1 /*
2  * SMP support for SoCs with SCU covered by mach-shmobile
3  *
4  * Copyright (C) 2013  Magnus Damm
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10 #include <linux/cpu.h>
11 #include <linux/delay.h>
12 #include <linux/init.h>
13 #include <linux/io.h>
14 #include <linux/smp.h>
15 #include <asm/cacheflush.h>
16 #include <asm/smp_plat.h>
17 #include <asm/smp_scu.h>
18 #include "common.h"
19 
20 
21 void __iomem *shmobile_scu_base;
22 
23 static int shmobile_smp_scu_notifier_call(struct notifier_block *nfb,
24 					  unsigned long action, void *hcpu)
25 {
26 	unsigned int cpu = (long)hcpu;
27 
28 	switch (action) {
29 	case CPU_UP_PREPARE:
30 		/* For this particular CPU register SCU SMP boot vector */
31 		shmobile_smp_hook(cpu, virt_to_phys(shmobile_boot_scu),
32 				  (unsigned long)shmobile_scu_base);
33 		break;
34 	};
35 
36 	return NOTIFY_OK;
37 }
38 
39 static struct notifier_block shmobile_smp_scu_notifier = {
40 	.notifier_call = shmobile_smp_scu_notifier_call,
41 };
42 
43 void __init shmobile_smp_scu_prepare_cpus(unsigned int max_cpus)
44 {
45 	/* install boot code shared by all CPUs */
46 	shmobile_boot_fn = virt_to_phys(shmobile_smp_boot);
47 
48 	/* enable SCU and cache coherency on booting CPU */
49 	scu_enable(shmobile_scu_base);
50 	scu_power_mode(shmobile_scu_base, SCU_PM_NORMAL);
51 
52 	/* Use CPU notifier for reset vector control */
53 	register_cpu_notifier(&shmobile_smp_scu_notifier);
54 }
55 
56 #ifdef CONFIG_HOTPLUG_CPU
57 void shmobile_smp_scu_cpu_die(unsigned int cpu)
58 {
59 	/* For this particular CPU deregister boot vector */
60 	shmobile_smp_hook(cpu, 0, 0);
61 
62 	dsb();
63 	flush_cache_all();
64 
65 	/* disable cache coherency */
66 	scu_power_mode(shmobile_scu_base, SCU_PM_POWEROFF);
67 
68 	/* jump to shared mach-shmobile sleep / reset code */
69 	shmobile_smp_sleep();
70 }
71 
72 static int shmobile_smp_scu_psr_core_disabled(int cpu)
73 {
74 	unsigned long mask = SCU_PM_POWEROFF << (cpu * 8);
75 
76 	if ((__raw_readl(shmobile_scu_base + 8) & mask) == mask)
77 		return 1;
78 
79 	return 0;
80 }
81 
82 int shmobile_smp_scu_cpu_kill(unsigned int cpu)
83 {
84 	int k;
85 
86 	/* this function is running on another CPU than the offline target,
87 	 * here we need wait for shutdown code in platform_cpu_die() to
88 	 * finish before asking SoC-specific code to power off the CPU core.
89 	 */
90 	for (k = 0; k < 1000; k++) {
91 		if (shmobile_smp_scu_psr_core_disabled(cpu))
92 			return 1;
93 
94 		mdelay(1);
95 	}
96 
97 	return 0;
98 }
99 #endif
100