// SPDX-License-Identifier: GPL-2.0
/* leon_pmc.c: LEON Power-down cpu_idle() handler
 *
 * Copyright (C) 2011 Daniel Hellstrom (daniel@gaisler.com) 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>
#include <asm/processor.h>

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

static 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
 */
static 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;

        /* Interrupts need to be enabled to not hang the CPU */
        raw_local_irq_enable();

        __asm__ __volatile__ (
                "wr     %%g0, %%asr19\n"
                "lda    [%0] %1, %%g0\n"
                :
                : "r"(address), "i"(ASI_LEON_BYPASS));

        raw_local_irq_disable();
}

/*
 * CPU idle callback function
 * See .../arch/sparc/kernel/process.c
 */
static void pmc_leon_idle(void)
{
        /* Interrupts need to be enabled to not hang the CPU */
        raw_local_irq_enable();

        /* For systems without power-down, this will be no-op */
        __asm__ __volatile__ ("wr       %g0, %asr19\n\t");

        raw_local_irq_disable();
}

/* 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())
                        sparc_idle = pmc_leon_idle_fixup;
                else
                        sparc_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);