smp.c 8.2 KB
Newer Older
V
Vineet Gupta 已提交
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
/*
 * 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>
35
#include <asm/mach_desc.h>
V
Vineet Gupta 已提交
36 37 38 39

arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;

40 41
struct plat_smp_ops  plat_smp_ops;

V
Vineet Gupta 已提交
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
/* 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
 *
 */
98
void __weak arc_platform_smp_wait_to_boot(int cpu)
V
Vineet Gupta 已提交
99 100 101 102 103 104 105 106 107 108 109
{
	/*
	 * 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");
}

110 111 112 113 114
const char *arc_platform_smp_cpuinfo(void)
{
	return plat_smp_ops.info;
}

V
Vineet Gupta 已提交
115 116 117 118 119
/*
 * The very first "C" code executed by secondary
 * Called from asm stub in head.S
 * "current"/R25 already setup by low level boot code
 */
120
void start_kernel_secondary(void)
V
Vineet Gupta 已提交
121 122 123 124 125 126 127 128 129 130
{
	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;
V
Vineet Gupta 已提交
131
	cpumask_set_cpu(cpu, mm_cpumask(mm));
V
Vineet Gupta 已提交
132 133 134 135 136 137

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

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

138 139
	if (machine_desc->init_smp)
		machine_desc->init_smp(smp_processor_id());
V
Vineet Gupta 已提交
140

141
	arc_local_timer_setup();
V
Vineet Gupta 已提交
142 143 144

	local_irq_enable();
	preempt_disable();
T
Thomas Gleixner 已提交
145
	cpu_startup_entry(CPUHP_ONLINE);
V
Vineet Gupta 已提交
146 147 148 149 150 151 152 153 154 155 156 157
}

/*
 * 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)
*/
158
int __cpu_up(unsigned int cpu, struct task_struct *idle)
V
Vineet Gupta 已提交
159 160 161 162 163 164 165 166
{
	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);

167 168
	if (plat_smp_ops.cpu_kick)
		plat_smp_ops.cpu_kick(cpu,
V
Vineet Gupta 已提交
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
				(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                           */
/*****************************************************************************/

enum ipi_msg_type {
V
Vineet Gupta 已提交
201
	IPI_EMPTY = 0,
V
Vineet Gupta 已提交
202 203
	IPI_RESCHEDULE = 1,
	IPI_CALL_FUNC,
V
Vineet Gupta 已提交
204
	IPI_CPU_STOP,
V
Vineet Gupta 已提交
205 206
};

V
Vineet Gupta 已提交
207 208 209 210 211
/*
 * In arches with IRQ for each msg type (above), receiver can use IRQ-id  to
 * figure out what msg was sent. For those which don't (ARC has dedicated IPI
 * IRQ), the msg-type needs to be conveyed via per-cpu data
 */
V
Vineet Gupta 已提交
212

V
Vineet Gupta 已提交
213
static DEFINE_PER_CPU(unsigned long, ipi_data);
V
Vineet Gupta 已提交
214

215
static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg)
V
Vineet Gupta 已提交
216
{
V
Vineet Gupta 已提交
217
	unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu);
218
	unsigned long old, new;
V
Vineet Gupta 已提交
219 220
	unsigned long flags;

V
Vineet Gupta 已提交
221 222
	pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu);

V
Vineet Gupta 已提交
223 224
	local_irq_save(flags);

225 226 227 228 229 230 231 232
	/*
	 * Atomically write new msg bit (in case others are writing too),
	 * and read back old value
	 */
	do {
		new = old = *ipi_data_ptr;
		new |= 1U << msg;
	} while (cmpxchg(ipi_data_ptr, old, new) != old);
V
Vineet Gupta 已提交
233

