Mirror/betaflight
1
0
Fork 0
mirror of https://github.com/betaflight/betaflight.git synced 2025-07-13 03:20:00 +03:00
Code Issues Wiki Activity

[H7][LIB][SPI] Use union to access size sensitive SPI data register

Browse source 
Application of

Use union to access access size sensitive registers (7a0d3e7)

to V1.4.0

----
Note from "Use union to access access size sensitive registers (7a0d3e7)":
----

Use union to access access size sensitive registers

As described in RM0433 section 49.4.13 "Data packing", STM32H7's SPI data register supports data packing and it is sensitive to actual access width.

The original code used pointer casting to obtain a code to access the register in a desired size.
However, these operation results in strict aliasing warnings (deferencing punned pointer) and are not desirable.

Here, we declare a union that allow access to a 32-bit register in 8, 16 or 32-bit width and cast pointer to the original RXDR and TXDR data registers and then access the portion of the register through an appropriate union member.

XXX FIXME Only handled 16-bit access case, as 32-bit (original declaration) and 8-bit (allowed) cases do not generate warnings, but these should be handled similarly for correctness and consistency of the code.
This commit is contained in:
jflyper 2019-04-20 18:48:43 +09:00
parent 8bbc1456f3
commit 6fbc0f44ca
1 changed files with 35 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

46
lib/main/STM32H7/Drivers/STM32H7xx_HAL_Driver/Src/stm32h7xx_hal_spi.c
View file

