stmp_device.c

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/*
 * Copyright (C) 1999 ARM Limited
 * Copyright (C) 2000 Deep Blue Solutions Ltd
 * Copyright 2006-2007,2010 Freescale Semiconductor, Inc. All Rights Reserved.
 * Copyright 2008 Juergen Beisert, [email protected]
 * Copyright 2009 Ilya Yanok, Emcraft Systems Ltd, [email protected]
 * Copyright (C) 2011 Wolfram Sang, Pengutronix e.K.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/io.h>
#include <linux/errno.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/stmp_device.h>

#define STMP_MODULE_CLKGATE (1 << 30)
#define STMP_MODULE_SFTRST  (1 << 31)

/*
 * Clear the bit and poll it cleared.  This is usually called with
 * a reset address and mask being either SFTRST(bit 31) or CLKGATE
 * (bit 30).
 */
static int stmp_clear_poll_bit(void __iomem *addr, u32 mask)
{
    int timeout = 0x400;

    writel(mask, addr + STMP_OFFSET_REG_CLR);
    udelay(1);
    while ((readl(addr) & mask) && --timeout)
        /* nothing */;

    return !timeout;
}

int stmp_reset_block(void __iomem *reset_addr)
{
    int ret;
    int timeout = 0x400;

    /* clear and poll SFTRST */
    ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_SFTRST);
    if (unlikely(ret))
        goto error;

    /* clear CLKGATE */
    writel(STMP_MODULE_CLKGATE, reset_addr + STMP_OFFSET_REG_CLR);

    /* set SFTRST to reset the block */
    writel(STMP_MODULE_SFTRST, reset_addr + STMP_OFFSET_REG_SET);
    udelay(1);

    /* poll CLKGATE becoming set */
    while ((!(readl(reset_addr) & STMP_MODULE_CLKGATE)) && --timeout)
        /* nothing */;
    if (unlikely(!timeout))
        goto error;

    /* clear and poll SFTRST */
    ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_SFTRST);
    if (unlikely(ret))
        goto error;

    /* clear and poll CLKGATE */
    ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_CLKGATE);
    if (unlikely(ret))
        goto error;

    return 0;

error:
    pr_err("%s(%p): module reset timeout\n", __func__, reset_addr);
    return -ETIMEDOUT;
}
EXPORT_SYMBOL(stmp_reset_block);