From 477c410be413aac0ff88b583fd7efc7873ef4768 Mon Sep 17 00:00:00 2001
From: Fergus Noble <fergusnoble@gmail.com>
Date: Tue, 31 Jan 2012 15:11:46 -0800
Subject: [PATCH] Added functions to enable and disable DMA from stm32 USART.

---
 include/libopencm3/stm32/usart.h |  4 ++++
 lib/stm32/usart.c                | 21 +++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/include/libopencm3/stm32/usart.h b/include/libopencm3/stm32/usart.h
index df6bc089..cbf622c2 100644
--- a/include/libopencm3/stm32/usart.h
+++ b/include/libopencm3/stm32/usart.h
@@ -308,5 +308,9 @@ void usart_wait_send_ready(u32 usart);
 void usart_wait_recv_ready(u32 usart);
 void usart_send_blocking(u32 usart, u16 data);
 u16 usart_recv_blocking(u32 usart);
+void usart_enable_rx_dma(u32 usart);
+void usart_disable_rx_dma(u32 usart);
+void usart_enable_tx_dma(u32 usart);
+void usart_disable_tx_dma(u32 usart);
 
 #endif
diff --git a/lib/stm32/usart.c b/lib/stm32/usart.c
index a2c9f16c..7995a527 100644
--- a/lib/stm32/usart.c
+++ b/lib/stm32/usart.c
@@ -148,3 +148,24 @@ u16 usart_recv_blocking(u32 usart)
 
 	return usart_recv(usart);
 }
+
+void usart_enable_rx_dma(u32 usart)
+{
+  USART_CR3(usart) |= USART_CR3_DMAR;
+}
+
+void usart_disable_rx_dma(u32 usart)
+{
+  USART_CR3(usart) &= ~USART_CR3_DMAR;
+}
+
+void usart_enable_tx_dma(u32 usart)
+{
+  USART_CR3(usart) |= USART_CR3_DMAT;
+}
+
+void usart_disable_tx_dma(u32 usart)
+{
+  USART_CR3(usart) &= ~USART_CR3_DMAT;
+}
+