1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Spin Table SMP initialisation
4 *
5 * Copyright (C) 2013 ARM Ltd.
6 */
7
8 #include <linux/delay.h>
9 #include <linux/init.h>
10 #include <linux/of.h>
11 #include <linux/smp.h>
12 #include <linux/types.h>
13 #include <linux/mm.h>
14
15 #include <asm/cacheflush.h>
16 #include <asm/cpu_ops.h>
17 #include <asm/cputype.h>
18 #include <asm/io.h>
19 #include <asm/smp_plat.h>
20
21 extern void secondary_holding_pen(void);
22 volatile unsigned long __section(".mmuoff.data.read")
23 secondary_holding_pen_release = INVALID_HWID;
24
25 static phys_addr_t cpu_release_addr[NR_CPUS];
26
27 /*
28 * Write secondary_holding_pen_release in a way that is guaranteed to be
29 * visible to all observers, irrespective of whether they're taking part
30 * in coherency or not. This is necessary for the hotplug code to work
31 * reliably.
32 */
write_pen_release(u64 val)33 static void write_pen_release(u64 val)
34 {
35 void *start = (void *)&secondary_holding_pen_release;
36 unsigned long size = sizeof(secondary_holding_pen_release);
37
38 secondary_holding_pen_release = val;
39 __flush_dcache_area(start, size);
40 }
41
42
smp_spin_table_cpu_init(unsigned int cpu)43 static int smp_spin_table_cpu_init(unsigned int cpu)
44 {
45 struct device_node *dn;
46 int ret;
47
48 dn = of_get_cpu_node(cpu, NULL);
49 if (!dn)
50 return -ENODEV;
51
52 /*
53 * Determine the address from which the CPU is polling.
54 */
55 ret = of_property_read_u64(dn, "cpu-release-addr",
56 &cpu_release_addr[cpu]);
57 if (ret)
58 pr_err("CPU %d: missing or invalid cpu-release-addr property\n",
59 cpu);
60
61 of_node_put(dn);
62
63 return ret;
64 }
65
smp_spin_table_cpu_prepare(unsigned int cpu)66 static int smp_spin_table_cpu_prepare(unsigned int cpu)
67 {
68 __le64 __iomem *release_addr;
69 phys_addr_t pa_holding_pen = __pa_symbol(function_nocfi(secondary_holding_pen));
70
71 if (!cpu_release_addr[cpu])
72 return -ENODEV;
73
74 /*
75 * The cpu-release-addr may or may not be inside the linear mapping.
76 * As ioremap_cache will either give us a new mapping or reuse the
77 * existing linear mapping, we can use it to cover both cases. In
78 * either case the memory will be MT_NORMAL.
79 */
80 release_addr = ioremap_cache(cpu_release_addr[cpu],
81 sizeof(*release_addr));
82 if (!release_addr)
83 return -ENOMEM;
84
85 /*
86 * We write the release address as LE regardless of the native
87 * endianness of the kernel. Therefore, any boot-loaders that
88 * read this address need to convert this address to the
89 * boot-loader's endianness before jumping. This is mandated by
90 * the boot protocol.
91 */
92 writeq_relaxed(pa_holding_pen, release_addr);
93 __flush_dcache_area((__force void *)release_addr,
94 sizeof(*release_addr));
95
96 /*
97 * Send an event to wake up the secondary CPU.
98 */
99 sev();
100
101 iounmap(release_addr);
102
103 return 0;
104 }
105
smp_spin_table_cpu_boot(unsigned int cpu)106 static int smp_spin_table_cpu_boot(unsigned int cpu)
107 {
108 /*
109 * Update the pen release flag.
110 */
111 write_pen_release(cpu_logical_map(cpu));
112
113 /*
114 * Send an event, causing the secondaries to read pen_release.
115 */
116 sev();
117
118 return 0;
119 }
120
121 const struct cpu_operations smp_spin_table_ops = {
122 .name = "spin-table",
123 .cpu_init = smp_spin_table_cpu_init,
124 .cpu_prepare = smp_spin_table_cpu_prepare,
125 .cpu_boot = smp_spin_table_cpu_boot,
126 };
127