1/*
  2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
  3 *
  4 *   This program is free software; you can redistribute it and/or
  5 *   modify it under the terms of the GNU General Public License
  6 *   as published by the Free Software Foundation, version 2.
  7 *
  8 *   This program is distributed in the hope that it will be useful, but
  9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 11 *   NON INFRINGEMENT.  See the GNU General Public License for
 12 *   more details.
 13 *
 14 * TILE SMP support routines.
 15 */
 16
 17#include <linux/smp.h>
 18#include <linux/interrupt.h>
 19#include <linux/io.h>
 20#include <linux/irq.h>
 21#include <linux/module.h>
 22#include <asm/cacheflush.h>
 23
 24HV_Topology smp_topology __write_once;
 25EXPORT_SYMBOL(smp_topology);
 26
 27#if CHIP_HAS_IPI()
 28static unsigned long __iomem *ipi_mappings[NR_CPUS];
 29#endif
 30
 31
 32/*
 33 * Top-level send_IPI*() functions to send messages to other cpus.
 34 */
 35
 36/* Set by smp_send_stop() to avoid recursive panics. */
 37static int stopping_cpus;
 38
 39static void __send_IPI_many(HV_Recipient *recip, int nrecip, int tag)
 40{
 41	int sent = 0;
 42	while (sent < nrecip) {
 43		int rc = hv_send_message(recip, nrecip,
 44					 (HV_VirtAddr)&tag, sizeof(tag));
 45		if (rc < 0) {
 46			if (!stopping_cpus)  /* avoid recursive panic */
 47				panic("hv_send_message returned %d", rc);
 48			break;
 49		}
 50		WARN_ONCE(rc == 0, "hv_send_message() returned zero\n");
 51		sent += rc;
 52	}
 53}
 54
 55void send_IPI_single(int cpu, int tag)
 56{
 57	HV_Recipient recip = {
 58		.y = cpu / smp_width,
 59		.x = cpu % smp_width,
 60		.state = HV_TO_BE_SENT
 61	};
 62	__send_IPI_many(&recip, 1, tag);
 63}
 64
 65void send_IPI_many(const struct cpumask *mask, int tag)
 66{
 67	HV_Recipient recip[NR_CPUS];
 68	int cpu;
 69	int nrecip = 0;
 70	int my_cpu = smp_processor_id();
 71	for_each_cpu(cpu, mask) {
 72		HV_Recipient *r;
 73		BUG_ON(cpu == my_cpu);
 74		r = &recip[nrecip++];
 75		r->y = cpu / smp_width;
 76		r->x = cpu % smp_width;
 77		r->state = HV_TO_BE_SENT;
 78	}
 79	__send_IPI_many(recip, nrecip, tag);
 80}
 81
 82void send_IPI_allbutself(int tag)
 83{
 84	struct cpumask mask;
 85	cpumask_copy(&mask, cpu_online_mask);
 86	cpumask_clear_cpu(smp_processor_id(), &mask);
 87	send_IPI_many(&mask, tag);
 88}
 89
 90/*
 91 * Functions related to starting/stopping cpus.
 92 */
 93
 94/* Handler to start the current cpu. */
 95static void smp_start_cpu_interrupt(void)
 96{
 97	get_irq_regs()->pc = start_cpu_function_addr;
 98}
 99
100/* Handler to stop the current cpu. */
101static void smp_stop_cpu_interrupt(void)
102{
103	set_cpu_online(smp_processor_id(), 0);
104	arch_local_irq_disable_all();
105	for (;;)
106		asm("nap; nop");
107}
108
109/* This function calls the 'stop' function on all other CPUs in the system. */
110void smp_send_stop(void)
111{
112	stopping_cpus = 1;
113	send_IPI_allbutself(MSG_TAG_STOP_CPU);
114}
115
116/* On panic, just wait; we may get an smp_send_stop() later on. */
117void panic_smp_self_stop(void)
118{
119	while (1)
120		asm("nap; nop");
121}
122
123/*
124 * Dispatch code called from hv_message_intr() for HV_MSG_TILE hv messages.
