smp.c revision 10b1271875abb9d590c14fa6c8b24b0d6f768ca2 
1/*
2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * RajeshwarR: Dec 11, 2007
9 *   -- Added support for Inter Processor Interrupts
10 *
11 * Vineetg: Nov 1st, 2007
12 *    -- Initial Write (Borrowed heavily from ARM)
13 */
14
15#include <linux/module.h>
16#include <linux/init.h>
17#include <linux/spinlock.h>
18#include <linux/sched.h>
19#include <linux/interrupt.h>
20#include <linux/profile.h>
21#include <linux/errno.h>
22#include <linux/err.h>
23#include <linux/mm.h>
24#include <linux/cpu.h>
25#include <linux/smp.h>
26#include <linux/irq.h>
27#include <linux/delay.h>
28#include <linux/atomic.h>
29#include <linux/percpu.h>
30#include <linux/cpumask.h>
31#include <linux/spinlock_types.h>
32#include <linux/reboot.h>
33#include <asm/processor.h>
34#include <asm/setup.h>
35#include <asm/mach_desc.h>
36
37arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
38arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
39
40struct plat_smp_ops  plat_smp_ops;
41
42/* XXX: per cpu ? Only needed once in early seconday boot */
43struct task_struct *secondary_idle_tsk;
44
45/* Called from start_kernel */
46void __init smp_prepare_boot_cpu(void)
47{
48}
49
50/*
51 * Initialise the CPU possible map early - this describes the CPUs
52 * which may be present or become present in the system.
53 */
54void __init smp_init_cpus(void)
55{
56	unsigned int i;
57
58	for (i = 0; i < NR_CPUS; i++)
59		set_cpu_possible(i, true);
60}
61
62/* called from init ( ) =>  process 1 */
63void __init smp_prepare_cpus(unsigned int max_cpus)
64{
65	int i;
66
67	/*
68	 * Initialise the present map, which describes the set of CPUs
69	 * actually populated at the present time.
70	 */
71	for (i = 0; i < max_cpus; i++)
72		set_cpu_present(i, true);
73}
74
75void __init smp_cpus_done(unsigned int max_cpus)
76{
77
78}
79
80/*
81 * After power-up, a non Master CPU needs to wait for Master to kick start it
82 *
83 * The default implementation halts
84 *
85 * This relies on platform specific support allowing Master to directly set
86 * this CPU's PC (to be @first_lines_of_secondary() and kick start it.
87 *
88 * In lack of such h/w assist, platforms can override this function
89 *   - make this function busy-spin on a token, eventually set by Master
90 *     (from arc_platform_smp_wakeup_cpu())
91 *   - Once token is available, jump to @first_lines_of_secondary
92 *     (using inline asm).
93 *
94 * Alert: can NOT use stack here as it has not been determined/setup for CPU.
95 *        If it turns out to be elaborate, it's better to code it in assembly
96 *
97 */
98void __attribute__((weak)) arc_platform_smp_wait_to_boot(int cpu)
99{
100	/*
101	 * As a hack for debugging - since debugger will single-step over the
102	 * FLAG insn - wrap the halt itself it in a self loop
103	 */
104	__asm__ __volatile__(
105	"1:		\n"
106	"	flag 1	\n"
107	"	b 1b	\n");
108}
109
110const char *arc_platform_smp_cpuinfo(void)
111{
112	return plat_smp_ops.info;
113}
114
115/*
116 * The very first "C" code executed by secondary
117 * Called from asm stub in head.S
118 * "current"/R25 already setup by low level boot code
119 */
120void __cpuinit start_kernel_secondary(void)
121{
122	struct mm_struct *mm = &init_mm;
123	unsigned int cpu = smp_processor_id();
124
125	/* MMU, Caches, Vector Table, Interrupts etc */
126	setup_processor();
127
128	atomic_inc(&mm->mm_users);
129	atomic_inc(&mm->mm_count);
130	current->active_mm = mm;
131
132	notify_cpu_starting(cpu);
133	set_cpu_online(cpu, true);
134
135	pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu);
136
137	if (machine_desc->init_smp)
138		machine_desc->init_smp(smp_processor_id());
139
140	arc_local_timer_setup(cpu);
141
142	local_irq_enable();
143	preempt_disable();
144	cpu_idle();
145}
146
147/*
148 * Called from kernel_init( ) -> smp_init( ) - for each CPU
149 *
150 * At this point, Secondary Processor  is "HALT"ed:
151 *  -It booted, but was halted in head.S
152 *  -It was configured to halt-on-reset
153 *  So need to wake it up.
