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