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 }; 75