[PATCH net] device property: change device_get_phy_mode() to prevent signedess bugs

[Dan Carpenter]

The device_get_phy_mode() was returning negative error codes on
failure and positive phy_interface_t values on success.  The problem is
that the phy_interface_t type is an enum which GCC treats as unsigned.
This lead to recurring signedness bugs where we check "if (phy_mode < 0)"
and "phy_mode" is unsigned.

In the commit 0c65b2b90d13 ("net: of_get_phy_mode: Change API to solve
int/unit warnings") we updated of_get_phy_mode() take a pointer to
phy_mode and only return zero on success and negatives on failure.  This
patch does the same thing for device_get_phy_mode().  Plus it's just
nice for the API to be the same in both places.

Fixes: b9f0b2f634c0 ("net: stmmac: platform: fix probe for ACPI devices")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
This is a change to drivers/base/ but all the users are ethernet drivers
so probably it makes sense for Dave to take this?

Also this fixes a bug in stmmac.  If you wanted I could make a one
liner fix for that and then write this change on top of that.  The bug
is only in v5.6 so it doesn't affect old kernels.

 drivers/base/property.c                               | 13 +++++++++++--
 drivers/net/ethernet/apm/xgene-v2/main.c              |  9 ++++-----
 drivers/net/ethernet/apm/xgene-v2/main.h              |  2 +-
 drivers/net/ethernet/apm/xgene/xgene_enet_main.c      |  6 +++---
 drivers/net/ethernet/apm/xgene/xgene_enet_main.h      |  2 +-
 drivers/net/ethernet/smsc/smsc911x.c                  |  8 +++-----
 drivers/net/ethernet/socionext/netsec.c               |  5 ++---
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c |  6 +++---
 include/linux/property.h                              |  3 ++-
 9 files changed, 30 insertions(+), 24 deletions(-)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 511f6d7acdfe..8854cfbd213b 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -863,9 +863,18 @@ EXPORT_SYMBOL_GPL(fwnode_get_phy_mode);
  * 'phy-connection-type', and return its index in phy_modes table, or errno in
  * error case.
  */
-int device_get_phy_mode(struct device *dev)
+int device_get_phy_mode(struct device *dev, phy_interface_t *interface)
 {
-	return fwnode_get_phy_mode(dev_fwnode(dev));
+	int mode;
+
+	*interface = PHY_INTERFACE_MODE_NA;
+
+	mode = fwnode_get_phy_mode(dev_fwnode(dev));
+	if (mode < 0)
+		return mode;
+
+	*interface = mode;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(device_get_phy_mode);
 
diff --git a/drivers/net/ethernet/apm/xgene-v2/main.c b/drivers/net/ethernet/apm/xgene-v2/main.c
index c48f60996761..706602918dd1 100644
--- a/drivers/net/ethernet/apm/xgene-v2/main.c
+++ b/drivers/net/ethernet/apm/xgene-v2/main.c
@@ -15,7 +15,7 @@ static int xge_get_resources(struct xge_pdata *pdata)
 {
 	struct platform_device *pdev;
 	struct net_device *ndev;
-	int phy_mode, ret = 0;
+	int ret = 0;
 	struct resource *res;
 	struct device *dev;
 
@@ -41,12 +41,11 @@ static int xge_get_resources(struct xge_pdata *pdata)
 
 	memcpy(ndev->perm_addr, ndev->dev_addr, ndev->addr_len);
 
-	phy_mode = device_get_phy_mode(dev);
-	if (phy_mode < 0) {
+	ret = device_get_phy_mode(dev, &pdata->resources.phy_mode);
+	if (ret) {
 		dev_err(dev, "Unable to get phy-connection-type\n");
-		return phy_mode;
+		return ret;
 	}
-	pdata->resources.phy_mode = phy_mode;
 
 	if (pdata->resources.phy_mode != PHY_INTERFACE_MODE_RGMII) {
 		dev_err(dev, "Incorrect phy-connection-type specified\n");
diff --git a/drivers/net/ethernet/apm/xgene-v2/main.h b/drivers/net/ethernet/apm/xgene-v2/main.h
index d41439d2709d..d687f0185908 100644
--- a/drivers/net/ethernet/apm/xgene-v2/main.h
+++ b/drivers/net/ethernet/apm/xgene-v2/main.h
@@ -35,7 +35,7 @@
 
 struct xge_resource {
 	void __iomem *base_addr;
-	int phy_mode;
+	phy_interface_t phy_mode;
 	u32 irq;
 };
 
diff --git a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
index 6aee2f0fc0db..da35e70ccceb 100644
--- a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
+++ b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
@@ -1736,10 +1736,10 @@ static int xgene_enet_get_resources(struct xgene_enet_pdata *pdata)
 
 	memcpy(ndev->perm_addr, ndev->dev_addr, ndev->addr_len);
 
