LXR linux/arch/arm64/kernel/acpi_parking

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * ARM64 ACPI Parking Protocol implementation
   4 *
   5 * Authors: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
   6 *          Mark Salter <msalter@redhat.com>
   7 */
   8#include <linux/acpi.h>
   9#include <linux/mm.h>
  10#include <linux/types.h>
  11
  12#include <asm/cpu_ops.h>
  13
  14struct parking_protocol_mailbox {
  15        __le32 cpu_id;
  16        __le32 reserved;
  17        __le64 entry_point;
  18};
  19
  20struct cpu_mailbox_entry {
  21        struct parking_protocol_mailbox __iomem *mailbox;
  22        phys_addr_t mailbox_addr;
  23        u8 version;
  24        u8 gic_cpu_id;
  25};
  26
  27static struct cpu_mailbox_entry cpu_mailbox_entries[NR_CPUS];
  28
  29void __init acpi_set_mailbox_entry(int cpu,
  30                                   struct acpi_madt_generic_interrupt *p)
  31{
  32        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
  33
  34        cpu_entry->mailbox_addr = p->parked_address;
  35        cpu_entry->version = p->parking_version;
  36        cpu_entry->gic_cpu_id = p->cpu_interface_number;
  37}
  38
  39bool acpi_parking_protocol_valid(int cpu)
  40{
  41        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
  42
  43        return cpu_entry->mailbox_addr && cpu_entry->version;
  44}
  45
  46static int acpi_parking_protocol_cpu_init(unsigned int cpu)
  47{
  48        pr_debug("%s: ACPI parked addr=%llx\n", __func__,
  49                  cpu_mailbox_entries[cpu].mailbox_addr);
  50
  51        return 0;
  52}
  53
  54static int acpi_parking_protocol_cpu_prepare(unsigned int cpu)
  55{
  56        return 0;
  57}
  58
  59static int acpi_parking_protocol_cpu_boot(unsigned int cpu)
  60{
  61        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
  62        struct parking_protocol_mailbox __iomem *mailbox;
  63        u32 cpu_id;
  64
  65        /*
  66         * Map mailbox memory with attribute device nGnRE (ie ioremap -
  67         * this deviates from the parking protocol specifications since
  68         * the mailboxes are required to be mapped nGnRnE; the attribute
  69         * discrepancy is harmless insofar as the protocol specification
  70         * is concerned).
  71         * If the mailbox is mistakenly allocated in the linear mapping
  72         * by FW ioremap will fail since the mapping will be prevented
  73         * by the kernel (it clashes with the linear mapping attributes
  74         * specifications).
  75         */
  76        mailbox = ioremap(cpu_entry->mailbox_addr, sizeof(*mailbox));
  77        if (!mailbox)
  78                return -EIO;
  79
  80        cpu_id = readl_relaxed(&mailbox->cpu_id);
  81        /*
  82         * Check if firmware has set-up the mailbox entry properly
  83         * before kickstarting the respective cpu.
  84         */
  85        if (cpu_id != ~0U) {
  86                iounmap(mailbox);
  87                return -ENXIO;
  88        }
  89
  90        /*
  91         * stash the mailbox address mapping to use it for further FW
  92         * checks in the postboot method
  93         */
  94        cpu_entry->mailbox = mailbox;
  95
  96        /*
  97         * We write the entry point and cpu id as LE regardless of the
  98         * native endianness of the kernel. Therefore, any boot-loaders
  99         * that read this address need to convert this address to the
 100         * Boot-Loader's endianness before jumping.
 101         */
 102        writeq_relaxed(__pa_symbol(secondary_entry), &mailbox->entry_point);
 103        writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id);
 104
 105        arch_send_wakeup_ipi_mask(cpumask_of(cpu));
 106
 107        return 0;
 108}
 109
 110static void acpi_parking_protocol_cpu_postboot(void)
 111{
 112        int cpu = smp_processor_id();
 113        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
 114        struct parking_protocol_mailbox __iomem *mailbox = cpu_entry->mailbox;
 115        u64 entry_point;
 116
 117        entry_point = readq_relaxed(&mailbox->entry_point);
 118        /*
 119         * Check if firmware has cleared the entry_point as expected
 120         * by the protocol specification.
 121         */
 122        WARN_ON(entry_point);
 123}
 124
 125const struct cpu_operations acpi_parking_protocol_ops = {
 126        .name           = "parking-protocol",
 127        .cpu_init       = acpi_parking_protocol_cpu_init,
 128        .cpu_prepare    = acpi_parking_protocol_cpu_prepare,
 129        .cpu_boot       = acpi_parking_protocol_cpu_boot,
 130        .cpu_postboot   = acpi_parking_protocol_cpu_postboot
 131};
 132