/*
 * 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/davinci_emac.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         (0xff)

        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;
        }
        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 __devinit 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) {
                dev_err(dev, "failed to alloc device data\n");
                return -ENOMEM;
        }

        data->pdata = pdata ? (*pdata) : default_pdata;

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

        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;
        snprintf(data->bus->id, MII_BUS_ID_SIZE, "%x", pdev->id);

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

        clk_enable(data->clk);

        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_disable(data->clk);
                clk_put(data->clk);
        }

        kfree(data);

        return ret;
}

static int __devexit 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_free(data->bus);

        if (data->clk) {
                clk_disable(data->clk);
                clk_put(data->clk);
        }

        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);

        if (data->clk)
                clk_disable(data->clk);

        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);
        if (data->clk)
                clk_enable(data->clk);

        /* 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 struct platform_driver davinci_mdio_driver = {
        .driver = {
                .name    = "davinci_mdio",
                .owner   = THIS_MODULE,
                .pm      = &davinci_mdio_pm_ops,
        },
        .probe = davinci_mdio_probe,
        .remove = __devexit_p(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");