xref: /linux/arch/hexagon/kernel/smp.c (revision 4413e16d9d21673bb5048a2e542f1aaa00015c2e)
1 /*
2  * SMP support for Hexagon
3  *
4  * Copyright (c) 2010-2012, Code Aurora Forum. 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 
44 struct ipi_data {
45 	unsigned long bits;
46 };
47 
48 static DEFINE_PER_CPU(struct ipi_data, ipi_data);
49 
50 static 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  */
86 void 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 
98 irqreturn_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 
109 void 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 
133 static struct irqaction ipi_intdesc = {
134 	.handler = handle_ipi,
135 	.flags = IRQF_TRIGGER_RISING,
136 	.name = "ipi_handler"
137 };
138 
139 void __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 
149 void __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 
197 int __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 
214 void __init smp_cpus_done(unsigned int max_cpus)
215 {
216 }
217 
218 void __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 
236 void smp_send_reschedule(int cpu)
237 {
238 	send_ipi(cpumask_of(cpu), IPI_RESCHEDULE);
239 }
240 
241 void 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 
249 void arch_send_call_function_single_ipi(int cpu)
250 {
251 	send_ipi(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
252 }
253 
254 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
255 {
256 	send_ipi(mask, IPI_CALL_FUNC);
257 }
258 
259 int setup_profiling_timer(unsigned int multiplier)
260 {
261 	return -EINVAL;
262 }
263 
264 void 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