xref: /openbmc/linux/arch/arm/mach-mvebu/platsmp-a9.c (revision c819e2cf)
1 /*
2  * Symmetric Multi Processing (SMP) support for Marvell EBU Cortex-A9
3  * based SOCs (Armada 375/38x).
4  *
5  * Copyright (C) 2014 Marvell
6  *
7  * Gregory CLEMENT <gregory.clement@free-electrons.com>
8  * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
9  *
10  * This file is licensed under the terms of the GNU General Public
11  * License version 2.  This program is licensed "as is" without any
12  * warranty of any kind, whether express or implied.
13  */
14 
15 #include <linux/init.h>
16 #include <linux/io.h>
17 #include <linux/of.h>
18 #include <linux/smp.h>
19 #include <linux/mbus.h>
20 #include <asm/smp_scu.h>
21 #include <asm/smp_plat.h>
22 #include "common.h"
23 #include "pmsu.h"
24 
25 extern void mvebu_cortex_a9_secondary_startup(void);
26 
27 static int __cpuinit mvebu_cortex_a9_boot_secondary(unsigned int cpu,
28 						    struct task_struct *idle)
29 {
30 	int ret, hw_cpu;
31 
32 	pr_info("Booting CPU %d\n", cpu);
33 
34 	/*
35 	 * Write the address of secondary startup into the system-wide
36 	 * flags register. The boot monitor waits until it receives a
37 	 * soft interrupt, and then the secondary CPU branches to this
38 	 * address.
39 	 */
40 	hw_cpu = cpu_logical_map(cpu);
41 	if (of_machine_is_compatible("marvell,armada375"))
42 		mvebu_system_controller_set_cpu_boot_addr(mvebu_cortex_a9_secondary_startup);
43 	else
44 		mvebu_pmsu_set_cpu_boot_addr(hw_cpu, mvebu_cortex_a9_secondary_startup);
45 	smp_wmb();
46 
47 	/*
48 	 * Doing this before deasserting the CPUs is needed to wake up CPUs
49 	 * in the offline state after using CPU hotplug.
50 	 */
51 	arch_send_wakeup_ipi_mask(cpumask_of(cpu));
52 
53 	ret = mvebu_cpu_reset_deassert(hw_cpu);
54 	if (ret) {
55 		pr_err("Could not start the secondary CPU: %d\n", ret);
56 		return ret;
57 	}
58 
59 	return 0;
60 }
61 /*
62  * When a CPU is brought back online, either through CPU hotplug, or
63  * because of the boot of a kexec'ed kernel, the PMSU configuration
64  * for this CPU might be in the deep idle state, preventing this CPU
65  * from receiving interrupts. Here, we therefore take out the current
66  * CPU from this state, which was entered by armada_38x_cpu_die()
67  * below.
68  */
69 static void armada_38x_secondary_init(unsigned int cpu)
70 {
71 	mvebu_v7_pmsu_idle_exit();
72 }
73 
74 #ifdef CONFIG_HOTPLUG_CPU
75 static void armada_38x_cpu_die(unsigned int cpu)
76 {
77 	/*
78 	 * CPU hotplug is implemented by putting offline CPUs into the
79 	 * deep idle sleep state.
80 	 */
81 	armada_38x_do_cpu_suspend(true);
82 }
83 
84 /*
85  * We need a dummy function, so that platform_can_cpu_hotplug() knows
86  * we support CPU hotplug. However, the function does not need to do
87  * anything, because CPUs going offline can enter the deep idle state
88  * by themselves, without any help from a still alive CPU.
89  */
90 static int armada_38x_cpu_kill(unsigned int cpu)
91 {
92 	return 1;
93 }
94 #endif
95 
96 static struct smp_operations mvebu_cortex_a9_smp_ops __initdata = {
97 	.smp_boot_secondary	= mvebu_cortex_a9_boot_secondary,
98 };
99 
100 static struct smp_operations armada_38x_smp_ops __initdata = {
101 	.smp_boot_secondary	= mvebu_cortex_a9_boot_secondary,
102 	.smp_secondary_init     = armada_38x_secondary_init,
103 #ifdef CONFIG_HOTPLUG_CPU
104 	.cpu_die		= armada_38x_cpu_die,
105 	.cpu_kill               = armada_38x_cpu_kill,
106 #endif
107 };
108 
109 CPU_METHOD_OF_DECLARE(mvebu_armada_375_smp, "marvell,armada-375-smp",
110 		      &mvebu_cortex_a9_smp_ops);
111 CPU_METHOD_OF_DECLARE(mvebu_armada_380_smp, "marvell,armada-380-smp",
112 		      &armada_38x_smp_ops);
113