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Linux/arch/arm/mach-mvebu/platsmp.c

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  1 /*
  2  * Symmetric Multi Processing (SMP) support for Armada XP
  3  *
  4  * Copyright (C) 2012 Marvell
  5  *
  6  * Lior Amsalem <alior@marvell.com>
  7  * Yehuda Yitschak <yehuday@marvell.com>
  8  * Gregory CLEMENT <gregory.clement@free-electrons.com>
  9  * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
 10  *
 11  * This file is licensed under the terms of the GNU General Public
 12  * License version 2.  This program is licensed "as is" without any
 13  * warranty of any kind, whether express or implied.
 14  *
 15  * The Armada XP SoC has 4 ARMv7 PJ4B CPUs running in full HW coherency
 16  * This file implements the routines for preparing the SMP infrastructure
 17  * and waking up the secondary CPUs
 18  */
 19 
 20 #include <linux/init.h>
 21 #include <linux/smp.h>
 22 #include <linux/clk.h>
 23 #include <linux/of.h>
 24 #include <linux/of_address.h>
 25 #include <linux/mbus.h>
 26 #include <asm/cacheflush.h>
 27 #include <asm/smp_plat.h>
 28 #include "common.h"
 29 #include "armada-370-xp.h"
 30 #include "pmsu.h"
 31 #include "coherency.h"
 32 
 33 #define ARMADA_XP_MAX_CPUS 4
 34 
 35 #define AXP_BOOTROM_BASE 0xfff00000
 36 #define AXP_BOOTROM_SIZE 0x100000
 37 
 38 static struct clk *get_cpu_clk(int cpu)
 39 {
 40         struct clk *cpu_clk;
 41         struct device_node *np = of_get_cpu_node(cpu, NULL);
 42 
 43         if (WARN(!np, "missing cpu node\n"))
 44                 return NULL;
 45         cpu_clk = of_clk_get(np, 0);
 46         if (WARN_ON(IS_ERR(cpu_clk)))
 47                 return NULL;
 48         return cpu_clk;
 49 }
 50 
 51 static void set_secondary_cpu_clock(unsigned int cpu)
 52 {
 53         int thiscpu;
 54         unsigned long rate;
 55         struct clk *cpu_clk;
 56 
 57         thiscpu = get_cpu();
 58 
 59         cpu_clk = get_cpu_clk(thiscpu);
 60         if (!cpu_clk)
 61                 goto out;
 62         clk_prepare_enable(cpu_clk);
 63         rate = clk_get_rate(cpu_clk);
 64 
 65         cpu_clk = get_cpu_clk(cpu);
 66         if (!cpu_clk)
 67                 goto out;
 68         clk_set_rate(cpu_clk, rate);
 69         clk_prepare_enable(cpu_clk);
 70 
 71 out:
 72         put_cpu();
 73 }
 74 
 75 static int armada_xp_boot_secondary(unsigned int cpu, struct task_struct *idle)
 76 {
 77         int ret, hw_cpu;
 78 
 79         pr_info("Booting CPU %d\n", cpu);
 80 
 81         hw_cpu = cpu_logical_map(cpu);
 82         set_secondary_cpu_clock(hw_cpu);
 83         mvebu_pmsu_set_cpu_boot_addr(hw_cpu, armada_xp_secondary_startup);
 84 
 85         /*
 86          * This is needed to wake up CPUs in the offline state after
 87          * using CPU hotplug.
 88          */
 89         arch_send_wakeup_ipi_mask(cpumask_of(cpu));
 90 
 91         /*
 92          * This is needed to take secondary CPUs out of reset on the
 93          * initial boot.
 94          */
 95         ret = mvebu_cpu_reset_deassert(hw_cpu);
 96         if (ret) {
 97                 pr_warn("unable to boot CPU: %d\n", ret);
 98                 return ret;
 99         }
100 
101         return 0;
102 }
103 
104 /*
105  * When a CPU is brought back online, either through CPU hotplug, or
106  * because of the boot of a kexec'ed kernel, the PMSU configuration
107  * for this CPU might be in the deep idle state, preventing this CPU
108  * from receiving interrupts. Here, we therefore take out the current
109  * CPU from this state, which was entered by armada_xp_cpu_die()
110  * below.
111  */
112 static void armada_xp_secondary_init(unsigned int cpu)
113 {
114         mvebu_v7_pmsu_idle_exit();
115 }
116 
117 static void __init armada_xp_smp_init_cpus(void)
118 {
119         unsigned int ncores = num_possible_cpus();
120 
121         if (ncores == 0 || ncores > ARMADA_XP_MAX_CPUS)
122                 panic("Invalid number of CPUs in DT\n");
123 }
124 
125 static void __init armada_xp_smp_prepare_cpus(unsigned int max_cpus)
126 {
127         struct device_node *node;
128         struct resource res;
129         int err;
130 
131         flush_cache_all();
132         set_cpu_coherent();
133 
134         /*
135          * In order to boot the secondary CPUs we need to ensure
136          * the bootROM is mapped at the correct address.
137          */
138         node = of_find_compatible_node(NULL, NULL, "marvell,bootrom");
139         if (!node)
140                 panic("Cannot find 'marvell,bootrom' compatible node");
141 
142         err = of_address_to_resource(node, 0, &res);
143         if (err < 0)
144                 panic("Cannot get 'bootrom' node address");
145 
146         if (res.start != AXP_BOOTROM_BASE ||
147             resource_size(&res) != AXP_BOOTROM_SIZE)
148                 panic("The address for the BootROM is incorrect");
149 }
150 
151 #ifdef CONFIG_HOTPLUG_CPU
152 static void armada_xp_cpu_die(unsigned int cpu)
153 {
154         /*
155          * CPU hotplug is implemented by putting offline CPUs into the
156          * deep idle sleep state.
157          */
158         armada_370_xp_pmsu_idle_enter(true);
159 }
160 
161 /*
162  * We need a dummy function, so that platform_can_cpu_hotplug() knows
163  * we support CPU hotplug. However, the function does not need to do
164  * anything, because CPUs going offline can enter the deep idle state
165  * by themselves, without any help from a still alive CPU.
166  */
167 static int armada_xp_cpu_kill(unsigned int cpu)
168 {
169         return 1;
170 }
171 #endif
172 
173 const struct smp_operations armada_xp_smp_ops __initconst = {
174         .smp_init_cpus          = armada_xp_smp_init_cpus,
175         .smp_prepare_cpus       = armada_xp_smp_prepare_cpus,
176         .smp_boot_secondary     = armada_xp_boot_secondary,
177         .smp_secondary_init     = armada_xp_secondary_init,
178 #ifdef CONFIG_HOTPLUG_CPU
179         .cpu_die                = armada_xp_cpu_die,
180         .cpu_kill               = armada_xp_cpu_kill,
181 #endif
182 };
183 
184 CPU_METHOD_OF_DECLARE(armada_xp_smp, "marvell,armada-xp-smp",
185                       &armada_xp_smp_ops);
186 

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