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