net: smc911x: Determine bus width at runtime

The SMC911x Ethernet MACs can be integrated using a 16 or 32-bit bus.
The driver needs to know about this choice, which is the reason for us
having a Kconfig symbol for that.

Now this bus width is already described using a devicetree property, and
since the driver is DM compliant and is using the DT now, we should query
this at runtime. We leave the Kconfig choice around, in case the DT is
missing this property.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/drivers/net/smc911x.c b/drivers/net/smc911x.c
index d596d96..3afebee 100644
--- a/drivers/net/smc911x.c
+++ b/drivers/net/smc911x.c
@@ -28,6 +28,7 @@
 	phys_addr_t		iobase;
 	const struct chip_id	*chipid;
 	unsigned char		enetaddr[6];
+	bool			use_32_bit_io;
 };
 
 static const struct chip_id chip_ids[] =  {
@@ -48,28 +49,24 @@
 
 #define DRIVERNAME "smc911x"
 
-#if defined (CONFIG_SMC911X_32_BIT)
 static u32 smc911x_reg_read(struct smc911x_priv *priv, u32 offset)
 {
-	return readl(priv->iobase + offset);
+	if (priv->use_32_bit_io)
+		return readl(priv->iobase + offset);
+
+	return (readw(priv->iobase + offset) & 0xffff) |
+	       (readw(priv->iobase + offset + 2) << 16);
 }
 
 static void smc911x_reg_write(struct smc911x_priv *priv, u32 offset, u32 val)
 {
-	writel(val, priv->iobase + offset);
+	if (priv->use_32_bit_io) {
+		writel(val, priv->iobase + offset);
+	} else {
+		writew(val & 0xffff, priv->iobase + offset);
+		writew(val >> 16, priv->iobase + offset + 2);
+	}
 }
-#else
-static u32 smc911x_reg_read(struct smc911x_priv *priv, u32 offset)
-{
-	return (readw(priv->iobase + offset) & 0xffff) |
-	       (readw(priv->iobase + offset + 2) << 16);
-}
-static void smc911x_reg_write(struct smc911x_priv *priv, u32 offset, u32 val)
-{
-	writew(val & 0xffff, priv->iobase + offset);
-	writew(val >> 16, priv->iobase + offset + 2);
-}
-#endif /* CONFIG_SMC911X_32_BIT */
 
 static u32 smc911x_get_mac_csr(struct smc911x_priv *priv, u8 reg)
 {
@@ -493,6 +490,8 @@
 	priv->iobase = base_addr;
 	priv->dev.iobase = base_addr;
 
+	priv->use_32_bit_io = CONFIG_IS_ENABLED(SMC911X_32_BIT);
+
 	/* Try to detect chip. Will fail if not present. */
 	ret = smc911x_detect_chip(priv);
 	if (ret) {
@@ -603,10 +602,18 @@
 {
 	struct smc911x_priv *priv = dev_get_priv(dev);
 	struct eth_pdata *pdata = dev_get_plat(dev);
+	u32 io_width;
+	int ret;
 
 	pdata->iobase = dev_read_addr(dev);
 	priv->iobase = pdata->iobase;
 
+	ret = dev_read_u32(dev, "reg-io-width", &io_width);
+	if (!ret)
+		priv->use_32_bit_io = (io_width == 4);
+	else
+		priv->use_32_bit_io = CONFIG_IS_ENABLED(SMC911X_32_BIT);
+
 	return 0;
 }