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Linux/arch/arm/kernel/psci_smp.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  *
  4  * Copyright (C) 2012 ARM Limited
  5  *
  6  * Author: Will Deacon <will.deacon@arm.com>
  7  */
  8 
  9 #include <linux/init.h>
 10 #include <linux/smp.h>
 11 #include <linux/of.h>
 12 #include <linux/delay.h>
 13 #include <linux/psci.h>
 14 
 15 #include <uapi/linux/psci.h>
 16 
 17 #include <asm/psci.h>
 18 #include <asm/smp_plat.h>
 19 
 20 /*
 21  * psci_smp assumes that the following is true about PSCI:
 22  *
 23  * cpu_suspend   Suspend the execution on a CPU
 24  * @state        we don't currently describe affinity levels, so just pass 0.
 25  * @entry_point  the first instruction to be executed on return
 26  * returns 0  success, < 0 on failure
 27  *
 28  * cpu_off       Power down a CPU
 29  * @state        we don't currently describe affinity levels, so just pass 0.
 30  * no return on successful call
 31  *
 32  * cpu_on        Power up a CPU
 33  * @cpuid        cpuid of target CPU, as from MPIDR
 34  * @entry_point  the first instruction to be executed on return
 35  * returns 0  success, < 0 on failure
 36  *
 37  * migrate       Migrate the context to a different CPU
 38  * @cpuid        cpuid of target CPU, as from MPIDR
 39  * returns 0  success, < 0 on failure
 40  *
 41  */
 42 
 43 extern void secondary_startup(void);
 44 
 45 static int psci_boot_secondary(unsigned int cpu, struct task_struct *idle)
 46 {
 47         if (psci_ops.cpu_on)
 48                 return psci_ops.cpu_on(cpu_logical_map(cpu),
 49                                         virt_to_idmap(&secondary_startup));
 50         return -ENODEV;
 51 }
 52 
 53 #ifdef CONFIG_HOTPLUG_CPU
 54 int psci_cpu_disable(unsigned int cpu)
 55 {
 56         /* Fail early if we don't have CPU_OFF support */
 57         if (!psci_ops.cpu_off)
 58                 return -EOPNOTSUPP;
 59 
 60         /* Trusted OS will deny CPU_OFF */
 61         if (psci_tos_resident_on(cpu))
 62                 return -EPERM;
 63 
 64         return 0;
 65 }
 66 
 67 void psci_cpu_die(unsigned int cpu)
 68 {
 69         u32 state = PSCI_POWER_STATE_TYPE_POWER_DOWN <<
 70                     PSCI_0_2_POWER_STATE_TYPE_SHIFT;
 71 
 72         if (psci_ops.cpu_off)
 73                 psci_ops.cpu_off(state);
 74 
 75         /* We should never return */
 76         panic("psci: cpu %d failed to shutdown\n", cpu);
 77 }
 78 
 79 int psci_cpu_kill(unsigned int cpu)
 80 {
 81         int err, i;
 82 
 83         if (!psci_ops.affinity_info)
 84                 return 1;
 85         /*
 86          * cpu_kill could race with cpu_die and we can
 87          * potentially end up declaring this cpu undead
 88          * while it is dying. So, try again a few times.
 89          */
 90 
 91         for (i = 0; i < 10; i++) {
 92                 err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
 93                 if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) {
 94                         pr_info("CPU%d killed.\n", cpu);
 95                         return 1;
 96                 }
 97 
 98                 msleep(10);
 99                 pr_info("Retrying again to check for CPU kill\n");
100         }
101 
102         pr_warn("CPU%d may not have shut down cleanly (AFFINITY_INFO reports %d)\n",
103                         cpu, err);
104         /* Make platform_cpu_kill() fail. */
105         return 0;
106 }
107 
108 #endif
109 
110 bool __init psci_smp_available(void)
111 {
112         /* is cpu_on available at least? */
113         return (psci_ops.cpu_on != NULL);
114 }
115 
116 const struct smp_operations psci_smp_ops __initconst = {
117         .smp_boot_secondary     = psci_boot_secondary,
118 #ifdef CONFIG_HOTPLUG_CPU
119         .cpu_disable            = psci_cpu_disable,
120         .cpu_die                = psci_cpu_die,
121         .cpu_kill               = psci_cpu_kill,
122 #endif
123 };
124 

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