From 457fac0997eb8dbbaac913c15a8659637e58f186 Mon Sep 17 00:00:00 2001
From: Michael Hope <michaelh@juju.net.nz>
Date: Wed, 20 Oct 2010 20:53:43 +1300
Subject: Added basic DMA support

---
 libmaple/dma.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 libmaple/dma.c

(limited to 'libmaple/dma.c')

diff --git a/libmaple/dma.c b/libmaple/dma.c
new file mode 100644
index 0000000..4ad7fd2
--- /dev/null
+++ b/libmaple/dma.c
@@ -0,0 +1,104 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 Michael Hope.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *****************************************************************************/
+
+/**
+ *  @file dma.c
+ *
+ *  @brief Direct Memory Access peripheral support
+ */
+
+#include "libmaple.h"
+#include "dma.h"
+#include "rcc.h"
+
+#define DMA_EN    BIT(0)
+
+typedef struct dma_regs
+{
+    uint32 CCR;
+    uint32 CNDTR;
+    uint32 CPAR;
+    uint32 CMAR;
+} dma_regs;
+
+/** Get the base address of the given channel, asserting and returning
+ * NULL on illegal
+ */
+static dma_regs *dma_get_regs(uint8 channel) {
+    if (channel >= 1 && channel <= 7) {
+        return (dma_regs *)(DMA1_CCR1 + DMA_CHANNEL_STRIDE * (channel-1));
+    }
+    else {
+        ASSERT(false);
+        return NULL;
+    }
+}
+
+/** Initialise a DMA channel.  Start the transfer using dma_start().
+ *
+ *  @param channel          the channel number (1..7)
+ *  @param peripheral       address of the peripheral
+ *  @param from_peripheral  true if transfer goes from the peripheral
+ *                          to memory
+ *  @param mode             OR of the dma_mode_flags
+ */
+void dma_init(uint8 channel, volatile void *peripheral, bool from_peripheral, enum dma_mode_flags mode) {
+    volatile dma_regs *regs = dma_get_regs(channel);
+
+    if (regs != NULL) {
+        rcc_clk_enable(RCC_DMA1);
+
+        /* Disable the channel.  PENDING: May not be needed */
+        regs->CCR = 0;
+
+        uint32 cr = 0
+                | (0 << 12)   // Low priority
+                | (0 << 10)   // Memory size = 8 bits
+                | (1 <<  8)   // Peripheral size = 16 bits
+                | (mode << 5) // Increment and circular modes
+                | (0 << 0);   // Not enabled
+
+        regs->CPAR = peripheral;
+
+        if (!from_peripheral) {
+            cr |= 1 << 4; // From memory
+        }
+
+        /* Stay disabled until started */
+        regs->CCR = cr;
+    }
+}
+
+void dma_start(uint8 channel, volatile void *buffer, uint16 count)
+{
+    volatile dma_regs *regs = dma_get_regs(channel);
+
+    if (regs != NULL) {
+        regs->CCR &= ~DMA_EN;
+        regs->CMAR = (uint32)buffer;
+        regs->CNDTR = count;
+
+        regs->CCR |= DMA_EN;
+    }
+}
-- 
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