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/types.h>
  21
  22#include <asm/cpu_ops.h>
  23
  24struct parking_protocol_mailbox {
  25        __le32 cpu_id;
  26        __le32 reserved;
  27        __le64 entry_point;
  28};
  29
  30struct cpu_mailbox_entry {
  31        struct parking_protocol_mailbox __iomem *mailbox;
  32        phys_addr_t mailbox_addr;
  33        u8 version;
  34        u8 gic_cpu_id;
  35};
  36
  37static struct cpu_mailbox_entry cpu_mailbox_entries[NR_CPUS];
  38
  39void __init acpi_set_mailbox_entry(int cpu,
  40                                   struct acpi_madt_generic_interrupt *p)
  41{
  42        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
  43
  44        cpu_entry->mailbox_addr = p->parked_address;
  45        cpu_entry->version = p->parking_version;
  46        cpu_entry->gic_cpu_id = p->cpu_interface_number;
  47}
  48
  49bool acpi_parking_protocol_valid(int cpu)
  50{
  51        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
  52
  53        return cpu_entry->mailbox_addr && cpu_entry->version;
  54}
  55
  56static int acpi_parking_protocol_cpu_init(unsigned int cpu)
  57{
  58        pr_debug("%s: ACPI parked addr=%llx\n", __func__,
  59                  cpu_mailbox_entries[cpu].mailbox_addr);
  60
  61        return 0;
  62}
  63
  64static int acpi_parking_protocol_cpu_prepare(unsigned int cpu)
  65{
  66        return 0;
  67}
  68
  69static int acpi_parking_protocol_cpu_boot(unsigned int cpu)
  70{
  71        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
  72        struct parking_protocol_mailbox __iomem *mailbox;
  73        __le32 cpu_id;
  74
  75        /*
  76         * Map mailbox memory with attribute device nGnRE (ie ioremap -
  77         * this deviates from the parking protocol specifications since
  78         * the mailboxes are required to be mapped nGnRnE; the attribute
  79         * discrepancy is harmless insofar as the protocol specification
  80         * is concerned).
  81         * If the mailbox is mistakenly allocated in the linear mapping
  82         * by FW ioremap will fail since the mapping will be prevented
  83         * by the kernel (it clashes with the linear mapping attributes
  84         * specifications).
  85         */
  86        mailbox = ioremap(cpu_entry->mailbox_addr, sizeof(*mailbox));
  87        if (!mailbox)
  88                return -EIO;
  89
  90        cpu_id = readl_relaxed(&mailbox->cpu_id);
  91        /*
  92         * Check if firmware has set-up the mailbox entry properly
  93         * before kickstarting the respective cpu.
  94         */
  95        if (cpu_id != ~0U) {
  96                iounmap(mailbox);
  97                return -ENXIO;
  98        }
  99
 100        /*
 101         * stash the mailbox address mapping to use it for further FW
 102         * checks in the postboot method
 103         */
 104        cpu_entry->mailbox = mailbox;
 105
 106        /*
 107         * We write the entry point and cpu id as LE regardless of the
 108         * native endianness of the kernel. Therefore, any boot-loaders
 109         * that read this address need to convert this address to the
 110         * Boot-Loader's endianness before jumping.
 111         */
 112        writeq_relaxed(__pa(secondary_entry), &mailbox->entry_point);
 113        writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id);
 114
 115        arch_send_wakeup_ipi_mask(cpumask_of(cpu));
 116
 117        return 0;
 118}
 119
 120static void acpi_parking_protocol_cpu_postboot(void)
 121{
 122        int cpu = smp_processor_id();
 123        struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
 124        struct parking_protocol_mailbox __iomem *mailbox = cpu_entry->mailbox;
 125        __le64 entry_point;
 126
 127        entry_point = readl_relaxed(&mailbox->entry_point);
 128        /*
 129         * Check if firmware has cleared the entry_point as expected
 130         * by the protocol specification.
 131         */
 132        WARN_ON(entry_point);
 133}
 134
 135const struct cpu_operations acpi_parking_protocol_ops = {
 136        .name           = "parking-protocol",
 137        .cpu_init       = acpi_parking_protocol_cpu_init,
 138        .cpu_prepare    = acpi_parking_protocol_cpu_prepare,
 139        .cpu_boot       = acpi_parking_protocol_cpu_boot,
 140        .cpu_postboot   = acpi_parking_protocol_cpu_postboot
 141};
 142