dma-debug: add dma_debug_driver kernel command line

This patch add the dma_debug_driver= boot parameter to enable the driver
filter for early boot.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index c6330b1..d0618aa 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -1109,3 +1109,21 @@
 }
 EXPORT_SYMBOL(debug_dma_sync_sg_for_device);
 
+static int __init dma_debug_driver_setup(char *str)
+{
+	int i;
+
+	for (i = 0; i < NAME_MAX_LEN - 1; ++i, ++str) {
+		current_driver_name[i] = *str;
+		if (*str == 0)
+			break;
+	}
+
+	if (current_driver_name[0])
+		printk(KERN_INFO "DMA-API: enable driver filter for "
+				 "driver [%s]\n", current_driver_name);
+
+
+	return 1;
+}
+__setup("dma_debug_driver=", dma_debug_driver_setup);