lib/stmp_device.c

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