1/*
2 * Copyright 2011 IBM Corporation.
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; either version
7 *  2 of the License, or (at your option) any later version.
8 *
9 */
10#include <linux/types.h>
11#include <linux/threads.h>
12#include <linux/kernel.h>
13#include <linux/irq.h>
14#include <linux/debugfs.h>
15#include <linux/smp.h>
16#include <linux/interrupt.h>
17#include <linux/seq_file.h>
18#include <linux/init.h>
19#include <linux/cpu.h>
20#include <linux/of.h>
21#include <linux/slab.h>
22#include <linux/spinlock.h>
23
24#include <asm/prom.h>
25#include <asm/io.h>
26#include <asm/smp.h>
27#include <asm/machdep.h>
28#include <asm/irq.h>
29#include <asm/errno.h>
30#include <asm/rtas.h>
31#include <asm/xics.h>
32#include <asm/firmware.h>
33
34/* Globals common to all ICP/ICS implementations */
35const struct icp_ops	*icp_ops;
36
37unsigned int xics_default_server		= 0xff;
38unsigned int xics_default_distrib_server	= 0;
39unsigned int xics_interrupt_server_size		= 8;
40
41DEFINE_PER_CPU(struct xics_cppr, xics_cppr);
42
43struct irq_domain *xics_host;
44
45static LIST_HEAD(ics_list);
46
47void xics_update_irq_servers(void)
48{
49	int i, j;
50	struct device_node *np;
51	u32 ilen;
52	const __be32 *ireg;
53	u32 hcpuid;
54
55	/* Find the server numbers for the boot cpu. */
56	np = of_get_cpu_node(boot_cpuid, NULL);
57	BUG_ON(!np);
58
59	hcpuid = get_hard_smp_processor_id(boot_cpuid);
60	xics_default_server = xics_default_distrib_server = hcpuid;
61
62	pr_devel("xics: xics_default_server = 0x%x\n", xics_default_server);
63
64	ireg = of_get_property(np, "ibm,ppc-interrupt-gserver#s", &ilen);
65	if (!ireg) {
66		of_node_put(np);
67		return;
68	}
69
70	i = ilen / sizeof(int);
71
72	/* Global interrupt distribution server is specified in the last
73	 * entry of "ibm,ppc-interrupt-gserver#s" property. Get the last
74	 * entry fom this property for current boot cpu id and use it as
75	 * default distribution server
76	 */
77	for (j = 0; j < i; j += 2) {
78		if (be32_to_cpu(ireg[j]) == hcpuid) {
79			xics_default_distrib_server = be32_to_cpu(ireg[j+1]);
80			break;
81		}
82	}
83	pr_devel("xics: xics_default_distrib_server = 0x%x\n",
84		 xics_default_distrib_server);
85	of_node_put(np);
86}
87
88/* GIQ stuff, currently only supported on RTAS setups, will have
89 * to be sorted properly for bare metal
90 */
91void xics_set_cpu_giq(unsigned int gserver, unsigned int join)
92{
93#ifdef CONFIG_PPC_RTAS
94	int index;
95	int status;
96
97	if (!rtas_indicator_present(GLOBAL_INTERRUPT_QUEUE, NULL))
98		return;
99
100	index = (1UL << xics_interrupt_server_size) - 1 - gserver;
101
102	status = rtas_set_indicator_fast(GLOBAL_INTERRUPT_QUEUE, index, join);
103
104	WARN(status < 0, "set-indicator(%d, %d, %u) returned %d\n",
105	     GLOBAL_INTERRUPT_QUEUE, index, join, status);
106#endif
107}
108
109void xics_setup_cpu(void)
110{
111	icp_ops->set_priority(LOWEST_PRIORITY);
112
113	xics_set_cpu_giq(xics_default_distrib_server, 1);
114}
115
116void xics_mask_unknown_vec(unsigned int vec)
117{
118	struct ics *ics;
119
120	pr_err("Interrupt 0x%x (real) is invalid, disabling it.\n", vec);
121
122	list_for_each_entry(ics, &ics_list, link)
123		ics->mask_unknown(ics, vec);
124}
125
126
127#ifdef CONFIG_SMP
128
129static void xics_request_ipi(void)
130{
131	unsigned int ipi;
132
133	ipi = irq_create_mapping(xics_host, XICS_IPI);
134	BUG_ON(ipi == NO_IRQ);
135
136	/*
137	 * IPIs are marked IRQF_PERCPU. The handler was set in map.
