
+    (void) obqGetEmptyBufferTimeout(&PORTAB_SDU1.obqueue, TIME_INFINITE);
+    memcpy(PORTAB_SDU1.obqueue.ptr, buf, SERIAL_USB_BUFFERS_SIZE);
+    obqPostFullBuffer(&PORTAB_SDU1.obqueue, SERIAL_USB_BUFFERS_SIZE);
+#endif
+  }
+  chprintf(chp, "\r\n\nstopped\r\n");
+}
+
+static const ShellCommand commands[] = {
+  {"write", cmd_write},
+  {NULL, NULL}
+};
+
+static const ShellConfig shell_cfg1 = {
+  (BaseSequentialStream *)&bsio1,
+  commands
+};
+
+/*===========================================================================*/
+/* Generic code.                                                             */
+/*===========================================================================*/
+
 /*
  * RX consumer thread, times are in milliseconds.
  */
@@ -36,13 +103,19 @@ static THD_FUNCTION(Thread1, arg) {
     uint8_t buf[16];
 
     n = chnRead(&PORTAB_SIO2, buf, 16);
-    if (n > 0) {
-      chnWrite(&PORTAB_SIO1, buf, n);
+    if (n == 0U) {
+      break;
+    }
+    n = chnWrite(&PORTAB_SIO1, buf, n);
+    if (n == 0) {
+      break;
     }
     errors = sioGetAndClearErrors(&PORTAB_SIO2);
     (void) errors;
 
-    sioSynchronizeRXIdle(&PORTAB_SIO2, TIME_INFINITE);
+    if (sioSynchronizeRXIdle(&PORTAB_SIO2, TIME_INFINITE) < MSG_OK) {
+      break;
+    }
   }
 }
 
@@ -50,6 +123,7 @@ static THD_FUNCTION(Thread1, arg) {
  * Application entry point.
  */
 int main(void) {
+  thread_t *tp;
 
   /*
    * System initializations.
@@ -70,14 +144,13 @@ int main(void) {
    * Activates the SIO drivers using the default configuration.
    */
   sioStart(&PORTAB_SIO1, NULL);
-  sioStartOperation(&PORTAB_SIO1, NULL);
   sioStart(&PORTAB_SIO2, NULL);
-  sioStartOperation(&PORTAB_SIO2, NULL);
 
   /*
    * Creates the RX consumer thread.
    */
-  chThdCreateStatic(waThread1, sizeof(waThread1), NORMALPRIO, Thread1, NULL);
+  tp = chThdCreateStatic(waThread1, sizeof(waThread1),
+                         NORMALPRIO + 1, Thread1, NULL);
 
   /*
    * Short TX writes.
@@ -88,7 +161,7 @@ int main(void) {
     for (c = 'A'; c <= 'Z'; c++) {
       chnWrite(&PORTAB_SIO2, (const uint8_t *)&c, 1);
       sioSynchronizeTXEnd(&PORTAB_SIO2, TIME_INFINITE);
-      chThdSleepMilliseconds(100);
+      chThdSleepMilliseconds(10);
     }
   } while (palReadLine(PORTAB_LINE_BUTTON) != PORTAB_BUTTON_PRESSED);
 
@@ -112,10 +185,29 @@ int main(void) {
   }
 
   /*
-   * Normal main() thread activity, in this demo it does nothing.
+   * Stopping SIOs.
+   */
+  sioStop(&PORTAB_SIO1);
+  sioStop(&PORTAB_SIO2);
+  chThdWait(tp);
+
+  /*
+   * Starting a buffered SIO, it must behave exactly as a serial driver.
+   */
+  bsioObjectInit(&bsio1, &PORTAB_SIO1,
+                 rxbuf, sizeof rxbuf,
+                 txbuf, sizeof txbuf);
+  bsioStart(&bsio1, NULL);
+
+  /*
+   * Normal main() thread activity, spawning shells.
    */
   while (true) {
-    chThdSleepMilliseconds(500);
+    tp = chThdCreateFromHeap(NULL, SHELL_WA_SIZE,
+                             "shell", NORMALPRIO + 1,
+                             shellThread, (void *)&shell_cfg1);
+    chThdWait(tp);               /* Waiting termination.             */
+    chThdSleepMilliseconds(1000);
   }
   return 0;
 }
diff --git a/testhal/STM32/multi/SIO/make/stm32g474re_nucleo64.make b/testhal/STM32/multi/SIO/make/stm32g474re_nucleo64.make
index 79864dc76..a56dfce6c 100644
--- a/testhal/STM32/multi/SIO/make/stm32g474re_nucleo64.make
+++ b/testhal/STM32/multi/SIO/make/stm32g474re_nucleo64.make
@@ -110,9 +110,11 @@ include $(CHIBIOS)/os/common/ports/ARMv7-M/compilers/GCC/mk/port.mk
 # Auto-build files in ./source recursively.
 include $(CHIBIOS)/tools/mk/autobuild.mk
 # Other files (optional).
-#include $(CHIBIOS)/os/test/test.mk
-#include $(CHIBIOS)/test/rt/rt_test.mk
-#include $(CHIBIOS)/test/oslib/oslib_test.mk
+include $(CHIBIOS)/os/test/test.mk
+include $(CHIBIOS)/test/rt/rt_test.mk
+include $(CHIBIOS)/test/oslib/oslib_test.mk
+include $(CHIBIOS)/os/hal/lib/streams/streams.mk
+include $(CHIBIOS)/os/various/shell/shell.mk
 
 # Define linker script file here.
 LDSCRIPT= $(STARTUPLD)/STM32G474xE.ld
diff --git a/testhal/STM32/multi/SIO/make/stm32l476vg_discovery.make b/testhal/STM32/multi/SIO/make/stm32l476vg_discovery.make
index 7797d2b86..78ea40500 100644
--- a/testhal/STM32/multi/SIO/make/stm32l476vg_discovery.make
+++ b/testhal/STM32/multi/SIO/make/stm32l476vg_discovery.make
@@ -110,9 +110,11 @@ include $(CHIBIOS)/os/common/ports/ARMv7-M/compilers/GCC/mk/port.mk
 # Auto-build files in ./source recursively.
 include $(CHIBIOS)/tools/mk/autobuild.mk
 # Other files (optional).
-#include $(CHIBIOS)/os/test/test.mk
-#include $(CHIBIOS)/test/rt/rt_test.mk
-#include $(CHIBIOS)/test/oslib/oslib_test.mk
+include $(CHIBIOS)/os/test/test.mk
+include $(CHIBIOS)/test/rt/rt_test.mk
+include $(CHIBIOS)/test/oslib/oslib_test.mk
+include $(CHIBIOS)/os/hal/lib/streams/streams.mk
+include $(CHIBIOS)/os/various/shell/shell.mk
 
 # Define linker script file here.
 LDSCRIPT= $(STARTUPLD)/STM32L476xG.ld