1 /*
2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
3 *
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.
7 *
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
12 * more details.
13 */
14
15 #include <linux/module.h>
16 #include <linux/init.h>
17 #include <linux/kernel.h>
18 #include <linux/mm.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>
31
32 /* State of each CPU. */
33 static DEFINE_PER_CPU(int, cpu_state) = { 0 };
34
35 /* The messaging code jumps to this pointer during boot-up */
36 unsigned long start_cpu_function_addr;
37
38 /* Called very early during startup to mark boot cpu as online */
smp_prepare_boot_cpu(void)39 void __init smp_prepare_boot_cpu(void)
40 {
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;
45
46 init_messaging();
47 }
48
49 static void start_secondary(void);
50
51 /*
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.
55 */
smp_prepare_cpus(unsigned int max_cpus)56 void __init smp_prepare_cpus(unsigned int max_cpus)
57 {
58 long rc;
59 int cpu, cpu_count;
60 int boot_cpu = smp_processor_id();
61
62 current_thread_info()->cpu = boot_cpu;
63
64 /*
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.
67 */
68 rc = sched_setaffinity(current->pid, cpumask_of(boot_cpu));
69 if (rc != 0)
70 pr_err("Couldn't set init affinity to boot cpu (%ld)\n", rc);
71
72 /* Print information about disabled and dataplane cpus. */
73 print_disabled_cpus();
74
75 /*
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.
80 */
81 start_cpu_function_addr = (unsigned long) &online_secondary;
82
83 /* Set up thread context for all new processors. */
84 cpu_count = 1;
85 for (cpu = 0; cpu < NR_CPUS; ++cpu) {
86 struct task_struct *idle;
87
88 if (cpu == boot_cpu)
89 continue;
90
91 if (!cpu_possible(cpu)) {
92 /*
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.
96 */
97 per_cpu(boot_sp, cpu) = 0;
98 per_cpu(boot_pc, cpu) = (unsigned long) smp_nap;
99 continue;
100 }
101
102 /* Create a new idle thread to run start_secondary() */
103 idle = fork_idle(cpu);
104 if (IS_ERR(idle))
105 panic("failed fork for CPU %d", cpu);
106 idle->thread.pc = (unsigned long) start_secondary;
107
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;
111
112 ++cpu_count;
113 }
114 BUG_ON(cpu_count > (max_cpus ? max_cpus : 1));
115
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();
121 }
122 }
123
124 static __initdata struct cpumask init_affinity;
125
reset_init_affinity(void)126 static __init int reset_init_affinity(void)
127 {
128 long rc = sched_setaffinity(current->pid, &init_affinity);
129 if (rc != 0)
130 pr_warning("couldn't reset init affinity (%ld)\n",
131 rc);
132 return 0;
133 }
134 late_initcall(reset_init_affinity);
135
136 static struct cpumask cpu_started __cpuinitdata;
137
138 /*
139 * Activate a secondary processor. Very minimal; don't add anything
140 * to this path without knowing what you're doing, since SMP booting
141 * is pretty fragile.
142 */
start_secondary(void)143 static void __cpuinit start_secondary(void)
144 {
145 int cpuid = smp_processor_id();
146
147 /* Set our thread pointer appropriately. */
148 set_my_cpu_offset(__per_cpu_offset[cpuid]);
149
150 preempt_disable();
151
152 /*
153 * In large machines even this will slow us down, since we
154 * will be contending for for the printk spinlock.
