[PATCH net-next 9/9] net: phy: vitesse: implement downshift in vsc73xx phys

[Pawel Dembicki <paweldembicki@gmail.com>]

This commit implements downshift feature in vsc73xx family phys.

By default downshift was enabled with maximum tries.

Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
---
 drivers/net/phy/vitesse.c | 100 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)

diff --git a/drivers/net/phy/vitesse.c b/drivers/net/phy/vitesse.c
index 19b7bf189be5..9228c6652627 100644
--- a/drivers/net/phy/vitesse.c
+++ b/drivers/net/phy/vitesse.c
@@ -10,8 +10,10 @@
 #include <linux/mii.h>
 #include <linux/ethtool.h>
 #include <linux/phy.h>
+#include <linux/bitfield.h>
 
 /* Vitesse Extended Page Magic Register(s) */
+#define MII_VSC73XX_EXT_PAGE_1E		0x01
 #define MII_VSC82X4_EXT_PAGE_16E	0x10
 #define MII_VSC82X4_EXT_PAGE_17E	0x11
 #define MII_VSC82X4_EXT_PAGE_18E	0x12
@@ -60,6 +62,15 @@
 /* Vitesse Extended Page Access Register */
 #define MII_VSC82X4_EXT_PAGE_ACCESS	0x1f
 
+/* Vitesse VSC73XX Extended Control Register */
+#define MII_VSC73XX_PHY_CTRL_EXT3		0x14
+
+#define MII_VSC73XX_PHY_CTRL_EXT3_DOWNSHIFT_EN	BIT(4)
+#define MII_VSC73XX_PHY_CTRL_EXT3_DOWNSHIFT_CNT	GENMASK(3, 2)
+#define MII_VSC73XX_PHY_CTRL_EXT3_DOWNSHIFT_STA	BIT(1)
+#define MII_VSC73XX_DOWNSHIFT_MAX		5
+#define MII_VSC73XX_DOWNSHIFT_INVAL		1
+
 /* VSC73XX PHY_BYPASS_CTRL register*/
 #define MII_VSC73XX_PHY_BYPASS_CTRL		MII_DCOUNTER
 #define MII_PBC_FORCED_SPEED_AUTO_MDIX_DIS	BIT(7)
@@ -133,6 +144,84 @@ static int vsc73xx_write_page(struct phy_device *phydev, int page)
 	return __phy_write(phydev, VSC73XX_EXT_PAGE_ACCESS, page);
 }
 
