[PATCH v2 net-next] net: phy: micrel: Adding SQI support for lan8814 phy

[Divya Koppera <Divya.Koppera@microchip.com>]

Supports SQI(Signal Quality Index) for lan8814 phy, where
it has SQI index of 0-7 values and this indicator can be used
for cable integrity diagnostic and investigating other noise
sources. It is not supported for 10Mbps speed

Signed-off-by: Divya Koppera <Divya.Koppera@microchip.com>
---
v1 -> v2
- Given SQI support for all pairs of wires in 1000/100 base-T phy's
  uAPI may run through all instances in future. At present returning
  only first instance as uAPI supports for only 1 pair.
- SQI is not supported for 10Mbps speed, handled accordingly.
---
 drivers/net/phy/micrel.c | 44 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index 7b8c5c8d013e..37845efe2cb6 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -1975,6 +1975,13 @@ static int ksz886x_cable_test_get_status(struct phy_device *phydev,
 #define LAN8814_CLOCK_MANAGEMENT			0xd
 #define LAN8814_LINK_QUALITY				0x8e
 
+#define LAN8814_DCQ_CTRL				0xe6
+#define LAN8814_DCQ_CTRL_READ_CAPTURE_			BIT(15)
+#define LAN8814_DCQ_CTRL_CHANNEL_MASK			GENMASK(1, 0)
+#define LAN8814_DCQ_SQI					0xe4
+#define LAN8814_DCQ_SQI_MAX				7
+#define LAN8814_DCQ_SQI_VAL_MASK			GENMASK(3, 1)
+
 static int lanphy_read_page_reg(struct phy_device *phydev, int page, u32 addr)
 {
 	int data;
@@ -2933,6 +2940,41 @@ static int lan8814_probe(struct phy_device *phydev)
 	return 0;
 }
 
+static int lan8814_get_sqi(struct phy_device *phydev)
+{
+	int ret, val, pair;
+	int sqi_val[4];
+
+	if (phydev->speed == SPEED_10)
+		return -EOPNOTSUPP;
+
+	for (pair = 0; pair < 4; pair++) {
+		val = lanphy_read_page_reg(phydev, 1, LAN8814_DCQ_CTRL);
+		if (val < 0)
+			return val;
+
+		val &= ~LAN8814_DCQ_CTRL_CHANNEL_MASK;
+		val |= pair;
+		val |= LAN8814_DCQ_CTRL_READ_CAPTURE_;
+		ret = lanphy_write_page_reg(phydev, 1, LAN8814_DCQ_CTRL, val);
+		if (ret < 0)
+			return ret;
+
+		ret = lanphy_read_page_reg(phydev, 1, LAN8814_DCQ_SQI);
+		if (ret < 0)
+			return ret;
+
+		sqi_val[pair] = FIELD_GET(LAN8814_DCQ_SQI_VAL_MASK, ret);
+	}
+
+	return *sqi_val;
+}
+
+static int lan8814_get_sqi_max(struct phy_device *phydev)
+{
+	return LAN8814_DCQ_SQI_MAX;
+}
+
 static struct phy_driver ksphy_driver[] = {
 {
 	.phy_id		= PHY_ID_KS8737,
@@ -3123,6 +3165,8 @@ static struct phy_driver ksphy_driver[] = {
 	.resume		= kszphy_resume,
 	.config_intr	= lan8814_config_intr,
 	.handle_interrupt = lan8814_handle_interrupt,
+	.get_sqi	= lan8814_get_sqi,
+	.get_sqi_max	= lan8814_get_sqi_max,
 }, {
 	.phy_id		= PHY_ID_LAN8804,
 	.phy_id_mask	= MICREL_PHY_ID_MASK,
-- 
2.17.1