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 */
22 static void write_release_addr(u32 release_phys)
23 {
24 u32 *virt = (u32 *) phys_to_virt(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
31 static 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, "lsi,axxia-syscon");
38 if (!syscon_np)
39 return -ENOENT;
40
41 syscon = of_iomap(syscon_np, 0);
42 of_node_put(syscon_np);
43 if (!syscon)
44 return -ENOMEM;
45
46 tmp = readl(syscon + SC_RST_CPU_HOLD);
47 writel(0xab, syscon + SC_CRIT_WRITE_KEY);
48 tmp &= ~(1 << cpu);
49 writel(tmp, syscon + SC_RST_CPU_HOLD);
50
51 return 0;
52 }
53
54 static 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, "cpu-release-addr", &release_phys))
71 continue;
72
73 if (cpu_count < max_cpus) {
74 set_cpu_present(cpu, true);
75 cpu_count++;
76 }
77
78 if (release_phys != 0)
79 write_release_addr(release_phys);
80 }
81 }
82
83 static const struct smp_operations axxia_smp_ops __initconst = {
84 .smp_prepare_cpus = axxia_smp_prepare_cpus,
85 .smp_boot_secondary = axxia_boot_secondary,
86 };
87 CPU_METHOD_OF_DECLARE(axxia_smp, "lsi,syscon-release", &axxia_smp_ops);
88
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