-	pdata->phy_mode = device_get_phy_mode(dev);
-	if (pdata->phy_mode < 0) {
+	ret = device_get_phy_mode(dev, &pdata->phy_mode);
+	if (ret) {
 		dev_err(dev, "Unable to get phy-connection-type\n");
-		return pdata->phy_mode;
+		return ret;
 	}
 	if (!phy_interface_mode_is_rgmii(pdata->phy_mode) &&
 	    pdata->phy_mode != PHY_INTERFACE_MODE_SGMII &&
diff --git a/drivers/net/ethernet/apm/xgene/xgene_enet_main.h b/drivers/net/ethernet/apm/xgene/xgene_enet_main.h
index 18f4923b1723..600cddf1942d 100644
--- a/drivers/net/ethernet/apm/xgene/xgene_enet_main.h
+++ b/drivers/net/ethernet/apm/xgene/xgene_enet_main.h
@@ -209,7 +209,7 @@ struct xgene_enet_pdata {
 	void __iomem *pcs_addr;
 	void __iomem *ring_csr_addr;
 	void __iomem *ring_cmd_addr;
-	int phy_mode;
+	phy_interface_t phy_mode;
 	enum xgene_enet_rm rm;
 	struct xgene_enet_cle cle;
 	u64 *extd_stats;
diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c
index 49a6a9167af4..2d773e5e67f8 100644
--- a/drivers/net/ethernet/smsc/smsc911x.c
+++ b/drivers/net/ethernet/smsc/smsc911x.c
@@ -2361,14 +2361,12 @@ static const struct smsc911x_ops shifted_smsc911x_ops = {
 static int smsc911x_probe_config(struct smsc911x_platform_config *config,
 				 struct device *dev)
 {
-	int phy_interface;
 	u32 width = 0;
 	int err;
 
-	phy_interface = device_get_phy_mode(dev);
-	if (phy_interface < 0)
-		phy_interface = PHY_INTERFACE_MODE_NA;
-	config->phy_interface = phy_interface;
+	err = device_get_phy_mode(dev, &config->phy_interface);
+	if (err)
+		config->phy_interface = PHY_INTERFACE_MODE_NA;
 
 	device_get_mac_address(dev, config->mac, ETH_ALEN);
 
diff --git a/drivers/net/ethernet/socionext/netsec.c b/drivers/net/ethernet/socionext/netsec.c
index e8224b543dfc..95ff91230523 100644
--- a/drivers/net/ethernet/socionext/netsec.c
+++ b/drivers/net/ethernet/socionext/netsec.c
@@ -1994,10 +1994,9 @@ static int netsec_probe(struct platform_device *pdev)
 	priv->msg_enable = NETIF_MSG_TX_ERR | NETIF_MSG_HW | NETIF_MSG_DRV |
 			   NETIF_MSG_LINK | NETIF_MSG_PROBE;
 
-	priv->phy_interface = device_get_phy_mode(&pdev->dev);
-	if ((int)priv->phy_interface < 0) {
+	ret = device_get_phy_mode(&pdev->dev, &priv->phy_interface);
+	if (ret) {
 		dev_err(&pdev->dev, "missing required property 'phy-mode'\n");
-		ret = -ENODEV;
 		goto free_ndev;
 	}
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index d10ac54bf385..aa77c332ea1d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -412,9 +412,9 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
 		*mac = NULL;
 	}
 
-	plat->phy_interface = device_get_phy_mode(&pdev->dev);
-	if (plat->phy_interface < 0)
-		return ERR_PTR(plat->phy_interface);
+	rc = device_get_phy_mode(&pdev->dev, &plat->phy_interface);
+	if (rc)
+		return ERR_PTR(rc);
 
 	plat->interface = stmmac_of_get_mac_mode(np);
 	if (plat->interface < 0)
diff --git a/include/linux/property.h b/include/linux/property.h
index d86de017c689..2ffe9842c997 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -12,6 +12,7 @@
 
 #include <linux/bits.h>
 #include <linux/fwnode.h>
+#include <linux/phy.h>
 #include <linux/types.h>
 
 struct device;
@@ -368,7 +369,7 @@ enum dev_dma_attr device_get_dma_attr(struct device *dev);
 
 const void *device_get_match_data(struct device *dev);
 
-int device_get_phy_mode(struct device *dev);
+int device_get_phy_mode(struct device *dev, phy_interface_t *interface);
 
 void *device_get_mac_address(struct device *dev, char *addr, int alen);
 
-- 
2.11.0