[PATCH 5/7] smc911x: improve detection handle

[Jean-Christophe PLAGNIOL-VILLARD]

detect if the bus is swapped and report a 32bit drivers is used on a 16bit bus

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>
---
 drivers/net/smc911x.c |   20 +++++++++++++++++++-
 drivers/net/smc911x.h |    2 ++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/net/smc911x.c b/drivers/net/smc911x.c
index de2f388..67d82df 100644
--- a/drivers/net/smc911x.c
+++ b/drivers/net/smc911x.c
@@ -450,9 +450,27 @@ static int smc911x_probe(struct device_d *dev)
 	}
 
 	val = smc911x_reg_read(priv, BYTE_TEST);
-	if(val != 0x87654321) {
+	if (val == 0x43218765) {
+		dev_info(dev, "BYTE_TEST looks swapped, "
+			   "applying WORD_SWAP");
+		smc911x_reg_write(priv, WORD_SWAP, 0xffffffff);
+
+		/* 1 dummy read of BYTE_TEST is needed after a write to
+		 * WORD_SWAP before its contents are valid */
+		val = smc911x_reg_read(priv, BYTE_TEST);
+
+		val = smc911x_reg_read(priv, BYTE_TEST);
+	}
+
+	if (val != 0x87654321) {
 		dev_err(dev, "no smc911x found on 0x%p (byte_test=0x%08x)\n",
 			priv->base, val);
+		if (((val >> 16) & 0xFFFF) == (val & 0xFFFF)) {
+			dev_err(dev, "top 16 bits equal to bottom 16 bits\n");
+			dev_err(dev,
+				   "This may mean the chip is set "
+				   "for 32 bit while the bus is reading 16 bit\n");
+		}
 		return -ENODEV;
 	}
 
diff --git a/drivers/net/smc911x.h b/drivers/net/smc911x.h
index baf3598..d409247 100644
--- a/drivers/net/smc911x.h
+++ b/drivers/net/smc911x.h
@@ -26,6 +26,8 @@
  * of the Lan911x memory space
  */
 
+#define WORD_SWAP		0x98
+
 #define RX_DATA_FIFO		 0x00
 
 #define TX_DATA_FIFO		 0x20
-- 
1.7.10.4