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 cpu_mailbox_entry {
  25         phys_addr_t mailbox_addr;
  26         u8 version;
  27         u8 gic_cpu_id;
  28 };
  29
  30 static struct cpu_mailbox_entry cpu_mailbox_entries[NR_CPUS];
  31
  32 void __init acpi_set_mailbox_entry(int cpu,
  33                                    struct acpi_madt_generic_interrupt *p)
  34 {
  35         struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
  36
  37         cpu_entry->mailbox_addr = p->parked_address;
  38         cpu_entry->version = p->parking_version;
  39         cpu_entry->gic_cpu_id = p->cpu_interface_number;
  40 }
  41
  42 bool acpi_parking_protocol_valid(int cpu)
  43 {
  44         struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
  45
  46         return cpu_entry->mailbox_addr && cpu_entry->version;
  47 }
  48
  49 static int acpi_parking_protocol_cpu_init(unsigned int cpu)
  50 {
  51         pr_debug("%s: ACPI parked addr=%llx\n", __func__,
  52                   cpu_mailbox_entries[cpu].mailbox_addr);
  53
  54         return 0;
  55 }
  56
  57 static int acpi_parking_protocol_cpu_prepare(unsigned int cpu)
  58 {
  59         return 0;
  60 }
  61
  62 struct parking_protocol_mailbox {
  63         __le32 cpu_id;
  64         __le32 reserved;
  65         __le64 entry_point;
  66 };
  67
  68 static int acpi_parking_protocol_cpu_boot(unsigned int cpu)
  69 {
  70         struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
  71         struct parking_protocol_mailbox __iomem *mailbox;
  72         __le32 cpu_id;
  73
  74         /*
  75          * Map mailbox memory with attribute device nGnRE (ie ioremap -
  76          * this deviates from the parking protocol specifications since
  77          * the mailboxes are required to be mapped nGnRnE; the attribute
  78          * discrepancy is harmless insofar as the protocol specification
  79          * is concerned).
  80          * If the mailbox is mistakenly allocated in the linear mapping
  81          * by FW ioremap will fail since the mapping will be prevented
  82          * by the kernel (it clashes with the linear mapping attributes
  83          * specifications).
  84          */
  85         mailbox = ioremap(cpu_entry->mailbox_addr, sizeof(*mailbox));
  86         if (!mailbox)
  87                 return -EIO;
  88
  89         cpu_id = readl_relaxed(&mailbox->cpu_id);
  90         /*
  91          * Check if firmware has set-up the mailbox entry properly
  92          * before kickstarting the respective cpu.
  93          */
  94         if (cpu_id != ~0U) {
  95                 iounmap(mailbox);
  96                 return -ENXIO;
  97         }
  98
  99         /*
 100          * We write the entry point and cpu id as LE regardless of the
 101          * native endianness of the kernel. Therefore, any boot-loaders
 102          * that read this address need to convert this address to the
 103          * Boot-Loader's endianness before jumping.
 104          */
 105         writeq_relaxed(__pa(secondary_entry), &mailbox->entry_point);
 106         writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id);
 107
 108         arch_send_wakeup_ipi_mask(cpumask_of(cpu));
 109
 110         iounmap(mailbox);
 111
 112         return 0;
 113 }
 114
 115 static void acpi_parking_protocol_cpu_postboot(void)
 116 {
 117         int cpu = smp_processor_id();
 118         struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
 119         struct parking_protocol_mailbox __iomem *mailbox;
 120         __le64 entry_point;
 121
 122         /*
 123          * Map mailbox memory with attribute device nGnRE (ie ioremap -
 124          * this deviates from the parking protocol specifications since
 125          * the mailboxes are required to be mapped nGnRnE; the attribute
 126          * discrepancy is harmless insofar as the protocol specification
 127          * is concerned).
 128          * If the mailbox is mistakenly allocated in the linear mapping
 129          * by FW ioremap will fail since the mapping will be prevented
 130          * by the kernel (it clashes with the linear mapping attributes
 131          * specifications).
 132          */
 133         mailbox = ioremap(cpu_entry->mailbox_addr, sizeof(*mailbox));
 134         if (!mailbox)
 135                 return;
 136
 137         entry_point = readl_relaxed(&mailbox->entry_point);
 138         /*
 139          * Check if firmware has cleared the entry_point as expected
 140          * by the protocol specification.
 141          */
 142         WARN_ON(entry_point);
 143
 144         iounmap(mailbox);
 145 }
 146
 147 const struct cpu_operations acpi_parking_protocol_ops = {
 148         .name           = "parking-protocol",
 149         .cpu_init       = acpi_parking_protocol_cpu_init,
 150         .cpu_prepare    = acpi_parking_protocol_cpu_prepare,
 151         .cpu_boot       = acpi_parking_protocol_cpu_boot,
 152         .cpu_postboot   = acpi_parking_protocol_cpu_postboot
 153 };