155 */
156 /* printk(KERN_DEBUG "Initializing CPU#%d\n", cpuid); */
157
158 /* Initialize the current asid for our first page table. */
159 __get_cpu_var(current_asid) = min_asid;
160
161 /* Set up this thread as another owner of the init_mm */
162 atomic_inc(&init_mm.mm_count);
163 current->active_mm = &init_mm;
164 if (current->mm)
165 BUG();
166 enter_lazy_tlb(&init_mm, current);
167
168 /* Allow hypervisor messages to be received */
169 init_messaging();
170 local_irq_enable();
171
172 /* Indicate that we're ready to come up. */
173 /* Must not do this before we're ready to receive messages */
174 if (cpumask_test_and_set_cpu(cpuid, &cpu_started)) {
175 pr_warning("CPU#%d already started!\n", cpuid);
176 for (;;)
177 local_irq_enable();
178 }
179
180 smp_nap();
181 }
182
183 /*
184 * Bring a secondary processor online.
185 */
online_secondary(void)186 void __cpuinit online_secondary(void)
187 {
188 /*
189 * low-memory mappings have been cleared, flush them from
190 * the local TLBs too.
191 */
192 local_flush_tlb();
193
194 BUG_ON(in_interrupt());
195
196 /* This must be done before setting cpu_online_mask */
197 wmb();
198
199 notify_cpu_starting(smp_processor_id());
200
201 /*
202 * We need to hold call_lock, so there is no inconsistency
203 * between the time smp_call_function() determines number of
204 * IPI recipients, and the time when the determination is made
205 * for which cpus receive the IPI. Holding this
206 * lock helps us to not include this cpu in a currently in progress
207 * smp_call_function().
208 */
209 ipi_call_lock();
210 set_cpu_online(smp_processor_id(), 1);
211 ipi_call_unlock();
212 __get_cpu_var(cpu_state) = CPU_ONLINE;
213
214 /* Set up tile-specific state for this cpu. */
215 setup_cpu(0);
216
217 /* Set up tile-timer clock-event device on this cpu */
218 setup_tile_timer();
219
220 preempt_enable();
221
222 cpu_idle();
223 }
224
__cpu_up(unsigned int cpu)225 int __cpuinit __cpu_up(unsigned int cpu)
226 {
227 /* Wait 5s total for all CPUs for them to come online */
228 static int timeout;
229 for (; !cpumask_test_cpu(cpu, &cpu_started); timeout++) {
230 if (timeout >= 50000) {
231 pr_info("skipping unresponsive cpu%d\n", cpu);
232 local_irq_enable();
233 return -EIO;
234 }
235 udelay(100);
236 }
237
238 local_irq_enable();
239 per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
240
241 /* Unleash the CPU! */
242 send_IPI_single(cpu, MSG_TAG_START_CPU);
243 while (!cpumask_test_cpu(cpu, cpu_online_mask))
244 cpu_relax();
245 return 0;
246 }
247
panic_start_cpu(void)248 static void panic_start_cpu(void)
249 {
250 panic("Received a MSG_START_CPU IPI after boot finished.");
251 }
252
smp_cpus_done(unsigned int max_cpus)253 void __init smp_cpus_done(unsigned int max_cpus)
254 {
255 int cpu, next, rc;
256
257 /* Reset the response to a (now illegal) MSG_START_CPU IPI. */
258 start_cpu_function_addr = (unsigned long) &panic_start_cpu;
259
260 cpumask_copy(&init_affinity, cpu_online_mask);
261
262 /*
263 * Pin ourselves to a single cpu in the initial affinity set
264 * so that kernel mappings for the rootfs are not in the dataplane,
265 * if set, and to avoid unnecessary migrating during bringup.
266 * Use the last cpu just in case the whole chip has been
267 * isolated from the scheduler, to keep init away from likely
268 * more useful user code. This also ensures that work scheduled
269 * via schedule_delayed_work() in the init routines will land
270 * on this cpu.
271 */
272 for (cpu = cpumask_first(&init_affinity);
273 (next = cpumask_next(cpu, &init_affinity)) < nr_cpu_ids;
274 cpu = next)
275 ;
276 rc = sched_setaffinity(current->pid, cpumask_of(cpu));
277 if (rc != 0)
278 pr_err("Couldn't set init affinity to cpu %d (%d)\n", cpu, rc);
279 }
280