Linux Kernel  3.7.1
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stmp_device.c
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1 /*
2  * Copyright (C) 1999 ARM Limited
3  * Copyright (C) 2000 Deep Blue Solutions Ltd
4  * Copyright 2006-2007,2010 Freescale Semiconductor, Inc. All Rights Reserved.
5  * Copyright 2008 Juergen Beisert, [email protected]
6  * Copyright 2009 Ilya Yanok, Emcraft Systems Ltd, [email protected]
7  * Copyright (C) 2011 Wolfram Sang, Pengutronix e.K.
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  */
14 
15 #include <linux/io.h>
16 #include <linux/errno.h>
17 #include <linux/delay.h>
18 #include <linux/module.h>
19 #include <linux/stmp_device.h>
20 
21 #define STMP_MODULE_CLKGATE (1 << 30)
22 #define STMP_MODULE_SFTRST (1 << 31)
23 
24 /*
25  * Clear the bit and poll it cleared. This is usually called with
26  * a reset address and mask being either SFTRST(bit 31) or CLKGATE
27  * (bit 30).
28  */
29 static int stmp_clear_poll_bit(void __iomem *addr, u32 mask)
30 {
31  int timeout = 0x400;
32 
33  writel(mask, addr + STMP_OFFSET_REG_CLR);
34  udelay(1);
35  while ((readl(addr) & mask) && --timeout)
36  /* nothing */;
37 
38  return !timeout;
39 }
40 
41 int stmp_reset_block(void __iomem *reset_addr)
42 {
43  int ret;
44  int timeout = 0x400;
45 
46  /* clear and poll SFTRST */
47  ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_SFTRST);
48  if (unlikely(ret))
49  goto error;
50 
51  /* clear CLKGATE */
53 
54  /* set SFTRST to reset the block */
56  udelay(1);
57 
58  /* poll CLKGATE becoming set */
59  while ((!(readl(reset_addr) & STMP_MODULE_CLKGATE)) && --timeout)
60  /* nothing */;
61  if (unlikely(!timeout))
62  goto error;
63 
64  /* clear and poll SFTRST */
65  ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_SFTRST);
66  if (unlikely(ret))
67  goto error;
68 
69  /* clear and poll CLKGATE */
70  ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_CLKGATE);
71  if (unlikely(ret))
72  goto error;
73 
74  return 0;
75 
76 error:
77  pr_err("%s(%p): module reset timeout\n", __func__, reset_addr);
78  return -ETIMEDOUT;
79 }