arch/arm/mach-mxs/system.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  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  */
  18
  19 #include <linux/kernel.h>
  20 #include <linux/clk.h>
  21 #include <linux/io.h>
  22 #include <linux/err.h>
  23 #include <linux/delay.h>
  24 #include <linux/init.h>
  25 #include <linux/module.h>
  26
  27 #include <asm/proc-fns.h>
  28 #include <asm/system.h>
  29
  30 #include <mach/mxs.h>
  31 #include <mach/common.h>
  32
  33 #define MX23_CLKCTRL_RESET_OFFSET       0x120
  34 #define MX28_CLKCTRL_RESET_OFFSET       0x1e0
  35 #define MXS_CLKCTRL_RESET_CHIP          (1 << 1)
  36
  37 #define MXS_MODULE_CLKGATE              (1 << 30)
  38 #define MXS_MODULE_SFTRST               (1 << 31)
  39
  40 static void __iomem *mxs_clkctrl_reset_addr;
  41
  42 /*
  43  * Reset the system. It is called by machine_restart().
  44  */
  45 void arch_reset(char mode, const char *cmd)
  46 {
  47         /* reset the chip */
  48         __mxs_setl(MXS_CLKCTRL_RESET_CHIP, mxs_clkctrl_reset_addr);
  49
  50         pr_err("Failed to assert the chip reset\n");
  51
  52         /* Delay to allow the serial port to show the message */
  53         mdelay(50);
  54
  55         /* We'll take a jump through zero as a poor second */
  56         cpu_reset(0);
  57 }
  58
  59 static int __init mxs_arch_reset_init(void)
  60 {
  61         struct clk *clk;
  62
  63         mxs_clkctrl_reset_addr = MXS_IO_ADDRESS(MXS_CLKCTRL_BASE_ADDR) +
  64                                 (cpu_is_mx23() ? MX23_CLKCTRL_RESET_OFFSET :
  65                                                  MX28_CLKCTRL_RESET_OFFSET);
  66
  67         clk = clk_get_sys("rtc", NULL);
  68         if (!IS_ERR(clk))
  69                 clk_enable(clk);
  70
  71         return 0;
  72 }
  73 core_initcall(mxs_arch_reset_init);
  74
  75 /*
  76  * Clear the bit and poll it cleared.  This is usually called with
  77  * a reset address and mask being either SFTRST(bit 31) or CLKGATE
  78  * (bit 30).
  79  */
  80 static int clear_poll_bit(void __iomem *addr, u32 mask)
  81 {
  82         int timeout = 0x400;
  83
  84         /* clear the bit */
  85         __mxs_clrl(mask, addr);
  86
  87         /*
  88          * SFTRST needs 3 GPMI clocks to settle, the reference manual
  89          * recommends to wait 1us.
  90          */
  91         udelay(1);
  92
  93         /* poll the bit becoming clear */
  94         while ((__raw_readl(addr) & mask) && --timeout)
  95                 /* nothing */;
  96
  97         return !timeout;
  98 }
  99
 100 int mxs_reset_block(void __iomem *reset_addr)
 101 {
 102         int ret;
 103         int timeout = 0x400;
 104
 105         /* clear and poll SFTRST */
 106         ret = clear_poll_bit(reset_addr, MXS_MODULE_SFTRST);
 107         if (unlikely(ret))
 108                 goto error;
 109
 110         /* clear CLKGATE */
 111         __mxs_clrl(MXS_MODULE_CLKGATE, reset_addr);
 112
 113         /* set SFTRST to reset the block */
 114         __mxs_setl(MXS_MODULE_SFTRST, reset_addr);
 115         udelay(1);
 116
 117         /* poll CLKGATE becoming set */
 118         while ((!(__raw_readl(reset_addr) & MXS_MODULE_CLKGATE)) && --timeout)
 119                 /* nothing */;
 120         if (unlikely(!timeout))
 121                 goto error;
 122
 123         /* clear and poll SFTRST */
 124         ret = clear_poll_bit(reset_addr, MXS_MODULE_SFTRST);
 125         if (unlikely(ret))
 126                 goto error;
 127
 128         /* clear and poll CLKGATE */
 129         ret = clear_poll_bit(reset_addr, MXS_MODULE_CLKGATE);
 130         if (unlikely(ret))
 131                 goto error;
 132
 133         return 0;
 134
 135 error:
 136         pr_err("%s(%p): module reset timeout\n", __func__, reset_addr);
 137         return -ETIMEDOUT;
 138 }
 139 EXPORT_SYMBOL(mxs_reset_block);