net: phy: microchip_t1: add cable test support for lan87xx phy

Add a basic cable test (diagnostic) support for lan87xx phy.
Tested with LAN8770 for connected/open/short wires using ethtool.
Signed-off-by: Yuiko Oshino <yuiko.oshino@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/microchip_t1.c

@@ -6,6 +6,8 @@
 #include <linux/delay.h>
 #include <linux/mii.h>
 #include <linux/phy.h>
+#include <linux/ethtool.h>
+#include <linux/ethtool_netlink.h>
 
 /* External Register Control Register */
 #define LAN87XX_EXT_REG_CTL                     (0x14)
@@ -35,8 +37,14 @@
 #define	PHYACC_ATTR_BANK_MISC		1
 #define	PHYACC_ATTR_BANK_PCS		2
 #define	PHYACC_ATTR_BANK_AFE		3
+#define	PHYACC_ATTR_BANK_DSP		4
 #define	PHYACC_ATTR_BANK_MAX		7
 
+/* measurement defines */
+#define	LAN87XX_CABLE_TEST_OK		0
+#define	LAN87XX_CABLE_TEST_OPEN	1
+#define	LAN87XX_CABLE_TEST_SAME_SHORT	2
+
 #define DRIVER_AUTHOR	"Nisar Sayed <nisar.sayed@microchip.com>"
 #define DRIVER_DESC	"Microchip LAN87XX T1 PHY driver"
 
@@ -226,11 +234,240 @@ static int lan87xx_config_init(struct phy_device *phydev)
 	return rc < 0 ? rc : 0;
 }
 