+static int vsc73xx_get_downshift(struct phy_device *phydev, u8 *data)
+{
+	int page, val, cnt, enable;
+
+	page = phy_select_page(phydev, MII_VSC73XX_EXT_PAGE_1E);
+	if (page < 0)
+		return page;
+
+	val = __phy_read(phydev, MII_VSC73XX_PHY_CTRL_EXT3);
+	if (val < 0)
+		goto restore_page;
+
+	enable = FIELD_GET(MII_VSC73XX_PHY_CTRL_EXT3_DOWNSHIFT_EN, val);
+	cnt = FIELD_GET(MII_VSC73XX_PHY_CTRL_EXT3_DOWNSHIFT_CNT, val) + 2;
+
+	*data = enable ? cnt : DOWNSHIFT_DEV_DISABLE;
+
+restore_page:
+	phy_restore_page(phydev, page, val);
+	return 0;
+}
+
+static int vsc73xx_set_downshift(struct phy_device *phydev, u8 cnt)
+{
+	int page, ret, val;
+
+	if (cnt > MII_VSC73XX_DOWNSHIFT_MAX)
+		return -E2BIG;
+	else if (cnt == MII_VSC73XX_DOWNSHIFT_INVAL)
+		return -EINVAL;
+
+	page = phy_select_page(phydev, MII_VSC73XX_EXT_PAGE_1E);
+	if (page < 0)
+		return page;
+
+	if (!cnt) {
+		ret = __phy_clear_bits(phydev, MII_VSC73XX_PHY_CTRL_EXT3,
+				       MII_VSC73XX_PHY_CTRL_EXT3_DOWNSHIFT_EN);
+	} else {
+		val = MII_VSC73XX_PHY_CTRL_EXT3_DOWNSHIFT_EN |
+		      FIELD_PREP(MII_VSC73XX_PHY_CTRL_EXT3_DOWNSHIFT_CNT,
+				 cnt - 2);
+
+		ret = __phy_modify(phydev, MII_VSC73XX_PHY_CTRL_EXT3,
+				   MII_VSC73XX_PHY_CTRL_EXT3_DOWNSHIFT_EN |
+				   MII_VSC73XX_PHY_CTRL_EXT3_DOWNSHIFT_CNT,
+				   val);
+	}
+
+	ret = phy_restore_page(phydev, page, ret);
+	if (ret < 0)
+		return ret;
+
+	return genphy_soft_reset(phydev);
+}
+
+static int vsc73xx_get_tunable(struct phy_device *phydev,
+			       struct ethtool_tunable *tuna, void *data)
+{
+	switch (tuna->id) {
+	case ETHTOOL_PHY_DOWNSHIFT:
+		return vsc73xx_get_downshift(phydev, data);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int vsc73xx_set_tunable(struct phy_device *phydev,
+			       struct ethtool_tunable *tuna, const void *data)
+{
+	switch (tuna->id) {
+	case ETHTOOL_PHY_DOWNSHIFT:
+		return vsc73xx_set_downshift(phydev, *(const u8 *)data);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
 static void vsc73xx_config_init(struct phy_device *phydev)
 {
 	/* Receiver init */
@@ -142,6 +231,9 @@ static void vsc73xx_config_init(struct phy_device *phydev)
 
 	/* Config LEDs 0x61 */
 	phy_modify(phydev, MII_TPISTATUS, 0xff00, 0x0061);
+
+	/* Enable downshift by default */
+	vsc73xx_set_downshift(phydev, MII_VSC73XX_DOWNSHIFT_MAX);
 }
 
 static int vsc738x_config_init(struct phy_device *phydev)
@@ -460,6 +552,8 @@ static struct phy_driver vsc82xx_driver[] = {
 	.config_aneg    = vsc73xx_config_aneg,
 	.read_page      = vsc73xx_read_page,
 	.write_page     = vsc73xx_write_page,
+	.get_tunable    = vsc73xx_get_tunable,
+	.set_tunable    = vsc73xx_set_tunable,
 }, {
 	.phy_id         = PHY_ID_VSC7388,
 	.name           = "Vitesse VSC7388",
@@ -469,6 +563,8 @@ static struct phy_driver vsc82xx_driver[] = {
 	.config_aneg    = vsc73xx_config_aneg,
 	.read_page      = vsc73xx_read_page,
 	.write_page     = vsc73xx_write_page,
+	.get_tunable    = vsc73xx_get_tunable,
+	.set_tunable    = vsc73xx_set_tunable,
 }, {
 	.phy_id         = PHY_ID_VSC7395,
 	.name           = "Vitesse VSC7395",
@@ -478,6 +574,8 @@ static struct phy_driver vsc82xx_driver[] = {
 	.config_aneg    = vsc73xx_config_aneg,
 	.read_page      = vsc73xx_read_page,
 	.write_page     = vsc73xx_write_page,
+	.get_tunable    = vsc73xx_get_tunable,
+	.set_tunable    = vsc73xx_set_tunable,
 }, {
 	.phy_id         = PHY_ID_VSC7398,
 	.name           = "Vitesse VSC7398",
@@ -487,6 +585,8 @@ static struct phy_driver vsc82xx_driver[] = {
 	.config_aneg    = vsc73xx_config_aneg,
 	.read_page      = vsc73xx_read_page,
 	.write_page     = vsc73xx_write_page,
+	.get_tunable    = vsc73xx_get_tunable,
+	.set_tunable    = vsc73xx_set_tunable,
 }, {
 	.phy_id         = PHY_ID_VSC8662,
 	.name           = "Vitesse VSC8662",
-- 
2.34.1