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
23static void noop_send_IPI(int cpu, int vector) { }
24static void noop_send_IPI_mask(const struct cpumask *cpumask, int vector) { }
25static void noop_send_IPI_mask_allbutself(const struct cpumask *cpumask, int vector) { }
26static void noop_send_IPI_allbutself(int vector) { }
27static void noop_send_IPI_all(int vector) { }
28static void noop_send_IPI_self(int vector) { }
29static void noop_apic_icr_write(u32 low, u32 id) { }
30
31static int noop_wakeup_secondary_cpu(u32 apicid, unsigned long start_eip,
32	unsigned int cpu)
33{
34	return -1;
35}
36
37static u64 noop_apic_icr_read(void) { return 0; }
38static u32 noop_get_apic_id(u32 apicid) { return 0; }
39static void noop_apic_eoi(void) { }
40
41static u32 noop_apic_read(u32 reg)
42{
43	WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_APIC) && !apic_is_disabled);
44	return 0;
45}
46
47static void noop_apic_write(u32 reg, u32 val)
48{
49	WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_APIC) && !apic_is_disabled);
50}
51
52struct apic apic_noop __ro_after_init = {
53	.name				= "noop",
54
55	.dest_mode_logical		= true,
56
57	.disable_esr			= 0,
58
59	.cpu_present_to_apicid		= default_cpu_present_to_apicid,
60
61	.max_apic_id			= 0xFE,
62	.get_apic_id			= noop_get_apic_id,
63
64	.calc_dest_apicid		= apic_flat_calc_apicid,
65
66	.send_IPI			= noop_send_IPI,
67	.send_IPI_mask			= noop_send_IPI_mask,
68	.send_IPI_mask_allbutself	= noop_send_IPI_mask_allbutself,
69	.send_IPI_allbutself		= noop_send_IPI_allbutself,
70	.send_IPI_all			= noop_send_IPI_all,
71	.send_IPI_self			= noop_send_IPI_self,
72
73	.wakeup_secondary_cpu		= noop_wakeup_secondary_cpu,
74
75	.read				= noop_apic_read,
76	.write				= noop_apic_write,
77	.eoi				= noop_apic_eoi,
78	.icr_read			= noop_apic_icr_read,
79	.icr_write			= noop_apic_icr_write,
80};