125 */
126void evaluate_message(int tag)
127{
128	switch (tag) {
129	case MSG_TAG_START_CPU: /* Start up a cpu */
130		smp_start_cpu_interrupt();
131		break;
132
133	case MSG_TAG_STOP_CPU: /* Sent to shut down slave CPU's */
134		smp_stop_cpu_interrupt();
135		break;
136
137	case MSG_TAG_CALL_FUNCTION_MANY: /* Call function on cpumask */
138		generic_smp_call_function_interrupt();
139		break;
140
141	case MSG_TAG_CALL_FUNCTION_SINGLE: /* Call function on one other CPU */
142		generic_smp_call_function_single_interrupt();
143		break;
144
145	default:
146		panic("Unknown IPI message tag %d", tag);
147		break;
148	}
149}
150
151
152/*
153 * flush_icache_range() code uses smp_call_function().
154 */
155
156struct ipi_flush {
157	unsigned long start;
158	unsigned long end;
159};
160
161static void ipi_flush_icache_range(void *info)
162{
163	struct ipi_flush *flush = (struct ipi_flush *) info;
164	__flush_icache_range(flush->start, flush->end);
165}
166
167void flush_icache_range(unsigned long start, unsigned long end)
168{
169	struct ipi_flush flush = { start, end };
170	preempt_disable();
171	on_each_cpu(ipi_flush_icache_range, &flush, 1);
172	preempt_enable();
173}
174
175
176/* Called when smp_send_reschedule() triggers IRQ_RESCHEDULE. */
177static irqreturn_t handle_reschedule_ipi(int irq, void *token)
178{
179	__get_cpu_var(irq_stat).irq_resched_count++;
180	scheduler_ipi();
181
182	return IRQ_HANDLED;
183}
184
185static struct irqaction resched_action = {
186	.handler = handle_reschedule_ipi,
187	.name = "resched",
188	.dev_id = handle_reschedule_ipi /* unique token */,
189};
190
191void __init ipi_init(void)
192{
193#if CHIP_HAS_IPI()
194	int cpu;
195	/* Map IPI trigger MMIO addresses. */
196	for_each_possible_cpu(cpu) {
197		HV_Coord tile;
198		HV_PTE pte;
199		unsigned long offset;
200
201		tile.x = cpu_x(cpu);
202		tile.y = cpu_y(cpu);
203		if (hv_get_ipi_pte(tile, KERNEL_PL, &pte) != 0)
204			panic("Failed to initialize IPI for cpu %d\n", cpu);
205
206		offset = PFN_PHYS(pte_pfn(pte));
207		ipi_mappings[cpu] = ioremap_prot(offset, PAGE_SIZE, pte);
208	}
209#endif
210
211	/* Bind handle_reschedule_ipi() to IRQ_RESCHEDULE. */
212	tile_irq_activate(IRQ_RESCHEDULE, TILE_IRQ_PERCPU);
213	BUG_ON(setup_irq(IRQ_RESCHEDULE, &resched_action));
214}
215
216#if CHIP_HAS_IPI()
217
218void smp_send_reschedule(int cpu)
219{
220	WARN_ON(cpu_is_offline(cpu));
221
222	/*
223	 * We just want to do an MMIO store.  The traditional writeq()
224	 * functions aren't really correct here, since they're always
225	 * directed at the PCI shim.  For now, just do a raw store,
226	 * casting away the __iomem attribute.
227	 */
228	((unsigned long __force *)ipi_mappings[cpu])[IRQ_RESCHEDULE] = 0;
229}
230
231#else
232
233void smp_send_reschedule(int cpu)
234{
235	HV_Coord coord;
236
237	WARN_ON(cpu_is_offline(cpu));
238
239	coord.y = cpu_y(cpu);
240	coord.x = cpu_x(cpu);
241	hv_trigger_ipi(coord, IRQ_RESCHEDULE);
242}
243
244#endif /* CHIP_HAS_IPI() */