lib/stmp_device.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 1999 ARM Limited
   4  * Copyright (C) 2000 Deep Blue Solutions Ltd
   5  * Copyright 2006-2007,2010 Freescale Semiconductor, Inc. All Rights Reserved.
   6  * Copyright 2008 Juergen Beisert, kernel@pengutronix.de
   7  * Copyright 2009 Ilya Yanok, Emcraft Systems Ltd, yanok@emcraft.com
   8  * Copyright (C) 2011 Wolfram Sang, Pengutronix e.K.
   9  */
  10
  11 #include <linux/io.h>
  12 #include <linux/errno.h>
  13 #include <linux/delay.h>
  14 #include <linux/compiler.h>
  15 #include <linux/export.h>
  16 #include <linux/stmp_device.h>
  17
  18 #define STMP_MODULE_CLKGATE     (1 << 30)
  19 #define STMP_MODULE_SFTRST      (1 << 31)
  20
  21 /*
  22  * Clear the bit and poll it cleared.  This is usually called with
  23  * a reset address and mask being either SFTRST(bit 31) or CLKGATE
  24  * (bit 30).
  25  */
  26 static int stmp_clear_poll_bit(void __iomem *addr, u32 mask)
  27 {
  28         int timeout = 0x400;
  29
  30         writel(mask, addr + STMP_OFFSET_REG_CLR);
  31         udelay(1);
  32         while ((readl(addr) & mask) && --timeout)
  33                 /* nothing */;
  34
  35         return !timeout;
  36 }
  37
  38 int stmp_reset_block(void __iomem *reset_addr)
  39 {
  40         int ret;
  41         int timeout = 0x400;
  42
  43         /* clear and poll SFTRST */
  44         ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_SFTRST);
  45         if (unlikely(ret))
  46                 goto error;
  47
  48         /* clear CLKGATE */
  49         writel(STMP_MODULE_CLKGATE, reset_addr + STMP_OFFSET_REG_CLR);
  50
  51         /* set SFTRST to reset the block */
  52         writel(STMP_MODULE_SFTRST, reset_addr + STMP_OFFSET_REG_SET);
  53         udelay(1);
  54
  55         /* poll CLKGATE becoming set */
  56         while ((!(readl(reset_addr) & STMP_MODULE_CLKGATE)) && --timeout)
  57                 /* nothing */;
  58         if (unlikely(!timeout))
  59                 goto error;
  60
  61         /* clear and poll SFTRST */
  62         ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_SFTRST);
  63         if (unlikely(ret))
  64                 goto error;
  65
  66         /* clear and poll CLKGATE */
  67         ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_CLKGATE);
  68         if (unlikely(ret))
  69                 goto error;
  70
  71         return 0;
  72
  73 error:
  74         pr_err("%s(%p): module reset timeout\n", __func__, reset_addr);
  75         return -ETIMEDOUT;
  76 }
  77 EXPORT_SYMBOL(stmp_reset_block);