138	 */
139	BUG_ON(request_irq(ipi, icp_ops->ipi_action,
140			   IRQF_PERCPU | IRQF_NO_THREAD, "IPI", NULL));
141}
142
143void __init xics_smp_probe(void)
144{
145	/* Setup cause_ipi callback  based on which ICP is used */
146	smp_ops->cause_ipi = icp_ops->cause_ipi;
147
148	/* Register all the IPIs */
149	xics_request_ipi();
150}
151
152#endif /* CONFIG_SMP */
153
154void xics_teardown_cpu(void)
155{
156	struct xics_cppr *os_cppr = this_cpu_ptr(&xics_cppr);
157
158	/*
159	 * we have to reset the cppr index to 0 because we're
160	 * not going to return from the IPI
161	 */
162	os_cppr->index = 0;
163	icp_ops->set_priority(0);
164	icp_ops->teardown_cpu();
165}
166
167void xics_kexec_teardown_cpu(int secondary)
168{
169	xics_teardown_cpu();
170
171	icp_ops->flush_ipi();
172
173	/*
174	 * Some machines need to have at least one cpu in the GIQ,
175	 * so leave the master cpu in the group.
176	 */
177	if (secondary)
178		xics_set_cpu_giq(xics_default_distrib_server, 0);
179}
180
181
182#ifdef CONFIG_HOTPLUG_CPU
183
184/* Interrupts are disabled. */
185void xics_migrate_irqs_away(void)
186{
187	int cpu = smp_processor_id(), hw_cpu = hard_smp_processor_id();
188	unsigned int irq, virq;
189	struct irq_desc *desc;
190
191	/* If we used to be the default server, move to the new "boot_cpuid" */
192	if (hw_cpu == xics_default_server)
193		xics_update_irq_servers();
194
195	/* Reject any interrupt that was queued to us... */
196	icp_ops->set_priority(0);
197
198	/* Remove ourselves from the global interrupt queue */
199	xics_set_cpu_giq(xics_default_distrib_server, 0);
200
201	/* Allow IPIs again... */
202	icp_ops->set_priority(DEFAULT_PRIORITY);
203
204	for_each_irq_desc(virq, desc) {
205		struct irq_chip *chip;
206		long server;
207		unsigned long flags;
208		struct ics *ics;
209
210		/* We can't set affinity on ISA interrupts */
211		if (virq < NUM_ISA_INTERRUPTS)
212			continue;
213		/* We only need to migrate enabled IRQS */
214		if (!desc->action)
215			continue;
216		if (desc->irq_data.domain != xics_host)
217			continue;
218		irq = desc->irq_data.hwirq;
219		/* We need to get IPIs still. */
220		if (irq == XICS_IPI || irq == XICS_IRQ_SPURIOUS)
221			continue;
222		chip = irq_desc_get_chip(desc);
223		if (!chip || !chip->irq_set_affinity)
224			continue;
225
226		raw_spin_lock_irqsave(&desc->lock, flags);
227
228		/* Locate interrupt server */
229		server = -1;
230		ics = irq_get_chip_data(virq);
231		if (ics)
232			server = ics->get_server(ics, irq);
233		if (server < 0) {
234			printk(KERN_ERR "%s: Can't find server for irq %d\n",
235			       __func__, irq);
236			goto unlock;
237		}
238
239		/* We only support delivery to all cpus or to one cpu.
240		 * The irq has to be migrated only in the single cpu
241		 * case.
242		 */
243		if (server != hw_cpu)
244			goto unlock;
245
246		/* This is expected during cpu offline. */
247		if (cpu_online(cpu))
248			pr_warning("IRQ %u affinity broken off cpu %u\n",
249			       virq, cpu);
250
251		/* Reset affinity to all cpus */
252		raw_spin_unlock_irqrestore(&desc->lock, flags);
253		irq_set_affinity(virq, cpu_all_mask);
254		continue;
255unlock:
256		raw_spin_unlock_irqrestore(&desc->lock, flags);
257	}
258}
259#endif /* CONFIG_HOTPLUG_CPU */
260
261#ifdef CONFIG_SMP
262/*
263 * For the moment we only implement delivery to all cpus or one cpu.
264 *
265 * If the requested affinity is cpu_all_mask, we set global affinity.
266 * If not we set it to the first cpu in the mask, even if multiple cpus
267 * are set. This is so things like irqbalance (which set core and package
268 * wide affinities) do the right thing.
269 *
270 * We need to fix this to implement support for the links
271 */
272int xics_get_irq_server(unsigned int virq, const struct cpumask *cpumask,
273			unsigned int strict_check)
274{
275
276	if (!distribute_irqs)
277		return xics_default_server;
278
279	if (!cpumask_subset(cpu_possible_mask, cpumask)) {
280		int server = cpumask_first_and(cpu_online_mask, cpumask);
281
282		if (server < nr_cpu_ids)
283			return get_hard_smp_processor_id(server);
284
285		if (strict_check)
286			return -1;
287	}
288
289	/*
290	 * Workaround issue with some versions of JS20 firmware that
291	 * deliver interrupts to cpus which haven't been started. This
292	 * happens when using the maxcpus= boot option.
