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
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