1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Broadcom BCM63138 DSL SoCs SMP support code
4 *
5 * Copyright (C) 2015, Broadcom Corporation
6 */
7
8#include <linux/delay.h>
9#include <linux/init.h>
10#include <linux/smp.h>
11#include <linux/io.h>
12#include <linux/of.h>
13#include <linux/of_address.h>
14
15#include <asm/cacheflush.h>
16#include <asm/smp_scu.h>
17#include <asm/smp_plat.h>
18#include <asm/vfp.h>
19
20#include "bcm63xx_smp.h"
21
22/* Size of mapped Cortex A9 SCU address space */
23#define CORTEX_A9_SCU_SIZE 0x58
24
25/*
26 * Enable the Cortex A9 Snoop Control Unit
27 *
28 * By the time this is called we already know there are multiple
29 * cores present. We assume we're running on a Cortex A9 processor,
30 * so any trouble getting the base address register or getting the
31 * SCU base is a problem.
32 *
33 * Return 0 if successful or an error code otherwise.
34 */
35static int __init scu_a9_enable(void)
36{
37 unsigned long config_base;
38 void __iomem *scu_base;
39 unsigned int i, ncores;
40
41 if (!scu_a9_has_base()) {
42 pr_err("no configuration base address register!\n");
43 return -ENXIO;
44 }
45
46 /* Config base address register value is zero for uniprocessor */
47 config_base = scu_a9_get_base();
48 if (!config_base) {
49 pr_err("hardware reports only one core\n");
50 return -ENOENT;
51 }
52
53 scu_base = ioremap(offset: (phys_addr_t)config_base, CORTEX_A9_SCU_SIZE);
54 if (!scu_base) {
55 pr_err("failed to remap config base (%lu/%u) for SCU\n",
56 config_base, CORTEX_A9_SCU_SIZE);
57 return -ENOMEM;
58 }
59
60 scu_enable(scu_base);
61
62 ncores = scu_base ? scu_get_core_count(scu_base) : 1;
63
64 if (ncores > nr_cpu_ids) {
65 pr_warn("SMP: %u cores greater than maximum (%u), clipping\n",
66 ncores, nr_cpu_ids);
67 ncores = nr_cpu_ids;
68 }
69
70 /* The BCM63138 SoC has two Cortex-A9 CPUs, CPU0 features a complete
71 * and fully functional VFP unit that can be used, but CPU1 does not.
72 * Since we will not be able to trap kernel-mode NEON to force
73 * migration to CPU0, just do not advertise VFP support at all.
74 *
75 * This will make vfp_init bail out and do not attempt to use VFP at
76 * all, for kernel-mode NEON, we do not want to introduce any
77 * conditionals in hot-paths, so we just restrict the system to UP.
78 */
79#ifdef CONFIG_VFP
80 if (ncores > 1) {
81 pr_warn("SMP: secondary CPUs lack VFP unit, disabling VFP\n");
82 vfp_disable();
83
84#ifdef CONFIG_KERNEL_MODE_NEON
85 WARN(1, "SMP: kernel-mode NEON enabled, restricting to UP\n");
86 ncores = 1;
87#endif
88 }
89#endif
90
91 for (i = 0; i < ncores; i++)
92 set_cpu_possible(cpu: i, possible: true);
93
94 iounmap(addr: scu_base); /* That's the last we'll need of this */
95
96 return 0;
97}
98
99static const struct of_device_id bcm63138_bootlut_ids[] = {
100 { .compatible = "brcm,bcm63138-bootlut", },
101 { /* sentinel */ },
102};
103
104#define BOOTLUT_RESET_VECT 0x20
105
106static int bcm63138_smp_boot_secondary(unsigned int cpu,
107 struct task_struct *idle)
108{
109 void __iomem *bootlut_base;
110 struct device_node *dn;
111 int ret = 0;
112 u32 val;
113
114 dn = of_find_matching_node(NULL, matches: bcm63138_bootlut_ids);
115 if (!dn) {
116 pr_err("SMP: unable to find bcm63138 boot LUT node\n");
117 return -ENODEV;
118 }
119
120 bootlut_base = of_iomap(node: dn, index: 0);
121 of_node_put(node: dn);
122
123 if (!bootlut_base) {
124 pr_err("SMP: unable to remap boot LUT base register\n");
125 return -ENOMEM;
126 }
127
128 /* Locate the secondary CPU node */
129 dn = of_get_cpu_node(cpu, NULL);
130 if (!dn) {
131 pr_err("SMP: failed to locate secondary CPU%d node\n", cpu);
132 ret = -ENODEV;
133 goto out;
134 }
135
136 /* Write the secondary init routine to the BootLUT reset vector */
137 val = __pa_symbol(secondary_startup);
138 writel_relaxed(val, bootlut_base + BOOTLUT_RESET_VECT);
139
140 /* Power up the core, will jump straight to its reset vector when we
141 * return
142 */
143 ret = bcm63xx_pmb_power_on_cpu(dn);
144 of_node_put(node: dn);
145
146out:
147 iounmap(addr: bootlut_base);
148
149 return ret;
150}
151
152static void __init bcm63138_smp_prepare_cpus(unsigned int max_cpus)
153{
154 int ret;
155
156 ret = scu_a9_enable();
157 if (ret) {
158 pr_warn("SMP: Cortex-A9 SCU setup failed\n");
159 return;
160 }
161}
162
163static const struct smp_operations bcm63138_smp_ops __initconst = {
164 .smp_prepare_cpus = bcm63138_smp_prepare_cpus,
165 .smp_boot_secondary = bcm63138_smp_boot_secondary,
166};
167
168CPU_METHOD_OF_DECLARE(bcm63138_smp, "brcm,bcm63138", &bcm63138_smp_ops);
169

source code of linux/arch/arm/mach-bcm/bcm63xx_smp.c