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
  13 #include <linux/threads.h>
  14 #include <linux/cpumask.h>
  15 #include <linux/string.h>
  16 #include <linux/kernel.h>
  17 #include <linux/ctype.h>
  18 #include <linux/errno.h>
  19 #include <asm/fixmap.h>
  20 #include <asm/mpspec.h>
  21 #include <asm/apicdef.h>
  22 #include <asm/apic.h>
  23 #include <asm/setup.h>
  24
  25 #include <linux/smp.h>
  26 #include <asm/ipi.h>
  27
  28 #include <linux/interrupt.h>
  29 #include <asm/acpi.h>
  30 #include <asm/e820/api.h>
  31
  32 static void noop_init_apic_ldr(void) { }
  33 static void noop_send_IPI(int cpu, int vector) { }
  34 static void noop_send_IPI_mask(const struct cpumask *cpumask, int vector) { }
  35 static void noop_send_IPI_mask_allbutself(const struct cpumask *cpumask, int vector) { }
  36 static void noop_send_IPI_allbutself(int vector) { }
  37 static void noop_send_IPI_all(int vector) { }
  38 static void noop_send_IPI_self(int vector) { }
  39 static void noop_apic_wait_icr_idle(void) { }
  40 static void noop_apic_icr_write(u32 low, u32 id) { }
  41
  42 static int noop_wakeup_secondary_cpu(int apicid, unsigned long start_eip)
  43 {
  44         return -1;
  45 }
  46
  47 static u32 noop_safe_apic_wait_icr_idle(void)
  48 {
  49         return 0;
  50 }
  51
  52 static u64 noop_apic_icr_read(void)
  53 {
  54         return 0;
  55 }
  56
  57 static int noop_phys_pkg_id(int cpuid_apic, int index_msb)
  58 {
  59         return 0;
  60 }
  61
  62 static unsigned int noop_get_apic_id(unsigned long x)
  63 {
  64         return 0;
  65 }
  66
  67 static int noop_probe(void)
  68 {
  69         /*
  70          * NOOP apic should not ever be
  71          * enabled via probe routine
  72          */
  73         return 0;
  74 }
  75
  76 static int noop_apic_id_registered(void)
  77 {
  78         /*
  79          * if we would be really "pedantic"
  80          * we should pass read_apic_id() here
  81          * but since NOOP suppose APIC ID = 0
  82          * lets save a few cycles
  83          */
  84         return physid_isset(0, phys_cpu_present_map);
  85 }
  86
  87 static u32 noop_apic_read(u32 reg)
  88 {
  89         WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_APIC) && !disable_apic);
  90         return 0;
  91 }
  92
  93 static void noop_apic_write(u32 reg, u32 v)
  94 {
  95         WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_APIC) && !disable_apic);
  96 }
  97
  98 #ifdef CONFIG_X86_32
  99 static int noop_x86_32_early_logical_apicid(int cpu)
 100 {
 101         return BAD_APICID;
 102 }
 103 #endif
 104
 105 struct apic apic_noop __ro_after_init = {
 106         .name                           = "noop",
 107         .probe                          = noop_probe,
 108         .acpi_madt_oem_check            = NULL,
 109
 110         .apic_id_valid                  = default_apic_id_valid,
 111         .apic_id_registered             = noop_apic_id_registered,
 112
 113         .irq_delivery_mode              = dest_LowestPrio,
 114         /* logical delivery broadcast to all CPUs: */
 115         .irq_dest_mode                  = 1,
 116
 117         .disable_esr                    = 0,
 118         .dest_logical                   = APIC_DEST_LOGICAL,
 119         .check_apicid_used              = default_check_apicid_used,
 120
 121         .init_apic_ldr                  = noop_init_apic_ldr,
 122
 123         .ioapic_phys_id_map             = default_ioapic_phys_id_map,
 124         .setup_apic_routing             = NULL,
 125
 126         .cpu_present_to_apicid          = default_cpu_present_to_apicid,
 127         .apicid_to_cpu_present          = physid_set_mask_of_physid,
 128
 129         .check_phys_apicid_present      = default_check_phys_apicid_present,
 130
 131         .phys_pkg_id                    = noop_phys_pkg_id,
 132
 133         .get_apic_id                    = noop_get_apic_id,
 134         .set_apic_id                    = NULL,
 135
 136         .calc_dest_apicid               = apic_flat_calc_apicid,
 137
 138         .send_IPI                       = noop_send_IPI,
 139         .send_IPI_mask                  = noop_send_IPI_mask,
 140         .send_IPI_mask_allbutself       = noop_send_IPI_mask_allbutself,
 141         .send_IPI_allbutself            = noop_send_IPI_allbutself,
 142         .send_IPI_all                   = noop_send_IPI_all,
 143         .send_IPI_self                  = noop_send_IPI_self,
 144
 145         .wakeup_secondary_cpu           = noop_wakeup_secondary_cpu,
 146
 147         .inquire_remote_apic            = NULL,
 148
 149         .read                           = noop_apic_read,
 150         .write                          = noop_apic_write,
 151         .eoi_write                      = noop_apic_write,
 152         .icr_read                       = noop_apic_icr_read,
 153         .icr_write                      = noop_apic_icr_write,
 154         .wait_icr_idle                  = noop_apic_wait_icr_idle,
 155         .safe_wait_icr_idle             = noop_safe_apic_wait_icr_idle,
 156
 157 #ifdef CONFIG_X86_32
 158         .x86_32_early_logical_apicid    = noop_x86_32_early_logical_apicid,
 159 #endif
 160 };