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 <[e-mail]>
Signed-off-by: Jeff Garzik <[e-mail]>

Documentation/powerpc/booting-without-of.txt

···
       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
···
 	board-control@e8000000 {
 		compatible = "fsl,fpga-pixis";
 		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

drivers/net/phy/Kconfig

···
 
 	  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

drivers/net/phy/Makefile

···
 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

drivers/net/phy/mdio-ofgpio.c

···
+/*
+ * OpenFirmware GPIO based MDIO bitbang driver.
+ *
+ * Copyright (c) 2008 CSE Semaphore Belgium.
+ *  by Laurent Pinchart <[e-mail]>
+ *
+ * Based on earlier work by
+ *
+ * Copyright (c) 2003 Intracom S.A.
+ *  by Pantelis Antoniou <[e-mail]>
+ *
+ * 2005 (c) MontaVista Software, Inc.
+ * Vitaly Bordug <[e-mail]>
+ *
+ * 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);