// SPDX-License-Identifier: GPL-2.0-only
/*
 * ARM64 ACPI Parking Protocol implementation
 *
 * Authors: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
 *          Mark Salter <msalter@redhat.com>
 */
#include <linux/acpi.h>
#include <linux/mm.h>
#include <linux/types.h>

#include <asm/cpu_ops.h>

struct parking_protocol_mailbox {
        __le32 cpu_id;
        __le32 reserved;
        __le64 entry_point;
};

struct cpu_mailbox_entry {
        struct parking_protocol_mailbox __iomem *mailbox;
        phys_addr_t mailbox_addr;
        u8 version;
        u8 gic_cpu_id;
};

static struct cpu_mailbox_entry cpu_mailbox_entries[NR_CPUS];

void __init acpi_set_mailbox_entry(int cpu,
                                   struct acpi_madt_generic_interrupt *p)
{
        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];

        cpu_entry->mailbox_addr = p->parked_address;
        cpu_entry->version = p->parking_version;
        cpu_entry->gic_cpu_id = p->cpu_interface_number;
}

bool acpi_parking_protocol_valid(int cpu)
{
        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];

        return cpu_entry->mailbox_addr && cpu_entry->version;
}

static int acpi_parking_protocol_cpu_init(unsigned int cpu)
{
        pr_debug("%s: ACPI parked addr=%llx\n", __func__,
                  cpu_mailbox_entries[cpu].mailbox_addr);

        return 0;
}

static int acpi_parking_protocol_cpu_prepare(unsigned int cpu)
{
        return 0;
}

static int acpi_parking_protocol_cpu_boot(unsigned int cpu)
{
        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
        struct parking_protocol_mailbox __iomem *mailbox;
        u32 cpu_id;

        /*
         * Map mailbox memory with attribute device nGnRE (ie ioremap -
         * this deviates from the parking protocol specifications since
         * the mailboxes are required to be mapped nGnRnE; the attribute
         * discrepancy is harmless insofar as the protocol specification
         * is concerned).
         * If the mailbox is mistakenly allocated in the linear mapping
         * by FW ioremap will fail since the mapping will be prevented
         * by the kernel (it clashes with the linear mapping attributes
         * specifications).
         */
        mailbox = ioremap(cpu_entry->mailbox_addr, sizeof(*mailbox));
        if (!mailbox)
                return -EIO;

        cpu_id = readl_relaxed(&mailbox->cpu_id);
        /*
         * Check if firmware has set-up the mailbox entry properly
         * before kickstarting the respective cpu.
         */
        if (cpu_id != ~0U) {
                iounmap(mailbox);
                return -ENXIO;
        }

        /*
         * stash the mailbox address mapping to use it for further FW
         * checks in the postboot method
         */
        cpu_entry->mailbox = mailbox;

        /*
         * We write the entry point and cpu id as LE regardless of the
         * native endianness of the kernel. Therefore, any boot-loaders
         * that read this address need to convert this address to the
         * Boot-Loader's endianness before jumping.
         */
        writeq_relaxed(__pa_symbol(secondary_entry),
                       &mailbox->entry_point);
        writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id);

        arch_send_wakeup_ipi(cpu);

        return 0;
}

static void acpi_parking_protocol_cpu_postboot(void)
{
        int cpu = smp_processor_id();
        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
        struct parking_protocol_mailbox __iomem *mailbox = cpu_entry->mailbox;
        u64 entry_point;

        entry_point = readq_relaxed(&mailbox->entry_point);
        /*
         * Check if firmware has cleared the entry_point as expected
         * by the protocol specification.
         */
        WARN_ON(entry_point);
}

const struct cpu_operations acpi_parking_protocol_ops = {
        .name           = "parking-protocol",
        .cpu_init       = acpi_parking_protocol_cpu_init,
        .cpu_prepare    = acpi_parking_protocol_cpu_prepare,
        .cpu_boot       = acpi_parking_protocol_cpu_boot,
        .cpu_postboot   = acpi_parking_protocol_cpu_postboot
};