rstc.c

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/*
 * reset controller for CSR SiRFprimaII
 *
 * Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
 *
 * Licensed under GPLv2 or later.
 */

#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/of_address.h>

void __iomem *sirfsoc_rstc_base;
static DEFINE_MUTEX(rstc_lock);

static struct of_device_id rstc_ids[]  = {
    { .compatible = "sirf,prima2-rstc" },
    {},
};

static int __init sirfsoc_of_rstc_init(void)
{
    struct device_node *np;

    np = of_find_matching_node(NULL, rstc_ids);
    if (!np)
        panic("unable to find compatible rstc node in dtb\n");

    sirfsoc_rstc_base = of_iomap(np, 0);
    if (!sirfsoc_rstc_base)
        panic("unable to map rstc cpu registers\n");

    of_node_put(np);

    return 0;
}
early_initcall(sirfsoc_of_rstc_init);

int sirfsoc_reset_device(struct device *dev)
{
    const unsigned int *prop = of_get_property(dev->of_node, "reset-bit", NULL);
    unsigned int reset_bit;

    if (!prop)
        return -ENODEV;

    reset_bit = be32_to_cpup(prop);

    mutex_lock(&rstc_lock);

    /*
     * Writing 1 to this bit resets corresponding block. Writing 0 to this
     * bit de-asserts reset signal of the corresponding block.
     * datasheet doesn't require explicit delay between the set and clear
     * of reset bit. it could be shorter if tests pass.
     */
    writel(readl(sirfsoc_rstc_base + (reset_bit / 32) * 4) | reset_bit,
        sirfsoc_rstc_base + (reset_bit / 32) * 4);
    msleep(10);
    writel(readl(sirfsoc_rstc_base + (reset_bit / 32) * 4) & ~reset_bit,
        sirfsoc_rstc_base + (reset_bit / 32) * 4);

    mutex_unlock(&rstc_lock);

    return 0;
}

#define SIRFSOC_SYS_RST_BIT  BIT(31)

void sirfsoc_restart(char mode, const char *cmd)
{
    writel(SIRFSOC_SYS_RST_BIT, sirfsoc_rstc_base);
}