1 /* SPDX-License-Identifier: GPL-2.0-only */
2
3 #include <console/console.h>
4 #include <cpu/x86/lapic.h>
5 #include <delay.h>
6 #include <halt.h>
7 #include <stdint.h>
8
9 /**
10 * Sending INIT IPI to self is equivalent of asserting #INIT with a bit of
11 * delay.
12 * An undefined number of instruction cycles will complete. All global locks
13 * must be released before INIT IPI and no printk is allowed after this.
14 * De-asserting INIT IPI is a no-op on later Intel CPUs.
15 *
16 * If you set DEBUG_HALT_SELF to 1, printk's after INIT IPI are enabled
17 * but running thread may halt without releasing the lock and effectively
18 * deadlock other CPUs.
19 */
20 #define DEBUG_HALT_SELF 0
21
22 #if DEBUG_HALT_SELF
23 #define dprintk(LEVEL, args...) do { printk(LEVEL, ##args); } while (0)
24 #else
25 #define dprintk(LEVEL, args...) do { } while (0)
26 #endif
27
wait_for_ipi_completion_without_printk(const int timeout_ms)28 static void wait_for_ipi_completion_without_printk(const int timeout_ms)
29 {
30 int loops = timeout_ms * 10;
31 uint32_t send_status;
32
33 /* wait for the ipi send to finish */
34 dprintk(BIOS_SPEW, "Waiting for send to finish...\n");
35 do {
36 dprintk(BIOS_SPEW, "+");
37 udelay(100);
38 send_status = lapic_busy();
39 } while (send_status && (--loops > 0));
40
41 if (send_status)
42 dprintk(BIOS_ERR, "timed out\n");
43 }
44
45 /**
46 * Normally this function is defined in lapic.h as an always inline function
47 * that just keeps the CPU in a hlt() loop. This does not work on all CPUs.
48 * I think all hyperthreading CPUs might need this version, but I could only
49 * verify this on the Intel Core Duo
50 */
stop_this_cpu(void)51 void stop_this_cpu(void)
52 {
53 const int timeout_100ms = 100;
54 unsigned long id = lapicid();
55
56 printk(BIOS_DEBUG, "CPU %ld going down...\n", id);
57
58 /* send an LAPIC INIT to myself */
59 lapic_send_ipi_self(LAPIC_INT_LEVELTRIG | LAPIC_INT_ASSERT | LAPIC_DM_INIT);
60 wait_for_ipi_completion_without_printk(timeout_100ms);
61
62 mdelay(10);
63
64 dprintk(BIOS_SPEW, "Deasserting INIT.\n");
65
66 /* Deassert the LAPIC INIT */
67 lapic_send_ipi_self(LAPIC_INT_LEVELTRIG | LAPIC_DM_INIT);
68 wait_for_ipi_completion_without_printk(timeout_100ms);
69
70 halt();
71 }
72