1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/arch/arm/mach-axxia/platsmp.c
4 *
5 * Copyright (C) 2012 LSI Corporation
6 */
7
8#include <linux/init.h>
9#include <linux/io.h>
10#include <linux/smp.h>
11#include <linux/of.h>
12#include <linux/of_address.h>
13#include <asm/cacheflush.h>
14
15/* Syscon register offsets for releasing cores from reset */
16#define SC_CRIT_WRITE_KEY 0x1000
17#define SC_RST_CPU_HOLD 0x1010
18
19/*
20 * Write the kernel entry point for secondary CPUs to the specified address
21 */
22static void write_release_addr(u32 release_phys)
23{
24 u32 *virt = (u32 *) phys_to_virt(address: release_phys);
25 writel_relaxed(__pa_symbol(secondary_startup), virt);
26 /* Make sure this store is visible to other CPUs */
27 smp_wmb();
28 __cpuc_flush_dcache_area(virt, sizeof(u32));
29}
30
31static int axxia_boot_secondary(unsigned int cpu, struct task_struct *idle)
32{
33 struct device_node *syscon_np;
34 void __iomem *syscon;
35 u32 tmp;
36
37 syscon_np = of_find_compatible_node(NULL, NULL, compat: "lsi,axxia-syscon");
38 if (!syscon_np)
39 return -ENOENT;
40
41 syscon = of_iomap(node: syscon_np, index: 0);
42 of_node_put(node: syscon_np);
43 if (!syscon)
44 return -ENOMEM;
45
46 tmp = readl(addr: syscon + SC_RST_CPU_HOLD);
47 writel(val: 0xab, addr: syscon + SC_CRIT_WRITE_KEY);
48 tmp &= ~(1 << cpu);
49 writel(val: tmp, addr: syscon + SC_RST_CPU_HOLD);
50
51 return 0;
52}
53
54static void __init axxia_smp_prepare_cpus(unsigned int max_cpus)
55{
56 int cpu_count = 0;
57 int cpu;
58
59 /*
60 * Initialise the present map, which describes the set of CPUs actually
61 * populated at the present time.
62 */
63 for_each_possible_cpu(cpu) {
64 struct device_node *np;
65 u32 release_phys;
66
67 np = of_get_cpu_node(cpu, NULL);
68 if (!np)
69 continue;
70 if (of_property_read_u32(np, propname: "cpu-release-addr", out_value: &release_phys))
71 continue;
72
73 if (cpu_count < max_cpus) {
74 set_cpu_present(cpu, present: true);
75 cpu_count++;
76 }
77
78 if (release_phys != 0)
79 write_release_addr(release_phys);
80 }
81}
82
83static const struct smp_operations axxia_smp_ops __initconst = {
84 .smp_prepare_cpus = axxia_smp_prepare_cpus,
85 .smp_boot_secondary = axxia_boot_secondary,
86};
87CPU_METHOD_OF_DECLARE(axxia_smp, "lsi,syscon-release", &axxia_smp_ops);
88

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