ibm_newemac: Allow the "no flow control" EMAC feature to work

Some PowerPC 40x chips have errata that force us not to use the integrated
flow control.  We have the feature defined, but it currently can't be used
because it is never added to EMAC_FTRS_POSSIBLE.

This adds a Kconfig option for affected platforms to select and puts the
feature in the EMAC_FTRS_POSSIBLE list.  This is set for PowerPC 405EZ
platforms as well.
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>

drivers/net/ibm_newemac/Kconfig

@@ -62,3 +62,7 @@ config IBM_NEW_EMAC_TAH
 config IBM_NEW_EMAC_EMAC4
 	bool
 	default n
+
+config IBM_NEW_EMAC_NO_FLOW_CTRL
+	bool
+	default n

drivers/net/ibm_newemac/core.c

@@ -2567,6 +2567,8 @@ static int __devinit emac_init_config(struct emac_instance *dev)
 		if (of_device_is_compatible(np, "ibm,emac-440ep") ||
 		    of_device_is_compatible(np, "ibm,emac-440gr"))
 			dev->features |= EMAC_FTR_440EP_PHY_CLK_FIX;
+		if (of_device_is_compatible(np, "ibm,emac-405ez"))
+			dev->features |= EMAC_FTR_NO_FLOW_CONTROL_40x;
 	}
 
 	/* Fixup some feature bits based on the device tree */

drivers/net/ibm_newemac/core.h

@@ -340,6 +340,9 @@ enum {
 #endif
 #ifdef CONFIG_IBM_NEW_EMAC_RGMII
 	    EMAC_FTR_HAS_RGMII	|
+#endif
+#ifdef CONFIG_IBM_NEW_EMAC_NO_FLOW_CTRL
+	    EMAC_FTR_NO_FLOW_CONTROL_40x |
 #endif
 	EMAC_FTR_440EP_PHY_CLK_FIX,
 };