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drivers: serial: stm32 uart check baudrate register value

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The baudrate register (BRR) of a stm32 USART cannot be lower than 16.
The baudrate register (BRR) of a stm32 LPUART cannot be lower than 0x300
and greater than 0xFFFFF.
Add assertion to check the range.
This could be the case when configuring a baudrate of 9600 on usart
clocked by LSE (32768Hz).

Signed-off-by: Francois Ramu <francois.ramu@st.com>
This commit is contained in:
Francois Ramu 2022-09-08 17:26:29 +02:00 • committed by Carles Cufí
commit 7b95803218
1 changed files with 10 additions and 0 deletions
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10
drivers/serial/uart_stm32.c
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@ -159,6 +159,13 @@ static inline void uart_stm32_set_baudrate(const struct device *dev, uint32_t ba
presc_val,
#endif
baud_rate);
/* Check BRR is greater than or equal to 0x300 */
__ASSERT(LL_LPUART_ReadReg(config->usart, BRR) >= 0x300U,
"BaudRateReg >= 0x300");
/* Check BRR is lower than or equal to 0xFFFFF */
__ASSERT(LL_LPUART_ReadReg(config->usart, BRR) < 0x000FFFFFU,
"BaudRateReg < 0xFFFF");
} else {
#endif /* HAS_LPUART_1 */
#ifdef USART_CR1_OVER8
@ -174,6 +181,9 @@ static inline void uart_stm32_set_baudrate(const struct device *dev, uint32_t ba
LL_USART_OVERSAMPLING_16,
#endif
baud_rate);
/* Check BRR is greater than or equal to 16d */
__ASSERT(LL_USART_ReadReg(config->usart, BRR) > 16,
"BaudRateReg >= 16");
#if HAS_LPUART_1
}