1/*
2** SMP Support
3**
4** Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
5** Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
6** Copyright (C) 2001,2004 Grant Grundler <grundler@parisc-linux.org>
7**
8** Lots of stuff stolen from arch/alpha/kernel/smp.c
9** ...and then parisc stole from arch/ia64/kernel/smp.c. Thanks David! :^)
10**
11** Thanks to John Curry and Ullas Ponnadi. I learned a lot from their work.
12** -grant (1/12/2001)
13**
14**	This program is free software; you can redistribute it and/or modify
15**	it under the terms of the GNU General Public License as published by
16**      the Free Software Foundation; either version 2 of the License, or
17**      (at your option) any later version.
18*/
19#include <linux/types.h>
20#include <linux/spinlock.h>
21
22#include <linux/kernel.h>
23#include <linux/module.h>
24#include <linux/sched.h>
25#include <linux/init.h>
26#include <linux/interrupt.h>
27#include <linux/smp.h>
28#include <linux/kernel_stat.h>
29#include <linux/mm.h>
30#include <linux/err.h>
31#include <linux/delay.h>
32#include <linux/bitops.h>
33#include <linux/ftrace.h>
34#include <linux/cpu.h>
35
36#include <linux/atomic.h>
37#include <asm/current.h>
38#include <asm/delay.h>
39#include <asm/tlbflush.h>
40
41#include <asm/io.h>
42#include <asm/irq.h>		/* for CPU_IRQ_REGION and friends */
43#include <asm/mmu_context.h>
44#include <asm/page.h>
45#include <asm/pgtable.h>
46#include <asm/pgalloc.h>
47#include <asm/processor.h>
48#include <asm/ptrace.h>
49#include <asm/unistd.h>
50#include <asm/cacheflush.h>
51
52#undef DEBUG_SMP
53#ifdef DEBUG_SMP
54static int smp_debug_lvl = 0;
55#define smp_debug(lvl, printargs...)		\
56		if (lvl >= smp_debug_lvl)	\
57			printk(printargs);
58#else
59#define smp_debug(lvl, ...)	do { } while(0)
60#endif /* DEBUG_SMP */
61
62volatile struct task_struct *smp_init_current_idle_task;
63
64/* track which CPU is booting */
65static volatile int cpu_now_booting;
66
67static int parisc_max_cpus = 1;
68
69static DEFINE_PER_CPU(spinlock_t, ipi_lock);
70
71enum ipi_message_type {
72	IPI_NOP=0,
73	IPI_RESCHEDULE=1,
74	IPI_CALL_FUNC,
75	IPI_CPU_START,
76	IPI_CPU_STOP,
77	IPI_CPU_TEST
78};
79
80
81/********** SMP inter processor interrupt and communication routines */
82
83#undef PER_CPU_IRQ_REGION
84#ifdef PER_CPU_IRQ_REGION
85/* XXX REVISIT Ignore for now.
86**    *May* need this "hook" to register IPI handler
87**    once we have perCPU ExtIntr switch tables.
88*/
89static void
90ipi_init(int cpuid)
91{
92#error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region
93
94	if(cpu_online(cpuid) )
95	{
96		switch_to_idle_task(current);
97	}
98
99	return;
100}
101#endif
102
103
104/*
105** Yoink this CPU from the runnable list...
