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  * FIXME: Remove this gunk. The above argument which was intentionally left
  13  * in place is silly to begin with because none of the callbacks except for
  14  * APIC::read/write() have a WARN_ON_ONCE() in them. Sigh...
  15  */
  16 #include <linux/cpumask.h>
  17 #include <linux/thread_info.h>
  18
  19 #include <asm/apic.h>
  20
  21 #include "local.h"
  22
  23 static void noop_send_IPI(int cpu, int vector) { }
  24 static void noop_send_IPI_mask(const struct cpumask *cpumask, int vector) { }
  25 static void noop_send_IPI_mask_allbutself(const struct cpumask *cpumask, int vector) { }
  26 static void noop_send_IPI_allbutself(int vector) { }
  27 static void noop_send_IPI_all(int vector) { }
  28 static void noop_send_IPI_self(int vector) { }
  29 static void noop_apic_icr_write(u32 low, u32 id) { }
  30 static int noop_wakeup_secondary_cpu(u32 apicid, unsigned long start_eip) { return -1; }
  31 static u64 noop_apic_icr_read(void) { return 0; }
  32 static u32 noop_get_apic_id(u32 apicid) { return 0; }
  33 static void noop_apic_eoi(void) { }
  34
  35 static u32 noop_apic_read(u32 reg)
  36 {
  37         WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_APIC) && !apic_is_disabled);
  38         return 0;
  39 }
  40
  41 static void noop_apic_write(u32 reg, u32 val)
  42 {
  43         WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_APIC) && !apic_is_disabled);
  44 }
  45
  46 struct apic apic_noop __ro_after_init = {
  47         .name                           = "noop",
  48
  49         .dest_mode_logical              = true,
  50
  51         .disable_esr                    = 0,
  52
  53         .cpu_present_to_apicid          = default_cpu_present_to_apicid,
  54
  55         .max_apic_id                    = 0xFE,
  56         .get_apic_id                    = noop_get_apic_id,
  57
  58         .calc_dest_apicid               = apic_flat_calc_apicid,
  59
  60         .send_IPI                       = noop_send_IPI,
  61         .send_IPI_mask                  = noop_send_IPI_mask,
  62         .send_IPI_mask_allbutself       = noop_send_IPI_mask_allbutself,
  63         .send_IPI_allbutself            = noop_send_IPI_allbutself,
  64         .send_IPI_all                   = noop_send_IPI_all,
  65         .send_IPI_self                  = noop_send_IPI_self,
  66
  67         .wakeup_secondary_cpu           = noop_wakeup_secondary_cpu,
  68
  69         .read                           = noop_apic_read,
  70         .write                          = noop_apic_write,
  71         .eoi                            = noop_apic_eoi,
  72         .icr_read                       = noop_apic_icr_read,
  73         .icr_write                      = noop_apic_icr_write,
  74 };