net: phy: LAN87xx: add ethtool SQI support

This patch add the support for measuring Signal Quality Index for
LAN87xx and LAN937x T1 Phy. It uses the SQI Method 5 for obtaining the
values.
Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/microchip_t1.c

@@ -68,7 +68,12 @@
 #define T1_POST_LCK_MUFACT_CFG_REG	0x1C
 #define T1_TX_RX_FIFO_CFG_REG		0x02
 #define T1_TX_LPF_FIR_CFG_REG		0x55
+#define T1_COEF_CLK_PWR_DN_CFG		0x04
+#define T1_COEF_RW_CTL_CFG		0x0D
 #define T1_SQI_CONFIG_REG		0x2E
+#define T1_SQI_CONFIG2_REG		0x4A
+#define T1_DCQ_SQI_REG			0xC3
+#define T1_DCQ_SQI_MSK			GENMASK(3, 1)
 #define T1_MDIO_CONTROL2_REG		0x10
 #define T1_INTERRUPT_SOURCE_REG		0x18
 #define T1_INTERRUPT2_SOURCE_REG	0x08
@@ -82,6 +87,9 @@
 #define T1_MODE_STAT_REG		0x11
 #define T1_LINK_UP_MSK			BIT(0)
 
+/* SQI defines */
+#define LAN87XX_MAX_SQI			0x07
+
 #define DRIVER_AUTHOR	"Nisar Sayed <nisar.sayed@microchip.com>"
 #define DRIVER_DESC	"Microchip LAN87XX/LAN937x T1 PHY driver"
 
@@ -346,9 +354,20 @@ static int lan87xx_phy_init(struct phy_device *phydev)
 		  T1_TX_LPF_FIR_CFG_REG, 0x1011, 0 },
 		{ PHYACC_ATTR_MODE_WRITE, PHYACC_ATTR_BANK_DSP,
 		  T1_TX_LPF_FIR_CFG_REG, 0x1000, 0 },
+		/* Setup SQI measurement */
+		{ PHYACC_ATTR_MODE_WRITE, PHYACC_ATTR_BANK_DSP,
+		  T1_COEF_CLK_PWR_DN_CFG,	0x16d6, 0 },
 		/* SQI enable */
 		{ PHYACC_ATTR_MODE_WRITE, PHYACC_ATTR_BANK_DSP,
 		  T1_SQI_CONFIG_REG,		0x9572, 0 },
+		/* SQI select mode 5 */
+		{ PHYACC_ATTR_MODE_WRITE, PHYACC_ATTR_BANK_DSP,
+		  T1_SQI_CONFIG2_REG,		0x0001, 0 },
+		/* Throws the first SQI reading */
+		{ PHYACC_ATTR_MODE_WRITE, PHYACC_ATTR_BANK_DSP,
+		  T1_COEF_RW_CTL_CFG,		0x0301,	0 },
+		{ PHYACC_ATTR_MODE_READ, PHYACC_ATTR_BANK_DSP,
+		  T1_DCQ_SQI_REG,		0,	0 },
 		/* Flag LPS and WUR as idle errors */
 		{ PHYACC_ATTR_MODE_WRITE, PHYACC_ATTR_BANK_SMI,
 		  T1_MDIO_CONTROL2_REG,		0x0014, 0 },
@@ -724,6 +743,31 @@ static int lan87xx_config_aneg(struct phy_device *phydev)
 	return phy_modify_changed(phydev, MII_CTRL1000, CTL1000_AS_MASTER, ctl);
 }
 
+static int lan87xx_get_sqi(struct phy_device *phydev)
+{
+	u8 sqi_value = 0;
+	int rc;
+
+	rc = access_ereg(phydev, PHYACC_ATTR_MODE_WRITE,
+			 PHYACC_ATTR_BANK_DSP, T1_COEF_RW_CTL_CFG, 0x0301);
+	if (rc < 0)
+		return rc;
+
+	rc = access_ereg(phydev, PHYACC_ATTR_MODE_READ,
+			 PHYACC_ATTR_BANK_DSP, T1_DCQ_SQI_REG, 0x0);
+	if (rc < 0)
+		return rc;
+
+	sqi_value = FIELD_GET(T1_DCQ_SQI_MSK, rc);
+
+	return sqi_value;
+}
+
+static int lan87xx_get_sqi_max(struct phy_device *phydev)
+{
+	return LAN87XX_MAX_SQI;
+}
+
 static struct phy_driver microchip_t1_phy_driver[] = {
 	{
 		PHY_ID_MATCH_MODEL(PHY_ID_LAN87XX),
@@ -737,6 +781,8 @@ static struct phy_driver microchip_t1_phy_driver[] = {
 		.resume         = genphy_resume,
 		.config_aneg    = lan87xx_config_aneg,
 		.read_status	= lan87xx_read_status,
+		.get_sqi	= lan87xx_get_sqi,
+		.get_sqi_max	= lan87xx_get_sqi_max,
 		.cable_test_start = lan87xx_cable_test_start,
 		.cable_test_get_status = lan87xx_cable_test_get_status,
 	},
@@ -750,6 +796,8 @@ static struct phy_driver microchip_t1_phy_driver[] = {
 		.resume		= genphy_resume,
 		.config_aneg    = lan87xx_config_aneg,
 		.read_status	= lan87xx_read_status,
+		.get_sqi	= lan87xx_get_sqi,
+		.get_sqi_max	= lan87xx_get_sqi_max,
 		.cable_test_start = lan87xx_cable_test_start,
 		.cable_test_get_status = lan87xx_cable_test_get_status,
 	}