aboutsummaryrefslogtreecommitdiffstats
path: root/arch/tile/kernel/smp.c
blob: a4293102ef81b6eaaa52464f66ce7865801775e7 (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
/*
 * Copyright 2010 Tilera Corporation. All Rights Reserved.
 *
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU General Public License
 *   as published by the Free Software Foundation, version 2.
 *
 *   This program is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 *   NON INFRINGEMENT.  See the GNU General Public License for
 *   more details.
 *
 * TILE SMP support routines.
 */

#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <asm/cacheflush.h>

HV_Topology smp_topology __write_once;
EXPORT_SYMBOL(smp_topology);

#if CHIP_HAS_IPI()
static unsigned long __iomem *ipi_mappings[NR_CPUS];
#endif


/*
 * Top-level send_IPI*() functions to send messages to other cpus.
 */

/* Set by smp_send_stop() to avoid recursive panics. */
static int stopping_cpus;

static void __send_IPI_many(HV_Recipient *recip, int nrecip, int tag)
{
	int sent = 0;
	while (sent < nrecip) {
		int rc = hv_send_message(recip, nrecip,
					 (HV_VirtAddr)&tag, sizeof(tag));
		if (rc < 0) {
			if (!stopping_cpus)  /* avoid recursive panic */
				panic("hv_send_message returned %d", rc);
			break;
		}
		WARN_ONCE(rc == 0, "hv_send_message() returned zero\n");
		sent += rc;
	}
}

void send_IPI_single(int cpu, int tag)
{
	HV_Recipient recip = {
		.y = cpu / smp_width,
		.x = cpu % smp_width,
		.state = HV_TO_BE_SENT
	};
	__send_IPI_many(&recip, 1, tag);
}

void send_IPI_many(const struct cpumask *mask, int tag)
{
	HV_Recipient recip[NR_CPUS];
	int cpu;
	int nrecip = 0;
	int my_cpu = smp_processor_id();
	for_each_cpu(cpu, mask) {
		HV_Recipient *r;
		BUG_ON(cpu == my_cpu);
		r = &recip[nrecip++];
		r->y = cpu / smp_width;
		r->x = cpu % smp_width;
		r->state = HV_TO_BE_SENT;
	}
	__send_IPI_many(recip, nrecip, tag);
}

void send_IPI_allbutself(int tag)
{
	struct cpumask mask;
	cpumask_copy(&mask, cpu_online_mask);
	cpumask_clear_cpu(smp_processor_id(), &mask);
	send_IPI_many(&mask, tag);
}


/*
 * Provide smp_call_function_mask, but also run function locally
 * if specified in the mask.
 */
void on_each_cpu_mask(const struct cpumask *mask, void (*func)(void *),
		      void *info, bool wait)
{
	int cpu = get_cpu();
	smp_call_function_many(mask, func, info, wait);
	if (cpumask_test_cpu(cpu, mask)) {
		local_irq_disable();
		func(info);
		local_irq_enable();
	}
	put_cpu();
}


/*
 * Functions related to starting/stopping cpus.
 */

/* Handler to start the current cpu. */
static void smp_start_cpu_interrupt(void)
{
	get_irq_regs()->pc = start_cpu_function_addr;
}

/* Handler to stop the current cpu. */
static void smp_stop_cpu_interrupt(void)
{
	set_cpu_online(smp_processor_id(), 0);
	arch_local_irq_disable_all();
	for (;;)
		asm("nap");
}

/* This function calls the 'stop' function on all other CPUs in the system. */
void smp_send_stop(void)
{
	stopping_cpus = 1;
	send_IPI_allbutself(MSG_TAG_STOP_CPU);
}


/*
 * Dispatch code called from hv_message_intr() for HV_MSG_TILE hv messages.
 */
void evaluate_message(int tag)
{
	switch (tag) {
	case MSG_TAG_START_CPU: /* Start up a cpu */
		smp_start_cpu_interrupt();
		break;

	case MSG_TAG_STOP_CPU: /* Sent to shut down slave CPU's */
		smp_stop_cpu_interrupt();
		break;

	case MSG_TAG_CALL_FUNCTION_MANY: /* Call function on cpumask */
		generic_smp_call_function_interrupt();
		break;

	case MSG_TAG_CALL_FUNCTION_SINGLE: /* Call function on one other CPU */
		generic_smp_call_function_single_interrupt();
		break;

	default:
		panic("Unknown IPI message tag %d", tag);
		break;
	}
}


/*
 * flush_icache_range() code uses smp_call_function().
 */

struct ipi_flush {
	unsigned long start;
	unsigned long end;
};

static void ipi_flush_icache_range(void *info)
{
	struct ipi_flush *flush = (struct ipi_flush *) info;
	__flush_icache_range(flush->start, flush->end);
}

void flush_icache_range(unsigned long start, unsigned long end)
{
	struct ipi_flush flush = { start, end };
	preempt_disable();
	on_each_cpu(ipi_flush_icache_range, &flush, 1);
	preempt_enable();
}


/* Called when smp_send_reschedule() triggers IRQ_RESCHEDULE. */
static irqreturn_t handle_reschedule_ipi(int irq, void *token)
{
	/*
	 * Nothing to do here; when we return from interrupt, the
	 * rescheduling will occur there. But do bump the interrupt
	 * profiler count in the meantime.
	 */
	__get_cpu_var(irq_stat).irq_resched_count++;

	return IRQ_HANDLED;
}

static struct irqaction resched_action = {
	.handler = handle_reschedule_ipi,
	.name = "resched",
	.dev_id = handle_reschedule_ipi /* unique token */,
};

void __init ipi_init(void)
{
#if CHIP_HAS_IPI()
	int cpu;
	/* Map IPI trigger MMIO addresses. */
	for_each_possible_cpu(cpu) {
		HV_Coord tile;
		HV_PTE pte;
		unsigned long offset;

		tile.x = cpu_x(cpu);
		tile.y = cpu_y(cpu);
		if (hv_get_ipi_pte(tile, KERNEL_PL, &pte) != 0)
			panic("Failed to initialize IPI for cpu %d\n", cpu);

		offset = hv_pte_get_pfn(pte) << PAGE_SHIFT;
		ipi_mappings[cpu] = ioremap_prot(offset, PAGE_SIZE, pte);
	}
#endif

	/* Bind handle_reschedule_ipi() to IRQ_RESCHEDULE. */
	tile_irq_activate(IRQ_RESCHEDULE, TILE_IRQ_PERCPU);
	BUG_ON(setup_irq(IRQ_RESCHEDULE, &resched_action));
}

#if CHIP_HAS_IPI()

void smp_send_reschedule(int cpu)
{
	WARN_ON(cpu_is_offline(cpu));

	/*
	 * We just want to do an MMIO store.  The traditional writeq()
	 * functions aren't really correct here, since they're always
	 * directed at the PCI shim.  For now, just do a raw store,
	 * casting away the __iomem attribute.
	 */
	((unsigned long __force *)ipi_mappings[cpu])[IRQ_RESCHEDULE] = 0;
}

#else

void smp_send_reschedule(int cpu)
{
	HV_Coord coord;

	WARN_ON(cpu_is_offline(cpu));

	coord.y = cpu_y(cpu);
	coord.x = cpu_x(cpu);
	hv_trigger_ipi(coord, IRQ_RESCHEDULE);
}

#endif /* CHIP_HAS_IPI() */