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(function_nocfi(secondary_entry)),
103 		       &mailbox->entry_point);
104 	writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id);
105 
106 	arch_send_wakeup_ipi_mask(cpumask_of(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