ulpi_viewport.c

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/*
 * Copyright (C) 2011 Google, Inc.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * 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.
 *
 */

#include <linux/kernel.h>
#include <linux/usb.h>
#include <linux/io.h>
#include <linux/usb/otg.h>
#include <linux/usb/ulpi.h>

#define ULPI_VIEW_WAKEUP    (1 << 31)
#define ULPI_VIEW_RUN       (1 << 30)
#define ULPI_VIEW_WRITE     (1 << 29)
#define ULPI_VIEW_READ      (0 << 29)
#define ULPI_VIEW_ADDR(x)   (((x) & 0xff) << 16)
#define ULPI_VIEW_DATA_READ(x)  (((x) >> 8) & 0xff)
#define ULPI_VIEW_DATA_WRITE(x) ((x) & 0xff)

static int ulpi_viewport_wait(void __iomem *view, u32 mask)
{
    unsigned long usec = 2000;

    while (usec--) {
        if (!(readl(view) & mask))
            return 0;

        udelay(1);
    };

    return -ETIMEDOUT;
}

static int ulpi_viewport_read(struct usb_phy *otg, u32 reg)
{
    int ret;
    void __iomem *view = otg->io_priv;

    writel(ULPI_VIEW_WAKEUP | ULPI_VIEW_WRITE, view);
    ret = ulpi_viewport_wait(view, ULPI_VIEW_WAKEUP);
    if (ret)
        return ret;

    writel(ULPI_VIEW_RUN | ULPI_VIEW_READ | ULPI_VIEW_ADDR(reg), view);
    ret = ulpi_viewport_wait(view, ULPI_VIEW_RUN);
    if (ret)
        return ret;

    return ULPI_VIEW_DATA_READ(readl(view));
}

static int ulpi_viewport_write(struct usb_phy *otg, u32 val, u32 reg)
{
    int ret;
    void __iomem *view = otg->io_priv;

    writel(ULPI_VIEW_WAKEUP | ULPI_VIEW_WRITE, view);
    ret = ulpi_viewport_wait(view, ULPI_VIEW_WAKEUP);
    if (ret)
        return ret;

    writel(ULPI_VIEW_RUN | ULPI_VIEW_WRITE | ULPI_VIEW_DATA_WRITE(val) |
                         ULPI_VIEW_ADDR(reg), view);

    return ulpi_viewport_wait(view, ULPI_VIEW_RUN);
}

struct usb_phy_io_ops ulpi_viewport_access_ops = {
    .read   = ulpi_viewport_read,
    .write  = ulpi_viewport_write,
};