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/mm.h>
  21 #include <linux/types.h>
  22
  23 #include <asm/cpu_ops.h>
  24
  25 struct parking_protocol_mailbox {
  26         __le32 cpu_id;
  27         __le32 reserved;
  28         __le64 entry_point;
  29 };
  30
  31 struct 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
  38 static struct cpu_mailbox_entry cpu_mailbox_entries[NR_CPUS];
  39
  40 void __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
  50 bool 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
  57 static 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
  65 static int acpi_parking_protocol_cpu_prepare(unsigned int cpu)
  66 {
  67         return 0;
  68 }
  69
  70 static 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
 121 static 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
 136 const 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 };