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_CPU_STOP:
68			/*
69			 * call vmstop()
70			 */
71			__vmstop();
72			break;
73
74		case IPI_RESCHEDULE:
75			scheduler_ipi();
76			break;
77		}
78	} while (msg < BITS_PER_LONG);
79}
80
81/*  Used for IPI call from other CPU's to unmask int  */
82void smp_vm_unmask_irq(void *info)
83{
84	__vmintop_locen((long) info);
85}
86
87
88/*
89 * This is based on Alpha's IPI stuff.
90 * Supposed to take (int, void*) as args now.
91 * Specifically, first arg is irq, second is the irq_desc.
92 */
93
94irqreturn_t handle_ipi(int irq, void *desc)
95{
96	int cpu = smp_processor_id();
97	struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
98	unsigned long ops;
99
100	while ((ops = xchg(&ipi->bits, 0)) != 0)
101		__handle_ipi(&ops, ipi, cpu);
102	return IRQ_HANDLED;
103}
104
105void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
106{
107	unsigned long flags;
108	unsigned long cpu;
109	unsigned long retval;
110
111	local_irq_save(flags);
112
113	for_each_cpu(cpu, cpumask) {
114		struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
115
116		set_bit(msg, &ipi->bits);
117		/*  Possible barrier here  */
118		retval = __vmintop_post(BASE_IPI_IRQ+cpu);
119
120		if (retval != 0) {
121			printk(KERN_ERR "interrupt %ld not configured?\n",
122				BASE_IPI_IRQ+cpu);
123		}
124	}
125
126	local_irq_restore(flags);
127}
128
129static struct irqaction ipi_intdesc = {
130	.handler = handle_ipi,
131	.flags = IRQF_TRIGGER_RISING,
132	.name = "ipi_handler"
133};
134
135void __init smp_prepare_boot_cpu(void)
136{
137}
138
139/*
140 * interrupts should already be disabled from the VM
141 * SP should already be correct; need to set THREADINFO_REG
142 * to point to current thread info
143 */
144
145void start_secondary(void)
146{
147	unsigned int cpu;
148	unsigned long thread_ptr;
149
150	/*  Calculate thread_info pointer from stack pointer  */
151	__asm__ __volatile__(
152		"%0 = SP;\n"
153		: "=r" (thread_ptr)
154	);
155
156	thread_ptr = thread_ptr & ~(THREAD_SIZE-1);
157
158	__asm__ __volatile__(
159		QUOTED_THREADINFO_REG " = %0;\n"
160		:
161		: "r" (thread_ptr)
162	);
163
164	/*  Set the memory struct  */
165	atomic_inc(&init_mm.mm_count);
166	current->active_mm = &init_mm;
167
168	cpu = smp_processor_id();
169
170	setup_irq(BASE_IPI_IRQ + cpu, &ipi_intdesc);
171
172	/*  Register the clock_event dummy  */
173	setup_percpu_clockdev();
174
175	printk(KERN_INFO "%s cpu %d\n", __func__, current_thread_info()->cpu);
176
177	notify_cpu_starting(cpu);
178
179	set_cpu_online(cpu, true);
180
181	local_irq_enable();
182
183	cpu_startup_entry(CPUHP_ONLINE);
184}
185
186
187/*
188 * called once for each present cpu
189 * apparently starts up the CPU and then
190 * maintains control until "cpu_online(cpu)" is set.
191 */
192
193int __cpu_up(unsigned int cpu, struct task_struct *idle)
194{
195	struct thread_info *thread = (struct thread_info *)idle->stack;
196	void *stack_start;
197
198	thread->cpu = cpu;
199
200	/*  Boot to the head.  */
201	stack_start =  ((void *) thread) + THREAD_SIZE;
202	__vmstart(start_secondary, stack_start);
203
204	while (!cpu_online(cpu))
205		barrier();
206
207	return 0;
208}
209
210void __init smp_cpus_done(unsigned int max_cpus)
211{
212}
213
214void __init smp_prepare_cpus(unsigned int max_cpus)
215{
216	int i;
217
218	/*
219	 * should eventually have some sort of machine
220	 * descriptor that has this stuff
221	 */
222
223	/*  Right now, let's just fake it. */
224	for (i = 0; i < max_cpus; i++)
225		set_cpu_present(i, true);
226
227	/*  Also need to register the interrupts for IPI  */
228	if (max_cpus > 1)
229		setup_irq(BASE_IPI_IRQ, &ipi_intdesc);
230}
231
232void smp_send_reschedule(int cpu)
233{
234	send_ipi(cpumask_of(cpu), IPI_RESCHEDULE);
235}
236
237void smp_send_stop(void)
238{
239	struct cpumask targets;
240	cpumask_copy(&targets, cpu_online_mask);
241	cpumask_clear_cpu(smp_processor_id(), &targets);
242	send_ipi(&targets, IPI_CPU_STOP);
243}
244
245void arch_send_call_function_single_ipi(int cpu)
246{
247	send_ipi(cpumask_of(cpu), IPI_CALL_FUNC);
248}
249
250void arch_send_call_function_ipi_mask(const struct cpumask *mask)
251{
252	send_ipi(mask, IPI_CALL_FUNC);
253}
254
255int setup_profiling_timer(unsigned int multiplier)
256{
257	return -EINVAL;
258}
259
260void smp_start_cpus(void)
261{
262	int i;
263
264	for (i = 0; i < NR_CPUS; i++)
265		set_cpu_possible(i, true);
266}
267