1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * arch/arm/mach-sti/platsmp.c
4 *
5 * Copyright (C) 2013 STMicroelectronics (R&D) Limited.
6 * http://www.st.com
7 *
8 * Cloned from linux/arch/arm/mach-vexpress/platsmp.c
9 *
10 * Copyright (C) 2002 ARM Ltd.
11 * All Rights Reserved
12 */
13#include <linux/init.h>
14#include <linux/errno.h>
15#include <linux/delay.h>
16#include <linux/smp.h>
17#include <linux/io.h>
18#include <linux/of.h>
19#include <linux/of_address.h>
20#include <linux/memblock.h>
21
22#include <asm/cacheflush.h>
23#include <asm/smp_plat.h>
24#include <asm/smp_scu.h>
25
26#include "smp.h"
27
28static u32 __iomem *cpu_strt_ptr;
29
30static int sti_boot_secondary(unsigned int cpu, struct task_struct *idle)
31{
32 unsigned long entry_pa = __pa_symbol(secondary_startup);
33
34 /*
35 * Secondary CPU is initialised and started by a U-BOOTROM firmware.
36 * Secondary CPU is spinning and waiting for a write at cpu_strt_ptr.
37 * Writing secondary_startup address at cpu_strt_ptr makes it to
38 * jump directly to secondary_startup().
39 */
40 __raw_writel(val: entry_pa, addr: cpu_strt_ptr);
41
42 /* wmb so that data is actually written before cache flush is done */
43 smp_wmb();
44 sync_cache_w(cpu_strt_ptr);
45
46 return 0;
47}
48
49static void __init sti_smp_prepare_cpus(unsigned int max_cpus)
50{
51 struct device_node *np;
52 void __iomem *scu_base;
53 u32 release_phys;
54 int cpu;
55
56 np = of_find_compatible_node(NULL, NULL, compat: "arm,cortex-a9-scu");
57
58 if (np) {
59 scu_base = of_iomap(node: np, index: 0);
60 scu_enable(scu_base);
61 of_node_put(node: np);
62 }
63
64 if (max_cpus <= 1)
65 return;
66
67 for_each_possible_cpu(cpu) {
68
69 np = of_get_cpu_node(cpu, NULL);
70
71 if (!np)
72 continue;
73
74 if (of_property_read_u32(np, propname: "cpu-release-addr",
75 out_value: &release_phys)) {
76 pr_err("CPU %d: missing or invalid cpu-release-addr "
77 "property\n", cpu);
78 continue;
79 }
80
81 /*
82 * cpu-release-addr is usually configured in SBC DMEM but can
83 * also be in RAM.
84 */
85
86 if (!memblock_is_memory(addr: release_phys))
87 cpu_strt_ptr =
88 ioremap(offset: release_phys, size: sizeof(release_phys));
89 else
90 cpu_strt_ptr =
91 (u32 __iomem *)phys_to_virt(address: release_phys);
92
93 set_cpu_possible(cpu, possible: true);
94 }
95}
96
97const struct smp_operations sti_smp_ops __initconst = {
98 .smp_prepare_cpus = sti_smp_prepare_cpus,
99 .smp_boot_secondary = sti_boot_secondary,
100};
101

source code of linux/arch/arm/mach-sti/platsmp.c