Re: [PATCH net-next 5/9] net: phy: icplus: add IP101A/IP101G model detection

Unfortunately, the IP101A and IP101G share the same PHY identifier.
While most of the functions are somewhat backwards compatible, there is
for example the APS_EN bit on the IP101A but on the IP101G this bit
reserved. Also, the IP101G has many more functionalities.

Deduce the model by accessing the page select register which - according
to the datasheet - is not available on the IP101A. If this register is
writable, assume we have an IP101G.

Signed-off-by: Michael Walle <redacted>
---
 drivers/net/phy/icplus.c | 43 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/icplus.c b/drivers/net/phy/icplus.c
index 036bac628b11..189a9a34ed5f 100644
--- a/drivers/net/phy/icplus.c
+++ b/drivers/net/phy/icplus.c

@@ -44,6 +44,8 @@ MODULE_LICENSE("GPL");
 #define IP101A_G_IRQ_DUPLEX_CHANGE	BIT(1)
 #define IP101A_G_IRQ_LINK_CHANGE	BIT(0)
 
+#define IP101G_PAGE_CONTROL				0x14
+#define IP101G_PAGE_CONTROL_MASK			GENMASK(4, 0)
 #define IP101G_DIGITAL_IO_SPEC_CTRL			0x1d
 #define IP101G_DIGITAL_IO_SPEC_CTRL_SEL_INTR32		BIT(2)
 

@@ -61,8 +63,14 @@ enum ip101gr_sel_intr32 {
 	IP101GR_SEL_INTR32_RXER,
 };
 
+enum ip101_model {
+	IP101A,
+	IP101G,
+};
+
 struct ip101a_g_phy_priv {
 	enum ip101gr_sel_intr32 sel_intr32;
+	enum ip101_model model;
 };
 
 static int ip175c_config_init(struct phy_device *phydev)

@@ -175,6 +183,39 @@ static int ip175c_config_aneg(struct phy_device *phydev)
 	return 0;
 }
 
+/* The IP101A and the IP101G share the same PHY identifier.The IP101G seems to
+ * be a successor of the IP101A and implements more functions. Amongst other
+ * things a page select register, which is not available on the IP101. Use this
+ * to distinguish these two.
+ */
+static int ip101a_g_detect_model(struct phy_device *phydev)
+{
+	struct ip101a_g_phy_priv *priv = phydev->priv;
+	int oldval, ret;
+
+	oldval = phy_read(phydev, IP101G_PAGE_CONTROL);
+	if (oldval < 0)
+		return oldval;
+
+	ret = phy_write(phydev, IP101G_PAGE_CONTROL, 0xffff);
+	if (ret)
+		return ret;
+
+	ret = phy_read(phydev, IP101G_PAGE_CONTROL);
+	if (ret < 0)
+		return ret;
+
+	if (ret == IP101G_PAGE_CONTROL_MASK)
+		priv->model = IP101G;
+	else
+		priv->model = IP101A;
+
+	phydev_dbg(phydev, "Detected %s\n",
+		   priv->model == IP101G ? "IP101G" : "IP101A");
+
+	return phy_write(phydev, IP101G_PAGE_CONTROL, oldval);
+}
+
 static int ip101a_g_probe(struct phy_device *phydev)
 {
 	struct device *dev = &phydev->mdio.dev;

@@ -203,7 +244,7 @@ static int ip101a_g_probe(struct phy_device *phydev)
 
 	phydev->priv = priv;
 
-	return 0;
+	return ip101a_g_detect_model(phydev);
 }
 
 static int ip101a_g_config_init(struct phy_device *phydev)