1/*
2 * Support for virtual IRQ subgroups.
3 *
4 * Copyright (C) 2010  Paul Mundt
5 *
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License.  See the file "COPYING" in the main directory of this archive
8 * for more details.
9 */
10#define pr_fmt(fmt) "intc: " fmt
11
12#include <linux/slab.h>
13#include <linux/irq.h>
14#include <linux/list.h>
15#include <linux/radix-tree.h>
16#include <linux/spinlock.h>
17#include <linux/export.h>
18#include "internals.h"
19
20static struct intc_map_entry intc_irq_xlate[INTC_NR_IRQS];
21
22struct intc_virq_list {
23	unsigned int irq;
24	struct intc_virq_list *next;
25};
26
27#define for_each_virq(entry, head) \
28	for (entry = head; entry; entry = entry->next)
29
30/*
31 * Tags for the radix tree
32 */
33#define INTC_TAG_VIRQ_NEEDS_ALLOC	0
34
35void intc_irq_xlate_set(unsigned int irq, intc_enum id, struct intc_desc_int *d)
36{
37	unsigned long flags;
38
39	raw_spin_lock_irqsave(&intc_big_lock, flags);
40	intc_irq_xlate[irq].enum_id = id;
41	intc_irq_xlate[irq].desc = d;
42	raw_spin_unlock_irqrestore(&intc_big_lock, flags);
43}
44
45struct intc_map_entry *intc_irq_xlate_get(unsigned int irq)
46{
47	return intc_irq_xlate + irq;
48}
49
50int intc_irq_lookup(const char *chipname, intc_enum enum_id)
51{
52	struct intc_map_entry *ptr;
53	struct intc_desc_int *d;
54	int irq = -1;
55
56	list_for_each_entry(d, &intc_list, list) {
57		int tagged;
58
59		if (strcmp(d->chip.name, chipname) != 0)
60			continue;
61
62		/*
63		 * Catch early lookups for subgroup VIRQs that have not
64		 * yet been allocated an IRQ. This already includes a
65		 * fast-path out if the tree is untagged, so there is no
66		 * need to explicitly test the root tree.
67		 */
68		tagged = radix_tree_tag_get(&d->tree, enum_id,
69					    INTC_TAG_VIRQ_NEEDS_ALLOC);
70		if (unlikely(tagged))
71			break;
72
73		ptr = radix_tree_lookup(&d->tree, enum_id);
74		if (ptr) {
75			irq = ptr - intc_irq_xlate;
76			break;
77		}
78	}
79
80	return irq;
81}
82EXPORT_SYMBOL_GPL(intc_irq_lookup);
83
84static int add_virq_to_pirq(unsigned int irq, unsigned int virq)
85{
86	struct intc_virq_list **last, *entry;
87	struct irq_data *data = irq_get_irq_data(irq);
88
89	/* scan for duplicates */
90	last = (struct intc_virq_list **)&data->handler_data;
91	for_each_virq(entry, data->handler_data) {
92		if (entry->irq == virq)
93			return 0;
94		last = &entry->next;
95	}
96
97	entry = kzalloc(sizeof(struct intc_virq_list), GFP_ATOMIC);
98	if (!entry) {
99		pr_err("can't allocate VIRQ mapping for %d\n", virq);
100		return -ENOMEM;
101	}
102
103	entry->irq = virq;
104
105	*last = entry;
106
107	return 0;
108}
109
110static void intc_virq_handler(unsigned int irq, struct irq_desc *desc)
111{
112	struct irq_data *data = irq_get_irq_data(irq);
113	struct irq_chip *chip = irq_data_get_irq_chip(data);
114	struct intc_virq_list *entry, *vlist = irq_data_get_irq_handler_data(data);
115	struct intc_desc_int *d = get_intc_desc(irq);
116
117	chip->irq_mask_ack(data);
118
119	for_each_virq(entry, vlist) {
120		unsigned long addr, handle;
121
122		handle = (unsigned long)irq_get_handler_data(entry->irq);
123		addr = INTC_REG(d, _INTC_ADDR_E(handle), 0);
124
125		if (intc_reg_fns[_INTC_FN(handle)](addr, handle, 0))
126			generic_handle_irq(entry->irq);
127	}
128
129	chip->irq_unmask(data);
130}
131
132static unsigned long __init intc_subgroup_data(struct intc_subgroup *subgroup,
133					       struct intc_desc_int *d,
