drivers/net/ethernet/ti/davinci_mdio.c - maze/linux - Git at Google

 /*
  * DaVinci MDIO Module driver
  *
  * Copyright (C) 2010 Texas Instruments.
  *
  * Shamelessly ripped out of davinci_emac.c, original copyrights follow:
  *
  * Copyright (C) 2009 Texas Instruments.
  *
  * ---------------------------------------------------------------------------
  *
  * 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; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  * ---------------------------------------------------------------------------
  */
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/platform_device.h>
 #include <linux/delay.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/phy.h>
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/pm_runtime.h>
 #include <linux/davinci_emac.h>
 #include <linux/of.h>
 #include <linux/of_device.h>

 /*
  * This timeout definition is a worst-case ultra defensive measure against
  * unexpected controller lock ups.  Ideally, we should never ever hit this
  * scenario in practice.
  */
 #define MDIO_TIMEOUT		100 /* msecs */

 #define PHY_REG_MASK		0x1f
 #define PHY_ID_MASK		0x1f

 #define DEF_OUT_FREQ		2200000		/* 2.2 MHz */

 struct davinci_mdio_regs {
 	u32	version;
 	u32	control;
 #define CONTROL_IDLE		BIT(31)
 #define CONTROL_ENABLE		BIT(30)
 #define CONTROL_MAX_DIV		(0xffff)

 	u32	alive;
 	u32	link;
 	u32	linkintraw;
 	u32	linkintmasked;
 	u32	__reserved_0[2];
 	u32	userintraw;
 	u32	userintmasked;
 	u32	userintmaskset;
 	u32	userintmaskclr;
 	u32	__reserved_1[20];

 	struct {
 		u32	access;
 #define USERACCESS_GO		BIT(31)
 #define USERACCESS_WRITE	BIT(30)
 #define USERACCESS_ACK		BIT(29)
 #define USERACCESS_READ		(0)
 #define USERACCESS_DATA		(0xffff)

 		u32	physel;
 	}	user[0];
 };

 struct mdio_platform_data default_pdata = {
 	.bus_freq = DEF_OUT_FREQ,
 };

 struct davinci_mdio_data {
 	struct mdio_platform_data pdata;
 	struct davinci_mdio_regs __iomem *regs;
 	spinlock_t	lock;
 	struct clk	*clk;
 	struct device	*dev;
 	struct mii_bus	*bus;
 	bool		suspended;
 	unsigned long	access_time; /* jiffies */
 };

 static void __davinci_mdio_reset(struct davinci_mdio_data *data)
 {
 	u32 mdio_in, div, mdio_out_khz, access_time;

 	mdio_in = clk_get_rate(data->clk);
 	div = (mdio_in / data->pdata.bus_freq) - 1;
 	if (div > CONTROL_MAX_DIV)
 		div = CONTROL_MAX_DIV;

 	/* set enable and clock divider */
 	__raw_writel(div | CONTROL_ENABLE, &data->regs->control);

 	/*
 	 * One mdio transaction consists of:
 	 *	32 bits of preamble
 	 *	32 bits of transferred data
 	 *	24 bits of bus yield (not needed unless shared?)
 	 */
 	mdio_out_khz = mdio_in / (1000 * (div + 1));
 	access_time  = (88 * 1000) / mdio_out_khz;

 	/*
 	 * In the worst case, we could be kicking off a user-access immediately
 	 * after the mdio bus scan state-machine triggered its own read.  If
 	 * so, our request could get deferred by one access cycle.  We
 	 * defensively allow for 4 access cycles.
 	 */
 	data->access_time = usecs_to_jiffies(access_time * 4);
 	if (!data->access_time)
 		data->access_time = 1;
 }

 static int davinci_mdio_reset(struct mii_bus *bus)
 {
 	struct davinci_mdio_data *data = bus->priv;
 	u32 phy_mask, ver;

 	__davinci_mdio_reset(data);

 	/* wait for scan logic to settle */
 	msleep(PHY_MAX_ADDR * data->access_time);

 	/* dump hardware version info */
 	ver = __raw_readl(&data->regs->version);
 	dev_info(data->dev, "davinci mdio revision %d.%d\n",
 		 (ver >> 8) & 0xff, ver & 0xff);