+static int microchip_cable_test_start_common(struct phy_device *phydev)
+{
+	int bmcr, bmsr, ret;
+
+	/* If auto-negotiation is enabled, but not complete, the cable
+	 * test never completes. So disable auto-neg.
+	 */
+	bmcr = phy_read(phydev, MII_BMCR);
+	if (bmcr < 0)
+		return bmcr;
+
+	bmsr = phy_read(phydev, MII_BMSR);
+
+	if (bmsr < 0)
+		return bmsr;
+
+	if (bmcr & BMCR_ANENABLE) {
+		ret =  phy_modify(phydev, MII_BMCR, BMCR_ANENABLE, 0);
+		if (ret < 0)
+			return ret;
+		ret = genphy_soft_reset(phydev);
+		if (ret < 0)
+			return ret;
+	}
+
+	/* If the link is up, allow it some time to go down */
+	if (bmsr & BMSR_LSTATUS)
+		msleep(1500);
+
+	return 0;
+}
+
+static int lan87xx_cable_test_start(struct phy_device *phydev)
+{
+	static const struct access_ereg_val cable_test[] = {
+		/* min wait */
+		{PHYACC_ATTR_MODE_WRITE, PHYACC_ATTR_BANK_DSP, 93,
+		 0, 0},
+		/* max wait */
+		{PHYACC_ATTR_MODE_WRITE, PHYACC_ATTR_BANK_DSP, 94,
+		 10, 0},
+		/* pulse cycle */
+		{PHYACC_ATTR_MODE_WRITE, PHYACC_ATTR_BANK_DSP, 95,
+		 90, 0},
+		/* cable diag thresh */
+		{PHYACC_ATTR_MODE_WRITE, PHYACC_ATTR_BANK_DSP, 92,
+		 60, 0},
+		/* max gain */
+		{PHYACC_ATTR_MODE_WRITE, PHYACC_ATTR_BANK_DSP, 79,
+		 31, 0},
+		/* clock align for each iteration */
+		{PHYACC_ATTR_MODE_MODIFY, PHYACC_ATTR_BANK_DSP, 55,
+		 0, 0x0038},
+		/* max cycle wait config */
+		{PHYACC_ATTR_MODE_WRITE, PHYACC_ATTR_BANK_DSP, 94,
+		 70, 0},
+		/* start cable diag*/
+		{PHYACC_ATTR_MODE_WRITE, PHYACC_ATTR_BANK_DSP, 90,
+		 1, 0},
+	};
+	int rc, i;
+
+	rc = microchip_cable_test_start_common(phydev);
+	if (rc < 0)
+		return rc;
+
+	/* start cable diag */
+	/* check if part is alive - if not, return diagnostic error */
+	rc = access_ereg(phydev, PHYACC_ATTR_MODE_READ, PHYACC_ATTR_BANK_SMI,
+			 0x00, 0);
+	if (rc < 0)
+		return rc;
+
+	/* master/slave specific configs */
+	rc = access_ereg(phydev, PHYACC_ATTR_MODE_READ, PHYACC_ATTR_BANK_SMI,
+			 0x0A, 0);
+	if (rc < 0)
+		return rc;
+
+	if ((rc & 0x4000) != 0x4000) {
+		/* DUT is Slave */
+		rc = access_ereg_modify_changed(phydev, PHYACC_ATTR_BANK_AFE,
+						0x0E, 0x5, 0x7);
+		if (rc < 0)
+			return rc;
+		rc = access_ereg_modify_changed(phydev, PHYACC_ATTR_BANK_SMI,
+						0x1A, 0x8, 0x8);
+		if (rc < 0)
+			return rc;
+	} else {
+		/* DUT is Master */
+		rc = access_ereg_modify_changed(phydev, PHYACC_ATTR_BANK_SMI,
+						0x10, 0x8, 0x40);
+		if (rc < 0)
+			return rc;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(cable_test); i++) {
+		if (cable_test[i].mode == PHYACC_ATTR_MODE_MODIFY) {
+			rc = access_ereg_modify_changed(phydev,
+							cable_test[i].bank,
+							cable_test[i].offset,
+							cable_test[i].val,
+							cable_test[i].mask);
+			/* wait 50ms */
+			msleep(50);
+		} else {
+			rc = access_ereg(phydev, cable_test[i].mode,
+					 cable_test[i].bank,
+					 cable_test[i].offset,
+					 cable_test[i].val);
+		}
+		if (rc < 0)
+			return rc;
+	}
+	/* cable diag started */
+
+	return 0;
+}
+
+static int lan87xx_cable_test_report_trans(u32 result)
+{
+	switch (result) {
+	case LAN87XX_CABLE_TEST_OK:
+		return ETHTOOL_A_CABLE_RESULT_CODE_OK;
+	case LAN87XX_CABLE_TEST_OPEN:
+		return ETHTOOL_A_CABLE_RESULT_CODE_OPEN;
+	case LAN87XX_CABLE_TEST_SAME_SHORT:
+		return ETHTOOL_A_CABLE_RESULT_CODE_SAME_SHORT;
+	default:
+		/* DIAGNOSTIC_ERROR */
+		return ETHTOOL_A_CABLE_RESULT_CODE_UNSPEC;
+	}
+}
+
+static int lan87xx_cable_test_report(struct phy_device *phydev)
