xref: /openbmc/linux/arch/arm/mach-sti/platsmp.c (revision ccb01374)
1 /*
2  *  arch/arm/mach-sti/platsmp.c
3  *
4  * Copyright (C) 2013 STMicroelectronics (R&D) Limited.
5  *		http://www.st.com
6  *
7  * Cloned from linux/arch/arm/mach-vexpress/platsmp.c
8  *
9  *  Copyright (C) 2002 ARM Ltd.
10  *  All Rights Reserved
11  *
12  * This program is free software; you can redistribute it and/or modify
13  * it under the terms of the GNU General Public License version 2 as
14  * published by the Free Software Foundation.
15  */
16 #include <linux/init.h>
17 #include <linux/errno.h>
18 #include <linux/delay.h>
19 #include <linux/smp.h>
20 #include <linux/io.h>
21 #include <linux/of.h>
22 #include <linux/of_address.h>
23 #include <linux/memblock.h>
24 
25 #include <asm/cacheflush.h>
26 #include <asm/smp_plat.h>
27 #include <asm/smp_scu.h>
28 
29 #include "smp.h"
30 
31 static u32 __iomem *cpu_strt_ptr;
32 
33 static int sti_boot_secondary(unsigned int cpu, struct task_struct *idle)
34 {
35 	unsigned long entry_pa = __pa_symbol(secondary_startup);
36 
37 	/*
38 	 * Secondary CPU is initialised and started by a U-BOOTROM firmware.
39 	 * Secondary CPU is spinning and waiting for a write at cpu_strt_ptr.
40 	 * Writing secondary_startup address at cpu_strt_ptr makes it to
41 	 * jump directly to secondary_startup().
42 	 */
43 	__raw_writel(entry_pa, cpu_strt_ptr);
44 
45 	/* wmb so that data is actually written before cache flush is done */
46 	smp_wmb();
47 	sync_cache_w(cpu_strt_ptr);
48 
49 	return 0;
50 }
51 
52 static void __init sti_smp_prepare_cpus(unsigned int max_cpus)
53 {
54 	struct device_node *np;
55 	void __iomem *scu_base;
56 	u32 release_phys;
57 	int cpu;
58 
59 	np = of_find_compatible_node(NULL, NULL, "arm,cortex-a9-scu");
60 
61 	if (np) {
62 		scu_base = of_iomap(np, 0);
63 		scu_enable(scu_base);
64 		of_node_put(np);
65 	}
66 
67 	if (max_cpus <= 1)
68 		return;
69 
70 	for_each_possible_cpu(cpu) {
71 
72 		np = of_get_cpu_node(cpu, NULL);
73 
74 		if (!np)
75 			continue;
76 
77 		if (of_property_read_u32(np, "cpu-release-addr",
78 						&release_phys)) {
79 			pr_err("CPU %d: missing or invalid cpu-release-addr "
80 				"property\n", cpu);
81 			continue;
82 		}
83 
84 		/*
85 		 * cpu-release-addr is usually configured in SBC DMEM but can
86 		 * also be in RAM.
87 		 */
88 
89 		if (!memblock_is_memory(release_phys))
90 			cpu_strt_ptr =
91 				ioremap(release_phys, sizeof(release_phys));
92 		else
93 			cpu_strt_ptr =
94 				(u32 __iomem *)phys_to_virt(release_phys);
95 
96 		set_cpu_possible(cpu, true);
97 	}
98 }
99 
100 const struct smp_operations sti_smp_ops __initconst = {
101 	.smp_prepare_cpus	= sti_smp_prepare_cpus,
102 	.smp_boot_secondary	= sti_boot_secondary,
103 };
104