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  */
scu_a9_enable(void)35 static 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 
99 static const struct of_device_id bcm63138_bootlut_ids[] = {
100 	{ .compatible = "brcm,bcm63138-bootlut", },
101 	{ /* sentinel */ },
102 };
103 
104 #define BOOTLUT_RESET_VECT	0x20
105 
bcm63138_smp_boot_secondary(unsigned int cpu,struct task_struct * idle)106 static 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 
146 out:
147 	iounmap(bootlut_base);
148 
149 	return ret;
150 }
151 
bcm63138_smp_prepare_cpus(unsigned int max_cpus)152 static 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 
163 static 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 
168 CPU_METHOD_OF_DECLARE(bcm63138_smp, "brcm,bcm63138", &bcm63138_smp_ops);
169