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
18static 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
39static 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
54static 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 */
82void 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}
101