net: mvmdio: new Marvell MDIO driver

This patch adds a separate driver for the MDIO interface of the
Marvell Ethernet controllers. There are two reasons to have a separate
driver rather than including it inside the MAC driver itself:

 *) The MDIO interface is shared by all Ethernet ports, so a driver
    must guarantee non-concurrent accesses to this MDIO interface. The
    most logical way is to have a separate driver that handles this
    single MDIO interface, used by all Ethernet ports.

 *) The MDIO interface is the same between the existing mv643xx_eth
    driver and the new mvneta driver. Even though it is for now only
    used by the mvneta driver, it will in the future be used by the
    mv643xx_eth driver as well.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: David S. Miller <davem@davemloft.net>

1 files changed, 230 insertions, 0 deletions

diff --git a/drivers/net/ethernet/marvell/mvmdio.c b/drivers/net/ethernet/marvell/mvmdio.c
new file mode 100644
index 000000000000..82fbd235e502
--- /dev/null
+++ b/drivers/net/ethernet/marvell/mvmdio.c
@@ -0,0 +1,230 @@
+/*
+ * Driver for the MDIO interface of Marvell network interfaces.
+ *
+ * Since the MDIO interface of Marvell network interfaces is shared
+ * between all network interfaces, having a single driver allows to
+ * handle concurrent accesses properly (you may have four Ethernet
+ * ports, but they in fact share the same SMI interface to access the
+ * MDIO bus). Moreover, this MDIO interface code is similar between
+ * the mv643xx_eth driver and the mvneta driver. For now, it is only
+ * used by the mvneta driver, but it could later be used by the
+ * mv643xx_eth driver as well.
+ *
+ * Copyright (C) 2012 Marvell
+ *
+ * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/phy.h>
+#include <linux/of_address.h>
+#include <linux/of_mdio.h>
+#include <linux/platform_device.h>
+
+#include <asm/delay.h>
+
+#define MVMDIO_SMI_DATA_SHIFT              0
+#define MVMDIO_SMI_PHY_ADDR_SHIFT          16
+#define MVMDIO_SMI_PHY_REG_SHIFT           21
+#define MVMDIO_SMI_READ_OPERATION          BIT(26)
+#define MVMDIO_SMI_WRITE_OPERATION         0
+#define MVMDIO_SMI_READ_VALID              BIT(27)
+#define MVMDIO_SMI_BUSY                    BIT(28)
+
+struct orion_mdio_dev {
+	struct mutex lock;
+	void __iomem *smireg;
+};
+
+/*
+ * Wait for the SMI unit to be ready for another operation
+ */
+static int orion_mdio_wait_ready(struct mii_bus *bus)
+{
+	struct orion_mdio_dev *dev = bus->priv;
+	int count;
+	u32 val;
+
+	count = 0;
+	while (1) {
+		val = readl(dev->smireg);
+		if (!(val & MVMDIO_SMI_BUSY))
+			break;
+
+		if (count > 100) {
+			dev_err(bus->parent, "Timeout: SMI busy for too long\n");
+			return -ETIMEDOUT;
+		}
+
+		udelay(10);
+		count++;
+	}
+
+	return 0;
+}
+
+static int orion_mdio_read(struct mii_bus *bus, int mii_id,
+			   int regnum)
+{
+	struct orion_mdio_dev *dev = bus->priv;
+	int count;
+	u32 val;
+	int ret;
+
+	mutex_lock(&dev->lock);
+
+	ret = orion_mdio_wait_ready(bus);
+	if (ret < 0) {
+		mutex_unlock(&dev->lock);
+		return ret;
+	}
+
+	writel(((mii_id << MVMDIO_SMI_PHY_ADDR_SHIFT) |
+		(regnum << MVMDIO_SMI_PHY_REG_SHIFT)  |
