1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * SMP support for SoCs with SCU covered by mach-shmobile
4  *
5  * Copyright (C) 2013  Magnus Damm
6  */
7 #include <linux/cpu.h>
8 #include <linux/delay.h>
9 #include <linux/init.h>
10 #include <linux/io.h>
11 #include <linux/smp.h>
12 #include <asm/cacheflush.h>
13 #include <asm/smp_plat.h>
14 #include <asm/smp_scu.h>
15 #include "common.h"
16 
17 
18 static phys_addr_t shmobile_scu_base_phys;
19 static void __iomem *shmobile_scu_base;
20 
21 static int shmobile_scu_cpu_prepare(unsigned int cpu)
22 {
23 	/* For this particular CPU register SCU SMP boot vector */
24 	shmobile_smp_hook(cpu, __pa_symbol(shmobile_boot_scu),
25 			  shmobile_scu_base_phys);
26 	return 0;
27 }
28 
29 void __init shmobile_smp_scu_prepare_cpus(phys_addr_t scu_base_phys,
30 					  unsigned int max_cpus)
31 {
32 	/* install boot code shared by all CPUs */
33 	shmobile_boot_fn = __pa_symbol(shmobile_smp_boot);
34 
35 	/* enable SCU and cache coherency on booting CPU */
36 	shmobile_scu_base_phys = scu_base_phys;
37 	shmobile_scu_base = ioremap(scu_base_phys, PAGE_SIZE);
38 	scu_enable(shmobile_scu_base);
39 	scu_power_mode(shmobile_scu_base, SCU_PM_NORMAL);
40 
41 	/* Use CPU notifier for reset vector control */
42 	cpuhp_setup_state_nocalls(CPUHP_ARM_SHMOBILE_SCU_PREPARE,
43 				  "arm/shmobile-scu:prepare",
44 				  shmobile_scu_cpu_prepare, NULL);
45 }
46 
47 #ifdef CONFIG_HOTPLUG_CPU
48 void shmobile_smp_scu_cpu_die(unsigned int cpu)
49 {
50 	/* For this particular CPU deregister boot vector */
51 	shmobile_smp_hook(cpu, 0, 0);
52 
53 	dsb();
54 	flush_cache_all();
55 
56 	/* disable cache coherency */
57 	scu_power_mode(shmobile_scu_base, SCU_PM_POWEROFF);
58 
59 	/* jump to shared mach-shmobile sleep / reset code */
60 	shmobile_smp_sleep();
61 }
62 
63 static int shmobile_smp_scu_psr_core_disabled(int cpu)
64 {
65 	unsigned long mask = SCU_PM_POWEROFF << (cpu * 8);
66 
67 	if ((readl(shmobile_scu_base + 8) & mask) == mask)
68 		return 1;
69 
70 	return 0;
71 }
72 
73 int shmobile_smp_scu_cpu_kill(unsigned int cpu)
74 {
75 	int k;
76 
77 	/* this function is running on another CPU than the offline target,
78 	 * here we need wait for shutdown code in platform_cpu_die() to
79 	 * finish before asking SoC-specific code to power off the CPU core.
80 	 */
81 	for (k = 0; k < 1000; k++) {
82 		if (shmobile_smp_scu_psr_core_disabled(cpu))
83 			return 1;
84 
85 		mdelay(1);
86 	}
87 
88 	return 0;
89 }
90 #endif
91