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, kernel@pengutronix.de
6 * Copyright 2009 Ilya Yanok, Emcraft Systems Ltd, yanok@emcraft.com
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/compiler.h>
19 #include <linux/export.h>
20 #include <linux/stmp_device.h>
21
22 #define STMP_MODULE_CLKGATE (1 << 30)
23 #define STMP_MODULE_SFTRST (1 << 31)
24
25 /*
26 * Clear the bit and poll it cleared. This is usually called with
27 * a reset address and mask being either SFTRST(bit 31) or CLKGATE
28 * (bit 30).
29 */
stmp_clear_poll_bit(void __iomem * addr,u32 mask)30 static int stmp_clear_poll_bit(void __iomem *addr, u32 mask)
31 {
32 int timeout = 0x400;
33
34 writel(mask, addr + STMP_OFFSET_REG_CLR);
35 udelay(1);
36 while ((readl(addr) & mask) && --timeout)
37 /* nothing */;
38
39 return !timeout;
40 }
41
stmp_reset_block(void __iomem * reset_addr)42 int stmp_reset_block(void __iomem *reset_addr)
43 {
44 int ret;
45 int timeout = 0x400;
46
47 /* clear and poll SFTRST */
48 ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_SFTRST);
49 if (unlikely(ret))
50 goto error;
51
52 /* clear CLKGATE */
53 writel(STMP_MODULE_CLKGATE, reset_addr + STMP_OFFSET_REG_CLR);
54
55 /* set SFTRST to reset the block */
56 writel(STMP_MODULE_SFTRST, reset_addr + STMP_OFFSET_REG_SET);
57 udelay(1);
58
59 /* poll CLKGATE becoming set */
60 while ((!(readl(reset_addr) & STMP_MODULE_CLKGATE)) && --timeout)
61 /* nothing */;
62 if (unlikely(!timeout))
63 goto error;
64
65 /* clear and poll SFTRST */
66 ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_SFTRST);
67 if (unlikely(ret))
68 goto error;
69
70 /* clear and poll CLKGATE */
71 ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_CLKGATE);
72 if (unlikely(ret))
73 goto error;
74
75 return 0;
76
77 error:
78 pr_err("%s(%p): module reset timeout\n", __func__, reset_addr);
79 return -ETIMEDOUT;
80 }
81 EXPORT_SYMBOL(stmp_reset_block);
82