+		MVMDIO_SMI_READ_OPERATION),
+	       dev->smireg);
+
+	/* Wait for the value to become available */
+	count = 0;
+	while (1) {
+		val = readl(dev->smireg);
+		if (val & MVMDIO_SMI_READ_VALID)
+			break;
+
+		if (count > 100) {
+			dev_err(bus->parent, "Timeout when reading PHY\n");
+			mutex_unlock(&dev->lock);
+			return -ETIMEDOUT;
+		}
+
+		udelay(10);
+		count++;
+	}
+
+	mutex_unlock(&dev->lock);
+
+	return val & 0xFFFF;
+}
+
+static int orion_mdio_write(struct mii_bus *bus, int mii_id,
+			    int regnum, u16 value)
+{
+	struct orion_mdio_dev *dev = bus->priv;
+	int ret;
+
+	mutex_lock(&dev->lock);
+
+	ret = orion_mdio_wait_ready(bus);
+	if (ret < 0) {
+		mutex_unlock(&dev->lock);
+		return ret;
+	}
+
+	writel(((mii_id << MVMDIO_SMI_PHY_ADDR_SHIFT) |
+		(regnum << MVMDIO_SMI_PHY_REG_SHIFT)  |
+		MVMDIO_SMI_WRITE_OPERATION            |
+		(value << MVMDIO_SMI_DATA_SHIFT)),
+	       dev->smireg);
+
+	mutex_unlock(&dev->lock);
+
+	return 0;
+}
+
+static int orion_mdio_reset(struct mii_bus *bus)
+{
+	return 0;
+}
+
+static int __devinit orion_mdio_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct mii_bus *bus;
+	struct orion_mdio_dev *dev;
+	int i, ret;
+
+	bus = mdiobus_alloc_size(sizeof(struct orion_mdio_dev));
+	if (!bus) {
+		dev_err(&pdev->dev, "Cannot allocate MDIO bus\n");
+		return -ENOMEM;
+	}
+
+	bus->name = "orion_mdio_bus";
+	bus->read = orion_mdio_read;
+	bus->write = orion_mdio_write;
+	bus->reset = orion_mdio_reset;
+	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-mii",
+		 dev_name(&pdev->dev));
+	bus->parent = &pdev->dev;
+
+	bus->irq = kmalloc(sizeof(int) * PHY_MAX_ADDR, GFP_KERNEL);
+	if (!bus->irq) {
+		dev_err(&pdev->dev, "Cannot allocate PHY IRQ array\n");
+		mdiobus_free(bus);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < PHY_MAX_ADDR; i++)
+		bus->irq[i] = PHY_POLL;
+
+	dev = bus->priv;
+	dev->smireg = of_iomap(pdev->dev.of_node, 0);
+	if (!dev->smireg) {
+		dev_err(&pdev->dev, "No SMI register address given in DT\n");
+		kfree(bus->irq);
+		mdiobus_free(bus);
+		return -ENODEV;
+	}
+
+	mutex_init(&dev->lock);
+
+	ret = of_mdiobus_register(bus, np);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Cannot register MDIO bus (%d)\n", ret);
+		iounmap(dev->smireg);
+		kfree(bus->irq);
+		mdiobus_free(bus);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, bus);
+
+	return 0;
+}
+
+static int __devexit orion_mdio_remove(struct platform_device *pdev)
+{
+	struct mii_bus *bus = platform_get_drvdata(pdev);
+	mdiobus_unregister(bus);
+	kfree(bus->irq);
+	mdiobus_free(bus);
+	return 0;
+}
+
+static const struct of_device_id orion_mdio_match[] = {
+	{ .compatible = "marvell,orion-mdio" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, orion_mdio_match);
+
+static struct platform_driver orion_mdio_driver = {
+	.probe = orion_mdio_probe,
+	.remove = __devexit_p(orion_mdio_remove),
+	.driver = {
+		.name = "orion-mdio",
+		.of_match_table = orion_mdio_match,
+	},
+};
+
+module_platform_driver(orion_mdio_driver);
+
+MODULE_DESCRIPTION("Marvell MDIO interface driver");
+MODULE_AUTHOR("Thomas Petazzoni <thomas.petazzoni@free-electrons.com>");
+MODULE_LICENSE("GPL");