drivers/usb/otg/ulpi_viewport.c

   1 /*
   2  * Copyright (C) 2011 Google, Inc.
   3  *
   4  * This software is licensed under the terms of the GNU General Public
   5  * License version 2, as published by the Free Software Foundation, and
   6  * may be copied, distributed, and modified under those terms.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  */
  14
  15 #include <linux/kernel.h>
  16 #include <linux/usb.h>
  17 #include <linux/io.h>
  18 #include <linux/usb/otg.h>
  19 #include <linux/usb/ulpi.h>
  20
  21 #define ULPI_VIEW_WAKEUP        (1 << 31)
  22 #define ULPI_VIEW_RUN           (1 << 30)
  23 #define ULPI_VIEW_WRITE         (1 << 29)
  24 #define ULPI_VIEW_READ          (0 << 29)
  25 #define ULPI_VIEW_ADDR(x)       (((x) & 0xff) << 16)
  26 #define ULPI_VIEW_DATA_READ(x)  (((x) >> 8) & 0xff)
  27 #define ULPI_VIEW_DATA_WRITE(x) ((x) & 0xff)
  28
  29 static int ulpi_viewport_wait(void __iomem *view, u32 mask)
  30 {
  31         unsigned long usec = 2000;
  32
  33         while (usec--) {
  34                 if (!(readl(view) & mask))
  35                         return 0;
  36
  37                 udelay(1);
  38         };
  39
  40         return -ETIMEDOUT;
  41 }
  42
  43 static int ulpi_viewport_read(struct usb_phy *otg, u32 reg)
  44 {
  45         int ret;
  46         void __iomem *view = otg->io_priv;
  47
  48         writel(ULPI_VIEW_WAKEUP | ULPI_VIEW_WRITE, view);
  49         ret = ulpi_viewport_wait(view, ULPI_VIEW_WAKEUP);
  50         if (ret)
  51                 return ret;
  52
  53         writel(ULPI_VIEW_RUN | ULPI_VIEW_READ | ULPI_VIEW_ADDR(reg), view);
  54         ret = ulpi_viewport_wait(view, ULPI_VIEW_RUN);
  55         if (ret)
  56                 return ret;
  57
  58         return ULPI_VIEW_DATA_READ(readl(view));
  59 }
  60
  61 static int ulpi_viewport_write(struct usb_phy *otg, u32 val, u32 reg)
  62 {
  63         int ret;
  64         void __iomem *view = otg->io_priv;
  65
  66         writel(ULPI_VIEW_WAKEUP | ULPI_VIEW_WRITE, view);
  67         ret = ulpi_viewport_wait(view, ULPI_VIEW_WAKEUP);
  68         if (ret)
  69                 return ret;
  70
  71         writel(ULPI_VIEW_RUN | ULPI_VIEW_WRITE | ULPI_VIEW_DATA_WRITE(val) |
  72                                                  ULPI_VIEW_ADDR(reg), view);
  73
  74         return ulpi_viewport_wait(view, ULPI_VIEW_RUN);
  75 }
  76
  77 struct usb_phy_io_ops ulpi_viewport_access_ops = {
  78         .read   = ulpi_viewport_read,
  79         .write  = ulpi_viewport_write,
  80 };