154 *
155 * Essential requirements being where to run from (PC) and stack (SP)
156*/
157int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *idle)
158{
159	unsigned long wait_till;
160
161	secondary_idle_tsk = idle;
162
163	pr_info("Idle Task [%d] %p", cpu, idle);
164	pr_info("Trying to bring up CPU%u ...\n", cpu);
165
166	if (plat_smp_ops.cpu_kick)
167		plat_smp_ops.cpu_kick(cpu,
168				(unsigned long)first_lines_of_secondary);
169
170	/* wait for 1 sec after kicking the secondary */
171	wait_till = jiffies + HZ;
172	while (time_before(jiffies, wait_till)) {
173		if (cpu_online(cpu))
174			break;
175	}
176
177	if (!cpu_online(cpu)) {
178		pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu);
179		return -1;
180	}
181
182	secondary_idle_tsk = NULL;
183
184	return 0;
185}
186
187/*
188 * not supported here
189 */
190int __init setup_profiling_timer(unsigned int multiplier)
191{
192	return -EINVAL;
193}
194
195/*****************************************************************************/
196/*              Inter Processor Interrupt Handling                           */
197/*****************************************************************************/
198
199/*
200 * structures for inter-processor calls
201 * A Collection of single bit ipi messages
202 *
203 */
204
205/*
206 * TODO_rajesh investigate tlb message types.
207 * IPI Timer not needed because each ARC has an individual Interrupting Timer
208 */
209enum ipi_msg_type {
210	IPI_NOP = 0,
211	IPI_RESCHEDULE = 1,
212	IPI_CALL_FUNC,
213	IPI_CALL_FUNC_SINGLE,
214	IPI_CPU_STOP
215};
216
217struct ipi_data {
218	unsigned long bits;
219};
220
221static DEFINE_PER_CPU(struct ipi_data, ipi_data);
222
223static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
224{
225	unsigned long flags;
226	unsigned int cpu;
227
228	local_irq_save(flags);
229
230	for_each_cpu(cpu, callmap) {
231		struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
232		set_bit(msg, &ipi->bits);
233	}
234
235	/* Call the platform specific cross-CPU call function  */
236	if (plat_smp_ops.ipi_send)
237		plat_smp_ops.ipi_send((void *)callmap);
238
239	local_irq_restore(flags);
240}
241
242void smp_send_reschedule(int cpu)
243{
244	ipi_send_msg(cpumask_of(cpu), IPI_RESCHEDULE);
245}
246
247void smp_send_stop(void)
248{
249	struct cpumask targets;
250	cpumask_copy(&targets, cpu_online_mask);
251	cpumask_clear_cpu(smp_processor_id(), &targets);
252	ipi_send_msg(&targets, IPI_CPU_STOP);
253}
254
255void arch_send_call_function_single_ipi(int cpu)
256{
257	ipi_send_msg(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
258}
259
260void arch_send_call_function_ipi_mask(const struct cpumask *mask)
261{
262	ipi_send_msg(mask, IPI_CALL_FUNC);
263}
264
265/*
266 * ipi_cpu_stop - handle IPI from smp_send_stop()
267 */
268static void ipi_cpu_stop(unsigned int cpu)
269{
270	machine_halt();
271}
272
273static inline void __do_IPI(unsigned long *ops, struct ipi_data *ipi, int cpu)
274{
275	unsigned long msg = 0;
276
277	do {
278		msg = find_next_bit(ops, BITS_PER_LONG, msg+1);
279
280		switch (msg) {
281		case IPI_RESCHEDULE:
282			scheduler_ipi();
283			break;
284
285		case IPI_CALL_FUNC:
286			generic_smp_call_function_interrupt();
287			break;
288
289		case IPI_CALL_FUNC_SINGLE:
290			generic_smp_call_function_single_interrupt();
291			break;
292
293		case IPI_CPU_STOP:
294			ipi_cpu_stop(cpu);
295			break;
296		}
297	} while (msg < BITS_PER_LONG);
298
299}
300
301/*
302 * arch-common ISR to handle for inter-processor interrupts
303 * Has hooks for platform specific IPI
304 */
305irqreturn_t do_IPI(int irq, void *dev_id)
306{
307	int cpu = smp_processor_id();
308	struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
309	unsigned long ops;
310
311	if (plat_smp_ops.ipi_clear)
312		plat_smp_ops.ipi_clear(cpu, irq);
313
314	/*
315	 * XXX: is this loop really needed
316	 * And do we need to move ipi_clean inside
317	 */
318	while ((ops = xchg(&ipi->bits, 0)) != 0)
319		__do_IPI(&ops, ipi, cpu);
320
321	return IRQ_HANDLED;
322}
323
324/*
325 * API called by platform code to hookup arch-common ISR to their IPI IRQ
326 */
327static DEFINE_PER_CPU(int, ipi_dev);
328int smp_ipi_irq_setup(int cpu, int irq)
329{
330	int *dev_id = &per_cpu(ipi_dev, smp_processor_id());
331	return request_percpu_irq(irq, do_IPI, "IPI Interrupt", dev_id);
332}
333