xref: /openbmc/linux/arch/arm64/kernel/cpu_ops.c (revision e7253313)
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 extern const struct cpu_operations acpi_parking_protocol_ops;
19 extern const struct cpu_operations cpu_psci_ops;
20 
21 const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
22 
23 static const struct cpu_operations *const dt_supported_cpu_ops[] __initconst = {
24 	&smp_spin_table_ops,
25 	&cpu_psci_ops,
26 	NULL,
27 };
28 
29 static const struct cpu_operations *const acpi_supported_cpu_ops[] __initconst = {
30 #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
31 	&acpi_parking_protocol_ops,
32 #endif
33 	&cpu_psci_ops,
34 	NULL,
35 };
36 
37 static const struct cpu_operations * __init cpu_get_ops(const char *name)
38 {
39 	const struct cpu_operations *const *ops;
40 
41 	ops = acpi_disabled ? dt_supported_cpu_ops : acpi_supported_cpu_ops;
42 
43 	while (*ops) {
44 		if (!strcmp(name, (*ops)->name))
45 			return *ops;
46 
47 		ops++;
48 	}
49 
50 	return NULL;
51 }
52 
53 static const char *__init cpu_read_enable_method(int cpu)
54 {
55 	const char *enable_method;
56 
57 	if (acpi_disabled) {
58 		struct device_node *dn = of_get_cpu_node(cpu, NULL);
59 
60 		if (!dn) {
61 			if (!cpu)
62 				pr_err("Failed to find device node for boot cpu\n");
63 			return NULL;
64 		}
65 
66 		enable_method = of_get_property(dn, "enable-method", NULL);
67 		if (!enable_method) {
68 			/*
69 			 * The boot CPU may not have an enable method (e.g.
70 			 * when spin-table is used for secondaries).
71 			 * Don't warn spuriously.
72 			 */
73 			if (cpu != 0)
74 				pr_err("%pOF: missing enable-method property\n",
75 					dn);
76 		}
77 		of_node_put(dn);
78 	} else {
79 		enable_method = acpi_get_enable_method(cpu);
80 		if (!enable_method) {
81 			/*
82 			 * In ACPI systems the boot CPU does not require
83 			 * checking the enable method since for some
84 			 * boot protocol (ie parking protocol) it need not
85 			 * be initialized. Don't warn spuriously.
86 			 */
87 			if (cpu != 0)
88 				pr_err("Unsupported ACPI enable-method\n");
89 		}
90 	}
91 
92 	return enable_method;
93 }
94 /*
95  * Read a cpu's enable method and record it in cpu_ops.
96  */
97 int __init cpu_read_ops(int cpu)
98 {
99 	const char *enable_method = cpu_read_enable_method(cpu);
100 
101 	if (!enable_method)
102 		return -ENODEV;
103 
104 	cpu_ops[cpu] = cpu_get_ops(enable_method);
105 	if (!cpu_ops[cpu]) {
106 		pr_warn("Unsupported enable-method: %s\n", enable_method);
107 		return -EOPNOTSUPP;
108 	}
109 
110 	return 0;
111 }
112