sc3c94: implement real DMA.

devices/common/scsi/sc53c94.cpp

@@ -602,6 +602,35 @@ bool Sc53C94::rcv_data()
     return true;
 }
 
+void Sc53C94::real_dma_xfer(int direction)
+{
+    bool is_done = false;
+
+    if (direction) {
+        ABORT_F("Sc53C94: real DMA transfers from host to target not implemented yet");
+    } else { // transfer data from target to host's memory
+        while (this->xfer_count) {
+            if (this->data_fifo_pos) {
+                this->dma_ch->push_data((char*)this->data_fifo, this->data_fifo_pos);
+
+                this->xfer_count -= this->data_fifo_pos;
+                this->data_fifo_pos = 0;
+                if (!this->xfer_count) {
+                    is_done = true;
+                    this->status |= STAT_TC; // signal zero transfer count
+                    this->cur_state = SeqState::XFER_END;
+                    this->sequencer();
+                }
+            }
+
+            // see if we need to refill FIFO
+            if (!this->data_fifo_pos && !is_done) {
+                this->sequencer();
+            }
+        }
+    }
+}
+
 static const DeviceDescription Sc53C94_Descriptor = {
     Sc53C94::create, {}, {}
 };

devices/common/scsi/sc53c94.h

@@ -29,6 +29,7 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 #ifndef SC_53C94_H
 #define SC_53C94_H
 
+#include <devices/common/dmacore.h>
 #include <devices/common/scsi/scsi.h>
 #include <devices/common/hwinterrupt.h>
 
@@ -160,6 +161,13 @@ public:
     void     write(uint8_t reg_offset, uint8_t value);
     uint16_t pseudo_dma_read();
 
+    // real DMA control
+    void     real_dma_xfer(int direction);
+
+    void set_dma_channel(DmaBidirChannel *dma_ch) {
+        this->dma_ch = dma_ch;
+    };
+
     // ScsiDevice methods
     void notify(ScsiBus* bus_obj, ScsiMsg msg_type, int param);
     bool prepare_data() { return false; };
@@ -220,6 +228,9 @@ private:
     InterruptCtrl* int_ctrl = nullptr;
     uint32_t       irq_id   = 0;
     uint8_t        irq      = 0;
+
+    // DMA related stuff
+    DmaBidirChannel*    dma_ch;
 };
 
 #endif // SC_53C94_H