smp.c revision e1858b2a21cd84a855945a4747fb2db41b250c22 
1/*
2 * SMP support for Hexagon
3 *
4 * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 and
8 * only version 2 as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
18 * 02110-1301, USA.
19 */
20
21#include <linux/err.h>
22#include <linux/errno.h>
23#include <linux/kernel.h>
24#include <linux/init.h>
25#include <linux/interrupt.h>
26#include <linux/module.h>
27#include <linux/percpu.h>
28#include <linux/sched.h>
29#include <linux/smp.h>
30#include <linux/spinlock.h>
31#include <linux/cpu.h>
32
33#include <asm/time.h>    /*  timer_interrupt  */
34#include <asm/hexagon_vm.h>
35
36#define BASE_IPI_IRQ 26
37
38/*
39 * cpu_possible_mask needs to be filled out prior to setup_per_cpu_areas
40 * (which is prior to any of our smp_prepare_cpu crap), in order to set
41 * up the...  per_cpu areas.
42 */
43
44struct ipi_data {
45	unsigned long bits;
46};
47
48static DEFINE_PER_CPU(struct ipi_data, ipi_data);
49
50static inline void __handle_ipi(unsigned long *ops, struct ipi_data *ipi,
51				int cpu)
52{
53	unsigned long msg = 0;
54	do {
55		msg = find_next_bit(ops, BITS_PER_LONG, msg+1);
56
57		switch (msg) {
58
59		case IPI_TIMER:
60			ipi_timer();
61			break;
62
63		case IPI_CALL_FUNC:
64			generic_smp_call_function_interrupt();
65			break;
66
67		case IPI_CALL_FUNC_SINGLE:
68			generic_smp_call_function_single_interrupt();
69			break;
70
71		case IPI_CPU_STOP:
72			/*
73			 * call vmstop()
74			 */
75			__vmstop();
76			break;
77
78		case IPI_RESCHEDULE:
79			scheduler_ipi();
80			break;
81		}
82	} while (msg < BITS_PER_LONG);
83}
84
85/*  Used for IPI call from other CPU's to unmask int  */
86void smp_vm_unmask_irq(void *info)
87{
88	__vmintop_locen((long) info);
89}
90
91
92/*
93 * This is based on Alpha's IPI stuff.
94 * Supposed to take (int, void*) as args now.
95 * Specifically, first arg is irq, second is the irq_desc.
96 */
97
98irqreturn_t handle_ipi(int irq, void *desc)
99{
100	int cpu = smp_processor_id();
101	struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
102	unsigned long ops;
103
104	while ((ops = xchg(&ipi->bits, 0)) != 0)
105		__handle_ipi(&ops, ipi, cpu);
106	return IRQ_HANDLED;
107}
108
109void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
110{
111	unsigned long flags;
112	unsigned long cpu;
113	unsigned long retval;
114
115	local_irq_save(flags);
116
117	for_each_cpu(cpu, cpumask) {
118		struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
119
120		set_bit(msg, &ipi->bits);
121		/*  Possible barrier here  */
122		retval = __vmintop_post(BASE_IPI_IRQ+cpu);
123
124		if (retval != 0) {
125			printk(KERN_ERR "interrupt %ld not configured?\n",
126				BASE_IPI_IRQ+cpu);
127		}
128	}
129
130	local_irq_restore(flags);
131}
132
133static struct irqaction ipi_intdesc = {
134	.handler = handle_ipi,
135	.flags = IRQF_TRIGGER_RISING,
136	.name = "ipi_handler"
137};
138
139void __init smp_prepare_boot_cpu(void)
140{
141}
142
143/*
144 * interrupts should already be disabled from the VM
145 * SP should already be correct; need to set THREADINFO_REG
146 * to point to current thread info
147 */
148
149void __cpuinit start_secondary(void)
150{
151	unsigned int cpu;
152	unsigned long thread_ptr;
153
154	/*  Calculate thread_info pointer from stack pointer  */
155	__asm__ __volatile__(
156		"%0 = SP;\n"
157		: "=r" (thread_ptr)
158	);
159
160	thread_ptr = thread_ptr & ~(THREAD_SIZE-1);
161
162	__asm__ __volatile__(
163		QUOTED_THREADINFO_REG " = %0;\n"
164		:
165		: "r" (thread_ptr)
166	);
167
168	/*  Set the memory struct  */
169	atomic_inc(&init_mm.mm_count);
170	current->active_mm = &init_mm;
171
172	cpu = smp_processor_id();
173
174	setup_irq(BASE_IPI_IRQ + cpu, &ipi_intdesc);
175
176	/*  Register the clock_event dummy  */
177	setup_percpu_clockdev();
178
179	printk(KERN_INFO "%s cpu %d\n", __func__, current_thread_info()->cpu);
180
181	notify_cpu_starting(cpu);
182
183	set_cpu_online(cpu, true);
184
185	local_irq_enable();
186
187	cpu_idle();
188}
189
190
191/*
192 * called once for each present cpu
193 * apparently starts up the CPU and then
194 * maintains control until "cpu_online(cpu)" is set.
195 */
196
197int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *idle)
198{
199	struct thread_info *thread = (struct thread_info *)idle->stack;
200	void *stack_start;
201
202	thread->cpu = cpu;
203
204	/*  Boot to the head.  */
205	stack_start =  ((void *) thread) + THREAD_SIZE;
206	__vmstart(start_secondary, stack_start);
207
208	while (!cpu_online(cpu))
209		barrier();
210
211	return 0;
212}
213
214void __init smp_cpus_done(unsigned int max_cpus)
215{
216}
217
218void __init smp_prepare_cpus(unsigned int max_cpus)
219{
220	int i;
221
222	/*
223	 * should eventually have some sort of machine
224	 * descriptor that has this stuff
225	 */
226
227	/*  Right now, let's just fake it. */
228	for (i = 0; i < max_cpus; i++)
229		set_cpu_present(i, true);
230
231	/*  Also need to register the interrupts for IPI  */
232	if (max_cpus > 1)
233		setup_irq(BASE_IPI_IRQ, &ipi_intdesc);
234}
235
236void smp_send_reschedule(int cpu)
237{
238	send_ipi(cpumask_of(cpu), IPI_RESCHEDULE);
239}
240
241void smp_send_stop(void)
242{
243	struct cpumask targets;
244	cpumask_copy(&targets, cpu_online_mask);
245	cpumask_clear_cpu(smp_processor_id(), &targets);
246	send_ipi(&targets, IPI_CPU_STOP);
247}
248
249void arch_send_call_function_single_ipi(int cpu)
250{
251	send_ipi(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
252}
253
254void arch_send_call_function_ipi_mask(const struct cpumask *mask)
255{
256	send_ipi(mask, IPI_CALL_FUNC);
257}
258
259int setup_profiling_timer(unsigned int multiplier)
260{
261	return -EINVAL;
262}
263
264void smp_start_cpus(void)
265{
266	int i;
267
268	for (i = 0; i < NR_CPUS; i++)
269		set_cpu_possible(i, true);
270}
271