 	/* get phy mask from the alive register */
 	phy_mask = __raw_readl(&data->regs->alive);
 	if (phy_mask) {
 		/* restrict mdio bus to live phys only */
 		dev_info(data->dev, "detected phy mask %x\n", ~phy_mask);
 		phy_mask = ~phy_mask;
 	} else {
 		/* desperately scan all phys */
 		dev_warn(data->dev, "no live phy, scanning all\n");
 		phy_mask = 0;
 	}
 	data->bus->phy_mask = phy_mask;

 	return 0;
 }

 /* wait until hardware is ready for another user access */
 static inline int wait_for_user_access(struct davinci_mdio_data *data)
 {
 	struct davinci_mdio_regs __iomem *regs = data->regs;
 	unsigned long timeout = jiffies + msecs_to_jiffies(MDIO_TIMEOUT);
 	u32 reg;

 	while (time_after(timeout, jiffies)) {
 		reg = __raw_readl(&regs->user[0].access);
 		if ((reg & USERACCESS_GO) == 0)
 			return 0;

 		reg = __raw_readl(&regs->control);
 		if ((reg & CONTROL_IDLE) == 0)
 			continue;

 		/*
 		 * An emac soft_reset may have clobbered the mdio controller's
 		 * state machine.  We need to reset and retry the current
 		 * operation
 		 */
 		dev_warn(data->dev, "resetting idled controller\n");
 		__davinci_mdio_reset(data);
 		return -EAGAIN;
 	}

 	reg = __raw_readl(&regs->user[0].access);
 	if ((reg & USERACCESS_GO) == 0)
 		return 0;

 	dev_err(data->dev, "timed out waiting for user access\n");
 	return -ETIMEDOUT;
 }

 /* wait until hardware state machine is idle */
 static inline int wait_for_idle(struct davinci_mdio_data *data)
 {
 	struct davinci_mdio_regs __iomem *regs = data->regs;
 	unsigned long timeout = jiffies + msecs_to_jiffies(MDIO_TIMEOUT);

 	while (time_after(timeout, jiffies)) {
 		if (__raw_readl(&regs->control) & CONTROL_IDLE)
 			return 0;
 	}
 	dev_err(data->dev, "timed out waiting for idle\n");
 	return -ETIMEDOUT;
 }

 static int davinci_mdio_read(struct mii_bus *bus, int phy_id, int phy_reg)
 {
 	struct davinci_mdio_data *data = bus->priv;
 	u32 reg;
 	int ret;

 	if (phy_reg & ~PHY_REG_MASK || phy_id & ~PHY_ID_MASK)
 		return -EINVAL;

 	spin_lock(&data->lock);

 	if (data->suspended) {
 		spin_unlock(&data->lock);
 		return -ENODEV;
 	}

 	reg = (USERACCESS_GO | USERACCESS_READ | (phy_reg << 21) |
 	       (phy_id << 16));

 	while (1) {
 		ret = wait_for_user_access(data);
 		if (ret == -EAGAIN)
 			continue;
 		if (ret < 0)
 			break;

 		__raw_writel(reg, &data->regs->user[0].access);

 		ret = wait_for_user_access(data);
 		if (ret == -EAGAIN)
 			continue;
 		if (ret < 0)
 			break;

 		reg = __raw_readl(&data->regs->user[0].access);
 		ret = (reg & USERACCESS_ACK) ? (reg & USERACCESS_DATA) : -EIO;
 		break;
 	}

 	spin_unlock(&data->lock);

 	return ret;
 }

 static int davinci_mdio_write(struct mii_bus *bus, int phy_id,
 			      int phy_reg, u16 phy_data)
 {
 	struct davinci_mdio_data *data = bus->priv;
 	u32 reg;
 	int ret;

 	if (phy_reg & ~PHY_REG_MASK || phy_id & ~PHY_ID_MASK)
 		return -EINVAL;

 	spin_lock(&data->lock);

 	if (data->suspended) {
 		spin_unlock(&data->lock);
 		return -ENODEV;
 	}

 	reg = (USERACCESS_GO | USERACCESS_WRITE | (phy_reg << 21) |
 		   (phy_id << 16) | (phy_data & USERACCESS_DATA));

 	while (1) {
 		ret = wait_for_user_access(data);
 		if (ret == -EAGAIN)
 			continue;
 		if (ret < 0)
 			break;

