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 static phys_addr_t shmobile_scu_base_phys;
22 static void __iomem *shmobile_scu_base;
23 
24 static int shmobile_scu_cpu_prepare(unsigned int cpu)
25 {
26 	/* For this particular CPU register SCU SMP boot vector */
27 	shmobile_smp_hook(cpu, __pa_symbol(shmobile_boot_scu),
28 			  shmobile_scu_base_phys);
29 	return 0;
30 }
31 
32 void __init shmobile_smp_scu_prepare_cpus(phys_addr_t scu_base_phys,
33 					  unsigned int max_cpus)
34 {
35 	/* install boot code shared by all CPUs */
36 	shmobile_boot_fn = __pa_symbol(shmobile_smp_boot);
37 
38 	/* enable SCU and cache coherency on booting CPU */
39 	shmobile_scu_base_phys = scu_base_phys;
40 	shmobile_scu_base = ioremap(scu_base_phys, PAGE_SIZE);
41 	scu_enable(shmobile_scu_base);
42 	scu_power_mode(shmobile_scu_base, SCU_PM_NORMAL);
43 
44 	/* Use CPU notifier for reset vector control */
45 	cpuhp_setup_state_nocalls(CPUHP_ARM_SHMOBILE_SCU_PREPARE,
46 				  "arm/shmobile-scu:prepare",
47 				  shmobile_scu_cpu_prepare, NULL);
48 }
49 
50 #ifdef CONFIG_HOTPLUG_CPU
51 void shmobile_smp_scu_cpu_die(unsigned int cpu)
52 {
53 	/* For this particular CPU deregister boot vector */
54 	shmobile_smp_hook(cpu, 0, 0);
55 
56 	dsb();
57 	flush_cache_all();
58 
59 	/* disable cache coherency */
60 	scu_power_mode(shmobile_scu_base, SCU_PM_POWEROFF);
61 
62 	/* jump to shared mach-shmobile sleep / reset code */
63 	shmobile_smp_sleep();
64 }
65 
66 static int shmobile_smp_scu_psr_core_disabled(int cpu)
67 {
68 	unsigned long mask = SCU_PM_POWEROFF << (cpu * 8);
69 
70 	if ((__raw_readl(shmobile_scu_base + 8) & mask) == mask)
71 		return 1;
72 
73 	return 0;
74 }
75 
76 int shmobile_smp_scu_cpu_kill(unsigned int cpu)
77 {
78 	int k;
79 
80 	/* this function is running on another CPU than the offline target,
81 	 * here we need wait for shutdown code in platform_cpu_die() to
82 	 * finish before asking SoC-specific code to power off the CPU core.
83 	 */
84 	for (k = 0; k < 1000; k++) {
85 		if (shmobile_smp_scu_psr_core_disabled(cpu))
86 			return 1;
87 
88 		mdelay(1);
89 	}
90 
91 	return 0;
92 }
93 #endif
94