net: phy: Add a helper to return the index for of the internal delay

Add a helper function that will return the index in the array for the
passed in internal delay value.  The helper requires the array, size and
delay value.

The helper will then return the index for the exact match or return the
index for the index to the closest smaller value.
Signed-off-by: Dan Murphy <dmurphy@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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");
@@ -2708,6 +2709,104 @@ 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 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)
+{
+	s32 delay;
+	int i;
+
+	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;

include/linux/phy.h

@@ -1443,6 +1443,10 @@ 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);