net: phy: dp83867: Add ability to disable output clock

Based on commit 13c83cf8af0d ("net: phy: dp83867: Add ability to disable
output clock") of mainline linux kernel.

Generally, the output clock pin is only used for testing and only serves as
a source of RF noise after this.  It could be used to daisy-chain PHYs, but
this is uncommon.  Since the PHY can disable the output, make doing so an
option.  I do this by adding another enumeration to the allowed values of
ti,clk-output-sel.

The code was not using the value DP83867_CLK_O_SEL_REF_CLK as one might
expect: to select the REF_CLK as the output.  Rather it meant "keep clock
output setting as is", which, depending on PHY strapping, might not be
outputting REF_CLK.

Change this so DP83867_CLK_O_SEL_REF_CLK means enable REF_CLK output.
Omitting the property will leave the setting as is (which was the previous
behavior in this case).

Out of range values were silently converted into DP83867_CLK_O_SEL_REF_CLK.
Change this so they generate an error.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

1 files changed, 36 insertions, 17 deletions

diff --git a/drivers/net/phy/dp83867.c b/drivers/net/phy/dp83867.c
index 8dc2163..cd3c1c5 100644
--- a/drivers/net/phy/dp83867.c
+++ b/drivers/net/phy/dp83867.c
@@ -83,6 +83,7 @@
 
 #define DP83867_IO_MUX_CFG_IO_IMPEDANCE_MAX	0x0
 #define DP83867_IO_MUX_CFG_IO_IMPEDANCE_MIN	0x1f
+#define DP83867_IO_MUX_CFG_CLK_O_DISABLE	BIT(6)
 #define DP83867_IO_MUX_CFG_CLK_O_SEL_SHIFT	8
 #define DP83867_IO_MUX_CFG_CLK_O_SEL_MASK	\
 		GENMASK(0x1f, DP83867_IO_MUX_CFG_CLK_O_SEL_SHIFT)
@@ -103,6 +104,7 @@ struct dp83867_private {
 	int io_impedance;
 	bool rxctrl_strap_quirk;
 	int port_mirroring;
+	bool set_clk_output;
 	unsigned int clk_output_sel;
 };
 
@@ -134,16 +136,28 @@ static int dp83867_of_init(struct phy_device *phydev)
 {
 	struct dp83867_private *dp83867 = phydev->priv;
 	ofnode node;
-	u16 val;
+	int ret;
 
 	node = phy_get_ofnode(phydev);
 	if (!ofnode_valid(node))
 		return -EINVAL;
 
-	/* Keep the default value if ti,clk-output-sel is not set */
-	dp83867->clk_output_sel =
-		ofnode_read_u32_default(node, "ti,clk-output-sel",
-					DP83867_CLK_O_SEL_REF_CLK);
+	/* Optional configuration */
+	ret = ofnode_read_u32(node, "ti,clk-output-sel",
+			      &dp83867->clk_output_sel);
+	/* If not set, keep default */
+	if (!ret) {
+		dp83867->set_clk_output = true;
+		/* Valid values are 0 to DP83867_CLK_O_SEL_REF_CLK or
+		 * DP83867_CLK_O_SEL_OFF.
+		 */
+		if (dp83867->clk_output_sel > DP83867_CLK_O_SEL_REF_CLK &&
+		    dp83867->clk_output_sel != DP83867_CLK_O_SEL_OFF) {
+			pr_debug("ti,clk-output-sel value %u out of range\n",
+				 dp83867->clk_output_sel);
+			return -EINVAL;
+		}
+	}
 
 	if (ofnode_read_bool(node, "ti,max-output-impedance"))
 		dp83867->io_impedance = DP83867_IO_MUX_CFG_IO_IMPEDANCE_MAX;
@@ -170,18 +184,6 @@ static int dp83867_of_init(struct phy_device *phydev)
 	if (ofnode_read_bool(node, "enet-phy-lane-no-swap"))
 		dp83867->port_mirroring = DP83867_PORT_MIRRORING_DIS;
 
-
-	/* Clock output selection if muxing property is set */
-	if (dp83867->clk_output_sel != DP83867_CLK_O_SEL_REF_CLK) {
-		val = phy_read_mmd(phydev, DP83867_DEVADDR,
-				   DP83867_IO_MUX_CFG);
-		val &= ~DP83867_IO_MUX_CFG_CLK_O_SEL_MASK;
-		val |= (dp83867->clk_output_sel <<
-			DP83867_IO_MUX_CFG_CLK_O_SEL_SHIFT);
-		phy_write_mmd(phydev, DP83867_DEVADDR,
-			      DP83867_IO_MUX_CFG, val);
-	}
-
 	return 0;
 }
 #else
@@ -313,6 +315,23 @@ static int dp83867_config(struct phy_device *phydev)
 	if (dp83867->port_mirroring != DP83867_PORT_MIRRORING_KEEP)
 		dp83867_config_port_mirroring(phydev);
 
+	/* Clock output selection if muxing property is set */
+	if (dp83867->set_clk_output) {
+		val = phy_read_mmd(phydev, DP83867_DEVADDR,
+				   DP83867_IO_MUX_CFG);
+
+		if (dp83867->clk_output_sel == DP83867_CLK_O_SEL_OFF) {
+			val |= DP83867_IO_MUX_CFG_CLK_O_DISABLE;
+		} else {
+			val &= ~(DP83867_IO_MUX_CFG_CLK_O_SEL_MASK |
+				 DP83867_IO_MUX_CFG_CLK_O_DISABLE);
+			val |= dp83867->clk_output_sel <<
+			       DP83867_IO_MUX_CFG_CLK_O_SEL_SHIFT;
+		}
+		phy_write_mmd(phydev, DP83867_DEVADDR,
+			      DP83867_IO_MUX_CFG, val);
+	}
+
 	genphy_config_aneg(phydev);
 	return 0;