106**
107*/
108static void
109halt_processor(void)
110{
111	/* REVISIT : redirect I/O Interrupts to another CPU? */
112	/* REVISIT : does PM *know* this CPU isn't available? */
113	set_cpu_online(smp_processor_id(), false);
114	local_irq_disable();
115	for (;;)
116		;
117}
118
119
120irqreturn_t __irq_entry
121ipi_interrupt(int irq, void *dev_id)
122{
123	int this_cpu = smp_processor_id();
124	struct cpuinfo_parisc *p = &per_cpu(cpu_data, this_cpu);
125	unsigned long ops;
126	unsigned long flags;
127
128	for (;;) {
129		spinlock_t *lock = &per_cpu(ipi_lock, this_cpu);
130		spin_lock_irqsave(lock, flags);
131		ops = p->pending_ipi;
132		p->pending_ipi = 0;
133		spin_unlock_irqrestore(lock, flags);
134
135		mb(); /* Order bit clearing and data access. */
136
137		if (!ops)
138		    break;
139
140		while (ops) {
141			unsigned long which = ffz(~ops);
142
143			ops &= ~(1 << which);
144
145			switch (which) {
146			case IPI_NOP:
147				smp_debug(100, KERN_DEBUG "CPU%d IPI_NOP\n", this_cpu);
148				break;
149
150			case IPI_RESCHEDULE:
151				smp_debug(100, KERN_DEBUG "CPU%d IPI_RESCHEDULE\n", this_cpu);
152				inc_irq_stat(irq_resched_count);
153				scheduler_ipi();
154				break;
155
156			case IPI_CALL_FUNC:
157				smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC\n", this_cpu);
158				generic_smp_call_function_interrupt();
159				break;
160
161			case IPI_CPU_START:
162				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_START\n", this_cpu);
163				break;
164
165			case IPI_CPU_STOP:
166				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_STOP\n", this_cpu);
167				halt_processor();
168				break;
169
170			case IPI_CPU_TEST:
171				smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
172				break;
173
174			default:
175				printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
176					this_cpu, which);
177				return IRQ_NONE;
178			} /* Switch */
179		/* let in any pending interrupts */
180		local_irq_enable();
181		local_irq_disable();
182		} /* while (ops) */
183	}
184	return IRQ_HANDLED;
185}
186
187
188static inline void
189ipi_send(int cpu, enum ipi_message_type op)
190{
191	struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpu);
192	spinlock_t *lock = &per_cpu(ipi_lock, cpu);
193	unsigned long flags;
194
195	spin_lock_irqsave(lock, flags);
196	p->pending_ipi |= 1 << op;
197	gsc_writel(IPI_IRQ - CPU_IRQ_BASE, p->hpa);
198	spin_unlock_irqrestore(lock, flags);
199}
200
201static void
202send_IPI_mask(const struct cpumask *mask, enum ipi_message_type op)
203{
204	int cpu;
205
206	for_each_cpu(cpu, mask)
207		ipi_send(cpu, op);
208}
209
210static inline void
211send_IPI_single(int dest_cpu, enum ipi_message_type op)
212{
213	BUG_ON(dest_cpu == NO_PROC_ID);
214
215	ipi_send(dest_cpu, op);
216}
217
218static inline void
219send_IPI_allbutself(enum ipi_message_type op)
220{
221	int i;
222
223	for_each_online_cpu(i) {
224		if (i != smp_processor_id())
225			send_IPI_single(i, op);
226	}
227}
228
229
230inline void
231smp_send_stop(void)	{ send_IPI_allbutself(IPI_CPU_STOP); }
232
233void
234smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }
235
236void
237smp_send_all_nop(void)
238{
239	send_IPI_allbutself(IPI_NOP);
240}
241
242void arch_send_call_function_ipi_mask(const struct cpumask *mask)
243{
244	send_IPI_mask(mask, IPI_CALL_FUNC);
245}
246
247void arch_send_call_function_single_ipi(int cpu)
248{
249	send_IPI_single(cpu, IPI_CALL_FUNC);
250}
251
252/*
253 * Called by secondaries to update state and initialize CPU registers.
254 */
255static void __init
256smp_cpu_init(int cpunum)
257{
258	extern int init_per_cpu(int);  /* arch/parisc/kernel/processor.c */
259	extern void init_IRQ(void);    /* arch/parisc/kernel/irq.c */
260	extern void start_cpu_itimer(void); /* arch/parisc/kernel/time.c */
261
262	/* Set modes and Enable floating point coprocessor */
263	(void) init_per_cpu(cpunum);
264
265	disable_sr_hashing();
266
267	mb();
268
269	/* Well, support 2.4 linux scheme as well. */
270	if (cpu_online(cpunum))	{
271		extern void machine_halt(void); /* arch/parisc.../process.c */
272
273		printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
274		machine_halt();
275	}
276
277	notify_cpu_starting(cpunum);
278
279	set_cpu_online(cpunum, true);
280
281	/* Initialise the idle task for this CPU */
282	atomic_inc(&init_mm.mm_count);
283	current->active_mm = &init_mm;
284	BUG_ON(current->mm);
285	enter_lazy_tlb(&init_mm, current);
286
287	init_IRQ();   /* make sure no IRQs are enabled or pending */
288	start_cpu_itimer();
289}
290
291
292/*
293 * Slaves start using C here. Indirectly called from smp_slave_stext.
