1/*
  2 * CPU kernel entry/exit control
  3 *
  4 * Copyright (C) 2013 ARM Ltd.
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2 as
  8 * published by the Free Software Foundation.
  9 *
 10 * This program is distributed in the hope that it will be useful,
 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13 * GNU General Public License for more details.
 14 *
 15 * You should have received a copy of the GNU General Public License
 16 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 17 */
 18
 19#include <linux/acpi.h>
 20#include <linux/errno.h>
 21#include <linux/of.h>
 22#include <linux/string.h>
 23#include <asm/acpi.h>
 24#include <asm/cpu_ops.h>
 25#include <asm/smp_plat.h>
 26
 27extern const struct cpu_operations smp_spin_table_ops;
 28extern const struct cpu_operations acpi_parking_protocol_ops;
 29extern const struct cpu_operations cpu_psci_ops;
 30
 31const struct cpu_operations *cpu_ops[NR_CPUS];
 32
 33static const struct cpu_operations *dt_supported_cpu_ops[] __initconst = {
 34	&smp_spin_table_ops,
 35	&cpu_psci_ops,
 36	NULL,
 37};
 38
 39static const struct cpu_operations *acpi_supported_cpu_ops[] __initconst = {
 40#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
 41	&acpi_parking_protocol_ops,
 42#endif
 43	&cpu_psci_ops,
 44	NULL,
 45};
 46
 47static const struct cpu_operations * __init cpu_get_ops(const char *name)
 48{
 49	const struct cpu_operations **ops;
 50
 51	ops = acpi_disabled ? dt_supported_cpu_ops : acpi_supported_cpu_ops;
 52
 53	while (*ops) {
 54		if (!strcmp(name, (*ops)->name))
 55			return *ops;
 56
 57		ops++;
 58	}
 59
 60	return NULL;
 61}
 62
 63static const char *__init cpu_read_enable_method(int cpu)
 64{
 65	const char *enable_method;
 66
 67	if (acpi_disabled) {
 68		struct device_node *dn = of_get_cpu_node(cpu, NULL);
 69
 70		if (!dn) {
 71			if (!cpu)
 72				pr_err("Failed to find device node for boot cpu\n");
 73			return NULL;
 74		}
 75
 76		enable_method = of_get_property(dn, "enable-method", NULL);
 77		if (!enable_method) {
 78			/*
 79			 * The boot CPU may not have an enable method (e.g.
 80			 * when spin-table is used for secondaries).
 81			 * Don't warn spuriously.
 82			 */
 83			if (cpu != 0)
 84				pr_err("%s: missing enable-method property\n",
 85					dn->full_name);
 86		}
 87	} else {
 88		enable_method = acpi_get_enable_method(cpu);
 89		if (!enable_method) {
 90			/*
 91			 * In ACPI systems the boot CPU does not require
 92			 * checking the enable method since for some
 93			 * boot protocol (ie parking protocol) it need not
 94			 * be initialized. Don't warn spuriously.
 95			 */
 96			if (cpu != 0)
 97				pr_err("Unsupported ACPI enable-method\n");
 98		}
 99	}
100
101	return enable_method;
102}
103/*
104 * Read a cpu's enable method and record it in cpu_ops.
105 */
106int __init cpu_read_ops(int cpu)
107{
108	const char *enable_method = cpu_read_enable_method(cpu);
109
110	if (!enable_method)
111		return -ENODEV;
112
113	cpu_ops[cpu] = cpu_get_ops(enable_method);
114	if (!cpu_ops[cpu]) {
115		pr_warn("Unsupported enable-method: %s\n", enable_method);
116		return -EOPNOTSUPP;
117	}
118
119	return 0;
120}