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