@ -178,6 +178,30 @@ static void SPI_AbortTransfer(SPI_HandleTypeDef *hspi);
static void SPI_CloseTransfer(SPI_HandleTypeDef *hspi); static void SPI_CloseTransfer(SPI_HandleTypeDef *hspi);
static uint32_t SPI_GetPacketSize(SPI_HandleTypeDef *hspi); static uint32_t SPI_GetPacketSize(SPI_HandleTypeDef *hspi);
/*
* Notes on variable size access to data registers (by jflyper@github.com)
*
* As described in RM0433 section 49.4.13 "Data packing", STM32H7's SPI data register
* supports data packing and it is sensitive to actual access width.
* The original code used pointer casting to obtain a code to access the register in
* a desired size.
* However, these operation results in strict aliasing warnings (deferencing punned pointer)
* and are not desirable.
*
* Here, we declare a union that allow access to a 32-bit register in 8, 16 or 32-bit width
* and cast pointer to the original RXDR and TXDR data registers and then access the
* portion of the register through an appropriate union member.
*
* XXX FIXME Only handled 16-bit access case, as 32-bit (original declaration) and 8-bit
* (allowed) cases do not generate warnings, but these should be handled similarly for
* correct-ness and consistency of the code.
*/
typedef union {
__IO uint32_t u_reg32;
__IO uint16_t u_reg16;
__IO uint8_t u_reg8;
} reg_u;
/** /**
* @} * @}
@ -882,7 +906,7 @@ HAL_StatusTypeDef HAL_SPI_Transmit(SPI_HandleTypeDef *hspi, const uint8_t *pData
} }
else else
{ {
*((__IO uint16_t *)&hspi->Instance->TXDR) = *((uint16_t *)hspi->pTxBuffPtr); ((reg_u *)&hspi->Instance->TXDR)->u_reg16 = *((uint16_t *)hspi->pTxBuffPtr);
hspi->pTxBuffPtr += sizeof(uint16_t); hspi->pTxBuffPtr += sizeof(uint16_t);
hspi->TxXferCount--; hspi->TxXferCount--;
} }
@ -921,7 +945,7 @@ HAL_StatusTypeDef HAL_SPI_Transmit(SPI_HandleTypeDef *hspi, const uint8_t *pData
} }
else if ((hspi->TxXferCount > 1UL) && (hspi->Init.FifoThreshold > SPI_FIFO_THRESHOLD_01DATA)) else if ((hspi->TxXferCount > 1UL) && (hspi->Init.FifoThreshold > SPI_FIFO_THRESHOLD_01DATA))
{ {
*((__IO uint16_t *)&hspi->Instance->TXDR) = *((uint16_t *)hspi->pTxBuffPtr); ((reg_u *)&hspi->Instance->TXDR)->u_reg16 = *((uint16_t *)hspi->pTxBuffPtr);
hspi->pTxBuffPtr += sizeof(uint16_t); hspi->pTxBuffPtr += sizeof(uint16_t);
hspi->TxXferCount -= (uint16_t)2UL; hspi->TxXferCount -= (uint16_t)2UL;
} }
@ -1096,7 +1120,7 @@ HAL_StatusTypeDef HAL_SPI_Receive(SPI_HandleTypeDef *hspi, uint8_t *pData, uint1
} }
else else
{ {
*((uint16_t *)hspi->pRxBuffPtr) = *((__IO uint16_t *)&hspi->Instance->RXDR); *((uint16_t *)hspi->pRxBuffPtr) = ((reg_u *)&hspi->Instance->RXDR)->u_reg16;
hspi->pRxBuffPtr += sizeof(uint16_t); hspi->pRxBuffPtr += sizeof(uint16_t);
hspi->RxXferCount--; hspi->RxXferCount--;
} }
@ -1136,7 +1160,7 @@ HAL_StatusTypeDef HAL_SPI_Receive(SPI_HandleTypeDef *hspi, uint8_t *pData, uint1
} }
else if ((hspi->Instance->SR & SPI_FLAG_FRLVL) > SPI_RX_FIFO_1PACKET) else if ((hspi->Instance->SR & SPI_FLAG_FRLVL) > SPI_RX_FIFO_1PACKET)
{ {
*((uint16_t *)hspi->pRxBuffPtr) = *((__IO uint16_t *)&hspi->Instance->RXDR); *((uint16_t *)hspi->pRxBuffPtr) = ((reg_u *)&hspi->Instance->RXDR)->u_reg16;
hspi->pRxBuffPtr += sizeof(uint16_t); hspi->pRxBuffPtr += sizeof(uint16_t);
hspi->RxXferCount -= (uint16_t)2UL; hspi->RxXferCount -= (uint16_t)2UL;
} }
@ -1327,7 +1351,7 @@ HAL_StatusTypeDef HAL_SPI_TransmitReceive(SPI_HandleTypeDef *hspi, const uint8_t
} }
else else
{ {
*((__IO uint16_t *)&hspi->Instance->TXDR) = *((uint16_t *)hspi->pTxBuffPtr); ((reg_u *)&hspi->Instance->TXDR)->u_reg16 = *((uint16_t *)hspi->pTxBuffPtr);
