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>

3 files changed, 242 insertions, 0 deletions

diff --git a/drivers/net/ethernet/marvell/Kconfig b/drivers/net/ethernet/marvell/Kconfig
index 0029934748bc..232ccb3cb08b 100644
--- a/drivers/net/ethernet/marvell/Kconfig
+++ b/drivers/net/ethernet/marvell/Kconfig
@@ -31,6 +31,17 @@ config MV643XX_ETH
           Some boards that use the Discovery chipset are the Momenco
           Ocelot C and Jaguar ATX and Pegasos II.
 
+config MVMDIO
+        tristate "Marvell MDIO interface support"
+        ---help---
+          This driver supports the MDIO interface found in the network
+          interface units of the Marvell EBU SoCs (Kirkwood, Orion5x,
+          Dove, Armada 370 and Armada XP).
+
+          For now, this driver is only needed for the MVNETA driver
+          (used on Armada 370 and XP), but it could be used in the
+          future by the MV643XX_ETH driver.
+
 config PXA168_ETH
         tristate "Marvell pxa168 ethernet support"
         depends on CPU_PXA168
diff --git a/drivers/net/ethernet/marvell/Makefile b/drivers/net/ethernet/marvell/Makefile
index 57e3234a37ba..0438599fba47 100644
--- a/drivers/net/ethernet/marvell/Makefile
+++ b/drivers/net/ethernet/marvell/Makefile
@@ -3,6 +3,7 @@
 #
 
 obj-$(CONFIG_MV643XX_ETH) += mv643xx_eth.o
+obj-$(CONFIG_MVMDIO) += mvmdio.o
 obj-$(CONFIG_PXA168_ETH) += pxa168_eth.o
 obj-$(CONFIG_SKGE) += skge.o
 obj-$(CONFIG_SKY2) += sky2.o
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");