summaryrefslogtreecommitdiff
path: root/arch/arc/kernel/smp.c
blob: bca3052c956dab7edc2c5ccffba613f7a1d5cd39 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
/*
 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * RajeshwarR: Dec 11, 2007
 *   -- Added support for Inter Processor Interrupts
 *
 * Vineetg: Nov 1st, 2007
 *    -- Initial Write (Borrowed heavily from ARM)
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/profile.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/mm.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/atomic.h>
#include <linux/percpu.h>
#include <linux/cpumask.h>
#include <linux/spinlock_types.h>
#include <linux/reboot.h>
#include <asm/processor.h>
#include <asm/setup.h>
#include <asm/mach_desc.h>

arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;

struct plat_smp_ops  plat_smp_ops;

/* XXX: per cpu ? Only needed once in early seconday boot */
struct task_struct *secondary_idle_tsk;

/* Called from start_kernel */
void __init smp_prepare_boot_cpu(void)
{
}

/*
 * Initialise the CPU possible map early - this describes the CPUs
 * which may be present or become present in the system.
 */
void __init smp_init_cpus(void)
{
	unsigned int i;

	for (i = 0; i < NR_CPUS; i++)
		set_cpu_possible(i, true);
}

/* called from init ( ) =>  process 1 */
void __init smp_prepare_cpus(unsigned int max_cpus)
{
	int i;

	/*
	 * Initialise the present map, which describes the set of CPUs
	 * actually populated at the present time.
	 */
	for (i = 0; i < max_cpus; i++)
		set_cpu_present(i, true);
}

void __init smp_cpus_done(unsigned int max_cpus)
{

}

/*
 * After power-up, a non Master CPU needs to wait for Master to kick start it
 *
 * The default implementation halts
 *
 * This relies on platform specific support allowing Master to directly set
 * this CPU's PC (to be @first_lines_of_secondary() and kick start it.
 *
 * In lack of such h/w assist, platforms can override this function
 *   - make this function busy-spin on a token, eventually set by Master
 *     (from arc_platform_smp_wakeup_cpu())
 *   - Once token is available, jump to @first_lines_of_secondary
 *     (using inline asm).
 *
 * Alert: can NOT use stack here as it has not been determined/setup for CPU.
 *        If it turns out to be elaborate, it's better to code it in assembly
 *
 */
void __attribute__((weak)) arc_platform_smp_wait_to_boot(int cpu)
{
	/*
	 * As a hack for debugging - since debugger will single-step over the
	 * FLAG insn - wrap the halt itself it in a self loop
	 */
	__asm__ __volatile__(
	"1:		\n"
	"	flag 1	\n"
	"	b 1b	\n");
}

const char *arc_platform_smp_cpuinfo(void)
{
	return plat_smp_ops.info;
}

/*
 * The very first "C" code executed by secondary
 * Called from asm stub in head.S
 * "current"/R25 already setup by low level boot code
 */
void start_kernel_secondary(void)
{
	struct mm_struct *mm = &init_mm;
	unsigned int cpu = smp_processor_id();

	/* MMU, Caches, Vector Table, Interrupts etc */
	setup_processor();

	atomic_inc(&mm->mm_users);
	atomic_inc(&mm->mm_count);
	current->active_mm = mm;

	notify_cpu_starting(cpu);
	set_cpu_online(cpu, true);

	pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu);

	if (machine_desc->init_smp)
		machine_desc->init_smp(smp_processor_id());

	arc_local_timer_setup(cpu);

	local_irq_enable();
	preempt_disable();
	cpu_startup_entry(CPUHP_ONLINE);
}

/*
 * Called from kernel_init( ) -> smp_init( ) - for each CPU
 *
 * At this point, Secondary Processor  is "HALT"ed:
 *  -It booted, but was halted in head.S
 *  -It was configured to halt-on-reset
 *  So need to wake it up.
 *
 * Essential requirements being where to run from (PC) and stack (SP)
*/
int __cpu_up(unsigned int cpu, struct task_struct *idle)
{
	unsigned long wait_till;

	secondary_idle_tsk = idle;

	pr_info("Idle Task [%d] %p", cpu, idle);
	pr_info("Trying to bring up CPU%u ...\n", cpu);

	if (plat_smp_ops.cpu_kick)
		plat_smp_ops.cpu_kick(cpu,
				(unsigned long)first_lines_of_secondary);

