spi: ti_qspi: Use DMA to read from qspi flash

ti_qspi uses memory map mode for faster read. Enabling DMA will increase
read speed by 3x @48MHz on DRA74 EVM.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Reviewed-by: Jagan Teki <jteki@openedev.com>

drivers/spi/ti_qspi.c

@@ -13,6 +13,8 @@
 #include <spi.h>
 #include <asm/gpio.h>
 #include <asm/omap_gpio.h>
+#include <asm/omap_common.h>
+#include <asm/ti-common/ti-edma3.h>
 
 /* ti qpsi register bit masks */
 #define QSPI_TIMEOUT                    2000000
@@ -347,3 +349,26 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
 
 	return 0;
 }
+
+/* TODO: control from sf layer to here through dm-spi */
+#ifdef CONFIG_TI_EDMA3
+void spi_flash_copy_mmap(void *data, void *offset, size_t len)
+{
+	unsigned int			addr = (unsigned int) (data);
+	unsigned int			edma_slot_num = 1;
+
+	/* Invalidate the area, so no writeback into the RAM races with DMA */
+	invalidate_dcache_range(addr, addr + roundup(len, ARCH_DMA_MINALIGN));
+
+	/* enable edma3 clocks */
+	enable_edma3_clocks();
+
+	/* Call edma3 api to do actual DMA transfer	*/
+	edma3_transfer(EDMA3_BASE, edma_slot_num, data, offset, len);
+
+	/* disable edma3 clocks */
+	disable_edma3_clocks();
+
+	*((unsigned int *)offset) += len;
+}
+#endif