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. */
33static DEFINE_PER_CPU(int, cpu_state) = { 0 };
34
35/* The messaging code jumps to this pointer during boot-up */
36unsigned long start_cpu_function_addr;
37
38/* Called very early during startup to mark boot cpu as online */
39void __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	__this_cpu_write(cpu_state, CPU_ONLINE);
45
46	init_messaging();
47}
48
49static 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 */
56void __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
124static __initdata struct cpumask init_affinity;
125
126static __init int reset_init_affinity(void)
127{
128	long rc = sched_setaffinity(current->pid, &init_affinity);
129	if (rc != 0)
130		pr_warn("couldn't reset init affinity (%ld)\n", rc);
131	return 0;
132}
133late_initcall(reset_init_affinity);
134
135static struct cpumask cpu_started;
136
137/*
138 * Activate a secondary processor.  Very minimal; don't add anything
139 * to this path without knowing what you're doing, since SMP booting
140 * is pretty fragile.
141 */
142static void start_secondary(void)
143{
144	int cpuid;
145
146	preempt_disable();
147
148	cpuid = smp_processor_id();
149
150	/* Set our thread pointer appropriately. */
151	set_my_cpu_offset(__per_cpu_offset[cpuid]);
152
153	/*
154	 * In large machines even this will slow us down, since we
155	 * will be contending for for the printk spinlock.
156	 */
157	/* printk(KERN_DEBUG "Initializing CPU#%d\n", cpuid); */
158
159	/* Initialize the current asid for our first page table. */
160	__this_cpu_write(current_asid, min_asid);
161
162	/* Set up this thread as another owner of the init_mm */
163	atomic_inc(&init_mm.mm_count);
164	current->active_mm = &init_mm;
165	if (current->mm)
166		BUG();
167	enter_lazy_tlb(&init_mm, current);
168
169	/* Allow hypervisor messages to be received */
170	init_messaging();
171	local_irq_enable();
172
173	/* Indicate that we're ready to come up. */
174	/* Must not do this before we're ready to receive messages */
175	if (cpumask_test_and_set_cpu(cpuid, &cpu_started)) {
176		pr_warn("CPU#%d already started!\n", cpuid);
177		for (;;)
178			local_irq_enable();
179	}
180
181	smp_nap();
182}
183
184/*
185 * Bring a secondary processor online.
186 */
187void online_secondary(void)
188{
189	/*
190	 * low-memory mappings have been cleared, flush them from
191	 * the local TLBs too.
192	 */
193	local_flush_tlb();
194
195	BUG_ON(in_interrupt());
196
197	/* This must be done before setting cpu_online_mask */
198	wmb();
199
200	notify_cpu_starting(smp_processor_id());
201
202	set_cpu_online(smp_processor_id(), 1);
203	__this_cpu_write(cpu_state, CPU_ONLINE);
204
205	/* Set up tile-specific state for this cpu. */
206	setup_cpu(0);
207
208	/* Set up tile-timer clock-event device on this cpu */
209	setup_tile_timer();
210
211	cpu_startup_entry(CPUHP_ONLINE);
212}
213
214int __cpu_up(unsigned int cpu, struct task_struct *tidle)
215{
216	/* Wait 5s total for all CPUs for them to come online */
217	static int timeout;
218	for (; !cpumask_test_cpu(cpu, &cpu_started); timeout++) {
219		if (timeout >= 50000) {
220			pr_info("skipping unresponsive cpu%d\n", cpu);
221			local_irq_enable();
222			return -EIO;
223		}
224		udelay(100);
225	}
226
227	local_irq_enable();
228	per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
229
230	/* Unleash the CPU! */
231	send_IPI_single(cpu, MSG_TAG_START_CPU);
232	while (!cpumask_test_cpu(cpu, cpu_online_mask))
233		cpu_relax();
234	return 0;
235}
236
237static void panic_start_cpu(void)
238{
239	panic("Received a MSG_START_CPU IPI after boot finished.");
240}
241
242void __init smp_cpus_done(unsigned int max_cpus)
243{
244	int cpu, next, rc;
245
246	/* Reset the response to a (now illegal) MSG_START_CPU IPI. */
247	start_cpu_function_addr = (unsigned long) &panic_start_cpu;
248
249	cpumask_copy(&init_affinity, cpu_online_mask);
250
251	/*
252	 * Pin ourselves to a single cpu in the initial affinity set
253	 * so that kernel mappings for the rootfs are not in the dataplane,
254	 * if set, and to avoid unnecessary migrating during bringup.
255	 * Use the last cpu just in case the whole chip has been
256	 * isolated from the scheduler, to keep init away from likely
257	 * more useful user code.  This also ensures that work scheduled
258	 * via schedule_delayed_work() in the init routines will land
259	 * on this cpu.
260	 */
261	for (cpu = cpumask_first(&init_affinity);
262	     (next = cpumask_next(cpu, &init_affinity)) < nr_cpu_ids;
263	     cpu = next)
264		;
265	rc = sched_setaffinity(current->pid, cpumask_of(cpu));
266	if (rc != 0)
267		pr_err("Couldn't set init affinity to cpu %d (%d)\n", cpu, rc);
268}
269