	/* wait for 1 sec after kicking the secondary */
	wait_till = jiffies + HZ;
	while (time_before(jiffies, wait_till)) {
		if (cpu_online(cpu))
			break;
	}

	if (!cpu_online(cpu)) {
		pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu);
		return -1;
	}

	secondary_idle_tsk = NULL;

	return 0;
}

/*
 * not supported here
 */
int __init setup_profiling_timer(unsigned int multiplier)
{
	return -EINVAL;
}

/*****************************************************************************/
/*              Inter Processor Interrupt Handling                           */
/*****************************************************************************/

/*
 * structures for inter-processor calls
 * A Collection of single bit ipi messages
 *
 */

/*
 * TODO_rajesh investigate tlb message types.
 * IPI Timer not needed because each ARC has an individual Interrupting Timer
 */
enum ipi_msg_type {
	IPI_NOP = 0,
	IPI_RESCHEDULE = 1,
	IPI_CALL_FUNC,
	IPI_CALL_FUNC_SINGLE,
	IPI_CPU_STOP
};

struct ipi_data {
	unsigned long bits;
};

static DEFINE_PER_CPU(struct ipi_data, ipi_data);

static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
{
	unsigned long flags;
	unsigned int cpu;

	local_irq_save(flags);

	for_each_cpu(cpu, callmap) {
		struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
		set_bit(msg, &ipi->bits);
	}

	/* Call the platform specific cross-CPU call function  */
	if (plat_smp_ops.ipi_send)
		plat_smp_ops.ipi_send((void *)callmap);

	local_irq_restore(flags);
}

void smp_send_reschedule(int cpu)
{
	ipi_send_msg(cpumask_of(cpu), IPI_RESCHEDULE);
}

void smp_send_stop(void)
{
	struct cpumask targets;
	cpumask_copy(&targets, cpu_online_mask);
	cpumask_clear_cpu(smp_processor_id(), &targets);
	ipi_send_msg(&targets, IPI_CPU_STOP);
}

void arch_send_call_function_single_ipi(int cpu)
{
	ipi_send_msg(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
}

void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
	ipi_send_msg(mask, IPI_CALL_FUNC);
}

/*
 * ipi_cpu_stop - handle IPI from smp_send_stop()
 */
static void ipi_cpu_stop(unsigned int cpu)
{
	machine_halt();
}

static inline void __do_IPI(unsigned long *ops, struct ipi_data *ipi, int cpu)
{
	unsigned long msg = 0;

	do {
		msg = find_next_bit(ops, BITS_PER_LONG, msg+1);

		switch (msg) {
		case IPI_RESCHEDULE:
			scheduler_ipi();
			break;

		case IPI_CALL_FUNC:
			generic_smp_call_function_interrupt();
			break;

		case IPI_CALL_FUNC_SINGLE:
			generic_smp_call_function_single_interrupt();
			break;

		case IPI_CPU_STOP:
			ipi_cpu_stop(cpu);
			break;
		}
	} while (msg < BITS_PER_LONG);

}

/*
 * arch-common ISR to handle for inter-processor interrupts
 * Has hooks for platform specific IPI
 */
irqreturn_t do_IPI(int irq, void *dev_id)
{
	int cpu = smp_processor_id();
	struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
	unsigned long ops;

	if (plat_smp_ops.ipi_clear)
		plat_smp_ops.ipi_clear(cpu, irq);

	/*
	 * XXX: is this loop really needed
	 * And do we need to move ipi_clean inside
	 */
	while ((ops = xchg(&ipi->bits, 0)) != 0)
		__do_IPI(&ops, ipi, cpu);

	return IRQ_HANDLED;
}

/*
 * API called by platform code to hookup arch-common ISR to their IPI IRQ
 */
static DEFINE_PER_CPU(int, ipi_dev);
int smp_ipi_irq_setup(int cpu, int irq)
{
	int *dev_id = &per_cpu(ipi_dev, smp_processor_id());
	return request_percpu_irq(irq, do_IPI, "IPI Interrupt", dev_id);
}