smp_scu.c

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/*
 *  linux/arch/arm/kernel/smp_scu.c
 *
 *  Copyright (C) 2002 ARM Ltd.
 *  All Rights Reserved
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/init.h>
#include <linux/io.h>

#include <asm/smp_plat.h>
#include <asm/smp_scu.h>
#include <asm/cacheflush.h>
#include <asm/cputype.h>

#define SCU_CTRL        0x00
#define SCU_CONFIG      0x04
#define SCU_CPU_STATUS      0x08
#define SCU_INVALIDATE      0x0c
#define SCU_FPGA_REVISION   0x10

#ifdef CONFIG_SMP
/*
 * Get the number of CPU cores from the SCU configuration
 */
unsigned int __init scu_get_core_count(void __iomem *scu_base)
{
    unsigned int ncores = __raw_readl(scu_base + SCU_CONFIG);
    return (ncores & 0x03) + 1;
}

/*
 * Enable the SCU
 */
void scu_enable(void __iomem *scu_base)
{
    u32 scu_ctrl;

#ifdef CONFIG_ARM_ERRATA_764369
    /* Cortex-A9 only */
    if ((read_cpuid(CPUID_ID) & 0xff0ffff0) == 0x410fc090) {
        scu_ctrl = __raw_readl(scu_base + 0x30);
        if (!(scu_ctrl & 1))
            __raw_writel(scu_ctrl | 0x1, scu_base + 0x30);
    }
#endif

    scu_ctrl = __raw_readl(scu_base + SCU_CTRL);
    /* already enabled? */
    if (scu_ctrl & 1)
        return;

    scu_ctrl |= 1;
    __raw_writel(scu_ctrl, scu_base + SCU_CTRL);

    /*
     * Ensure that the data accessed by CPU0 before the SCU was
     * initialised is visible to the other CPUs.
     */
    flush_cache_all();
}
#endif

/*
 * Set the executing CPUs power mode as defined.  This will be in
 * preparation for it executing a WFI instruction.
 *
 * This function must be called with preemption disabled, and as it
 * has the side effect of disabling coherency, caches must have been
 * flushed.  Interrupts must also have been disabled.
 */
int scu_power_mode(void __iomem *scu_base, unsigned int mode)
{
    unsigned int val;
    int cpu = cpu_logical_map(smp_processor_id());

    if (mode > 3 || mode == 1 || cpu > 3)
        return -EINVAL;

    val = __raw_readb(scu_base + SCU_CPU_STATUS + cpu) & ~0x03;
    val |= mode;
    __raw_writeb(val, scu_base + SCU_CPU_STATUS + cpu);

    return 0;
}