From 8e00dd00cbc42cd341eaabc6df0f0a4f815b64bb Mon Sep 17 00:00:00 2001
From: ALTracer <11005378+ALTracer@users.noreply.github.com>
Date: Thu, 22 Aug 2024 07:15:39 +0300
Subject: [PATCH] stm32: usart: extend LPUART clock range

---
 lib/stm32/common/usart_common_all.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/stm32/common/usart_common_all.c b/lib/stm32/common/usart_common_all.c
index cfbdc74ab3..40c80e505b 100644
--- a/lib/stm32/common/usart_common_all.c
+++ b/lib/stm32/common/usart_common_all.c
@@ -97,6 +97,9 @@ void usart_set_baudrate(uint32_t usart, uint32_t baud)
 /*---------------------------------------------------------------------------*/
 /** @brief USART Get Baudrate.
 
+Note: For LPUART, baudrates over 2**24 (~16.7 Mbaud) may overflow
+the calculation and are therefore not supported by this function.
+
 @param[in] usart unsigned 32 bit. USART block register address base @ref usart_reg_base
 @returns baud unsigned 32 bit. Baud rate specified in Hz.
 */
@@ -108,7 +111,8 @@ uint32_t usart_get_baudrate(uint32_t usart)
 
 #ifdef LPUART1
 	if (usart == LPUART1) {
-		return (256U * clock) / reg_brr;
+		return (clock / reg_brr) * 256
+			+ ((clock % reg_brr) * 256) / reg_brr;
 	}
 #endif