 		__raw_writel(reg, &data->regs->user[0].access);

 		ret = wait_for_user_access(data);
 		if (ret == -EAGAIN)
 			continue;
 		break;
 	}

 	spin_unlock(&data->lock);

 	return 0;
 }

 static int davinci_mdio_probe_dt(struct mdio_platform_data *data,
 			 struct platform_device *pdev)
 {
 	struct device_node *node = pdev->dev.of_node;
 	u32 prop;

 	if (!node)
 		return -EINVAL;

 	if (of_property_read_u32(node, "bus_freq", &prop)) {
 		pr_err("Missing bus_freq property in the DT.\n");
 		return -EINVAL;
 	}
 	data->bus_freq = prop;

 	return 0;
 }


 static int davinci_mdio_probe(struct platform_device *pdev)
 {
 	struct mdio_platform_data *pdata = pdev->dev.platform_data;
 	struct device *dev = &pdev->dev;
 	struct davinci_mdio_data *data;
 	struct resource *res;
 	struct phy_device *phy;
 	int ret, addr;

 	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	data->bus = mdiobus_alloc();
 	if (!data->bus) {
 		dev_err(dev, "failed to alloc mii bus\n");
 		ret = -ENOMEM;
 		goto bail_out;
 	}

 	if (dev->of_node) {
 		if (davinci_mdio_probe_dt(&data->pdata, pdev))
 			data->pdata = default_pdata;
 		snprintf(data->bus->id, MII_BUS_ID_SIZE, "%s", pdev->name);
 	} else {
 		data->pdata = pdata ? (*pdata) : default_pdata;
 		snprintf(data->bus->id, MII_BUS_ID_SIZE, "%s-%x",
 			 pdev->name, pdev->id);
 	}

 	data->bus->name		= dev_name(dev);
 	data->bus->read		= davinci_mdio_read,
 	data->bus->write	= davinci_mdio_write,
 	data->bus->reset	= davinci_mdio_reset,
 	data->bus->parent	= dev;
 	data->bus->priv		= data;

 	pm_runtime_enable(&pdev->dev);
 	pm_runtime_get_sync(&pdev->dev);
 	data->clk = clk_get(&pdev->dev, "fck");
 	if (IS_ERR(data->clk)) {
 		dev_err(dev, "failed to get device clock\n");
 		ret = PTR_ERR(data->clk);
 		data->clk = NULL;
 		goto bail_out;
 	}

 	dev_set_drvdata(dev, data);
 	data->dev = dev;
 	spin_lock_init(&data->lock);

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {
 		dev_err(dev, "could not find register map resource\n");
 		ret = -ENOENT;
 		goto bail_out;
 	}

 	res = devm_request_mem_region(dev, res->start, resource_size(res),
 					    dev_name(dev));
 	if (!res) {
 		dev_err(dev, "could not allocate register map resource\n");
 		ret = -ENXIO;
 		goto bail_out;
 	}

 	data->regs = devm_ioremap_nocache(dev, res->start, resource_size(res));
 	if (!data->regs) {
 		dev_err(dev, "could not map mdio registers\n");
 		ret = -ENOMEM;
 		goto bail_out;
 	}

 	/* register the mii bus */
 	ret = mdiobus_register(data->bus);
 	if (ret)
 		goto bail_out;

 	/* scan and dump the bus */
 	for (addr = 0; addr < PHY_MAX_ADDR; addr++) {
 		phy = data->bus->phy_map[addr];
 		if (phy) {
 			dev_info(dev, "phy[%d]: device %s, driver %s\n",
 				 phy->addr, dev_name(&phy->dev),
 				 phy->drv ? phy->drv->name : "unknown");
 		}
 	}

 	return 0;

 bail_out:
 	if (data->bus)
 		mdiobus_free(data->bus);

 	if (data->clk)
 		clk_put(data->clk);
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);

 	kfree(data);

 	return ret;
 }

 static int davinci_mdio_remove(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct davinci_mdio_data *data = dev_get_drvdata(dev);

 	if (data->bus) {
 		mdiobus_unregister(data->bus);
 		mdiobus_free(data->bus);
 	}

 	if (data->clk)
 		clk_put(data->clk);
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);

 	dev_set_drvdata(dev, NULL);

 	kfree(data);

 	return 0;
 }

 static int davinci_mdio_suspend(struct device *dev)
 {
 	struct davinci_mdio_data *data = dev_get_drvdata(dev);
 	u32 ctrl;

 	spin_lock(&data->lock);

