1 /*
2  *  drivers/irqchip/irq-crossbar.c
3  *
4  *  Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com
5  *  Author: Sricharan R <r.sricharan@ti.com>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  */
12 #include <linux/err.h>
13 #include <linux/io.h>
14 #include <linux/irqchip.h>
15 #include <linux/irqdomain.h>
16 #include <linux/of_address.h>
17 #include <linux/of_irq.h>
18 #include <linux/slab.h>
19 
20 #define IRQ_FREE	-1
21 #define IRQ_RESERVED	-2
22 #define IRQ_SKIP	-3
23 #define GIC_IRQ_START	32
24 
25 /**
26  * struct crossbar_device - crossbar device description
27  * @lock: spinlock serializing access to @irq_map
28  * @int_max: maximum number of supported interrupts
29  * @safe_map: safe default value to initialize the crossbar
30  * @max_crossbar_sources: Maximum number of crossbar sources
31  * @irq_map: array of interrupts to crossbar number mapping
32  * @crossbar_base: crossbar base address
33  * @register_offsets: offsets for each irq number
34  * @write: register write function pointer
35  */
36 struct crossbar_device {
37 	raw_spinlock_t lock;
38 	uint int_max;
39 	uint safe_map;
40 	uint max_crossbar_sources;
41 	uint *irq_map;
42 	void __iomem *crossbar_base;
43 	int *register_offsets;
44 	void (*write)(int, int);
45 };
46 
47 static struct crossbar_device *cb;
48 
49 static void crossbar_writel(int irq_no, int cb_no)
50 {
51 	writel(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
52 }
53 
54 static void crossbar_writew(int irq_no, int cb_no)
55 {
56 	writew(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
57 }
58 
59 static void crossbar_writeb(int irq_no, int cb_no)
60 {
61 	writeb(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
62 }
63 
64 static struct irq_chip crossbar_chip = {
65 	.name			= "CBAR",
66 	.irq_eoi		= irq_chip_eoi_parent,
67 	.irq_mask		= irq_chip_mask_parent,
68 	.irq_unmask		= irq_chip_unmask_parent,
69 	.irq_retrigger		= irq_chip_retrigger_hierarchy,
70 	.irq_set_type		= irq_chip_set_type_parent,
71 	.flags			= IRQCHIP_MASK_ON_SUSPEND |
72 				  IRQCHIP_SKIP_SET_WAKE,
73 #ifdef CONFIG_SMP
74 	.irq_set_affinity	= irq_chip_set_affinity_parent,
75 #endif
76 };
77 
78 static int allocate_gic_irq(struct irq_domain *domain, unsigned virq,
79 			    irq_hw_number_t hwirq)
80 {
81 	struct irq_fwspec fwspec;
82 	int i;
83 	int err;
84 
85 	if (!irq_domain_get_of_node(domain->parent))
86 		return -EINVAL;
87 
88 	raw_spin_lock(&cb->lock);
89 	for (i = cb->int_max - 1; i >= 0; i--) {
90 		if (cb->irq_map[i] == IRQ_FREE) {
91 			cb->irq_map[i] = hwirq;
92 			break;
93 		}
94 	}
95 	raw_spin_unlock(&cb->lock);
96 
97 	if (i < 0)
98 		return -ENODEV;
99 
100 	fwspec.fwnode = domain->parent->fwnode;
101 	fwspec.param_count = 3;
102 	fwspec.param[0] = 0;	/* SPI */
103 	fwspec.param[1] = i;
104 	fwspec.param[2] = IRQ_TYPE_LEVEL_HIGH;
105 
106 	err = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
107 	if (err)
108 		cb->irq_map[i] = IRQ_FREE;
109 	else
110 		cb->write(i, hwirq);
111 
112 	return err;
113 }
114 
115 static int crossbar_domain_alloc(struct irq_domain *d, unsigned int virq,
116 				 unsigned int nr_irqs, void *data)
117 {
118 	struct irq_fwspec *fwspec = data;
119 	irq_hw_number_t hwirq;
120 	int i;
121 
122 	if (fwspec->param_count != 3)
123 		return -EINVAL;	/* Not GIC compliant */
124 	if (fwspec->param[0] != 0)
125 		return -EINVAL;	/* No PPI should point to this domain */
126 
127 	hwirq = fwspec->param[1];
128 	if ((hwirq + nr_irqs) > cb->max_crossbar_sources)
129 		return -EINVAL;	/* Can't deal with this */
130 
131 	for (i = 0; i < nr_irqs; i++) {
132 		int err = allocate_gic_irq(d, virq + i, hwirq + i);
133 
134 		if (err)
135 			return err;
136 
137 		irq_domain_set_hwirq_and_chip(d, virq + i, hwirq + i,
138 					      &crossbar_chip, NULL);
139 	}
140 
141 	return 0;
142 }
143 
144 /**
145  * crossbar_domain_free - unmap/free a crossbar<->irq connection
146  * @domain: domain of irq to unmap
147  * @virq: virq number
148  * @nr_irqs: number of irqs to free
149  *
150  * We do not maintain a use count of total number of map/unmap
151  * calls for a particular irq to find out if a irq can be really
152  * unmapped. This is because unmap is called during irq_dispose_mapping(irq),
153  * after which irq is anyways unusable. So an explicit map has to be called
154  * after that.