293	 */
294	if (cpumask_equal(cpu_online_mask, cpu_present_mask))
295		return xics_default_distrib_server;
296
297	return xics_default_server;
298}
299#endif /* CONFIG_SMP */
300
301static int xics_host_match(struct irq_domain *h, struct device_node *node)
302{
303	struct ics *ics;
304
305	list_for_each_entry(ics, &ics_list, link)
306		if (ics->host_match(ics, node))
307			return 1;
308
309	return 0;
310}
311
312/* Dummies */
313static void xics_ipi_unmask(struct irq_data *d) { }
314static void xics_ipi_mask(struct irq_data *d) { }
315
316static struct irq_chip xics_ipi_chip = {
317	.name = "XICS",
318	.irq_eoi = NULL, /* Patched at init time */
319	.irq_mask = xics_ipi_mask,
320	.irq_unmask = xics_ipi_unmask,
321};
322
323static int xics_host_map(struct irq_domain *h, unsigned int virq,
324			 irq_hw_number_t hw)
325{
326	struct ics *ics;
327
328	pr_devel("xics: map virq %d, hwirq 0x%lx\n", virq, hw);
329
330	/* They aren't all level sensitive but we just don't really know */
331	irq_set_status_flags(virq, IRQ_LEVEL);
332
333	/* Don't call into ICS for IPIs */
334	if (hw == XICS_IPI) {
335		irq_set_chip_and_handler(virq, &xics_ipi_chip,
336					 handle_percpu_irq);
337		return 0;
338	}
339
340	/* Let the ICS setup the chip data */
341	list_for_each_entry(ics, &ics_list, link)
342		if (ics->map(ics, virq) == 0)
343			return 0;
344
345	return -EINVAL;
346}
347
348static int xics_host_xlate(struct irq_domain *h, struct device_node *ct,
349			   const u32 *intspec, unsigned int intsize,
350			   irq_hw_number_t *out_hwirq, unsigned int *out_flags)
351
352{
353	/* Current xics implementation translates everything
354	 * to level. It is not technically right for MSIs but this
355	 * is irrelevant at this point. We might get smarter in the future
356	 */
357	*out_hwirq = intspec[0];
358	*out_flags = IRQ_TYPE_LEVEL_LOW;
359
360	return 0;
361}
362
363static struct irq_domain_ops xics_host_ops = {
364	.match = xics_host_match,
365	.map = xics_host_map,
366	.xlate = xics_host_xlate,
367};
368
369static void __init xics_init_host(void)
370{
371	xics_host = irq_domain_add_tree(NULL, &xics_host_ops, NULL);
372	BUG_ON(xics_host == NULL);
373	irq_set_default_host(xics_host);
374}
375
376void __init xics_register_ics(struct ics *ics)
377{
378	list_add(&ics->link, &ics_list);
379}
380
381static void __init xics_get_server_size(void)
382{
383	struct device_node *np;
384	const __be32 *isize;
385
386	/* We fetch the interrupt server size from the first ICS node
387	 * we find if any
388	 */
389	np = of_find_compatible_node(NULL, NULL, "ibm,ppc-xics");
390	if (!np)
391		return;
392	isize = of_get_property(np, "ibm,interrupt-server#-size", NULL);
393	if (!isize)
394		return;
395	xics_interrupt_server_size = be32_to_cpu(*isize);
396	of_node_put(np);
397}
398
399void __init xics_init(void)
400{
401	int rc = -1;
402
403	/* Fist locate ICP */
404	if (firmware_has_feature(FW_FEATURE_LPAR))
405		rc = icp_hv_init();
406	if (rc < 0)
407		rc = icp_native_init();
408	if (rc < 0) {
409		pr_warning("XICS: Cannot find a Presentation Controller !\n");
410		return;
411	}
412
413	/* Copy get_irq callback over to ppc_md */
414	ppc_md.get_irq = icp_ops->get_irq;
415
416	/* Patch up IPI chip EOI */
417	xics_ipi_chip.irq_eoi = icp_ops->eoi;
418
419	/* Now locate ICS */
420	rc = ics_rtas_init();
421	if (rc < 0)
422		rc = ics_opal_init();
423	if (rc < 0)
424		pr_warning("XICS: Cannot find a Source Controller !\n");
425
426	/* Initialize common bits */
427	xics_get_server_size();
428	xics_update_irq_servers();
429	xics_init_host();
430	xics_setup_cpu();
431}
432