1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * CPU kernel entry/exit control
4  *
5  * Copyright (C) 2013 ARM Ltd.
6  */
7 
8 #include <linux/acpi.h>
9 #include <linux/cache.h>
10 #include <linux/errno.h>
11 #include <linux/of.h>
12 #include <linux/string.h>
13 #include <asm/acpi.h>
14 #include <asm/cpu_ops.h>
15 #include <asm/smp_plat.h>
16 
17 extern const struct cpu_operations smp_spin_table_ops;
18 #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
19 extern const struct cpu_operations acpi_parking_protocol_ops;
20 #endif
21 extern const struct cpu_operations cpu_psci_ops;
22 
23 static const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
24 
25 static const struct cpu_operations *const dt_supported_cpu_ops[] __initconst = {
26 	&smp_spin_table_ops,
27 	&cpu_psci_ops,
28 	NULL,
29 };
30 
31 static const struct cpu_operations *const acpi_supported_cpu_ops[] __initconst = {
32 #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
33 	&acpi_parking_protocol_ops,
34 #endif
35 	&cpu_psci_ops,
36 	NULL,
37 };
38 
cpu_get_ops(const char * name)39 static const struct cpu_operations * __init cpu_get_ops(const char *name)
40 {
41 	const struct cpu_operations *const *ops;
42 
43 	ops = acpi_disabled ? dt_supported_cpu_ops : acpi_supported_cpu_ops;
44 
45 	while (*ops) {
46 		if (!strcmp(name, (*ops)->name))
47 			return *ops;
48 
49 		ops++;
50 	}
51 
52 	return NULL;
53 }
54 
cpu_read_enable_method(int cpu)55 static const char *__init cpu_read_enable_method(int cpu)
56 {
57 	const char *enable_method;
58 
59 	if (acpi_disabled) {
60 		struct device_node *dn = of_get_cpu_node(cpu, NULL);
61 
62 		if (!dn) {
63 			if (!cpu)
64 				pr_err("Failed to find device node for boot cpu\n");
65 			return NULL;
66 		}
67 
68 		enable_method = of_get_property(dn, "enable-method", NULL);
69 		if (!enable_method) {
70 			/*
71 			 * The boot CPU may not have an enable method (e.g.
72 			 * when spin-table is used for secondaries).
73 			 * Don't warn spuriously.
74 			 */
75 			if (cpu != 0)
76 				pr_err("%pOF: missing enable-method property\n",
77 					dn);
78 		}
79 		of_node_put(dn);
80 	} else {
81 		enable_method = acpi_get_enable_method(cpu);
82 		if (!enable_method) {
83 			/*
84 			 * In ACPI systems the boot CPU does not require
85 			 * checking the enable method since for some
86 			 * boot protocol (ie parking protocol) it need not
87 			 * be initialized. Don't warn spuriously.
88 			 */
89 			if (cpu != 0)
90 				pr_err("Unsupported ACPI enable-method\n");
91 		}
92 	}
93 
94 	return enable_method;
95 }
96 /*
97  * Read a cpu's enable method and record it in cpu_ops.
98  */
init_cpu_ops(int cpu)99 int __init init_cpu_ops(int cpu)
100 {
101 	const char *enable_method = cpu_read_enable_method(cpu);
102 
103 	if (!enable_method)
104 		return -ENODEV;
105 
106 	cpu_ops[cpu] = cpu_get_ops(enable_method);
107 	if (!cpu_ops[cpu]) {
108 		pr_warn("Unsupported enable-method: %s\n", enable_method);
109 		return -EOPNOTSUPP;
110 	}
111 
112 	return 0;
113 }
114 
get_cpu_ops(int cpu)115 const struct cpu_operations *get_cpu_ops(int cpu)
116 {
117 	return cpu_ops[cpu];
118 }
119