155  */
156 static void crossbar_domain_free(struct irq_domain *domain, unsigned int virq,
157 				 unsigned int nr_irqs)
158 {
159 	int i;
160 
161 	raw_spin_lock(&cb->lock);
162 	for (i = 0; i < nr_irqs; i++) {
163 		struct irq_data *d = irq_domain_get_irq_data(domain, virq + i);
164 
165 		irq_domain_reset_irq_data(d);
166 		cb->irq_map[d->hwirq] = IRQ_FREE;
167 		cb->write(d->hwirq, cb->safe_map);
168 	}
169 	raw_spin_unlock(&cb->lock);
170 }
171 
172 static int crossbar_domain_translate(struct irq_domain *d,
173 				     struct irq_fwspec *fwspec,
174 				     unsigned long *hwirq,
175 				     unsigned int *type)
176 {
177 	if (is_of_node(fwspec->fwnode)) {
178 		if (fwspec->param_count != 3)
179 			return -EINVAL;
180 
181 		/* No PPI should point to this domain */
182 		if (fwspec->param[0] != 0)
183 			return -EINVAL;
184 
185 		*hwirq = fwspec->param[1];
186 		*type = fwspec->param[2];
187 		return 0;
188 	}
189 
190 	return -EINVAL;
191 }
192 
193 static const struct irq_domain_ops crossbar_domain_ops = {
194 	.alloc		= crossbar_domain_alloc,
195 	.free		= crossbar_domain_free,
196 	.translate	= crossbar_domain_translate,
197 };
198 
199 static int __init crossbar_of_init(struct device_node *node)
200 {
201 	int i, size, max = 0, reserved = 0, entry;
202 	const __be32 *irqsr;
203 	int ret = -ENOMEM;
204 
205 	cb = kzalloc(sizeof(*cb), GFP_KERNEL);
206 
207 	if (!cb)
208 		return ret;
209 
210 	cb->crossbar_base = of_iomap(node, 0);
211 	if (!cb->crossbar_base)
212 		goto err_cb;
213 
214 	of_property_read_u32(node, "ti,max-crossbar-sources",
215 			     &cb->max_crossbar_sources);
216 	if (!cb->max_crossbar_sources) {
217 		pr_err("missing 'ti,max-crossbar-sources' property\n");
218 		ret = -EINVAL;
219 		goto err_base;
220 	}
221 
222 	of_property_read_u32(node, "ti,max-irqs", &max);
223 	if (!max) {
224 		pr_err("missing 'ti,max-irqs' property\n");
225 		ret = -EINVAL;
226 		goto err_base;
227 	}
228 	cb->irq_map = kcalloc(max, sizeof(int), GFP_KERNEL);
229 	if (!cb->irq_map)
230 		goto err_base;
231 
232 	cb->int_max = max;
233 
234 	for (i = 0; i < max; i++)
235 		cb->irq_map[i] = IRQ_FREE;
236 
237 	/* Get and mark reserved irqs */
238 	irqsr = of_get_property(node, "ti,irqs-reserved", &size);
239 	if (irqsr) {
240 		size /= sizeof(__be32);
241 
242 		for (i = 0; i < size; i++) {
243 			of_property_read_u32_index(node,
244 						   "ti,irqs-reserved",
245 						   i, &entry);
246 			if (entry >= max) {
247 				pr_err("Invalid reserved entry\n");
248 				ret = -EINVAL;
249 				goto err_irq_map;
250 			}
251 			cb->irq_map[entry] = IRQ_RESERVED;
252 		}
253 	}
254 
255 	/* Skip irqs hardwired to bypass the crossbar */
256 	irqsr = of_get_property(node, "ti,irqs-skip", &size);
