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/export.h>
16 #include <linux/kernel.h>
17 #include <linux/usb.h>
18 #include <linux/io.h>
19 #include <linux/usb/otg.h>
20 #include <linux/usb/ulpi.h>
21 
22 #define ULPI_VIEW_WAKEUP	(1 << 31)
23 #define ULPI_VIEW_RUN		(1 << 30)
24 #define ULPI_VIEW_WRITE		(1 << 29)
25 #define ULPI_VIEW_READ		(0 << 29)
26 #define ULPI_VIEW_ADDR(x)	(((x) & 0xff) << 16)
27 #define ULPI_VIEW_DATA_READ(x)	(((x) >> 8) & 0xff)
28 #define ULPI_VIEW_DATA_WRITE(x)	((x) & 0xff)
29 
30 static int ulpi_viewport_wait(void __iomem *view, u32 mask)
31 {
32 	unsigned long usec = 2000;
33 
34 	while (usec--) {
35 		if (!(readl(view) & mask))
36 			return 0;
37 
38 		udelay(1);
39 	}
40 
41 	return -ETIMEDOUT;
42 }
43 
44 static int ulpi_viewport_read(struct usb_phy *otg, u32 reg)
45 {
46 	int ret;
47 	void __iomem *view = otg->io_priv;
48 
49 	writel(ULPI_VIEW_WAKEUP | ULPI_VIEW_WRITE, view);
50 	ret = ulpi_viewport_wait(view, ULPI_VIEW_WAKEUP);
51 	if (ret)
52 		return ret;
53 
54 	writel(ULPI_VIEW_RUN | ULPI_VIEW_READ | ULPI_VIEW_ADDR(reg), view);
55 	ret = ulpi_viewport_wait(view, ULPI_VIEW_RUN);
56 	if (ret)
57 		return ret;
58 
59 	return ULPI_VIEW_DATA_READ(readl(view));
60 }
61 
62 static int ulpi_viewport_write(struct usb_phy *otg, u32 val, u32 reg)
63 {
64 	int ret;
65 	void __iomem *view = otg->io_priv;
66 
67 	writel(ULPI_VIEW_WAKEUP | ULPI_VIEW_WRITE, view);
68 	ret = ulpi_viewport_wait(view, ULPI_VIEW_WAKEUP);
69 	if (ret)
70 		return ret;
71 
72 	writel(ULPI_VIEW_RUN | ULPI_VIEW_WRITE | ULPI_VIEW_DATA_WRITE(val) |
73 						 ULPI_VIEW_ADDR(reg), view);
74 
75 	return ulpi_viewport_wait(view, ULPI_VIEW_RUN);
76 }
77 
78 struct usb_phy_io_ops ulpi_viewport_access_ops = {
79 	.read	= ulpi_viewport_read,
80 	.write	= ulpi_viewport_write,
81 };
82 EXPORT_SYMBOL_GPL(ulpi_viewport_access_ops);
83