2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation, version 2.
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 * NON INFRINGEMENT. See the GNU General Public License for
15 #include <linux/module.h>
16 #include <linux/init.h>
17 #include <linux/kernel.h>
19 #include <linux/sched.h>
20 #include <linux/kernel_stat.h>
21 #include <linux/bootmem.h>
22 #include <linux/notifier.h>
23 #include <linux/cpu.h>
24 #include <linux/percpu.h>
25 #include <linux/delay.h>
26 #include <linux/err.h>
27 #include <linux/irq.h>
28 #include <asm/mmu_context.h>
29 #include <asm/tlbflush.h>
30 #include <asm/sections.h>
32 /* State of each CPU. */
33 static DEFINE_PER_CPU(int, cpu_state
) = { 0 };
35 /* The messaging code jumps to this pointer during boot-up */
36 unsigned long start_cpu_function_addr
;
38 /* Called very early during startup to mark boot cpu as online */
39 void __init
smp_prepare_boot_cpu(void)
41 int cpu
= smp_processor_id();
42 set_cpu_online(cpu
, 1);
43 set_cpu_present(cpu
, 1);
44 __get_cpu_var(cpu_state
) = CPU_ONLINE
;
49 static void start_secondary(void);
52 * Called at the top of init() to launch all the other CPUs.
53 * They run free to complete their initialization and then wait
54 * until they get an IPI from the boot cpu to come online.
56 void __init
smp_prepare_cpus(unsigned int max_cpus
)
60 int boot_cpu
= smp_processor_id();
62 current_thread_info()->cpu
= boot_cpu
;
65 * Pin this task to the boot CPU while we bring up the others,
66 * just to make sure we don't uselessly migrate as they come up.
68 rc
= sched_setaffinity(current
->pid
, cpumask_of(boot_cpu
));
70 pr_err("Couldn't set init affinity to boot cpu (%ld)\n", rc
);
72 /* Print information about disabled and dataplane cpus. */
73 print_disabled_cpus();
76 * Tell the messaging subsystem how to respond to the
77 * startup message. We use a level of indirection to avoid
78 * confusing the linker with the fact that the messaging
79 * subsystem is calling __init code.
81 start_cpu_function_addr
= (unsigned long) &online_secondary
;
83 /* Set up thread context for all new processors. */
85 for (cpu
= 0; cpu
< NR_CPUS
; ++cpu
) {
86 struct task_struct
*idle
;
91 if (!cpu_possible(cpu
)) {
93 * Make this processor do nothing on boot.
94 * Note that we don't give the boot_pc function
95 * a stack, so it has to be assembly code.
97 per_cpu(boot_sp
, cpu
) = 0;
98 per_cpu(boot_pc
, cpu
) = (unsigned long) smp_nap
;
102 /* Create a new idle thread to run start_secondary() */
103 idle
= fork_idle(cpu
);
105 panic("failed fork for CPU %d", cpu
);
106 idle
->thread
.pc
= (unsigned long) start_secondary
;
108 /* Make this thread the boot thread for this processor */
109 per_cpu(boot_sp
, cpu
) = task_ksp0(idle
);
110 per_cpu(boot_pc
, cpu
) = idle
->thread
.pc
;
114 BUG_ON(cpu_count
> (max_cpus
? max_cpus
: 1));
116 /* Fire up the other tiles, if any */
117 init_cpu_present(cpu_possible_mask
);
118 if (cpumask_weight(cpu_present_mask
) > 1) {
119 mb(); /* make sure all data is visible to new processors */
120 hv_start_all_tiles();
124 static __initdata
struct cpumask init_affinity
;
126 static __init
int reset_init_affinity(void)
128 long rc
= sched_setaffinity(current
->pid
, &init_affinity
);
130 pr_warning("couldn't reset init affinity (%ld)\n",
134 late_initcall(reset_init_affinity
);
136 static struct cpumask cpu_started
;
139 * Activate a secondary processor. Very minimal; don't add anything
140 * to this path without knowing what you're doing, since SMP booting
143 static void start_secondary(void)
149 cpuid
= smp_processor_id();
151 /* Set our thread pointer appropriately. */
152 set_my_cpu_offset(__per_cpu_offset
[cpuid
]);
155 * In large machines even this will slow us down, since we
156 * will be contending for for the printk spinlock.
158 /* printk(KERN_DEBUG "Initializing CPU#%d\n", cpuid); */
160 /* Initialize the current asid for our first page table. */
161 __get_cpu_var(current_asid
) = min_asid
;
163 /* Set up this thread as another owner of the init_mm */
164 atomic_inc(&init_mm
.mm_count
);
165 current
->active_mm
= &init_mm
;
168 enter_lazy_tlb(&init_mm
, current
);
170 /* Allow hypervisor messages to be received */
174 /* Indicate that we're ready to come up. */
175 /* Must not do this before we're ready to receive messages */
176 if (cpumask_test_and_set_cpu(cpuid
, &cpu_started
)) {
177 pr_warning("CPU#%d already started!\n", cpuid
);
186 * Bring a secondary processor online.
188 void online_secondary(void)
191 * low-memory mappings have been cleared, flush them from
192 * the local TLBs too.
196 BUG_ON(in_interrupt());
198 /* This must be done before setting cpu_online_mask */
201 notify_cpu_starting(smp_processor_id());
203 set_cpu_online(smp_processor_id(), 1);
204 __get_cpu_var(cpu_state
) = CPU_ONLINE
;
206 /* Set up tile-specific state for this cpu. */
209 /* Set up tile-timer clock-event device on this cpu */
212 cpu_startup_entry(CPUHP_ONLINE
);
215 int __cpu_up(unsigned int cpu
, struct task_struct
*tidle
)
217 /* Wait 5s total for all CPUs for them to come online */
219 for (; !cpumask_test_cpu(cpu
, &cpu_started
); timeout
++) {
220 if (timeout
>= 50000) {
221 pr_info("skipping unresponsive cpu%d\n", cpu
);
229 per_cpu(cpu_state
, cpu
) = CPU_UP_PREPARE
;
231 /* Unleash the CPU! */
232 send_IPI_single(cpu
, MSG_TAG_START_CPU
);
233 while (!cpumask_test_cpu(cpu
, cpu_online_mask
))
238 static void panic_start_cpu(void)
240 panic("Received a MSG_START_CPU IPI after boot finished.");
243 void __init
smp_cpus_done(unsigned int max_cpus
)
247 /* Reset the response to a (now illegal) MSG_START_CPU IPI. */
248 start_cpu_function_addr
= (unsigned long) &panic_start_cpu
;
250 cpumask_copy(&init_affinity
, cpu_online_mask
);
253 * Pin ourselves to a single cpu in the initial affinity set
254 * so that kernel mappings for the rootfs are not in the dataplane,
255 * if set, and to avoid unnecessary migrating during bringup.
256 * Use the last cpu just in case the whole chip has been
257 * isolated from the scheduler, to keep init away from likely
258 * more useful user code. This also ensures that work scheduled
259 * via schedule_delayed_work() in the init routines will land
262 for (cpu
= cpumask_first(&init_affinity
);
263 (next
= cpumask_next(cpu
, &init_affinity
)) < nr_cpu_ids
;
266 rc
= sched_setaffinity(current
->pid
, cpumask_of(cpu
));
268 pr_err("Couldn't set init affinity to cpu %d (%d)\n", cpu
, rc
);