hspi->pTxBuffPtr += sizeof(uint16_t); hspi->pTxBuffPtr += sizeof(uint16_t);
hspi->TxXferCount--; hspi->TxXferCount--;
initial_TxXferCount = hspi->TxXferCount; initial_TxXferCount = hspi->TxXferCount;
@ -1346,7 +1370,7 @@ HAL_StatusTypeDef HAL_SPI_TransmitReceive(SPI_HandleTypeDef *hspi, const uint8_t
} }
else else
{ {
*((uint16_t *)hspi->pRxBuffPtr) = *((__IO uint16_t *)&hspi->Instance->RXDR); *((uint16_t *)hspi->pRxBuffPtr) = ((reg_u *)&hspi->Instance->RXDR)->u_reg16;
hspi->pRxBuffPtr += sizeof(uint16_t); hspi->pRxBuffPtr += sizeof(uint16_t);
hspi->RxXferCount--; hspi->RxXferCount--;
initial_RxXferCount = hspi->RxXferCount; initial_RxXferCount = hspi->RxXferCount;
@ -1385,7 +1409,7 @@ HAL_StatusTypeDef HAL_SPI_TransmitReceive(SPI_HandleTypeDef *hspi, const uint8_t
} }
else if ((initial_TxXferCount > 1UL) && (hspi->Init.FifoThreshold > SPI_FIFO_THRESHOLD_01DATA)) else if ((initial_TxXferCount > 1UL) && (hspi->Init.FifoThreshold > SPI_FIFO_THRESHOLD_01DATA))
{ {
*((__IO uint16_t *)&hspi->Instance->TXDR) = *((uint16_t *)hspi->pTxBuffPtr); ((reg_u *)&hspi->Instance->TXDR)->u_reg16 = *((uint16_t *)hspi->pTxBuffPtr);
hspi->pTxBuffPtr += sizeof(uint16_t); hspi->pTxBuffPtr += sizeof(uint16_t);
hspi->TxXferCount -= (uint16_t)2UL; hspi->TxXferCount -= (uint16_t)2UL;
initial_TxXferCount = hspi->TxXferCount; initial_TxXferCount = hspi->TxXferCount;
@ -1411,7 +1435,7 @@ HAL_StatusTypeDef HAL_SPI_TransmitReceive(SPI_HandleTypeDef *hspi, const uint8_t
} }
else if ((hspi->Instance->SR & SPI_FLAG_FRLVL) > SPI_RX_FIFO_1PACKET) else if ((hspi->Instance->SR & SPI_FLAG_FRLVL) > SPI_RX_FIFO_1PACKET)
{ {
*((uint16_t *)hspi->pRxBuffPtr) = *((__IO uint16_t *)&hspi->Instance->RXDR); *((uint16_t *)hspi->pRxBuffPtr) = ((reg_u *)&hspi->Instance->RXDR)->u_reg16;
hspi->pRxBuffPtr += sizeof(uint16_t); hspi->pRxBuffPtr += sizeof(uint16_t);
hspi->RxXferCount -= (uint16_t)2UL; hspi->RxXferCount -= (uint16_t)2UL;
initial_RxXferCount = hspi->RxXferCount; initial_RxXferCount = hspi->RxXferCount;
@ -2783,7 +2807,7 @@ void HAL_SPI_IRQHandler(SPI_HandleTypeDef *hspi)
/* Receive data in 16 Bit mode */ /* Receive data in 16 Bit mode */
else if (hspi->Init.DataSize > SPI_DATASIZE_8BIT) else if (hspi->Init.DataSize > SPI_DATASIZE_8BIT)
{ {
*((uint16_t *)hspi->pRxBuffPtr) = *((__IO uint16_t *)&hspi->Instance->RXDR); *((uint16_t *)hspi->pRxBuffPtr) = ((reg_u *)&hspi->Instance->RXDR)->u_reg16;
hspi->pRxBuffPtr += sizeof(uint16_t); hspi->pRxBuffPtr += sizeof(uint16_t);
} }
/* Receive data in 8 Bit mode */ /* Receive data in 8 Bit mode */
@ -3431,7 +3455,7 @@ static void SPI_RxISR_8BIT(SPI_HandleTypeDef *hspi)
static void SPI_RxISR_16BIT(SPI_HandleTypeDef *hspi) static void SPI_RxISR_16BIT(SPI_HandleTypeDef *hspi)
{ {
/* Receive data in 16 Bit mode */ /* Receive data in 16 Bit mode */
*((uint16_t *)hspi->pRxBuffPtr) = (*(__IO uint16_t *)&hspi->Instance->RXDR); *((uint16_t *)hspi->pRxBuffPtr) = ((reg_u *)&hspi->Instance->RXDR)->u_reg16;
hspi->pRxBuffPtr += sizeof(uint16_t); hspi->pRxBuffPtr += sizeof(uint16_t);
hspi->RxXferCount--; hspi->RxXferCount--;
@ -3541,7 +3565,7 @@ static void SPI_TxISR_8BIT(SPI_HandleTypeDef *hspi)
static void SPI_TxISR_16BIT(SPI_HandleTypeDef *hspi) static void SPI_TxISR_16BIT(SPI_HandleTypeDef *hspi)
{ {
/* Transmit data in 16 Bit mode */ /* Transmit data in 16 Bit mode */
*((__IO uint16_t *)&hspi->Instance->TXDR) = *((uint16_t *)hspi->pTxBuffPtr); ((reg_u *)&hspi->Instance->TXDR)->u_reg16 = *((uint16_t *)hspi->pTxBuffPtr);
hspi->pTxBuffPtr += sizeof(uint16_t); hspi->pTxBuffPtr += sizeof(uint16_t);
hspi->TxXferCount--; hspi->TxXferCount--;