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/cache.h>
 21#include <linux/errno.h>
 22#include <linux/of.h>
 23#include <linux/string.h>
 24#include <asm/acpi.h>
 25#include <asm/cpu_ops.h>
 26#include <asm/smp_plat.h>
 27
 28extern const struct cpu_operations smp_spin_table_ops;
 29extern const struct cpu_operations acpi_parking_protocol_ops;
 30extern const struct cpu_operations cpu_psci_ops;
 31
 32const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
 33
 34static const struct cpu_operations *const dt_supported_cpu_ops[] __initconst = {
 35	&smp_spin_table_ops,
 36	&cpu_psci_ops,
 37	NULL,
 38};
 39
 40static const struct cpu_operations *const acpi_supported_cpu_ops[] __initconst = {
 41#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
 42	&acpi_parking_protocol_ops,
 43#endif
 44	&cpu_psci_ops,
 45	NULL,
 46};
 47
 48static const struct cpu_operations * __init cpu_get_ops(const char *name)
 49{
 50	const struct cpu_operations *const *ops;
 51
 52	ops = acpi_disabled ? dt_supported_cpu_ops : acpi_supported_cpu_ops;
 53
 54	while (*ops) {
 55		if (!strcmp(name, (*ops)->name))
 56			return *ops;
 57
 58		ops++;
 59	}
 60
 61	return NULL;
 62}
 63
 64static const char *__init cpu_read_enable_method(int cpu)
 65{
 66	const char *enable_method;
 67
 68	if (acpi_disabled) {
 69		struct device_node *dn = of_get_cpu_node(cpu, NULL);
 70
 71		if (!dn) {
 72			if (!cpu)
 73				pr_err("Failed to find device node for boot cpu\n");
 74			return NULL;
 75		}
 76
 77		enable_method = of_get_property(dn, "enable-method", NULL);
 78		if (!enable_method) {
 79			/*
 80			 * The boot CPU may not have an enable method (e.g.
 81			 * when spin-table is used for secondaries).
 82			 * Don't warn spuriously.
 83			 */
 84			if (cpu != 0)
 85				pr_err("%pOF: missing enable-method property\n",
 86					dn);
 87		}
 88	} else {
 89		enable_method = acpi_get_enable_method(cpu);
 90		if (!enable_method) {
 91			/*
 92			 * In ACPI systems the boot CPU does not require
 93			 * checking the enable method since for some
 94			 * boot protocol (ie parking protocol) it need not
 95			 * be initialized. Don't warn spuriously.
 96			 */
 97			if (cpu != 0)
 98				pr_err("Unsupported ACPI enable-method\n");
 99		}
100	}
101
102	return enable_method;
103}
104/*
105 * Read a cpu's enable method and record it in cpu_ops.
106 */
107int __init cpu_read_ops(int cpu)
108{
109	const char *enable_method = cpu_read_enable_method(cpu);
110
111	if (!enable_method)
112		return -ENODEV;
113
114	cpu_ops[cpu] = cpu_get_ops(enable_method);
115	if (!cpu_ops[cpu]) {
116		pr_warn("Unsupported enable-method: %s\n", enable_method);
117		return -EOPNOTSUPP;
118	}
119
120	return 0;
121}