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 *entry;
87	struct intc_virq_list **last = NULL;
88
89	/* scan for duplicates */
90	for_each_virq(entry, irq_get_handler_data(irq)) {
91		if (entry->irq == virq)
92			return 0;
93		last = &entry->next;
94	}
95
96	entry = kzalloc(sizeof(struct intc_virq_list), GFP_ATOMIC);
97	if (!entry)
98		return -ENOMEM;
99
100	entry->irq = virq;
101
102	if (last)
103		*last = entry;
104	else
105		irq_set_handler_data(irq, entry);
106
107	return 0;
108}
109
110static void intc_virq_handler(struct irq_desc *desc)
111{
112	unsigned int irq = irq_desc_get_irq(desc);
113	struct irq_data *data = irq_desc_get_irq_data(desc);
114	struct irq_chip *chip = irq_data_get_irq_chip(data);
115	struct intc_virq_list *entry, *vlist = irq_data_get_irq_handler_data(data);
116	struct intc_desc_int *d = get_intc_desc(irq);
117
118	chip->irq_mask_ack(data);
119
120	for_each_virq(entry, vlist) {
121		unsigned long addr, handle;
122		struct irq_desc *vdesc = irq_to_desc(entry->irq);
123
124		if (vdesc) {
125			handle = (unsigned long)irq_desc_get_handler_data(vdesc);
126			addr = INTC_REG(d, _INTC_ADDR_E(handle), 0);
127			if (intc_reg_fns[_INTC_FN(handle)](addr, handle, 0))
128				generic_handle_irq_desc(vdesc);
129		}
130	}
131
132	chip->irq_unmask(data);
133}
134
135static unsigned long __init intc_subgroup_data(struct intc_subgroup *subgroup,
136					       struct intc_desc_int *d,
137					       unsigned int index)
138{
139	unsigned int fn = REG_FN_TEST_BASE + (subgroup->reg_width >> 3) - 1;
140
141	return _INTC_MK(fn, MODE_ENABLE_REG, intc_get_reg(d, subgroup->reg),
142			0, 1, (subgroup->reg_width - 1) - index);
143}
144
145static void __init intc_subgroup_init_one(struct intc_desc *desc,
146					  struct intc_desc_int *d,
147					  struct intc_subgroup *subgroup)
148{
149	struct intc_map_entry *mapped;
150	unsigned int pirq;
151	unsigned long flags;
152	int i;
153
154	mapped = radix_tree_lookup(&d->tree, subgroup->parent_id);
155	if (!mapped) {
156		WARN_ON(1);
157		return;
158	}
159
160	pirq = mapped - intc_irq_xlate;
161
162	raw_spin_lock_irqsave(&d->lock, flags);
163
164	for (i = 0; i < ARRAY_SIZE(subgroup->enum_ids); i++) {
165		struct intc_subgroup_entry *entry;
166		int err;
167
168		if (!subgroup->enum_ids[i])
169			continue;
170
171		entry = kmalloc(sizeof(*entry), GFP_NOWAIT);
172		if (!entry)
173			break;
174
175		entry->pirq = pirq;
176		entry->enum_id = subgroup->enum_ids[i];
177		entry->handle = intc_subgroup_data(subgroup, d, i);
178
179		err = radix_tree_insert(&d->tree, entry->enum_id, entry);
180		if (unlikely(err < 0))
181			break;
182
183		radix_tree_tag_set(&d->tree, entry->enum_id,
184				   INTC_TAG_VIRQ_NEEDS_ALLOC);
185	}
186
187	raw_spin_unlock_irqrestore(&d->lock, flags);
188}
189
190void __init intc_subgroup_init(struct intc_desc *desc, struct intc_desc_int *d)
191{
192	int i;
193
194	if (!desc->hw.subgroups)
195		return;
196
197	for (i = 0; i < desc->hw.nr_subgroups; i++)
198		intc_subgroup_init_one(desc, d, desc->hw.subgroups + i);
199}
200
201static void __init intc_subgroup_map(struct intc_desc_int *d)
202{
203	struct intc_subgroup_entry *entries[32];
204	unsigned long flags;
205	unsigned int nr_found;
206	int i;
207
208	raw_spin_lock_irqsave(&d->lock, flags);
209
210restart:
211	nr_found = radix_tree_gang_lookup_tag_slot(&d->tree,
212			(void ***)entries, 0, ARRAY_SIZE(entries),
213			INTC_TAG_VIRQ_NEEDS_ALLOC);
214
215	for (i = 0; i < nr_found; i++) {
216		struct intc_subgroup_entry *entry;
217		int irq;
218
219		entry = radix_tree_deref_slot((void **)entries[i]);
220		if (unlikely(!entry))
221			continue;
222		if (radix_tree_deref_retry(entry))
223			goto restart;
224
225		irq = irq_alloc_desc(numa_node_id());
226		if (unlikely(irq < 0)) {
227			pr_err("no more free IRQs, bailing..\n");
228			break;
229		}
230
231		activate_irq(irq);
232
233		pr_info("Setting up a chained VIRQ from %d -> %d\n",
234			irq, entry->pirq);
235
236		intc_irq_xlate_set(irq, entry->enum_id, d);
237
238		irq_set_chip_and_handler_name(irq, irq_get_chip(entry->pirq),
239					      handle_simple_irq, "virq");
240		irq_set_chip_data(irq, irq_get_chip_data(entry->pirq));
241
242		irq_set_handler_data(irq, (void *)entry->handle);
243
244		/*
245		 * Set the virtual IRQ as non-threadable.
246		 */
247		irq_set_nothread(irq);
248
249		/* Set handler data before installing the handler */
250		add_virq_to_pirq(entry->pirq, irq);
251		irq_set_chained_handler(entry->pirq, intc_virq_handler);
252
253		radix_tree_tag_clear(&d->tree, entry->enum_id,
254				     INTC_TAG_VIRQ_NEEDS_ALLOC);
255		radix_tree_replace_slot(&d->tree, (void **)entries[i],
256					&intc_irq_xlate[irq]);
257	}
258
259	raw_spin_unlock_irqrestore(&d->lock, flags);
260}
261
262void __init intc_finalize(void)
263{
264	struct intc_desc_int *d;
265
266	list_for_each_entry(d, &intc_list, list)
267		if (radix_tree_tagged(&d->tree, INTC_TAG_VIRQ_NEEDS_ALLOC))
268			intc_subgroup_map(d);
269}
270