Eric Lee / smarc-fsl-linux-kernel

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arch/arm/mach-mxs/ocotp.c 2.25 KB
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67f43086a   Shawn Guo   ARM: mxs: add oco... 
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  /*
   * Copyright 2010 Freescale Semiconductor, Inc. All Rights Reserved.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   */
  
  #include <linux/delay.h>
  #include <linux/err.h>
  #include <linux/mutex.h>
ad377c630   Wolfram Sang   arm: mxs: include... 
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  #include <asm/processor.h>	/* for cpu_relax() */
67f43086a   Shawn Guo   ARM: mxs: add oco... 
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  #include <mach/mxs.h>
  
  #define OCOTP_WORD_OFFSET		0x20
  #define OCOTP_WORD_COUNT		0x20
  
  #define BM_OCOTP_CTRL_BUSY		(1 << 8)
  #define BM_OCOTP_CTRL_ERROR		(1 << 9)
  #define BM_OCOTP_CTRL_RD_BANK_OPEN	(1 << 12)
  
  static DEFINE_MUTEX(ocotp_mutex);
  static u32 ocotp_words[OCOTP_WORD_COUNT];
  
  const u32 *mxs_get_ocotp(void)
  {
  	void __iomem *ocotp_base = MXS_IO_ADDRESS(MXS_OCOTP_BASE_ADDR);
  	int timeout = 0x400;
  	size_t i;
  	static int once = 0;
  
  	if (once)
  		return ocotp_words;
  
  	mutex_lock(&ocotp_mutex);
  
  	/*
  	 * clk_enable(hbus_clk) for ocotp can be skipped
  	 * as it must be on when system is running.
  	 */
  
  	/* try to clear ERROR bit */
  	__mxs_clrl(BM_OCOTP_CTRL_ERROR, ocotp_base);
  
  	/* check both BUSY and ERROR cleared */
  	while ((__raw_readl(ocotp_base) &
  		(BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)) && --timeout)
  		cpu_relax();
  
  	if (unlikely(!timeout))
  		goto error_unlock;
  
  	/* open OCOTP banks for read */
  	__mxs_setl(BM_OCOTP_CTRL_RD_BANK_OPEN, ocotp_base);
  
  	/* approximately wait 32 hclk cycles */
  	udelay(1);
  
  	/* poll BUSY bit becoming cleared */
  	timeout = 0x400;
  	while ((__raw_readl(ocotp_base) & BM_OCOTP_CTRL_BUSY) && --timeout)
  		cpu_relax();
  
  	if (unlikely(!timeout))
  		goto error_unlock;
  
  	for (i = 0; i < OCOTP_WORD_COUNT; i++)
  		ocotp_words[i] = __raw_readl(ocotp_base + OCOTP_WORD_OFFSET +
  						i * 0x10);
  
  	/* close banks for power saving */
  	__mxs_clrl(BM_OCOTP_CTRL_RD_BANK_OPEN, ocotp_base);
  
  	once = 1;
  
  	mutex_unlock(&ocotp_mutex);
  
  	return ocotp_words;
  
  error_unlock:
  	mutex_unlock(&ocotp_mutex);
  	pr_err("%s: timeout in reading OCOTP
  ", __func__);
  	return NULL;
  }