1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * linux/arch/arm/mach-spear13xx/hotplug.c
4 *
5 * Copyright (C) 2012 ST Microelectronics Ltd.
6 * Deepak Sikri <deepak.sikri@st.com>
7 *
8 * based upon linux/arch/arm/mach-realview/hotplug.c
9 */
10 #include <linux/kernel.h>
11 #include <linux/errno.h>
12 #include <linux/smp.h>
13 #include <asm/cp15.h>
14 #include <asm/smp_plat.h>
15
16 #include "generic.h"
17
18 static inline void cpu_enter_lowpower(void)
19 {
20 unsigned int v;
21
22 asm volatile(
23 " mcr p15, 0, %1, c7, c5, 0\n"
24 " dsb\n"
25 /*
26 * Turn off coherency
27 */
28 " mrc p15, 0, %0, c1, c0, 1\n"
29 " bic %0, %0, #0x20\n"
30 " mcr p15, 0, %0, c1, c0, 1\n"
31 " mrc p15, 0, %0, c1, c0, 0\n"
32 " bic %0, %0, %2\n"
33 " mcr p15, 0, %0, c1, c0, 0\n"
34 : "=&r" (v)
35 : "r" (0), "Ir" (CR_C)
36 : "cc", "memory");
37 }
38
39 static inline void cpu_leave_lowpower(void)
40 {
41 unsigned int v;
42
43 asm volatile("mrc p15, 0, %0, c1, c0, 0\n"
44 " orr %0, %0, %1\n"
45 " mcr p15, 0, %0, c1, c0, 0\n"
46 " mrc p15, 0, %0, c1, c0, 1\n"
47 " orr %0, %0, #0x20\n"
48 " mcr p15, 0, %0, c1, c0, 1\n"
49 : "=&r" (v)
50 : "Ir" (CR_C)
51 : "cc");
52 }
53
54 static inline void spear13xx_do_lowpower(unsigned int cpu, int *spurious)
55 {
56 for (;;) {
57 wfi();
58
59 if (spear_pen_release == cpu) {
60 /*
61 * OK, proper wakeup, we're done
62 */
63 break;
64 }
65
66 /*
67 * Getting here, means that we have come out of WFI without
68 * having been woken up - this shouldn't happen
69 *
70 * Just note it happening - when we're woken, we can report
71 * its occurrence.
72 */
73 (*spurious)++;
74 }
75 }
76
77 /*
78 * platform-specific code to shutdown a CPU
79 *
80 * Called with IRQs disabled
81 */
82 void spear13xx_cpu_die(unsigned int cpu)
83 {
84 int spurious = 0;
85
86 /*
87 * we're ready for shutdown now, so do it
88 */
89 cpu_enter_lowpower();
90 spear13xx_do_lowpower(cpu, &spurious);
91
92 /*
93 * bring this CPU back into the world of cache
94 * coherency, and then restore interrupts
95 */
96 cpu_leave_lowpower();
97
98 if (spurious)
99 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
100 }