arch/arm64/kernel/acpi_parking_protocol.c

   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
  24 struct parking_protocol_mailbox {
  25         __le32 cpu_id;
  26         __le32 reserved;
  27         __le64 entry_point;
  28 };
  29
  30 struct 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
  37 static struct cpu_mailbox_entry cpu_mailbox_entries[NR_CPUS];
  38
  39 void __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
  49 bool 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
  56 static 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
  64 static int acpi_parking_protocol_cpu_prepare(unsigned int cpu)
  65 {
  66         return 0;
  67 }
  68
  69 static 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
 120 static 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
 135 const 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 };