net: phy: Create phy_supported_speeds function which lists speeds currently supported by a phydevice

phy_supported_speeds provides a means to get a list of all the speeds a
phy device currently supports.

Signed-off-by: Zach Brown <zach.brown@ni.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy.c

@@ -260,6 +260,41 @@ static inline unsigned int phy_find_valid(unsigned int idx, u32 features)
 	return idx < MAX_NUM_SETTINGS ? idx : MAX_NUM_SETTINGS - 1;
 }
 
+/**
+ * phy_supported_speeds - return all speeds currently supported by a phy device
+ * @phy: The phy device to return supported speeds of.
+ * @speeds: buffer to store supported speeds in.
+ * @size:   size of speeds buffer.
+ *
+ * Description: Returns the number of supported speeds, and fills the speeds
+ * buffer with the supported speeds. If speeds buffer is too small to contain
+ * all currently supported speeds, will return as many speeds as can fit.
+ */
+unsigned int phy_supported_speeds(struct phy_device *phy,
+				  unsigned int *speeds,
+				  unsigned int size)
+{
+	unsigned int count = 0;
+	unsigned int idx = 0;
+
+	while (idx < MAX_NUM_SETTINGS && count < size) {
+		idx = phy_find_valid(idx, phy->supported);
+
+		if (!(settings[idx].setting & phy->supported))
+			break;
+
+		/* Assumes settings are grouped by speed */
+		if ((count == 0) ||
+		    (speeds[count - 1] != settings[idx].speed)) {
+			speeds[count] = settings[idx].speed;
+			count++;
+		}
+		idx++;
+	}
+
+	return count;
+}
+
 /**
  * phy_check_valid - check if there is a valid PHY setting which matches
  *		     speed, duplex, and feature mask

include/linux/phy.h

@@ -84,6 +84,21 @@ typedef enum {
 	PHY_INTERFACE_MODE_MAX,
 } phy_interface_t;
 
+/**
+ * phy_supported_speeds - return all speeds currently supported by a phy device
+ * @phy: The phy device to return supported speeds of.
+ * @speeds: buffer to store supported speeds in.
+ * @size: size of speeds buffer.
+ *
+ * Description: Returns the number of supported speeds, and
+ * fills the speeds * buffer with the supported speeds. If speeds buffer is
+ * too small to contain * all currently supported speeds, will return as
+ * many speeds as can fit.
+ */
+unsigned int phy_supported_speeds(struct phy_device *phy,
+				      unsigned int *speeds,
+				      unsigned int size);
+
 /**
  * It maps 'enum phy_interface_t' found in include/linux/phy.h
  * into the device tree binding of 'phy-mode', so that Ethernet