 	/* shutdown the scan state machine */
 	ctrl = __raw_readl(&data->regs->control);
 	ctrl &= ~CONTROL_ENABLE;
 	__raw_writel(ctrl, &data->regs->control);
 	wait_for_idle(data);

 	pm_runtime_put_sync(data->dev);

 	data->suspended = true;
 	spin_unlock(&data->lock);

 	return 0;
 }

 static int davinci_mdio_resume(struct device *dev)
 {
 	struct davinci_mdio_data *data = dev_get_drvdata(dev);
 	u32 ctrl;

 	spin_lock(&data->lock);
 	pm_runtime_get_sync(data->dev);

 	/* restart the scan state machine */
 	ctrl = __raw_readl(&data->regs->control);
 	ctrl |= CONTROL_ENABLE;
 	__raw_writel(ctrl, &data->regs->control);

 	data->suspended = false;
 	spin_unlock(&data->lock);

 	return 0;
 }

 static const struct dev_pm_ops davinci_mdio_pm_ops = {
 	.suspend	= davinci_mdio_suspend,
 	.resume		= davinci_mdio_resume,
 };

 static const struct of_device_id davinci_mdio_of_mtable[] = {
 	{ .compatible = "ti,davinci_mdio", },
 	{ /* sentinel */ },
 };
 MODULE_DEVICE_TABLE(of, davinci_mdio_of_mtable);

 static struct platform_driver davinci_mdio_driver = {
 	.driver = {
 		.name	 = "davinci_mdio",
 		.owner	 = THIS_MODULE,
 		.pm	 = &davinci_mdio_pm_ops,
 		.of_match_table = of_match_ptr(davinci_mdio_of_mtable),
 	},
 	.probe = davinci_mdio_probe,
 	.remove = davinci_mdio_remove,
 };

 static int __init davinci_mdio_init(void)
 {
 	return platform_driver_register(&davinci_mdio_driver);
 }
 device_initcall(davinci_mdio_init);

 static void __exit davinci_mdio_exit(void)
 {
 	platform_driver_unregister(&davinci_mdio_driver);
 }
 module_exit(davinci_mdio_exit);

 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("DaVinci MDIO driver");
	/*
	* DaVinci MDIO Module driver
	*
	* Copyright (C) 2010 Texas Instruments.
	*
	* Shamelessly ripped out of davinci_emac.c, original copyrights follow:
	*
	* Copyright (C) 2009 Texas Instruments.
	*
	* ---------------------------------------------------------------------------
	*
	* 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; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	* ---------------------------------------------------------------------------
	*/
	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/platform_device.h>
	#include <linux/delay.h>
	#include <linux/sched.h>
	#include <linux/slab.h>
	#include <linux/phy.h>
	#include <linux/clk.h>
	#include <linux/err.h>
	#include <linux/io.h>
	#include <linux/pm_runtime.h>
	#include <linux/davinci_emac.h>
	#include <linux/of.h>
	#include <linux/of_device.h>

	/*
	* This timeout definition is a worst-case ultra defensive measure against
	* unexpected controller lock ups. Ideally, we should never ever hit this
	* scenario in practice.
	*/
	#define MDIO_TIMEOUT 100 /* msecs */

	#define PHY_REG_MASK 0x1f
	#define PHY_ID_MASK 0x1f

	#define DEF_OUT_FREQ 2200000 /* 2.2 MHz */

	struct davinci_mdio_regs {
	u32 version;
	u32 control;
	#define CONTROL_IDLE BIT(31)
	#define CONTROL_ENABLE BIT(30)
	#define CONTROL_MAX_DIV (0xffff)

	u32 alive;
	u32 link;
	u32 linkintraw;
	u32 linkintmasked;
	u32 __reserved_0[2];
	u32 userintraw;
	u32 userintmasked;
	u32 userintmaskset;
	u32 userintmaskclr;
	u32 __reserved_1[20];

	struct {
	u32 access;
	#define USERACCESS_GO BIT(31)
	#define USERACCESS_WRITE BIT(30)
	#define USERACCESS_ACK BIT(29)
	#define USERACCESS_READ (0)
	#define USERACCESS_DATA (0xffff)

