1 /*
2  * Copyright 2010 Freescale Semiconductor, Inc. All Rights Reserved.
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation; either version 2 of the License, or
7  * (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  */
14 
15 #include <linux/delay.h>
16 #include <linux/err.h>
17 #include <linux/mutex.h>
18 
19 #include <asm/processor.h>	/* for cpu_relax() */
20 
21 #include <mach/mxs.h>
22 
23 #define OCOTP_WORD_OFFSET		0x20
24 #define OCOTP_WORD_COUNT		0x20
25 
26 #define BM_OCOTP_CTRL_BUSY		(1 << 8)
27 #define BM_OCOTP_CTRL_ERROR		(1 << 9)
28 #define BM_OCOTP_CTRL_RD_BANK_OPEN	(1 << 12)
29 
30 static DEFINE_MUTEX(ocotp_mutex);
31 static u32 ocotp_words[OCOTP_WORD_COUNT];
32 
mxs_get_ocotp(void)33 const u32 *mxs_get_ocotp(void)
34 {
35 	void __iomem *ocotp_base = MXS_IO_ADDRESS(MXS_OCOTP_BASE_ADDR);
36 	int timeout = 0x400;
37 	size_t i;
38 	static int once = 0;
39 
40 	if (once)
41 		return ocotp_words;
42 
43 	mutex_lock(&ocotp_mutex);
44 
45 	/*
46 	 * clk_enable(hbus_clk) for ocotp can be skipped
47 	 * as it must be on when system is running.
48 	 */
49 
50 	/* try to clear ERROR bit */
51 	__mxs_clrl(BM_OCOTP_CTRL_ERROR, ocotp_base);
52 
53 	/* check both BUSY and ERROR cleared */
54 	while ((__raw_readl(ocotp_base) &
55 		(BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)) && --timeout)
56 		cpu_relax();
57 
58 	if (unlikely(!timeout))
59 		goto error_unlock;
60 
61 	/* open OCOTP banks for read */
62 	__mxs_setl(BM_OCOTP_CTRL_RD_BANK_OPEN, ocotp_base);
63 
64 	/* approximately wait 32 hclk cycles */
65 	udelay(1);
66 
67 	/* poll BUSY bit becoming cleared */
68 	timeout = 0x400;
69 	while ((__raw_readl(ocotp_base) & BM_OCOTP_CTRL_BUSY) && --timeout)
70 		cpu_relax();
71 
72 	if (unlikely(!timeout))
73 		goto error_unlock;
74 
75 	for (i = 0; i < OCOTP_WORD_COUNT; i++)
76 		ocotp_words[i] = __raw_readl(ocotp_base + OCOTP_WORD_OFFSET +
77 						i * 0x10);
78 
79 	/* close banks for power saving */
80 	__mxs_clrl(BM_OCOTP_CTRL_RD_BANK_OPEN, ocotp_base);
81 
82 	once = 1;
83 
84 	mutex_unlock(&ocotp_mutex);
85 
86 	return ocotp_words;
87 
88 error_unlock:
89 	mutex_unlock(&ocotp_mutex);
90 	pr_err("%s: timeout in reading OCOTP\n", __func__);
91 	return NULL;
92 }
93