[RFC][PATCH] PowerPC 4xx: ibm_newemac 440GX phy clock workaround.

[Valentine Barshak]

The PowerPC 440GX Taishan board fails to reset EMAC3 (reset timeout error)
and because of that it can't find PHY chip. The older ibm_emac driver had
a workaround for that: the EMAC_CLK_INTERNAL/EMAC_CLK_EXTERNAL macros which
toggle the Ethernet Clock Select bit in the SDR0_MFR register. This patch
does the same for "ibm,emac-440gx" compatible chips.

Signed-off-by: Valentine Barshak <vbarshak at ru.mvista.com>
---
 drivers/net/ibm_newemac/core.c |   16 +++++++++++++++-
 drivers/net/ibm_newemac/core.h |    8 ++++++--
 2 files changed, 21 insertions(+), 3 deletions(-)

diff -pruN linux-2.6.orig/drivers/net/ibm_newemac/core.c linux-2.6/drivers/net/ibm_newemac/core.c
--- linux-2.6.orig/drivers/net/ibm_newemac/core.c	2008-02-21 16:45:36.000000000 +0300
+++ linux-2.6/drivers/net/ibm_newemac/core.c	2008-02-21 17:21:21.000000000 +0300
@@ -43,6 +43,8 @@
 #include <asm/io.h>
 #include <asm/dma.h>
 #include <asm/uaccess.h>
+#include <asm/dcr.h>
+#include <asm/dcr-regs.h>
 
 #include "core.h"
 
@@ -2480,8 +2482,11 @@ static int __devinit emac_init_config(st
 	}
 
 	/* Check EMAC version */
-	if (of_device_is_compatible(np, "ibm,emac4"))
+	if (of_device_is_compatible(np, "ibm,emac4")) {
 		dev->features |= EMAC_FTR_EMAC4;
+		if (of_device_is_compatible(np, "ibm,emac-440gx"))
+			dev->features |= EMAC_FTR_440GX_PHY_CLK_FIX;
+	}
 
 	/* Fixup some feature bits based on the device tree */
 	if (of_get_property(np, "has-inverted-stacr-oc", NULL))
@@ -2673,8 +2678,17 @@ static int __devinit emac_probe(struct o
 	dev->stop_timeout = STOP_TIMEOUT_100;
 	INIT_DELAYED_WORK(&dev->link_work, emac_link_timer);
 
+	/* Enable internal phy clock source */
+	if (emac_has_feature(dev, EMAC_FTR_440GX_PHY_CLK_FIX))
+		mtdcri(SDR0, SDR0_MFR, mfdcri(SDR0, SDR0_MFR) | SDR0_MFR_ECS);
+
 	/* Find PHY if any */
 	err = emac_init_phy(dev);
+
+	/* Enable external phy clock source */
+	if (emac_has_feature(dev, EMAC_FTR_440GX_PHY_CLK_FIX))
+		mtdcri(SDR0, SDR0_MFR, mfdcri(SDR0, SDR0_MFR) & ~SDR0_MFR_ECS);
+
 	if (err != 0)
 		goto err_detach_tah;
 
diff -pruN linux-2.6.orig/drivers/net/ibm_newemac/core.h linux-2.6/drivers/net/ibm_newemac/core.h
--- linux-2.6.orig/drivers/net/ibm_newemac/core.h	2008-02-21 16:45:36.000000000 +0300
+++ linux-2.6/drivers/net/ibm_newemac/core.h	2008-02-21 17:21:47.000000000 +0300
@@ -301,6 +301,10 @@ struct emac_instance {
  * Set if we have new type STACR with STAOPC
  */
 #define EMAC_FTR_HAS_NEW_STACR		0x00000040
+/*
+ * Set if we need phy clock workaround for 440gx
+ */
+#define EMAC_FTR_440GX_PHY_CLK_FIX	0x00000080
 
 
 /* Right now, we don't quite handle the always/possible masks on the
@@ -312,8 +316,8 @@ enum {
 
 	EMAC_FTRS_POSSIBLE	=
 #ifdef CONFIG_IBM_NEW_EMAC_EMAC4
-	    EMAC_FTR_EMAC4	| EMAC_FTR_HAS_NEW_STACR	|
-	    EMAC_FTR_STACR_OC_INVERT	|
+	    EMAC_FTR_EMAC4 | EMAC_FTR_HAS_NEW_STACR |
+	    EMAC_FTR_STACR_OC_INVERT | EMAC_FTR_440GX_PHY_CLK_FIX |
 #endif
 #ifdef CONFIG_IBM_NEW_EMAC_TAH
 	    EMAC_FTR_HAS_TAH	|