	u32 physel;
	} user[0];
	};

	struct mdio_platform_data default_pdata = {
	.bus_freq = DEF_OUT_FREQ,
	};

	struct davinci_mdio_data {
	struct mdio_platform_data pdata;
	struct davinci_mdio_regs __iomem *regs;
	spinlock_t lock;
	struct clk *clk;
	struct device *dev;
	struct mii_bus *bus;
	bool suspended;
	unsigned long access_time; /* jiffies */
	};

	static void __davinci_mdio_reset(struct davinci_mdio_data *data)
	{
	u32 mdio_in, div, mdio_out_khz, access_time;

	mdio_in = clk_get_rate(data->clk);
	div = (mdio_in / data->pdata.bus_freq) - 1;
	if (div > CONTROL_MAX_DIV)
	div = CONTROL_MAX_DIV;

	/* set enable and clock divider */
	__raw_writel(div \| CONTROL_ENABLE, &data->regs->control);

	/*
	* One mdio transaction consists of:
	* 32 bits of preamble
	* 32 bits of transferred data
	* 24 bits of bus yield (not needed unless shared?)
	*/
	mdio_out_khz = mdio_in / (1000 * (div + 1));
	access_time = (88 * 1000) / mdio_out_khz;

	/*
	* In the worst case, we could be kicking off a user-access immediately
	* after the mdio bus scan state-machine triggered its own read. If
	* so, our request could get deferred by one access cycle. We
	* defensively allow for 4 access cycles.
	*/
	data->access_time = usecs_to_jiffies(access_time * 4);
	if (!data->access_time)
	data->access_time = 1;
	}

	static int davinci_mdio_reset(struct mii_bus *bus)
	{
	struct davinci_mdio_data *data = bus->priv;
	u32 phy_mask, ver;

	__davinci_mdio_reset(data);

	/* wait for scan logic to settle */
	msleep(PHY_MAX_ADDR * data->access_time);

	/* dump hardware version info */
	ver = __raw_readl(&data->regs->version);
	dev_info(data->dev, "davinci mdio revision %d.%d\n",
	(ver >> 8) & 0xff, ver & 0xff);

	/* get phy mask from the alive register */
	phy_mask = __raw_readl(&data->regs->alive);
	if (phy_mask) {
	/* restrict mdio bus to live phys only */
	dev_info(data->dev, "detected phy mask %x\n", ~phy_mask);
	phy_mask = ~phy_mask;
	} else {
	/* desperately scan all phys */
	dev_warn(data->dev, "no live phy, scanning all\n");
	phy_mask = 0;
	}
	data->bus->phy_mask = phy_mask;

	return 0;
	}

	/* wait until hardware is ready for another user access */
	static inline int wait_for_user_access(struct davinci_mdio_data *data)
	{
	struct davinci_mdio_regs __iomem *regs = data->regs;
	unsigned long timeout = jiffies + msecs_to_jiffies(MDIO_TIMEOUT);
	u32 reg;

	while (time_after(timeout, jiffies)) {
	reg = __raw_readl(&regs->user[0].access);
	if ((reg & USERACCESS_GO) == 0)
	return 0;

	reg = __raw_readl(&regs->control);
	if ((reg & CONTROL_IDLE) == 0)
	continue;

	/*
	* An emac soft_reset may have clobbered the mdio controller's
	* state machine. We need to reset and retry the current
	* operation
	*/
	dev_warn(data->dev, "resetting idled controller\n");
	__davinci_mdio_reset(data);
	return -EAGAIN;
	}

	reg = __raw_readl(&regs->user[0].access);
	if ((reg & USERACCESS_GO) == 0)
	return 0;

	dev_err(data->dev, "timed out waiting for user access\n");
	return -ETIMEDOUT;
	}

