LXR linux/arch/arm64/kernel/acpi_parking

   1/*
   2 * ARM64 ACPI Parking Protocol implementation
   3 *
   4 * Authors: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
   5 *          Mark Salter <msalter@redhat.com>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19#include <linux/acpi.h>
  20#include <linux/mm.h>
  21#include <linux/types.h>
  22
  23#include <asm/cpu_ops.h>
  24
  25struct parking_protocol_mailbox {
  26        __le32 cpu_id;
  27        __le32 reserved;
  28        __le64 entry_point;
  29};
  30
  31struct cpu_mailbox_entry {
  32        struct parking_protocol_mailbox __iomem *mailbox;
  33        phys_addr_t mailbox_addr;
  34        u8 version;
  35        u8 gic_cpu_id;
  36};
  37
  38static struct cpu_mailbox_entry cpu_mailbox_entries[NR_CPUS];
  39
  40void __init acpi_set_mailbox_entry(int cpu,
  41                                   struct acpi_madt_generic_interrupt *p)
  42{
  43        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
  44
  45        cpu_entry->mailbox_addr = p->parked_address;
  46        cpu_entry->version = p->parking_version;
  47        cpu_entry->gic_cpu_id = p->cpu_interface_number;
  48}
  49
  50bool acpi_parking_protocol_valid(int cpu)
  51{
  52        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
  53
  54        return cpu_entry->mailbox_addr && cpu_entry->version;
  55}
  56
  57static int acpi_parking_protocol_cpu_init(unsigned int cpu)
  58{
  59        pr_debug("%s: ACPI parked addr=%llx\n", __func__,
  60                  cpu_mailbox_entries[cpu].mailbox_addr);
  61
  62        return 0;
  63}
  64
  65static int acpi_parking_protocol_cpu_prepare(unsigned int cpu)
  66{
  67        return 0;
  68}
  69
  70static int acpi_parking_protocol_cpu_boot(unsigned int cpu)
  71{
  72        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
  73        struct parking_protocol_mailbox __iomem *mailbox;
  74        u32 cpu_id;
  75
  76        /*
  77         * Map mailbox memory with attribute device nGnRE (ie ioremap -
  78         * this deviates from the parking protocol specifications since
  79         * the mailboxes are required to be mapped nGnRnE; the attribute
  80         * discrepancy is harmless insofar as the protocol specification
  81         * is concerned).
  82         * If the mailbox is mistakenly allocated in the linear mapping
  83         * by FW ioremap will fail since the mapping will be prevented
  84         * by the kernel (it clashes with the linear mapping attributes
  85         * specifications).
  86         */
  87        mailbox = ioremap(cpu_entry->mailbox_addr, sizeof(*mailbox));
  88        if (!mailbox)
  89                return -EIO;
  90
  91        cpu_id = readl_relaxed(&mailbox->cpu_id);
  92        /*
  93         * Check if firmware has set-up the mailbox entry properly
  94         * before kickstarting the respective cpu.
  95         */
  96        if (cpu_id != ~0U) {
  97                iounmap(mailbox);
  98                return -ENXIO;
  99        }
 100
 101        /*
 102         * stash the mailbox address mapping to use it for further FW
 103         * checks in the postboot method
 104         */
 105        cpu_entry->mailbox = mailbox;
 106
 107        /*
 108         * We write the entry point and cpu id as LE regardless of the
 109         * native endianness of the kernel. Therefore, any boot-loaders
 110         * that read this address need to convert this address to the
 111         * Boot-Loader's endianness before jumping.
 112         */
 113        writeq_relaxed(__pa_symbol(secondary_entry), &mailbox->entry_point);
 114        writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id);
 115
 116        arch_send_wakeup_ipi_mask(cpumask_of(cpu));
 117
 118        return 0;
 119}
 120
 121static void acpi_parking_protocol_cpu_postboot(void)
 122{
 123        int cpu = smp_processor_id();
 124        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
 125        struct parking_protocol_mailbox __iomem *mailbox = cpu_entry->mailbox;
 126        u64 entry_point;
 127
 128        entry_point = readq_relaxed(&mailbox->entry_point);
 129        /*
 130         * Check if firmware has cleared the entry_point as expected
 131         * by the protocol specification.
 132         */
 133        WARN_ON(entry_point);
 134}
 135
 136const struct cpu_operations acpi_parking_protocol_ops = {
 137        .name           = "parking-protocol",
 138        .cpu_init       = acpi_parking_protocol_cpu_init,
 139        .cpu_prepare    = acpi_parking_protocol_cpu_prepare,
 140        .cpu_boot       = acpi_parking_protocol_cpu_boot,
 141        .cpu_postboot   = acpi_parking_protocol_cpu_postboot
 142};
 143