134					       unsigned int index)
135{
136	unsigned int fn = REG_FN_TEST_BASE + (subgroup->reg_width >> 3) - 1;
137
138	return _INTC_MK(fn, MODE_ENABLE_REG, intc_get_reg(d, subgroup->reg),
139			0, 1, (subgroup->reg_width - 1) - index);
140}
141
142static void __init intc_subgroup_init_one(struct intc_desc *desc,
143					  struct intc_desc_int *d,
144					  struct intc_subgroup *subgroup)
145{
146	struct intc_map_entry *mapped;
147	unsigned int pirq;
148	unsigned long flags;
149	int i;
150
151	mapped = radix_tree_lookup(&d->tree, subgroup->parent_id);
152	if (!mapped) {
153		WARN_ON(1);
154		return;
155	}
156
157	pirq = mapped - intc_irq_xlate;
158
159	raw_spin_lock_irqsave(&d->lock, flags);
160
161	for (i = 0; i < ARRAY_SIZE(subgroup->enum_ids); i++) {
162		struct intc_subgroup_entry *entry;
163		int err;
164
165		if (!subgroup->enum_ids[i])
166			continue;
167
168		entry = kmalloc(sizeof(*entry), GFP_NOWAIT);
169		if (!entry)
170			break;
171
172		entry->pirq = pirq;
173		entry->enum_id = subgroup->enum_ids[i];
174		entry->handle = intc_subgroup_data(subgroup, d, i);
175
176		err = radix_tree_insert(&d->tree, entry->enum_id, entry);
177		if (unlikely(err < 0))
178			break;
179
180		radix_tree_tag_set(&d->tree, entry->enum_id,
181				   INTC_TAG_VIRQ_NEEDS_ALLOC);
182	}
183
184	raw_spin_unlock_irqrestore(&d->lock, flags);
185}
186
187void __init intc_subgroup_init(struct intc_desc *desc, struct intc_desc_int *d)
188{
189	int i;
190
191	if (!desc->hw.subgroups)
192		return;
193
194	for (i = 0; i < desc->hw.nr_subgroups; i++)
195		intc_subgroup_init_one(desc, d, desc->hw.subgroups + i);
196}
197
198static void __init intc_subgroup_map(struct intc_desc_int *d)
199{
200	struct intc_subgroup_entry *entries[32];
201	unsigned long flags;
202	unsigned int nr_found;
203	int i;
204
205	raw_spin_lock_irqsave(&d->lock, flags);
206
207restart:
208	nr_found = radix_tree_gang_lookup_tag_slot(&d->tree,
209			(void ***)entries, 0, ARRAY_SIZE(entries),
210			INTC_TAG_VIRQ_NEEDS_ALLOC);
211
212	for (i = 0; i < nr_found; i++) {
213		struct intc_subgroup_entry *entry;
214		int irq;
215
216		entry = radix_tree_deref_slot((void **)entries[i]);
217		if (unlikely(!entry))
218			continue;
219		if (radix_tree_deref_retry(entry))
220			goto restart;
221
222		irq = irq_alloc_desc(numa_node_id());
223		if (unlikely(irq < 0)) {
224			pr_err("no more free IRQs, bailing..\n");
225			break;
226		}
227
228		activate_irq(irq);
229
230		pr_info("Setting up a chained VIRQ from %d -> %d\n",
231			irq, entry->pirq);
232
233		intc_irq_xlate_set(irq, entry->enum_id, d);
234
235		irq_set_chip_and_handler_name(irq, irq_get_chip(entry->pirq),
236					      handle_simple_irq, "virq");
237		irq_set_chip_data(irq, irq_get_chip_data(entry->pirq));
238
239		irq_set_handler_data(irq, (void *)entry->handle);
240
241		/*
242		 * Set the virtual IRQ as non-threadable.
243		 */
244		irq_set_nothread(irq);
245
246		irq_set_chained_handler(entry->pirq, intc_virq_handler);
247		add_virq_to_pirq(entry->pirq, irq);
248
249		radix_tree_tag_clear(&d->tree, entry->enum_id,
250				     INTC_TAG_VIRQ_NEEDS_ALLOC);
251		radix_tree_replace_slot((void **)entries[i],
252					&intc_irq_xlate[irq]);
253	}
254
255	raw_spin_unlock_irqrestore(&d->lock, flags);
256}
257
258void __init intc_finalize(void)
259{
260	struct intc_desc_int *d;
261
262	list_for_each_entry(d, &intc_list, list)
263		if (radix_tree_tagged(&d->tree, INTC_TAG_VIRQ_NEEDS_ALLOC))
264			intc_subgroup_map(d);
265}
266