234 235 236 237 238 239 240 241 242
	/*
	 * Call the platform specific IPI kick function, but avoid if possible:
	 * Only do so if there's no pending msg from other concurrent sender(s).
	 * Otherwise, recevier will see this msg as well when it takes the
	 * IPI corresponding to that msg. This is true, even if it is already in
	 * IPI handler, because !@old means it has not yet dequeued the msg(s)
	 * so @new msg can be a free-loader
	 */
	if (plat_smp_ops.ipi_send && !old)
243
		plat_smp_ops.ipi_send(cpu);
V
Vineet Gupta 已提交
244 245 246 247

	local_irq_restore(flags);
}

248 249 250 251 252 253 254 255
static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
{
	unsigned int cpu;

	for_each_cpu(cpu, callmap)
		ipi_send_msg_one(cpu, msg);
}

V
Vineet Gupta 已提交
256 257
void smp_send_reschedule(int cpu)
{
258
	ipi_send_msg_one(cpu, IPI_RESCHEDULE);
V
Vineet Gupta 已提交
259 260 261 262 263 264 265 266 267 268 269 270
}

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)
{
271
	ipi_send_msg_one(cpu, IPI_CALL_FUNC);
V
Vineet Gupta 已提交
272 273 274 275 276 277 278 279 280 281
}

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()
 */
282
static void ipi_cpu_stop(void)
V
Vineet Gupta 已提交
283 284 285 286
{
	machine_halt();
}

287
static inline void __do_IPI(unsigned long msg)
V
Vineet Gupta 已提交
288
{
289 290 291 292
	switch (msg) {
	case IPI_RESCHEDULE:
		scheduler_ipi();
		break;
V
Vineet Gupta 已提交
293

294 295 296
	case IPI_CALL_FUNC:
		generic_smp_call_function_interrupt();
		break;
V
Vineet Gupta 已提交
297

298 299 300
	case IPI_CPU_STOP:
		ipi_cpu_stop();
		break;
V
Vineet Gupta 已提交
301

302 303
	default:
		pr_warn("IPI with unexpected msg %ld\n", msg);
V
Vineet Gupta 已提交
304
	}
V
Vineet Gupta 已提交
305 306 307 308 309 310 311 312
}

/*
 * arch-common ISR to handle for inter-processor interrupts
 * Has hooks for platform specific IPI
 */
irqreturn_t do_IPI(int irq, void *dev_id)
{
V
Vineet Gupta 已提交
313 314 315 316
	unsigned long pending;

	pr_debug("IPI [%ld] received on cpu %d\n",
		 *this_cpu_ptr(&ipi_data), smp_processor_id());
V
Vineet Gupta 已提交
317

318
	if (plat_smp_ops.ipi_clear)
319
		plat_smp_ops.ipi_clear(irq);
V
Vineet Gupta 已提交
320 321

	/*
322 323
	 * "dequeue" the msg corresponding to this IPI (and possibly other
	 * piggybacked msg from elided IPIs: see ipi_send_msg_one() above)
V
Vineet Gupta 已提交
324
	 */
325 326 327 328 329 330 331
	pending = xchg(this_cpu_ptr(&ipi_data), 0);

	do {
		unsigned long msg = __ffs(pending);
		__do_IPI(msg);
		pending &= ~(1U << msg);
	} while (pending);
V
Vineet Gupta 已提交
332 333 334 335 336 337 338 339

	return IRQ_HANDLED;
}

/*
 * API called by platform code to hookup arch-common ISR to their IPI IRQ
 */
static DEFINE_PER_CPU(int, ipi_dev);
N
Noam Camus 已提交
340 341 342 343 344 345 346

static struct irqaction arc_ipi_irq = {
        .name    = "IPI Interrupt",
        .flags   = IRQF_PERCPU,
        .handler = do_IPI,
};

V
Vineet Gupta 已提交
347 348
int smp_ipi_irq_setup(int cpu, int irq)
{
N
Noam Camus 已提交
349 350 351 352 353 354
	if (!cpu)
		return setup_irq(irq, &arc_ipi_irq);
	else
		arch_unmask_irq(irq);

	return 0;
V
Vineet Gupta 已提交
355
}