ppc4xx: Initialize magnetic coupler on VOM405 boards

This patch fixes an ugly behavior of the IL712 magnetic coupler
as used on VOM405. These parts will remember their last state
over a power cycle which might cause unwanted behavior.
Signed-off-by: NMatthias Fuchs <matthias.fuchs@esd.eu>
Signed-off-by: NStefan Roese <sr@denx.de>

board/esd/vom405/vom405.c

@@ -26,11 +26,40 @@
 #include <asm/io.h>
 #include <command.h>
 #include <malloc.h>
+#include <sja1000.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
 extern void lxt971_no_sleep(void);
 
+/*
+ * generate a short spike on the CAN tx line
+ * to bring the couplers in sync
+ */
+void init_coupler(u32 addr)
+{
+	struct sja1000_basic_s *ctrl = (struct sja1000_basic_s *)addr;
+
+	/* reset */
+	out_8(&ctrl->cr, CR_RR);
+
+	/* dominant */
+	out_8(&ctrl->btr0, 0x00); /* btr setup is required */
+	out_8(&ctrl->btr1, 0x14); /* we use 1Mbit/s */
+	out_8(&ctrl->oc, OC_TP1 | OC_TN1 | OC_POL1 |
+	      OC_TP0 | OC_TN0 | OC_POL0 | OC_MODE1);
+	out_8(&ctrl->cr, 0x00);
+
+	/* delay */
+	in_8(&ctrl->cr);
+	in_8(&ctrl->cr);
+	in_8(&ctrl->cr);
+	in_8(&ctrl->cr);
+
+	/* reset */
+	out_8(&ctrl->cr, CR_RR);
+}
+
 int board_early_init_f (void)
 {
 	/*
@@ -77,6 +106,12 @@ int misc_init_r (void)
 	gd->bd->bi_flashstart = 0 - gd->bd->bi_flashsize;
 	gd->bd->bi_flashoffset = 0;
 
+	/*
+	 * Init magnetic coupler
+	 */
+	if (!getenv("noinitcoupler"))
+		init_coupler(CAN_BA);
+
 	return (0);
 }