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((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(i, true);
93
94	iounmap(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, 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(dn, 0);
121	of_node_put(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(dn);
145
146out:
147	iounmap(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