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),
103 &mailbox->entry_point);
104 writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id);
105
106 arch_send_wakeup_ipi(cpu);
107
108 return 0;
109 }
110
111 static void acpi_parking_protocol_cpu_postboot(void)
112 {
113 int cpu = smp_processor_id();
114 struct cpu_mailbox_entry *cpu_entry = &cpu_mailbox_entries[cpu];
115 struct parking_protocol_mailbox __iomem *mailbox = cpu_entry->mailbox;
116 u64 entry_point;
117
118 entry_point = readq_relaxed(&mailbox->entry_point);
119 /*
120 * Check if firmware has cleared the entry_point as expected
121 * by the protocol specification.
122 */
123 WARN_ON(entry_point);
124 }
125
126 const struct cpu_operations acpi_parking_protocol_ops = {
127 .name = "parking-protocol",
128 .cpu_init = acpi_parking_protocol_cpu_init,
129 .cpu_prepare = acpi_parking_protocol_cpu_prepare,
130 .cpu_boot = acpi_parking_protocol_cpu_boot,
131 .cpu_postboot = acpi_parking_protocol_cpu_postboot
132 };
133
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