294 * Do what start_kernel() and main() do for boot strap processor (aka monarch)
295 */
296void __init smp_callin(void)
297{
298	int slave_id = cpu_now_booting;
299
300	smp_cpu_init(slave_id);
301	preempt_disable();
302
303	flush_cache_all_local(); /* start with known state */
304	flush_tlb_all_local(NULL);
305
306	local_irq_enable();  /* Interrupts have been off until now */
307
308	cpu_startup_entry(CPUHP_ONLINE);
309
310	/* NOTREACHED */
311	panic("smp_callin() AAAAaaaaahhhh....\n");
312}
313
314/*
315 * Bring one cpu online.
316 */
317int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
318{
319	const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
320	long timeout;
321
322	task_thread_info(idle)->cpu = cpuid;
323
324	/* Let _start know what logical CPU we're booting
325	** (offset into init_tasks[],cpu_data[])
326	*/
327	cpu_now_booting = cpuid;
328
329	/*
330	** boot strap code needs to know the task address since
331	** it also contains the process stack.
332	*/
333	smp_init_current_idle_task = idle ;
334	mb();
335
336	printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);
337
338	/*
339	** This gets PDC to release the CPU from a very tight loop.
340	**
341	** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
342	** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which
343	** is executed after receiving the rendezvous signal (an interrupt to
344	** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the
345	** contents of memory are valid."
346	*/
347	gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
348	mb();
349
350	/*
351	 * OK, wait a bit for that CPU to finish staggering about.
352	 * Slave will set a bit when it reaches smp_cpu_init().
353	 * Once the "monarch CPU" sees the bit change, it can move on.
354	 */
355	for (timeout = 0; timeout < 10000; timeout++) {
356		if(cpu_online(cpuid)) {
357			/* Which implies Slave has started up */
358			cpu_now_booting = 0;
359			smp_init_current_idle_task = NULL;
360			goto alive ;
361		}
362		udelay(100);
363		barrier();
364	}
365	printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
366	return -1;
367
368alive:
369	/* Remember the Slave data */
370	smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
371		cpuid, timeout * 100);
372	return 0;
373}
374
375void __init smp_prepare_boot_cpu(void)
376{
377	int bootstrap_processor = per_cpu(cpu_data, 0).cpuid;
378
379	/* Setup BSP mappings */
380	printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor);
381
382	set_cpu_online(bootstrap_processor, true);
383	set_cpu_present(bootstrap_processor, true);
384}
385
386
387
388/*
389** inventory.c:do_inventory() hasn't yet been run and thus we
390** don't 'discover' the additional CPUs until later.
391*/
392void __init smp_prepare_cpus(unsigned int max_cpus)
393{
394	int cpu;
395
396	for_each_possible_cpu(cpu)
397		spin_lock_init(&per_cpu(ipi_lock, cpu));
398
399	init_cpu_present(cpumask_of(0));
400
401	parisc_max_cpus = max_cpus;
402	if (!max_cpus)
403		printk(KERN_INFO "SMP mode deactivated.\n");
404}
405
406
407void smp_cpus_done(unsigned int cpu_max)
408{
409	return;
410}
411
412
413int __cpu_up(unsigned int cpu, struct task_struct *tidle)
414{
415	if (cpu != 0 && cpu < parisc_max_cpus)
416		smp_boot_one_cpu(cpu, tidle);
417
418	return cpu_online(cpu) ? 0 : -ENOSYS;
419}
420
421#ifdef CONFIG_PROC_FS
422int __init
423setup_profiling_timer(unsigned int multiplier)
424{
425	return -EINVAL;
426}
427#endif
428