net: phy: Broadcom iProc MDIO bus driver

This patch adds support for the Broadcom iProc MDIO bus interface.
The MDIO interface can be found in the Broadcom iProc family Soc's.

The MDIO bus is accessed using a combination of command and data
registers. This MDIO driver provides access to the Etherent GPHY's
connected to the MDIO bus.
Signed-off-by: Arun Parameswaran <arunp@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/Kconfig

@@ -225,6 +225,15 @@ config MDIO_BCM_UNIMAC
 	  This hardware can be found in the Broadcom GENET Ethernet MAC
 	  controllers as well as some Broadcom Ethernet switches such as the
 	  Starfighter 2 switches.
+
+config MDIO_BCM_IPROC
+	tristate "Broadcom iProc MDIO bus controller"
+	depends on ARCH_BCM_IPROC || COMPILE_TEST
+	depends on HAS_IOMEM && OF_MDIO
+	help
+	  This module provides a driver for the MDIO busses found in the
+	  Broadcom iProc SoC's.
+
 endif # PHYLIB
 
 config MICREL_KS8995MA

drivers/net/phy/Makefile

@@ -38,3 +38,4 @@ obj-$(CONFIG_MDIO_SUN4I)	+= mdio-sun4i.o
 obj-$(CONFIG_MDIO_MOXART)	+= mdio-moxart.o
 obj-$(CONFIG_MDIO_BCM_UNIMAC)	+= mdio-bcm-unimac.o
 obj-$(CONFIG_MICROCHIP_PHY)	+= microchip.o
+obj-$(CONFIG_MDIO_BCM_IPROC)	+= mdio-bcm-iproc.o

