arch/arm64/kernel/acpi_parking_protocol.c

   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
  14 struct parking_protocol_mailbox {
  15         __le32 cpu_id;
  16         __le32 reserved;
  17         __le64 entry_point;
  18 };
  19
  20 struct 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
  27 static struct cpu_mailbox_entry cpu_mailbox_entries[NR_CPUS];
  28
  29 void __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
  39 bool 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
  46 static 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
  54 static int acpi_parking_protocol_cpu_prepare(unsigned int cpu)
  55 {
  56         return 0;
  57 }
  58
  59 static 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
 110 static 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
 125 const 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 };