net: phy: Add gmiitorgmii converter support

This patch adds support for gmiitorgmii converter.

The GMII to RGMII IP core provides the Reduced Gigabit Media
Independent Interface (RGMII) between Ethernet physical media
Devices and the Gigabit Ethernet controller. This core can
Switch dynamically between the three different speed modes of
Operation by configuring the converter register through mdio write.

MDIO interface is used to set operating speed of Ethernet MAC.

This converter sits between the MAC and the external phy
MAC <==> GMII2RGMII <==> RGMII_PHY

Signed-off-by: Kedareswara rao Appana <appanad@xilinx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/Kconfig

@@ -312,6 +312,13 @@ config MICROSEMI_PHY
     ---help---
       Currently supports the VSC8531 and VSC8541 PHYs
 
+config XILINX_GMII2RGMII
+       tristate "Xilinx GMII2RGMII converter driver"
+       ---help---
+         This driver support xilinx GMII to RGMII IP core it provides
+         the Reduced Gigabit Media Independent Interface(RGMII) between
+         Ethernet physical media devices and the Gigabit Ethernet controller.
+
 endif # PHYLIB
 
 config MICREL_KS8995MA

drivers/net/phy/Makefile

@@ -50,3 +50,4 @@ obj-$(CONFIG_MDIO_BCM_IPROC)	+= mdio-bcm-iproc.o
 obj-$(CONFIG_INTEL_XWAY_PHY)	+= intel-xway.o
 obj-$(CONFIG_MDIO_HISI_FEMAC)	+= mdio-hisi-femac.o
 obj-$(CONFIG_MDIO_XGENE)	+= mdio-xgene.o
+obj-$(CONFIG_XILINX_GMII2RGMII) += xilinx_gmii2rgmii.o

drivers/net/phy/xilinx_gmii2rgmii.c

@@ -0,0 +1,109 @@
+/* Xilinx GMII2RGMII Converter driver
+ *
+ * Copyright (C) 2016 Xilinx, Inc.
+ *
+ * Author: Kedareswara rao Appana <appanad@xilinx.com>
+ *
+ * Description:
+ * This driver is developed for Xilinx GMII2RGMII Converter
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/mii.h>
+#include <linux/mdio.h>
+#include <linux/phy.h>
+#include <linux/of_mdio.h>
+
+#define XILINX_GMII2RGMII_REG		0x10
+#define XILINX_GMII2RGMII_SPEED_MASK	(BMCR_SPEED1000 | BMCR_SPEED100)
+
+struct gmii2rgmii {
+	struct phy_device *phy_dev;
+	struct phy_driver *phy_drv;
+	struct phy_driver conv_phy_drv;
+	int addr;
+};
+
+static int xgmiitorgmii_read_status(struct phy_device *phydev)
+{
+	struct gmii2rgmii *priv = phydev->priv;
+	u16 val = 0;
+
+	priv->phy_drv->read_status(phydev);
+
+	val = mdiobus_read(phydev->mdio.bus, priv->addr, XILINX_GMII2RGMII_REG);
+	val &= XILINX_GMII2RGMII_SPEED_MASK;
+
+	if (phydev->speed == SPEED_1000)
+		val |= BMCR_SPEED1000;
+	else if (phydev->speed == SPEED_100)
+		val |= BMCR_SPEED100;
+	else
+		val |= BMCR_SPEED10;
+
+	mdiobus_write(phydev->mdio.bus, priv->addr, XILINX_GMII2RGMII_REG, val);
+
+	return 0;
+}
+
+int xgmiitorgmii_probe(struct mdio_device *mdiodev)
+{
+	struct device *dev = &mdiodev->dev;
+	struct device_node *np = dev->of_node, *phy_node;
+	struct gmii2rgmii *priv;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	phy_node = of_parse_phandle(np, "phy-handle", 0);
+	if (IS_ERR(phy_node)) {
+		dev_err(dev, "Couldn't parse phy-handle\n");
+		return -ENODEV;
+	}
+
+	priv->phy_dev = of_phy_find_device(phy_node);
+	if (!priv->phy_dev) {
+		dev_info(dev, "Couldn't find phydev\n");
+		return -EPROBE_DEFER;
+	}
+
+	priv->addr = mdiodev->addr;
+	priv->phy_drv = priv->phy_dev->drv;
+	memcpy(&priv->conv_phy_drv, priv->phy_dev->drv,
+	       sizeof(struct phy_driver));
+	priv->conv_phy_drv.read_status = xgmiitorgmii_read_status;
+	priv->phy_dev->priv = priv;
+	priv->phy_dev->drv = &priv->conv_phy_drv;
+
+	return 0;
+}
+
+static const struct of_device_id xgmiitorgmii_of_match[] = {
+	{ .compatible = "xlnx,gmii-to-rgmii-1.0" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, xgmiitorgmii_of_match);
+
+static struct mdio_driver xgmiitorgmii_driver = {
+	.probe	= xgmiitorgmii_probe,
+	.mdiodrv.driver = {
+		.name = "xgmiitorgmii",
+		.of_match_table = xgmiitorgmii_of_match,
+	},
+};
+
+mdio_module_driver(xgmiitorgmii_driver);
+
+MODULE_DESCRIPTION("Xilinx GMII2RGMII converter driver");
+MODULE_LICENSE("GPL");