257 	if (irqsr) {
258 		size /= sizeof(__be32);
259 
260 		for (i = 0; i < size; i++) {
261 			of_property_read_u32_index(node,
262 						   "ti,irqs-skip",
263 						   i, &entry);
264 			if (entry >= max) {
265 				pr_err("Invalid skip entry\n");
266 				ret = -EINVAL;
267 				goto err_irq_map;
268 			}
269 			cb->irq_map[entry] = IRQ_SKIP;
270 		}
271 	}
272 
273 
274 	cb->register_offsets = kcalloc(max, sizeof(int), GFP_KERNEL);
275 	if (!cb->register_offsets)
276 		goto err_irq_map;
277 
278 	of_property_read_u32(node, "ti,reg-size", &size);
279 
280 	switch (size) {
281 	case 1:
282 		cb->write = crossbar_writeb;
283 		break;
284 	case 2:
285 		cb->write = crossbar_writew;
286 		break;
287 	case 4:
288 		cb->write = crossbar_writel;
289 		break;
290 	default:
291 		pr_err("Invalid reg-size property\n");
292 		ret = -EINVAL;
293 		goto err_reg_offset;
294 		break;
295 	}
296 
297 	/*
298 	 * Register offsets are not linear because of the
299 	 * reserved irqs. so find and store the offsets once.
300 	 */
301 	for (i = 0; i < max; i++) {
302 		if (cb->irq_map[i] == IRQ_RESERVED)
303 			continue;
304 
305 		cb->register_offsets[i] = reserved;
306 		reserved += size;
307 	}
308 
309 	of_property_read_u32(node, "ti,irqs-safe-map", &cb->safe_map);
310 	/* Initialize the crossbar with safe map to start with */
311 	for (i = 0; i < max; i++) {
312 		if (cb->irq_map[i] == IRQ_RESERVED ||
313 		    cb->irq_map[i] == IRQ_SKIP)
314 			continue;
315 
316 		cb->write(i, cb->safe_map);
317 	}
318 
319 	raw_spin_lock_init(&cb->lock);
320 
321 	return 0;
322 
323 err_reg_offset:
324 	kfree(cb->register_offsets);
325 err_irq_map:
326 	kfree(cb->irq_map);
327 err_base:
328 	iounmap(cb->crossbar_base);
329 err_cb:
330 	kfree(cb);
331 
332 	cb = NULL;
333 	return ret;
334 }
335 
336 static int __init irqcrossbar_init(struct device_node *node,
337 				   struct device_node *parent)
338 {
339 	struct irq_domain *parent_domain, *domain;
340 	int err;
341 
342 	if (!parent) {
343 		pr_err("%s: no parent, giving up\n", node->full_name);
344 		return -ENODEV;
345 	}
346 
347 	parent_domain = irq_find_host(parent);
348 	if (!parent_domain) {
349 		pr_err("%s: unable to obtain parent domain\n", node->full_name);
350 		return -ENXIO;
351 	}
352 
353 	err = crossbar_of_init(node);
354 	if (err)
355 		return err;
356 
357 	domain = irq_domain_add_hierarchy(parent_domain, 0,
358 					  cb->max_crossbar_sources,
359 					  node, &crossbar_domain_ops,
360 					  NULL);
361 	if (!domain) {
362 		pr_err("%s: failed to allocated domain\n", node->full_name);
363 		return -ENOMEM;
364 	}
365 
366 	return 0;
367 }
368 
369 IRQCHIP_DECLARE(ti_irqcrossbar, "ti,irq-crossbar", irqcrossbar_init);
370