Use DMA for transfers.

Author: martinling

firmware/hackrf_usb/usb_api_transceiver.c

@@ -27,6 +27,7 @@
 #include "operacake_sctimer.h"
 
 #include <libopencm3/cm3/vector.h>
+#include <libopencm3/lpc43xx/gpdma.h>
 #include "usb_buffer.h"
 #include "usb_api_m0_state.h"
 
@@ -40,6 +41,7 @@
 #include "usb.h"
 #include "usb_queue.h"
 #include "platform_detect.h"
+#include "gpdma.h"
 
 #include <stddef.h>
 #include <string.h>
@@ -50,7 +52,10 @@
 #define USB_TRANSFER_SIZE 0x4000
 #define DMA_TRANSFER_SIZE 0x2000
 
+#define DMA_CHANNEL 1
+
 uint32_t dma_started, usb_started, usb_completed;
+volatile bool dma_busy;
 
 typedef struct {
 	uint32_t freq_mhz;
@@ -320,6 +325,7 @@ void transceiver_shutdown(void)
 
 void transceiver_startup(const transceiver_mode_t mode)
 {
+	dma_busy = false;
 	dma_started = 0;
 	usb_started = 0;
 	usb_completed = 0;
@@ -409,15 +415,43 @@ usb_request_status_t usb_vendor_request_set_rx_overrun_limit(
 	return USB_REQUEST_STATUS_OK;
 }
 
-void transceiver_start_dma(void* src, void* dest, size_t size, void (*callback)(size_t))
+void transceiver_start_dma(void* src, void* dest, size_t size)
 {
-	memcpy(dest, src, size);
-	callback(size);
+	uint32_t num_transfers = size >> 2;
+	gpdma_controller_enable();
+	GPDMA_CSRCADDR(DMA_CHANNEL) = (uint32_t) src;
+	GPDMA_CDESTADDR(DMA_CHANNEL) = (uint32_t) dest;
+	GPDMA_CLLI(DMA_CHANNEL) = 0;
+	GPDMA_CCONTROL(DMA_CHANNEL) = GPDMA_CCONTROL_TRANSFERSIZE(num_transfers) |
+		GPDMA_CCONTROL_SBSIZE(7)                        // 256-transfer src bursts
+		| GPDMA_CCONTROL_DBSIZE(7)                      // 256-transfer dst bursts
+		| GPDMA_CCONTROL_SWIDTH(2)                      // 32-bit src transfers
+		| GPDMA_CCONTROL_DWIDTH(2)                      // 32-bit dst transfers
+		| GPDMA_CCONTROL_S(0)                           // AHB Master 0
+		| GPDMA_CCONTROL_D(1)                           // AHB Master 1
+		| GPDMA_CCONTROL_SI(1)                          // increment source
+		| GPDMA_CCONTROL_DI(1)                          // increment destination
+		| GPDMA_CCONTROL_PROT1(0)                       // user mode
+		| GPDMA_CCONTROL_PROT2(0)                       // not bufferable
+		| GPDMA_CCONTROL_PROT3(0)                       // not cacheable
+		| GPDMA_CCONTROL_I(1);                          // interrupt enabled
+	GPDMA_CCONFIG(DMA_CHANNEL) = GPDMA_CCONFIG_FLOWCNTRL(0) // memory-to-memory
+		| GPDMA_CCONFIG_IE(0)                           // no error interrupt
+		| GPDMA_CCONFIG_ITC(1) // terminal count interrupt
+		| GPDMA_CCONFIG_L(0)   // do not lock
+		| GPDMA_CCONFIG_H(0);  // do not halt
+	GPDMA_INTTCCLEAR = (1 << DMA_CHANNEL);
+	nvic_enable_irq(NVIC_DMA_IRQ);
+	gpdma_channel_enable(DMA_CHANNEL);
+	dma_busy = true;
 }
 
-void transceiver_dma_transfer_complete(size_t bytes_transferred)
+void dma_isr()
 {
-	m0_state.m4_count += bytes_transferred;
+	gpdma_channel_disable(DMA_CHANNEL);
+	GPDMA_INTTCCLEAR = (1 << DMA_CHANNEL);
+	m0_state.m4_count += DMA_TRANSFER_SIZE;
+	dma_busy = false;
 }
 
 void transceiver_bulk_transfer_complete(void* user_data, unsigned int bytes_transferred)
@@ -438,15 +472,14 @@ void rx_mode(uint32_t seq)
 		uint32_t data_available = data_gathered - dma_started;
 		uint32_t space_in_use = usb_completed - dma_completed;
 		uint32_t space_available = USB_BULK_BUFFER_SIZE - space_in_use;
-		if ((data_available >= DMA_TRANSFER_SIZE) &&
+		if (!dma_busy && (data_available >= DMA_TRANSFER_SIZE) &&
 		    (space_available >= DMA_TRANSFER_SIZE)) {
 			uint32_t samp_offset = dma_started & USB_SAMP_BUFFER_MASK;
 			uint32_t bulk_offset = dma_started & USB_BULK_BUFFER_MASK;
 			transceiver_start_dma(
 				&usb_samp_buffer[samp_offset],
 				&usb_bulk_buffer[bulk_offset],
-				DMA_TRANSFER_SIZE,
-				transceiver_dma_transfer_complete);
+				DMA_TRANSFER_SIZE);
 			dma_started += DMA_TRANSFER_SIZE;
 		}
 		if ((m0_state.m4_count - usb_started) >= USB_TRANSFER_SIZE) {
@@ -490,15 +523,14 @@ void tx_mode(uint32_t seq)
 		uint32_t data_available = usb_completed - dma_started;
 		uint32_t space_in_use = dma_completed - data_used;
 		uint32_t space_available = USB_SAMP_BUFFER_SIZE - space_in_use;
-		if ((data_available >= DMA_TRANSFER_SIZE) &&
+		if (!dma_busy && (data_available >= DMA_TRANSFER_SIZE) &&
 		    (space_available >= DMA_TRANSFER_SIZE)) {
 			uint32_t samp_offset = dma_started & USB_SAMP_BUFFER_MASK;
 			uint32_t bulk_offset = dma_started & USB_BULK_BUFFER_MASK;
 			transceiver_start_dma(
 				&usb_bulk_buffer[bulk_offset],
 				&usb_samp_buffer[samp_offset],
-				DMA_TRANSFER_SIZE,
-				transceiver_dma_transfer_complete);
+				DMA_TRANSFER_SIZE);
 			dma_started += DMA_TRANSFER_SIZE;
 		}
 		if ((usb_started - m0_state.m4_count) <= USB_TRANSFER_SIZE) {