drivers/net/phy/mdio-bcm-iproc.c

+/*
+ * Copyright (C) 2015 Broadcom Corporation
+ *
+ * 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 version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/of_mdio.h>
+#include <linux/phy.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+
+#define IPROC_GPHY_MDCDIV    0x1a
+
+#define MII_CTRL_OFFSET      0x000
+
+#define MII_CTRL_DIV_SHIFT   0
+#define MII_CTRL_PRE_SHIFT   7
+#define MII_CTRL_BUSY_SHIFT  8
+
+#define MII_DATA_OFFSET      0x004
+#define MII_DATA_MASK        0xffff
+#define MII_DATA_TA_SHIFT    16
+#define MII_DATA_TA_VAL      2
+#define MII_DATA_RA_SHIFT    18
+#define MII_DATA_PA_SHIFT    23
+#define MII_DATA_OP_SHIFT    28
+#define MII_DATA_OP_WRITE    1
+#define MII_DATA_OP_READ     2
+#define MII_DATA_SB_SHIFT    30
+
+struct iproc_mdio_priv {
+	struct mii_bus *mii_bus;
+	void __iomem *base;
+};
+
+static inline int iproc_mdio_wait_for_idle(void __iomem *base)
+{
+	u32 val;
+	unsigned int timeout = 1000; /* loop for 1s */
+
+	do {
+		val = readl(base + MII_CTRL_OFFSET);
+		if ((val & BIT(MII_CTRL_BUSY_SHIFT)) == 0)
+			return 0;
+
+		usleep_range(1000, 2000);
+	} while (timeout--);
+
+	return -ETIMEDOUT;
+}
+
+static inline void iproc_mdio_config_clk(void __iomem *base)
+{
+	u32 val;
+
+	val = (IPROC_GPHY_MDCDIV << MII_CTRL_DIV_SHIFT) |
+		  BIT(MII_CTRL_PRE_SHIFT);
+	writel(val, base + MII_CTRL_OFFSET);
+}
+
+static int iproc_mdio_read(struct mii_bus *bus, int phy_id, int reg)
+{
+	struct iproc_mdio_priv *priv = bus->priv;
+	u32 cmd;
+	int rc;
+
+	rc = iproc_mdio_wait_for_idle(priv->base);
+	if (rc)
+		return rc;
+
+	iproc_mdio_config_clk(priv->base);
+
+	/* Prepare the read operation */
+	cmd = (MII_DATA_TA_VAL << MII_DATA_TA_SHIFT) |
+		(reg << MII_DATA_RA_SHIFT) |
+		(phy_id << MII_DATA_PA_SHIFT) |
+		BIT(MII_DATA_SB_SHIFT) |
+		(MII_DATA_OP_READ << MII_DATA_OP_SHIFT);
+
+	writel(cmd, priv->base + MII_DATA_OFFSET);
+
+	rc = iproc_mdio_wait_for_idle(priv->base);
+	if (rc)
+		return rc;
+
+	cmd = readl(priv->base + MII_DATA_OFFSET) & MII_DATA_MASK;
+
+	return cmd;
+}
+
+static int iproc_mdio_write(struct mii_bus *bus, int phy_id,
+			    int reg, u16 val)
+{
+	struct iproc_mdio_priv *priv = bus->priv;
+	u32 cmd;
+	int rc;
+
+	rc = iproc_mdio_wait_for_idle(priv->base);
+	if (rc)
+		return rc;
+
+	iproc_mdio_config_clk(priv->base);
+
+	/* Prepare the write operation */
+	cmd = (MII_DATA_TA_VAL << MII_DATA_TA_SHIFT) |
+		(reg << MII_DATA_RA_SHIFT) |
+		(phy_id << MII_DATA_PA_SHIFT) |
+		BIT(MII_DATA_SB_SHIFT) |
+		(MII_DATA_OP_WRITE << MII_DATA_OP_SHIFT) |
+		((u32)(val) & MII_DATA_MASK);
+
+	writel(cmd, priv->base + MII_DATA_OFFSET);
+
+	rc = iproc_mdio_wait_for_idle(priv->base);
+	if (rc)
+		return rc;
+
+	return 0;
+}
+
+static int iproc_mdio_probe(struct platform_device *pdev)
+{
+	struct iproc_mdio_priv *priv;
+	struct mii_bus *bus;
+	struct resource *res;
+	int rc;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(priv->base)) {
+		dev_err(&pdev->dev, "failed to ioremap register\n");
+		return PTR_ERR(priv->base);
+	}
+
+	priv->mii_bus = mdiobus_alloc();
+	if (!priv->mii_bus) {
+		dev_err(&pdev->dev, "MDIO bus alloc failed\n");
+		return -ENOMEM;
+	}
+
+	bus = priv->mii_bus;
+	bus->priv = priv;
+	bus->name = "iProc MDIO bus";
+	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-%d", pdev->name, pdev->id);
+	bus->parent = &pdev->dev;
+	bus->read = iproc_mdio_read;
+	bus->write = iproc_mdio_write;
+
+	rc = of_mdiobus_register(bus, pdev->dev.of_node);
+	if (rc) {
+		dev_err(&pdev->dev, "MDIO bus registration failed\n");
+		goto err_iproc_mdio;
+	}
+
+	platform_set_drvdata(pdev, priv);
+
+	dev_info(&pdev->dev, "Broadcom iProc MDIO bus at 0x%p\n", priv->base);
+
+	return 0;
+
+err_iproc_mdio:
+	mdiobus_free(bus);
+	return rc;
+}
+
+static int iproc_mdio_remove(struct platform_device *pdev)
+{
+	struct iproc_mdio_priv *priv = platform_get_drvdata(pdev);
+
+	mdiobus_unregister(priv->mii_bus);
+	mdiobus_free(priv->mii_bus);
+
+	return 0;
+}
+
+static const struct of_device_id iproc_mdio_of_match[] = {
+	{ .compatible = "brcm,iproc-mdio", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, iproc_mdio_of_match);
+
+static struct platform_driver iproc_mdio_driver = {
+	.driver = {
+		.name = "iproc-mdio",
+		.of_match_table = iproc_mdio_of_match,
+	},
+	.probe = iproc_mdio_probe,
+	.remove = iproc_mdio_remove,
+};
+
+module_platform_driver(iproc_mdio_driver);
+
+MODULE_AUTHOR("Broadcom Corporation");
+MODULE_DESCRIPTION("Broadcom iProc MDIO bus controller");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:iproc-mdio");