	/* wait until hardware state machine is idle */
	static inline int wait_for_idle(struct davinci_mdio_data *data)
	{
	struct davinci_mdio_regs __iomem *regs = data->regs;
	unsigned long timeout = jiffies + msecs_to_jiffies(MDIO_TIMEOUT);

	while (time_after(timeout, jiffies)) {
	if (__raw_readl(&regs->control) & CONTROL_IDLE)
	return 0;
	}
	dev_err(data->dev, "timed out waiting for idle\n");
	return -ETIMEDOUT;
	}

	static int davinci_mdio_read(struct mii_bus *bus, int phy_id, int phy_reg)
	{
	struct davinci_mdio_data *data = bus->priv;
	u32 reg;
	int ret;

	if (phy_reg & ~PHY_REG_MASK \|\| phy_id & ~PHY_ID_MASK)
	return -EINVAL;

	spin_lock(&data->lock);

	if (data->suspended) {
	spin_unlock(&data->lock);
	return -ENODEV;
	}

	reg = (USERACCESS_GO \| USERACCESS_READ \| (phy_reg << 21) \|
	(phy_id << 16));

	while (1) {
	ret = wait_for_user_access(data);
	if (ret == -EAGAIN)
	continue;
	if (ret < 0)
	break;

	__raw_writel(reg, &data->regs->user[0].access);

	ret = wait_for_user_access(data);
	if (ret == -EAGAIN)
	continue;
	if (ret < 0)
	break;

	reg = __raw_readl(&data->regs->user[0].access);
	ret = (reg & USERACCESS_ACK) ? (reg & USERACCESS_DATA) : -EIO;
	break;
	}

	spin_unlock(&data->lock);

	return ret;
	}

	static int davinci_mdio_write(struct mii_bus *bus, int phy_id,
	int phy_reg, u16 phy_data)
	{
	struct davinci_mdio_data *data = bus->priv;
	u32 reg;
	int ret;

	if (phy_reg & ~PHY_REG_MASK \|\| phy_id & ~PHY_ID_MASK)
	return -EINVAL;

	spin_lock(&data->lock);

	if (data->suspended) {
	spin_unlock(&data->lock);
	return -ENODEV;
	}

	reg = (USERACCESS_GO \| USERACCESS_WRITE \| (phy_reg << 21) \|
	(phy_id << 16) \| (phy_data & USERACCESS_DATA));

	while (1) {
	ret = wait_for_user_access(data);
	if (ret == -EAGAIN)
	continue;
	if (ret < 0)
	break;

	__raw_writel(reg, &data->regs->user[0].access);

	ret = wait_for_user_access(data);
	if (ret == -EAGAIN)
	continue;
	break;
	}

	spin_unlock(&data->lock);

	return 0;
	}

	static int davinci_mdio_probe_dt(struct mdio_platform_data *data,
	struct platform_device *pdev)
	{
	struct device_node *node = pdev->dev.of_node;
	u32 prop;

	if (!node)
	return -EINVAL;

	if (of_property_read_u32(node, "bus_freq", &prop)) {
	pr_err("Missing bus_freq property in the DT.\n");
	return -EINVAL;
	}
	data->bus_freq = prop;

	return 0;
	}


	static int davinci_mdio_probe(struct platform_device *pdev)
	{
	struct mdio_platform_data *pdata = pdev->dev.platform_data;
	struct device *dev = &pdev->dev;
	struct davinci_mdio_data *data;
	struct resource *res;
	struct phy_device *phy;
	int ret, addr;

	data = kzalloc(sizeof(*data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	data->bus = mdiobus_alloc();
	if (!data->bus) {
	dev_err(dev, "failed to alloc mii bus\n");
	ret = -ENOMEM;
	goto bail_out;
	}

	if (dev->of_node) {
	if (davinci_mdio_probe_dt(&data->pdata, pdev))
	data->pdata = default_pdata;
	snprintf(data->bus->id, MII_BUS_ID_SIZE, "%s", pdev->name);
	} else {
	data->pdata = pdata ? (*pdata) : default_pdata;
	snprintf(data->bus->id, MII_BUS_ID_SIZE, "%s-%x",
	pdev->name, pdev->id);
	}

	data->bus->name = dev_name(dev);
	data->bus->read = davinci_mdio_read,
	data->bus->write = davinci_mdio_write,
	data->bus->reset = davinci_mdio_reset,
	data->bus->parent = dev;
	data->bus->priv = data;

	pm_runtime_enable(&pdev->dev);
	pm_runtime_get_sync(&pdev->dev);
	data->clk = clk_get(&pdev->dev, "fck");
	if (IS_ERR(data->clk)) {
	dev_err(dev, "failed to get device clock\n");
	ret = PTR_ERR(data->clk);
	data->clk = NULL;
	goto bail_out;
	}