+{
+	int pos_peak_cycle = 0, pos_peak_in_phases = 0, pos_peak_phase = 0;
+	int neg_peak_cycle = 0, neg_peak_in_phases = 0, neg_peak_phase = 0;
+	int noise_margin = 20, time_margin = 89, jitter_var = 30;
+	int min_time_diff = 96, max_time_diff = 96 + time_margin;
+	bool fault = false, check_a = false, check_b = false;
+	int gain_idx = 0, pos_peak = 0, neg_peak = 0;
+	int pos_peak_time = 0, neg_peak_time = 0;
+	int pos_peak_in_phases_hybrid = 0;
+	int detect = -1;
+
+	gain_idx = access_ereg(phydev, PHYACC_ATTR_MODE_READ,
+			       PHYACC_ATTR_BANK_DSP, 151, 0);
+	/* read non-hybrid results */
+	pos_peak = access_ereg(phydev, PHYACC_ATTR_MODE_READ,
+			       PHYACC_ATTR_BANK_DSP, 153, 0);
+	neg_peak = access_ereg(phydev, PHYACC_ATTR_MODE_READ,
+			       PHYACC_ATTR_BANK_DSP, 154, 0);
+	pos_peak_time = access_ereg(phydev, PHYACC_ATTR_MODE_READ,
+				    PHYACC_ATTR_BANK_DSP, 156, 0);
+	neg_peak_time = access_ereg(phydev, PHYACC_ATTR_MODE_READ,
+				    PHYACC_ATTR_BANK_DSP, 157, 0);
+
+	pos_peak_cycle = (pos_peak_time >> 7) & 0x7F;
+	/* calculate non-hybrid values */
+	pos_peak_phase = pos_peak_time & 0x7F;
+	pos_peak_in_phases = (pos_peak_cycle * 96) + pos_peak_phase;
+	neg_peak_cycle = (neg_peak_time >> 7) & 0x7F;
+	neg_peak_phase = neg_peak_time & 0x7F;
+	neg_peak_in_phases = (neg_peak_cycle * 96) + neg_peak_phase;
+
+	/* process values */
+	check_a =
+		((pos_peak_in_phases - neg_peak_in_phases) >= min_time_diff) &&
+		((pos_peak_in_phases - neg_peak_in_phases) < max_time_diff) &&
+		pos_peak_in_phases_hybrid < pos_peak_in_phases &&
+		(pos_peak_in_phases_hybrid < (neg_peak_in_phases + jitter_var));
+	check_b =
+		((neg_peak_in_phases - pos_peak_in_phases) >= min_time_diff) &&
+		((neg_peak_in_phases - pos_peak_in_phases) < max_time_diff) &&
+		pos_peak_in_phases_hybrid < neg_peak_in_phases &&
+		(pos_peak_in_phases_hybrid < (pos_peak_in_phases + jitter_var));
+
+	if (pos_peak_in_phases > neg_peak_in_phases && check_a)
+		detect = 2;
+	else if ((neg_peak_in_phases > pos_peak_in_phases) && check_b)
+		detect = 1;
+
+	if (pos_peak > noise_margin && neg_peak > noise_margin &&
+	    gain_idx >= 0) {
+		if (detect == 1 || detect == 2)
+			fault = true;
+	}
+
+	if (!fault)
+		detect = 0;
+
+	ethnl_cable_test_result(phydev, ETHTOOL_A_CABLE_PAIR_A,
+				lan87xx_cable_test_report_trans(detect));
+
+	return 0;
+}
+
+static int lan87xx_cable_test_get_status(struct phy_device *phydev,
+					 bool *finished)
+{
+	int rc = 0;
+
+	*finished = false;
+
+	/* check if cable diag was finished */
+	rc = access_ereg(phydev, PHYACC_ATTR_MODE_READ, PHYACC_ATTR_BANK_DSP,
+			 90, 0);
+	if (rc < 0)
+		return rc;
+
+	if ((rc & 2) == 2) {
+		/* stop cable diag*/
+		rc = access_ereg(phydev, PHYACC_ATTR_MODE_WRITE,
+				 PHYACC_ATTR_BANK_DSP,
+				 90, 0);
+		if (rc < 0)
+			return rc;
+
+		*finished = true;
+
+		return lan87xx_cable_test_report(phydev);
+	}
+
+	return 0;
+}
+
 static struct phy_driver microchip_t1_phy_driver[] = {
 	{
 		.phy_id         = 0x0007c150,
 		.phy_id_mask    = 0xfffffff0,
 		.name           = "Microchip LAN87xx T1",
+		.flags          = PHY_POLL_CABLE_TEST,
 
 		.features       = PHY_BASIC_T1_FEATURES,
 
@@ -241,6 +478,8 @@ static struct phy_driver microchip_t1_phy_driver[] = {
 
 		.suspend        = genphy_suspend,
 		.resume         = genphy_resume,
+		.cable_test_start = lan87xx_cable_test_start,
+		.cable_test_get_status = lan87xx_cable_test_get_status,
 	}
 };