arch/x86/kernel/apic/apic_noop.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * NOOP APIC driver.
   4  *
   5  * Does almost nothing and should be substituted by a real apic driver via
   6  * probe routine.
   7  *
   8  * Though in case if apic is disabled (for some reason) we try
   9  * to not uglify the caller's code and allow to call (some) apic routines
  10  * like self-ipi, etc...
  11  */
  12 #include <linux/cpumask.h>
  13
  14 #include <asm/apic.h>
  15
  16 static void noop_init_apic_ldr(void) { }
  17 static void noop_send_IPI(int cpu, int vector) { }
  18 static void noop_send_IPI_mask(const struct cpumask *cpumask, int vector) { }
  19 static void noop_send_IPI_mask_allbutself(const struct cpumask *cpumask, int vector) { }
  20 static void noop_send_IPI_allbutself(int vector) { }
  21 static void noop_send_IPI_all(int vector) { }
  22 static void noop_send_IPI_self(int vector) { }
  23 static void noop_apic_wait_icr_idle(void) { }
  24 static void noop_apic_icr_write(u32 low, u32 id) { }
  25
  26 static int noop_wakeup_secondary_cpu(int apicid, unsigned long start_eip)
  27 {
  28         return -1;
  29 }
  30
  31 static u32 noop_safe_apic_wait_icr_idle(void)
  32 {
  33         return 0;
  34 }
  35
  36 static u64 noop_apic_icr_read(void)
  37 {
  38         return 0;
  39 }
  40
  41 static int noop_phys_pkg_id(int cpuid_apic, int index_msb)
  42 {
  43         return 0;
  44 }
  45
  46 static unsigned int noop_get_apic_id(unsigned long x)
  47 {
  48         return 0;
  49 }
  50
  51 static int noop_probe(void)
  52 {
  53         /*
  54          * NOOP apic should not ever be
  55          * enabled via probe routine
  56          */
  57         return 0;
  58 }
  59
  60 static int noop_apic_id_registered(void)
  61 {
  62         /*
  63          * if we would be really "pedantic"
  64          * we should pass read_apic_id() here
  65          * but since NOOP suppose APIC ID = 0
  66          * lets save a few cycles
  67          */
  68         return physid_isset(0, phys_cpu_present_map);
  69 }
  70
  71 static u32 noop_apic_read(u32 reg)
  72 {
  73         WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_APIC) && !disable_apic);
  74         return 0;
  75 }
  76
  77 static void noop_apic_write(u32 reg, u32 v)
  78 {
  79         WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_APIC) && !disable_apic);
  80 }
  81
  82 #ifdef CONFIG_X86_32
  83 static int noop_x86_32_early_logical_apicid(int cpu)
  84 {
  85         return BAD_APICID;
  86 }
  87 #endif
  88
  89 struct apic apic_noop __ro_after_init = {
  90         .name                           = "noop",
  91         .probe                          = noop_probe,
  92         .acpi_madt_oem_check            = NULL,
  93
  94         .apic_id_valid                  = default_apic_id_valid,
  95         .apic_id_registered             = noop_apic_id_registered,
  96
  97         .irq_delivery_mode              = dest_Fixed,
  98         /* logical delivery broadcast to all CPUs: */
  99         .irq_dest_mode                  = 1,
 100
 101         .disable_esr                    = 0,
 102         .dest_logical                   = APIC_DEST_LOGICAL,
 103         .check_apicid_used              = default_check_apicid_used,
 104
 105         .init_apic_ldr                  = noop_init_apic_ldr,
 106
 107         .ioapic_phys_id_map             = default_ioapic_phys_id_map,
 108         .setup_apic_routing             = NULL,
 109
 110         .cpu_present_to_apicid          = default_cpu_present_to_apicid,
 111         .apicid_to_cpu_present          = physid_set_mask_of_physid,
 112
 113         .check_phys_apicid_present      = default_check_phys_apicid_present,
 114
 115         .phys_pkg_id                    = noop_phys_pkg_id,
 116
 117         .get_apic_id                    = noop_get_apic_id,
 118         .set_apic_id                    = NULL,
 119
 120         .calc_dest_apicid               = apic_flat_calc_apicid,
 121
 122         .send_IPI                       = noop_send_IPI,
 123         .send_IPI_mask                  = noop_send_IPI_mask,
 124         .send_IPI_mask_allbutself       = noop_send_IPI_mask_allbutself,
 125         .send_IPI_allbutself            = noop_send_IPI_allbutself,
 126         .send_IPI_all                   = noop_send_IPI_all,
 127         .send_IPI_self                  = noop_send_IPI_self,
 128
 129         .wakeup_secondary_cpu           = noop_wakeup_secondary_cpu,
 130
 131         .inquire_remote_apic            = NULL,
 132
 133         .read                           = noop_apic_read,
 134         .write                          = noop_apic_write,
 135         .eoi_write                      = noop_apic_write,
 136         .icr_read                       = noop_apic_icr_read,
 137         .icr_write                      = noop_apic_icr_write,
 138         .wait_icr_idle                  = noop_apic_wait_icr_idle,
 139         .safe_wait_icr_idle             = noop_safe_apic_wait_icr_idle,
 140
 141 #ifdef CONFIG_X86_32
 142         .x86_32_early_logical_apicid    = noop_x86_32_early_logical_apicid,
 143 #endif
 144 };