arch/arm/mach-mxs/ocotp.c

   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 <mach/mxs.h>
  20
  21 #define OCOTP_WORD_OFFSET               0x20
  22 #define OCOTP_WORD_COUNT                0x20
  23
  24 #define BM_OCOTP_CTRL_BUSY              (1 << 8)
  25 #define BM_OCOTP_CTRL_ERROR             (1 << 9)
  26 #define BM_OCOTP_CTRL_RD_BANK_OPEN      (1 << 12)
  27
  28 static DEFINE_MUTEX(ocotp_mutex);
  29 static u32 ocotp_words[OCOTP_WORD_COUNT];
  30
  31 const u32 *mxs_get_ocotp(void)
  32 {
  33         void __iomem *ocotp_base = MXS_IO_ADDRESS(MXS_OCOTP_BASE_ADDR);
  34         int timeout = 0x400;
  35         size_t i;
  36         static int once = 0;
  37
  38         if (once)
  39                 return ocotp_words;
  40
  41         mutex_lock(&ocotp_mutex);
  42
  43         /*
  44          * clk_enable(hbus_clk) for ocotp can be skipped
  45          * as it must be on when system is running.
  46          */
  47
  48         /* try to clear ERROR bit */
  49         __mxs_clrl(BM_OCOTP_CTRL_ERROR, ocotp_base);
  50
  51         /* check both BUSY and ERROR cleared */
  52         while ((__raw_readl(ocotp_base) &
  53                 (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)) && --timeout)
  54                 cpu_relax();
  55
  56         if (unlikely(!timeout))
  57                 goto error_unlock;
  58
  59         /* open OCOTP banks for read */
  60         __mxs_setl(BM_OCOTP_CTRL_RD_BANK_OPEN, ocotp_base);
  61
  62         /* approximately wait 32 hclk cycles */
  63         udelay(1);
  64
  65         /* poll BUSY bit becoming cleared */
  66         timeout = 0x400;
  67         while ((__raw_readl(ocotp_base) & BM_OCOTP_CTRL_BUSY) && --timeout)
  68                 cpu_relax();
  69
  70         if (unlikely(!timeout))
  71                 goto error_unlock;
  72
  73         for (i = 0; i < OCOTP_WORD_COUNT; i++)
  74                 ocotp_words[i] = __raw_readl(ocotp_base + OCOTP_WORD_OFFSET +
  75                                                 i * 0x10);
  76
  77         /* close banks for power saving */
  78         __mxs_clrl(BM_OCOTP_CTRL_RD_BANK_OPEN, ocotp_base);
  79
  80         once = 1;
  81
  82         mutex_unlock(&ocotp_mutex);
  83
  84         return ocotp_words;
  85
  86 error_unlock:
  87         mutex_unlock(&ocotp_mutex);
  88         pr_err("%s: timeout in reading OCOTP\n", __func__);
  89         return NULL;
  90 }