leon_pmc.c

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/* leon_pmc.c: LEON Power-down cpu_idle() handler
 *
 * Copyright (C) 2011 Daniel Hellstrom ([email protected]) Aeroflex Gaisler AB
 */

#include <linux/init.h>
#include <linux/pm.h>

#include <asm/leon_amba.h>
#include <asm/cpu_type.h>
#include <asm/leon.h>

/* List of Systems that need fixup instructions around power-down instruction */
unsigned int pmc_leon_fixup_ids[] = {
    AEROFLEX_UT699,
    GAISLER_GR712RC,
    LEON4_NEXTREME1,
    0
};

int pmc_leon_need_fixup(void)
{
    unsigned int systemid = amba_system_id >> 16;
    unsigned int *id;

    id = &pmc_leon_fixup_ids[0];
    while (*id != 0) {
        if (*id == systemid)
            return 1;
        id++;
    }

    return 0;
}

/*
 * CPU idle callback function for systems that need some extra handling
 * See .../arch/sparc/kernel/process.c
 */
void pmc_leon_idle_fixup(void)
{
    /* Prepare an address to a non-cachable region. APB is always
     * none-cachable. One instruction is executed after the Sleep
     * instruction, we make sure to read the bus and throw away the
     * value by accessing a non-cachable area, also we make sure the
     * MMU does not get a TLB miss here by using the MMU BYPASS ASI.
     */
    register unsigned int address = (unsigned int)leon3_irqctrl_regs;
    __asm__ __volatile__ (
        "mov    %%g0, %%asr19\n"
        "lda    [%0] %1, %%g0\n"
        :
        : "r"(address), "i"(ASI_LEON_BYPASS));
}

/*
 * CPU idle callback function
 * See .../arch/sparc/kernel/process.c
 */
void pmc_leon_idle(void)
{
    /* For systems without power-down, this will be no-op */
    __asm__ __volatile__ ("mov  %g0, %asr19\n\t");
}

/* Install LEON Power Down function */
static int __init leon_pmc_install(void)
{
    if (sparc_cpu_model == sparc_leon) {
        /* Assign power management IDLE handler */
        if (pmc_leon_need_fixup())
            pm_idle = pmc_leon_idle_fixup;
        else
            pm_idle = pmc_leon_idle;

        printk(KERN_INFO "leon: power management initialized\n");
    }

    return 0;
}

/* This driver is not critical to the boot process, don't care
 * if initialized late.
 */
late_initcall(leon_pmc_install);