net: OpenFirmware GPIO based MDIO bitbang driver

This patch adds an MDIO bitbang driver that uses the GPIO library and its
OF bindings to access the bus I/Os.

Signed-off-by: Laurent Pinchart <laurentp@cse-semaphore.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

4 files changed, 233 insertions, 0 deletions

diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt
index 1d2a772506cf..46a9dba11f2f 100644
--- a/Documentation/powerpc/booting-without-of.txt
+++ b/Documentation/powerpc/booting-without-of.txt
@@ -58,6 +58,7 @@ Table of Contents
       o) Xilinx IP cores
       p) Freescale Synchronous Serial Interface
           q) USB EHCI controllers
+      r) MDIO on GPIOs
 
   VII - Marvell Discovery mv64[345]6x System Controller chips
     1) The /system-controller node
@@ -2870,6 +2871,26 @@ platforms are moved over to use the flattened-device-tree model.
                 reg = <0xe8000000 32>;
         };
 
+   r) MDIO on GPIOs
+
+   Currently defined compatibles:
+   - virtual,gpio-mdio
+
+   MDC and MDIO lines connected to GPIO controllers are listed in the
+   gpios property as described in section VIII.1 in the following order:
+
+   MDC, MDIO.
+
+   Example:
+
+        mdio {
+                compatible = "virtual,mdio-gpio";
+                #address-cells = <1>;
+                #size-cells = <0>;
+                gpios = <&qe_pio_a 11
+                         &qe_pio_c 6>;
+        };
+
 VII - Marvell Discovery mv64[345]6x System Controller chips
 ===========================================================
 
diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index 284217c12839..d55932acd887 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -84,4 +84,10 @@ config MDIO_BITBANG
 
           If in doubt, say N.
 
