/*
 * 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/iopoll.h>
#include <linux/pm_runtime.h>
#include <linux/davinci_emac.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_mdio.h>
#include <linux/pinctrl/consumer.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_of_param {
        int autosuspend_delay_ms;
};

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];
};

static const 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;
        struct clk      *clk;
        struct device   *dev;
        struct mii_bus  *bus;
        bool            active_in_suspend;
        unsigned long   access_time; /* jiffies */
        /* Indicates that driver shouldn't modify phy_mask in case
         * if MDIO bus is registered from DT.
         */
        bool            skip_scan;
        u32             clk_div;
};

static void davinci_mdio_init_clk(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;

        data->clk_div = div;
        /*
         * 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 void davinci_mdio_enable(struct davinci_mdio_data *data)
{
        /* set enable and clock divider */
        __raw_writel(data->clk_div | CONTROL_ENABLE, &data->regs->control);
}

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

        ret = pm_runtime_get_sync(data->dev);
        if (ret < 0) {
                pm_runtime_put_noidle(data->dev);
                return ret;
        }

        /* 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, bus freq %ld\n",
                 (ver >> 8) & 0xff, ver & 0xff,
                 data->pdata.bus_freq);

        if (data->skip_scan)
                goto done;

        /* 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;

done:
        pm_runtime_mark_last_busy(data->dev);
        pm_runtime_put_autosuspend(data->dev);

        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) {
                        usleep_range(100, 200);
                        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_enable(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;
        u32 val, ret;

        ret = readl_poll_timeout(&regs->control, val, val & CONTROL_IDLE,
                                 0, MDIO_TIMEOUT * 1000);
        if (ret)
                dev_err(data->dev, "timed out waiting for idle\n");

        return ret;
}

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;

        ret = pm_runtime_get_sync(data->dev);
        if (ret < 0) {
                pm_runtime_put_noidle(data->dev);
                return ret;
        }

        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;
        }

        pm_runtime_mark_last_busy(data->dev);
        pm_runtime_put_autosuspend(data->dev);
        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;

        ret = pm_runtime_get_sync(data->dev);
        if (ret < 0) {
                pm_runtime_put_noidle(data->dev);
                return ret;
        }

        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;
        }

        pm_runtime_mark_last_busy(data->dev);
        pm_runtime_put_autosuspend(data->dev);

        return ret;
}

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)) {
                dev_err(&pdev->dev, "Missing bus_freq property in the DT.\n");
                return -EINVAL;
        }
        data->bus_freq = prop;

        return 0;
}

#if IS_ENABLED(CONFIG_OF)
static const struct davinci_mdio_of_param of_cpsw_mdio_data = {
        .autosuspend_delay_ms = 100,
};

static const struct of_device_id davinci_mdio_of_mtable[] = {
        { .compatible = "ti,davinci_mdio", },
        { .compatible = "ti,cpsw-mdio", .data = &of_cpsw_mdio_data},
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, davinci_mdio_of_mtable);
#endif

static int davinci_mdio_probe(struct platform_device *pdev)
{
        struct mdio_platform_data *pdata = dev_get_platdata(&pdev->dev);
        struct device *dev = &pdev->dev;
        struct davinci_mdio_data *data;
        struct resource *res;
        struct phy_device *phy;
        int ret, addr;
        int autosuspend_delay_ms = -1;

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

        data->bus = devm_mdiobus_alloc(dev);
        if (!data->bus) {
                dev_err(dev, "failed to alloc mii bus\n");
                return -ENOMEM;
        }

        if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
                const struct of_device_id       *of_id;

                ret = davinci_mdio_probe_dt(&data->pdata, pdev);
                if (ret)
                        return ret;
                snprintf(data->bus->id, MII_BUS_ID_SIZE, "%s", pdev->name);

                of_id = of_match_device(davinci_mdio_of_mtable, &pdev->dev);
                if (of_id) {
                        const struct davinci_mdio_of_param *of_mdio_data;

                        of_mdio_data = of_id->data;
                        if (of_mdio_data)
                                autosuspend_delay_ms =
                                        of_mdio_data->autosuspend_delay_ms;
                }
        } 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;

        data->clk = devm_clk_get(dev, "fck");
        if (IS_ERR(data->clk)) {
                dev_err(dev, "failed to get device clock\n");
                return PTR_ERR(data->clk);
        }

        dev_set_drvdata(dev, data);
        data->dev = dev;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        data->regs = devm_ioremap_resource(dev, res);
        if (IS_ERR(data->regs))
                return PTR_ERR(data->regs);

        davinci_mdio_init_clk(data);

        pm_runtime_set_autosuspend_delay(&pdev->dev, autosuspend_delay_ms);
        pm_runtime_use_autosuspend(&pdev->dev);
        pm_runtime_enable(&pdev->dev);

        /* register the mii bus
         * Create PHYs from DT only in case if PHY child nodes are explicitly
         * defined to support backward compatibility with DTs which assume that
         * Davinci MDIO will always scan the bus for PHYs detection.
         */
        if (dev->of_node && of_get_child_count(dev->of_node))
                data->skip_scan = true;

        ret = of_mdiobus_register(data->bus, dev->of_node);
        if (ret)
                goto bail_out;

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

        return 0;

bail_out:
        pm_runtime_dont_use_autosuspend(&pdev->dev);
        pm_runtime_disable(&pdev->dev);
        return ret;
}

static int davinci_mdio_remove(struct platform_device *pdev)
{
        struct davinci_mdio_data *data = platform_get_drvdata(pdev);

        if (data->bus)
                mdiobus_unregister(data->bus);

        pm_runtime_dont_use_autosuspend(&pdev->dev);
        pm_runtime_disable(&pdev->dev);

        return 0;
}

#ifdef CONFIG_PM
static int davinci_mdio_runtime_suspend(struct device *dev)
{
        struct davinci_mdio_data *data = dev_get_drvdata(dev);
        u32 ctrl;

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

        return 0;
}

static int davinci_mdio_runtime_resume(struct device *dev)
{
        struct davinci_mdio_data *data = dev_get_drvdata(dev);

        davinci_mdio_enable(data);
        return 0;
}
#endif

#ifdef CONFIG_PM_SLEEP
static int davinci_mdio_suspend(struct device *dev)
{
        struct davinci_mdio_data *data = dev_get_drvdata(dev);
        int ret = 0;

        data->active_in_suspend = !pm_runtime_status_suspended(dev);
        if (data->active_in_suspend)
                ret = pm_runtime_force_suspend(dev);
        if (ret < 0)
                return ret;

        /* Select sleep pin state */
        pinctrl_pm_select_sleep_state(dev);

        return 0;
}

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

        /* Select default pin state */
        pinctrl_pm_select_default_state(dev);

        if (data->active_in_suspend)
                pm_runtime_force_resume(dev);

        return 0;
}
#endif

static const struct dev_pm_ops davinci_mdio_pm_ops = {
        SET_RUNTIME_PM_OPS(davinci_mdio_runtime_suspend,
                           davinci_mdio_runtime_resume, NULL)
        SET_LATE_SYSTEM_SLEEP_PM_OPS(davinci_mdio_suspend, davinci_mdio_resume)
};

static struct platform_driver davinci_mdio_driver = {
        .driver = {
                .name    = "davinci_mdio",
                .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");