LXR linux/lib/stmp

   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 */
  30static 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
  42int 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
  77error:
  78        pr_err("%s(%p): module reset timeout\n", __func__, reset_addr);
  79        return -ETIMEDOUT;
  80}
  81EXPORT_SYMBOL(stmp_reset_block);
  82