+config MDIO_OF_GPIO
+        tristate "Support for GPIO lib-based bitbanged MDIO buses"
+        depends on MDIO_BITBANG && OF_GPIO
+        ---help---
+          Supports GPIO lib-based MDIO busses.
+
 endif # PHYLIB
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index 5997d6ef702b..eee329fa6f53 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -15,3 +15,4 @@ obj-$(CONFIG_ICPLUS_PHY)	+= icplus.o
 obj-$(CONFIG_REALTEK_PHY)       += realtek.o
 obj-$(CONFIG_FIXED_PHY)         += fixed.o
 obj-$(CONFIG_MDIO_BITBANG)      += mdio-bitbang.o
+obj-$(CONFIG_MDIO_OF_GPIO)      += mdio-ofgpio.o
diff --git a/drivers/net/phy/mdio-ofgpio.c b/drivers/net/phy/mdio-ofgpio.c
new file mode 100644
index 000000000000..7edfc0c34835
--- /dev/null
+++ b/drivers/net/phy/mdio-ofgpio.c
@@ -0,0 +1,205 @@
+/*
+ * OpenFirmware GPIO based MDIO bitbang driver.
+ *
+ * Copyright (c) 2008 CSE Semaphore Belgium.
+ *  by Laurent Pinchart <laurentp@cse-semaphore.com>
+ *
+ * Based on earlier work by
+ *
+ * Copyright (c) 2003 Intracom S.A.
+ *  by Pantelis Antoniou <panto@intracom.gr>
+ *
+ * 2005 (c) MontaVista Software, Inc.
+ * Vitaly Bordug <vbordug@ru.mvista.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/module.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/mdio-bitbang.h>
+#include <linux/of_gpio.h>
+#include <linux/of_platform.h>
+
+struct mdio_gpio_info {
+        struct mdiobb_ctrl ctrl;
+        int mdc, mdio;
+};
+
+static void mdio_dir(struct mdiobb_ctrl *ctrl, int dir)
+{
+        struct mdio_gpio_info *bitbang =
+                container_of(ctrl, struct mdio_gpio_info, ctrl);
+
+        if (dir)
+                gpio_direction_output(bitbang->mdio, 1);
+        else
+                gpio_direction_input(bitbang->mdio);
+}
+
+static int mdio_read(struct mdiobb_ctrl *ctrl)
+{
+        struct mdio_gpio_info *bitbang =
+                container_of(ctrl, struct mdio_gpio_info, ctrl);
+
+        return gpio_get_value(bitbang->mdio);
+}
+
+static void mdio(struct mdiobb_ctrl *ctrl, int what)
+{
+        struct mdio_gpio_info *bitbang =
+                container_of(ctrl, struct mdio_gpio_info, ctrl);
+
+        gpio_set_value(bitbang->mdio, what);
+}
+
+static void mdc(struct mdiobb_ctrl *ctrl, int what)
+{
+        struct mdio_gpio_info *bitbang =
+                container_of(ctrl, struct mdio_gpio_info, ctrl);
+
+        gpio_set_value(bitbang->mdc, what);
+}
+
+static struct mdiobb_ops mdio_gpio_ops = {
+        .owner = THIS_MODULE,
+        .set_mdc = mdc,
+        .set_mdio_dir = mdio_dir,
+        .set_mdio_data = mdio,
+        .get_mdio_data = mdio_read,
+};
+
+static int __devinit mdio_ofgpio_bitbang_init(struct mii_bus *bus,
+                                         struct device_node *np)
+{
+        struct mdio_gpio_info *bitbang = bus->priv;
+
+        bitbang->mdc = of_get_gpio(np, 0);
+        bitbang->mdio = of_get_gpio(np, 1);
+
+        if (bitbang->mdc < 0 || bitbang->mdio < 0)
+                return -ENODEV;
+
+        snprintf(bus->id, MII_BUS_ID_SIZE, "%x", bitbang->mdc);
+        return 0;
+}
+
+static void __devinit add_phy(struct mii_bus *bus, struct device_node *np)
+{
+        const u32 *data;
+        int len, id, irq;
+
+        data = of_get_property(np, "reg", &len);
+        if (!data || len != 4)
+                return;
+
+        id = *data;
+        bus->phy_mask &= ~(1 << id);
+
+        irq = of_irq_to_resource(np, 0, NULL);
+        if (irq != NO_IRQ)
+                bus->irq[id] = irq;
+}
+
+static int __devinit mdio_ofgpio_probe(struct of_device *ofdev,
+                                        const struct of_device_id *match)
+{
+        struct device_node *np = NULL;
+        struct mii_bus *new_bus;
+        struct mdio_gpio_info *bitbang;
+        int ret = -ENOMEM;
+        int i;
+
+        bitbang = kzalloc(sizeof(struct mdio_gpio_info), GFP_KERNEL);
+        if (!bitbang)
+                goto out;
+
+        bitbang->ctrl.ops = &mdio_gpio_ops;
+
+        new_bus = alloc_mdio_bitbang(&bitbang->ctrl);
+        if (!new_bus)
+                goto out_free_priv;
+
+        new_bus->name = "GPIO Bitbanged MII",
+
+        ret = mdio_ofgpio_bitbang_init(new_bus, ofdev->node);
+        if (ret)
+                goto out_free_bus;
+
+        new_bus->phy_mask = ~0;
+        new_bus->irq = kmalloc(sizeof(int) * PHY_MAX_ADDR, GFP_KERNEL);
+        if (!new_bus->irq)
+                goto out_free_bus;
+
+        for (i = 0; i < PHY_MAX_ADDR; i++)
+                new_bus->irq[i] = -1;
+
+        while ((np = of_get_next_child(ofdev->node, np)))
+                if (!strcmp(np->type, "ethernet-phy"))
+                        add_phy(new_bus, np);
+
+        new_bus->dev = &ofdev->dev;
+        dev_set_drvdata(&ofdev->dev, new_bus);
+
+        ret = mdiobus_register(new_bus);
+        if (ret)
+                goto out_free_irqs;
+
+        return 0;
+
+out_free_irqs:
+        dev_set_drvdata(&ofdev->dev, NULL);
+        kfree(new_bus->irq);
+out_free_bus:
+        kfree(new_bus);
+out_free_priv:
+        free_mdio_bitbang(new_bus);
+out:
+        return ret;
+}
+
+static int mdio_ofgpio_remove(struct of_device *ofdev)
+{
+        struct mii_bus *bus = dev_get_drvdata(&ofdev->dev);
+        struct mdio_gpio_info *bitbang = bus->priv;
+
+        mdiobus_unregister(bus);
+        free_mdio_bitbang(bus);
+        dev_set_drvdata(&ofdev->dev, NULL);
+        kfree(bus->irq);
+        kfree(bitbang);
+        kfree(bus);
+
+        return 0;
+}
+
+static struct of_device_id mdio_ofgpio_match[] = {
+        {
+                .compatible = "virtual,mdio-gpio",
+        },
+        {},
+};
+
+static struct of_platform_driver mdio_ofgpio_driver = {
+        .name = "mdio-gpio",
+        .match_table = mdio_ofgpio_match,
+        .probe = mdio_ofgpio_probe,
+        .remove = mdio_ofgpio_remove,
+};
+
+static int mdio_ofgpio_init(void)
+{
+        return of_register_platform_driver(&mdio_ofgpio_driver);
+}
+
+static void mdio_ofgpio_exit(void)
+{
+        of_unregister_platform_driver(&mdio_ofgpio_driver);
+}
+
+module_init(mdio_ofgpio_init);
+module_exit(mdio_ofgpio_exit);