i40e: Add support for ethtool -s <interface> speed <speed in Mb>

Add ability to change speed through ethtool -s <interface> speed <speed in Mb>
Driver advertises all link modes that support requested speed.
Autoneg must be set off e.g.:
	ethtool -s <interface> autoneg off speed <speed in Mb>.

Add helper function that translate speed in Mb to
enum i40e_aq_link_speed and compare it to supported speeds from
given ethtool_link_ksettings. Add in i40e_set_link_ksettings hold
for requested speed and set copy_ks.base.speed to safe_ks.base.speed
to be sure that user is not changing unsupported setting.
In i40e_speed_to_link_speed compare requested speed with supported
speeds. Set speed to requested speed.

Signed-off-by: Norbert Zulinski <norbertx.zulinski@intel.com>
Signed-off-by: Mateusz Palczewski <mateusz.palczewski@intel.com>
Tested-by: Dave Switzer <david.switzer@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/i40e/i40e_ethtool.c

@@ -1143,6 +1143,71 @@ static int i40e_get_link_ksettings(struct net_device *netdev,
 	return 0;
 }
 
+#define I40E_LBIT_SIZE 8
+/**
+ * i40e_speed_to_link_speed - Translate decimal speed to i40e_aq_link_speed
+ * @speed: speed in decimal
+ * @ks: ethtool ksettings
+ *
+ * Return i40e_aq_link_speed based on speed
+ **/
+static enum i40e_aq_link_speed
+i40e_speed_to_link_speed(__u32 speed, const struct ethtool_link_ksettings *ks)
+{
+	enum i40e_aq_link_speed link_speed = I40E_LINK_SPEED_UNKNOWN;
+	bool speed_changed = false;
+	int i, j;
+
+	static const struct {
+		__u32 speed;
+		enum i40e_aq_link_speed link_speed;
+		__u8 bit[I40E_LBIT_SIZE];
+	} i40e_speed_lut[] = {
+#define I40E_LBIT(mode) ETHTOOL_LINK_MODE_ ## mode ##_Full_BIT
+		{SPEED_100, I40E_LINK_SPEED_100MB, {I40E_LBIT(100baseT)} },
+		{SPEED_1000, I40E_LINK_SPEED_1GB,
+		 {I40E_LBIT(1000baseT), I40E_LBIT(1000baseX),
+		  I40E_LBIT(1000baseKX)} },
+		{SPEED_10000, I40E_LINK_SPEED_10GB,
+		 {I40E_LBIT(10000baseT), I40E_LBIT(10000baseKR),
+		  I40E_LBIT(10000baseLR), I40E_LBIT(10000baseCR),
+		  I40E_LBIT(10000baseSR), I40E_LBIT(10000baseKX4)} },
+
+		{SPEED_25000, I40E_LINK_SPEED_25GB,
+		 {I40E_LBIT(25000baseCR), I40E_LBIT(25000baseKR),
+		  I40E_LBIT(25000baseSR)} },
+		{SPEED_40000, I40E_LINK_SPEED_40GB,
+		 {I40E_LBIT(40000baseKR4), I40E_LBIT(40000baseCR4),
+		  I40E_LBIT(40000baseSR4), I40E_LBIT(40000baseLR4)} },
+		{SPEED_20000, I40E_LINK_SPEED_20GB,
+		 {I40E_LBIT(20000baseKR2)} },
+		{SPEED_2500, I40E_LINK_SPEED_2_5GB, {I40E_LBIT(2500baseT)} },
+		{SPEED_5000, I40E_LINK_SPEED_5GB, {I40E_LBIT(2500baseT)} }
+#undef I40E_LBIT
+};
+
+	for (i = 0; i < ARRAY_SIZE(i40e_speed_lut); i++) {
+		if (i40e_speed_lut[i].speed == speed) {
+			for (j = 0; j < I40E_LBIT_SIZE; j++) {
+				if (test_bit(i40e_speed_lut[i].bit[j],
+					     ks->link_modes.supported)) {
+					speed_changed = true;
+					break;
+				}
+				if (!i40e_speed_lut[i].bit[j])
+					break;
+			}
+			if (speed_changed) {
+				link_speed = i40e_speed_lut[i].link_speed;
+				break;
+			}
+		}
+	}
+	return link_speed;
+}
+
+#undef I40E_LBIT_SIZE
+
 /**
  * i40e_set_link_ksettings - Set Speed and Duplex
  * @netdev: network interface device structure
@@ -1159,12 +1224,14 @@ static int i40e_set_link_ksettings(struct net_device *netdev,
 	struct ethtool_link_ksettings copy_ks;
 	struct i40e_aq_set_phy_config config;
 	struct i40e_pf *pf = np->vsi->back;
+	enum i40e_aq_link_speed link_speed;
 	struct i40e_vsi *vsi = np->vsi;
 	struct i40e_hw *hw = &pf->hw;
 	bool autoneg_changed = false;
 	i40e_status status = 0;
 	int timeout = 50;
 	int err = 0;
+	__u32 speed;
 	u8 autoneg;
 
 	/* Changing port settings is not supported if this isn't the
@@ -1197,6 +1264,7 @@ static int i40e_set_link_ksettings(struct net_device *netdev,
 
 	/* save autoneg out of ksettings */
 	autoneg = copy_ks.base.autoneg;
+	speed = copy_ks.base.speed;
 
 	/* get our own copy of the bits to check against */
 	memset(&safe_ks, 0, sizeof(struct ethtool_link_ksettings));
@@ -1215,6 +1283,7 @@ static int i40e_set_link_ksettings(struct net_device *netdev,
 
 	/* set autoneg back to what it currently is */
 	copy_ks.base.autoneg = safe_ks.base.autoneg;
+	copy_ks.base.speed  = safe_ks.base.speed;
 
 	/* If copy_ks.base and safe_ks.base are not the same now, then they are
 	 * trying to set something that we do not support.
@@ -1331,6 +1400,27 @@ static int i40e_set_link_ksettings(struct net_device *netdev,
 						  40000baseLR4_Full))
 		config.link_speed |= I40E_LINK_SPEED_40GB;
 
+	/* Autonegotiation must be disabled to change speed */
+	if ((speed != SPEED_UNKNOWN && safe_ks.base.speed != speed) &&
+	    (autoneg == AUTONEG_DISABLE ||
+	    (safe_ks.base.autoneg == AUTONEG_DISABLE && !autoneg_changed))) {
+		link_speed = i40e_speed_to_link_speed(speed, ks);
+		if (link_speed == I40E_LINK_SPEED_UNKNOWN) {
+			netdev_info(netdev, "Given speed is not supported\n");
+			err = -EOPNOTSUPP;
+			goto done;
+		} else {
+			config.link_speed = link_speed;
+		}
+	} else {
+		if (safe_ks.base.speed != speed) {
+			netdev_info(netdev,
+				    "Unable to set speed, disable autoneg\n");
+			err = -EOPNOTSUPP;
+			goto done;
+		}
+	}
+
 	/* If speed didn't get set, set it to what it currently is.
 	 * This is needed because if advertise is 0 (as it is when autoneg
 	 * is disabled) then speed won't get set.