net: smc91x: Fix device tree based configuration so it's usable

Commit 89ce376c (drivers/net: Use of_match_ptr() macro in smc91x.c)
added minimal device tree support to smc91x, but it's not working on
many platforms because of the lack of some key configuration bits.

Fix the issue by parsing the necessary configuration like the
smc911x driver is doing. As most smc91x users seem to use 16-bit
access, let's default to that if no reg-io-width is specified.

Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: netdev@vger.kernel.org
Cc: devicetree@vger.kernel.org
Acked-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/smsc-lan91c111.txt

@@ -8,3 +8,7 @@ Required properties:
 Optional properties:
 - phy-device : phandle to Ethernet phy
 - local-mac-address : Ethernet mac address to use
+- reg-io-width : Mask of sizes (in bytes) of the IO accesses that
+  are supported on the device.  Valid value for SMSC LAN91c111 are
+  1, 2 or 4.  If it's omitted or invalid, the size would be 2 meaning
+  16-bit access only.

drivers/net/ethernet/smsc/smc91x.c

@@ -82,6 +82,7 @@ static const char version[] =
 #include <linux/mii.h>
 #include <linux/workqueue.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
@@ -2184,6 +2185,15 @@ static void smc_release_datacs(struct platform_device *pdev, struct net_device *
 	}
 }
 
+#if IS_BUILTIN(CONFIG_OF)
+static const struct of_device_id smc91x_match[] = {
+	{ .compatible = "smsc,lan91c94", },
+	{ .compatible = "smsc,lan91c111", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, smc91x_match);
+#endif
+
 /*
  * smc_init(void)
  *   Input parameters:
@@ -2198,6 +2208,7 @@ static void smc_release_datacs(struct platform_device *pdev, struct net_device *
 static int smc_drv_probe(struct platform_device *pdev)
 {
 	struct smc91x_platdata *pd = dev_get_platdata(&pdev->dev);
+	const struct of_device_id *match = NULL;
 	struct smc_local *lp;
 	struct net_device *ndev;
 	struct resource *res, *ires;
@@ -2217,11 +2228,34 @@ static int smc_drv_probe(struct platform_device *pdev)
 	 */
 
 	lp = netdev_priv(ndev);
+	lp->cfg.flags = 0;
 
 	if (pd) {
 		memcpy(&lp->cfg, pd, sizeof(lp->cfg));
 		lp->io_shift = SMC91X_IO_SHIFT(lp->cfg.flags);
+	}
+
+#if IS_BUILTIN(CONFIG_OF)
+	match = of_match_device(of_match_ptr(smc91x_match), &pdev->dev);
+	if (match) {
+		struct device_node *np = pdev->dev.of_node;
+		u32 val;
+
+		/* Combination of IO widths supported, default to 16-bit */
+		if (!of_property_read_u32(np, "reg-io-width", &val)) {
+			if (val & 1)
+				lp->cfg.flags |= SMC91X_USE_8BIT;
+			if ((val == 0) || (val & 2))
+				lp->cfg.flags |= SMC91X_USE_16BIT;
+			if (val & 4)
+				lp->cfg.flags |= SMC91X_USE_32BIT;
 		} else {
+			lp->cfg.flags |= SMC91X_USE_16BIT;
+		}
+	}
+#endif
+
+	if (!pd && !match) {
 		lp->cfg.flags |= (SMC_CAN_USE_8BIT)  ? SMC91X_USE_8BIT  : 0;
 		lp->cfg.flags |= (SMC_CAN_USE_16BIT) ? SMC91X_USE_16BIT : 0;
 		lp->cfg.flags |= (SMC_CAN_USE_32BIT) ? SMC91X_USE_32BIT : 0;
@@ -2370,15 +2404,6 @@ static int smc_drv_resume(struct device *dev)
 	return 0;
 }
 
-#ifdef CONFIG_OF
-static const struct of_device_id smc91x_match[] = {
-	{ .compatible = "smsc,lan91c94", },
-	{ .compatible = "smsc,lan91c111", },
-	{},
-};
-MODULE_DEVICE_TABLE(of, smc91x_match);
-#endif
-
 static struct dev_pm_ops smc_drv_pm_ops = {
 	.suspend	= smc_drv_suspend,
 	.resume		= smc_drv_resume,