	dev_set_drvdata(dev, data);
	data->dev = dev;
	spin_lock_init(&data->lock);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
	dev_err(dev, "could not find register map resource\n");
	ret = -ENOENT;
	goto bail_out;
	}

	res = devm_request_mem_region(dev, res->start, resource_size(res),
	dev_name(dev));
	if (!res) {
	dev_err(dev, "could not allocate register map resource\n");
	ret = -ENXIO;
	goto bail_out;
	}

	data->regs = devm_ioremap_nocache(dev, res->start, resource_size(res));
	if (!data->regs) {
	dev_err(dev, "could not map mdio registers\n");
	ret = -ENOMEM;
	goto bail_out;
	}

	/* register the mii bus */
	ret = mdiobus_register(data->bus);
	if (ret)
	goto bail_out;

	/* scan and dump the bus */
	for (addr = 0; addr < PHY_MAX_ADDR; addr++) {
	phy = data->bus->phy_map[addr];
	if (phy) {
	dev_info(dev, "phy[%d]: device %s, driver %s\n",
	phy->addr, dev_name(&phy->dev),
	phy->drv ? phy->drv->name : "unknown");
	}
	}

	return 0;

	bail_out:
	if (data->bus)
	mdiobus_free(data->bus);

	if (data->clk)
	clk_put(data->clk);
	pm_runtime_put_sync(&pdev->dev);
	pm_runtime_disable(&pdev->dev);

	kfree(data);

	return ret;
	}

	static int davinci_mdio_remove(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct davinci_mdio_data *data = dev_get_drvdata(dev);

	if (data->bus) {
	mdiobus_unregister(data->bus);
	mdiobus_free(data->bus);
	}

	if (data->clk)
	clk_put(data->clk);
	pm_runtime_put_sync(&pdev->dev);
	pm_runtime_disable(&pdev->dev);

	dev_set_drvdata(dev, NULL);

	kfree(data);

	return 0;
	}

	static int davinci_mdio_suspend(struct device *dev)
	{
	struct davinci_mdio_data *data = dev_get_drvdata(dev);
	u32 ctrl;

	spin_lock(&data->lock);

	/* shutdown the scan state machine */
	ctrl = __raw_readl(&data->regs->control);
	ctrl &= ~CONTROL_ENABLE;
	__raw_writel(ctrl, &data->regs->control);
	wait_for_idle(data);

	pm_runtime_put_sync(data->dev);

	data->suspended = true;
	spin_unlock(&data->lock);

	return 0;
	}

	static int davinci_mdio_resume(struct device *dev)
	{
	struct davinci_mdio_data *data = dev_get_drvdata(dev);
	u32 ctrl;

	spin_lock(&data->lock);
	pm_runtime_get_sync(data->dev);

	/* restart the scan state machine */
	ctrl = __raw_readl(&data->regs->control);
	ctrl \|= CONTROL_ENABLE;
	__raw_writel(ctrl, &data->regs->control);

	data->suspended = false;
	spin_unlock(&data->lock);

	return 0;
	}

	static const struct dev_pm_ops davinci_mdio_pm_ops = {
	.suspend = davinci_mdio_suspend,
	.resume = davinci_mdio_resume,
	};

	static const struct of_device_id davinci_mdio_of_mtable[] = {
	{ .compatible = "ti,davinci_mdio", },
	{ /* sentinel */ },
	};
	MODULE_DEVICE_TABLE(of, davinci_mdio_of_mtable);

	static struct platform_driver davinci_mdio_driver = {
	.driver = {
	.name = "davinci_mdio",
	.owner = THIS_MODULE,
	.pm = &davinci_mdio_pm_ops,
	.of_match_table = of_match_ptr(davinci_mdio_of_mtable),
	},
	.probe = davinci_mdio_probe,
	.remove = davinci_mdio_remove,
	};

	static int __init davinci_mdio_init(void)
	{
	return platform_driver_register(&davinci_mdio_driver);
	}
	device_initcall(davinci_mdio_init);

	static void __exit davinci_mdio_exit(void)
	{
	platform_driver_unregister(&davinci_mdio_driver);
	}
	module_exit(davinci_mdio_exit);

	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("DaVinci MDIO driver");