[net-next,v9,2/5] net: phy: Add a helper to return the index for of the internal delay

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 04946de74fa0..0bb08bc0370c 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -31,6 +31,7 @@ 
 #include <linux/mdio.h>
 #include <linux/io.h>
 #include <linux/uaccess.h>
+#include <linux/property.h>
 
 MODULE_DESCRIPTION("PHY library");
 MODULE_AUTHOR("Andy Fleming");
@@ -2657,6 +2658,105 @@  void phy_get_pause(struct phy_device *phydev, bool *tx_pause, bool *rx_pause)
 }
 EXPORT_SYMBOL(phy_get_pause);
 
+#if IS_ENABLED(CONFIG_OF_MDIO)
+static int phy_get_int_delay_property(struct device *dev, const char *name)
+{
+	s32 int_delay;
+	int ret;
+
+	ret = device_property_read_u32(dev, name, &int_delay);
+	if (ret)
+		return ret;
+
+	return int_delay;
+}
+#else
+static inline int phy_get_int_delay_property(struct device *dev,
+					     const char *name)
+{
+	return -EINVAL;
+}
+#endif
+
+/**
+ * phy_get_delay_index - returns the index of the internal delay
+ * @phydev: phy_device struct
+ * @dev: pointer to the devices device struct
+ * @delay_values: array of delays the PHY supports
+ * @size: the size of the delay array
+ * @is_rx: boolean to indicate to get the rx internal delay
+ *
+ * Returns the index within the array of internal delay passed in.
+ * If the device property is not present then the interface type is checked
+ * if the interface defines use of internal delay then a 1 is returned otherwise
+ * a 0 is returned.
+ * The array must be in ascending order. If PHY does not have an ascending order
+ * array then size = 0 and the value of the delay property is returned.
+ * Return -EINVAL if the delay is invalid or cannot be found.
+ */
+s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
+			   const int *delay_values, int size, bool is_rx)
+{
+	int i;
+	s32 delay;
+
+	if (is_rx) {
+		delay = phy_get_int_delay_property(dev, "rx-internal-delay-ps");
+		if (delay < 0 && size == 0) {
+			if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+			    phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID)
+				return 1;
+			else
+				return 0;
+		}
+
+	} else {
+		delay = phy_get_int_delay_property(dev, "tx-internal-delay-ps");
+		if (delay < 0 && size == 0) {
+			if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+			    phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID)
+				return 1;
+			else
+				return 0;
+		}
+	}
+
+	if (delay < 0)
+		return delay;
+
+	if (delay && size == 0)
+		return delay;
+
+	if (delay < delay_values[0] || delay > delay_values[size - 1]) {
+		phydev_err(phydev, "Delay %d is out of range\n", delay);
+		return -EINVAL;
+	}
+
+	if (delay == delay_values[0])
+		return 0;
+
+	for (i = 1; i < size; i++) {
+		if (delay == delay_values[i])
+			return i;
+
+		/* Find an approximate index by looking up the table */
+		if (delay > delay_values[i - 1] &&
+		    delay < delay_values[i]) {
+			if (delay - delay_values[i - 1] <
+			    delay_values[i] - delay)
+				return i - 1;
+			else
+				return i;
+		}
+	}
+
+	phydev_err(phydev, "error finding internal delay index for %d\n",
+		   delay);
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL(phy_get_internal_delay);
+
 static bool phy_drv_supports_irq(struct phy_driver *phydrv)
 {
 	return phydrv->config_intr && phydrv->ack_interrupt;
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 8c05d0fb5c00..917bfd422e06 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -1430,6 +1430,10 @@  void phy_set_asym_pause(struct phy_device *phydev, bool rx, bool tx);
 bool phy_validate_pause(struct phy_device *phydev,
 			struct ethtool_pauseparam *pp);
 void phy_get_pause(struct phy_device *phydev, bool *tx_pause, bool *rx_pause);
+
+s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
+			   const int *delay_values, int size, bool is_rx);
+
 void phy_resolve_pause(unsigned long *local_adv, unsigned long *partner_adv,
 		       bool *tx_pause, bool *rx_pause);