1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright 2007, Michael Ellerman, IBM Corporation.
4  */
5 
6 
7 #include <linux/interrupt.h>
8 #include <linux/irq.h>
9 #include <linux/kernel.h>
10 #include <linux/pci.h>
11 #include <linux/msi.h>
12 #include <linux/export.h>
13 #include <linux/of_platform.h>
14 #include <linux/slab.h>
15 
16 #include <asm/debugfs.h>
17 #include <asm/dcr.h>
18 #include <asm/machdep.h>
19 #include <asm/prom.h>
20 
21 #include "cell.h"
22 
23 /*
24  * MSIC registers, specified as offsets from dcr_base
25  */
26 #define MSIC_CTRL_REG	0x0
27 
28 /* Base Address registers specify FIFO location in BE memory */
29 #define MSIC_BASE_ADDR_HI_REG	0x3
30 #define MSIC_BASE_ADDR_LO_REG	0x4
31 
32 /* Hold the read/write offsets into the FIFO */
33 #define MSIC_READ_OFFSET_REG	0x5
34 #define MSIC_WRITE_OFFSET_REG	0x6
35 
36 
37 /* MSIC control register flags */
38 #define MSIC_CTRL_ENABLE		0x0001
39 #define MSIC_CTRL_FIFO_FULL_ENABLE	0x0002
40 #define MSIC_CTRL_IRQ_ENABLE		0x0008
41 #define MSIC_CTRL_FULL_STOP_ENABLE	0x0010
42 
43 /*
44  * The MSIC can be configured to use a FIFO of 32KB, 64KB, 128KB or 256KB.
45  * Currently we're using a 64KB FIFO size.
46  */
47 #define MSIC_FIFO_SIZE_SHIFT	16
48 #define MSIC_FIFO_SIZE_BYTES	(1 << MSIC_FIFO_SIZE_SHIFT)
49 
50 /*
51  * To configure the FIFO size as (1 << n) bytes, we write (n - 15) into bits
52  * 8-9 of the MSIC control reg.
53  */
54 #define MSIC_CTRL_FIFO_SIZE	(((MSIC_FIFO_SIZE_SHIFT - 15) << 8) & 0x300)
55 
56 /*
57  * We need to mask the read/write offsets to make sure they stay within
58  * the bounds of the FIFO. Also they should always be 16-byte aligned.
59  */
60 #define MSIC_FIFO_SIZE_MASK	((MSIC_FIFO_SIZE_BYTES - 1) & ~0xFu)
61 
62 /* Each entry in the FIFO is 16 bytes, the first 4 bytes hold the irq # */
63 #define MSIC_FIFO_ENTRY_SIZE	0x10
64 
65 
66 struct axon_msic {
67 	struct irq_domain *irq_domain;
68 	__le32 *fifo_virt;
69 	dma_addr_t fifo_phys;
70 	dcr_host_t dcr_host;
71 	u32 read_offset;
72 #ifdef DEBUG
73 	u32 __iomem *trigger;
74 #endif
75 };
76 
77 #ifdef DEBUG
78 void axon_msi_debug_setup(struct device_node *dn, struct axon_msic *msic);
79 #else
80 static inline void axon_msi_debug_setup(struct device_node *dn,
81 					struct axon_msic *msic) { }
82 #endif
83 
84 
85 static void msic_dcr_write(struct axon_msic *msic, unsigned int dcr_n, u32 val)
86 {
87 	pr_devel("axon_msi: dcr_write(0x%x, 0x%x)\n", val, dcr_n);
88 
89 	dcr_write(msic->dcr_host, dcr_n, val);
90 }
91 
92 static void axon_msi_cascade(struct irq_desc *desc)
93 {
94 	struct irq_chip *chip = irq_desc_get_chip(desc);
95 	struct axon_msic *msic = irq_desc_get_handler_data(desc);
96 	u32 write_offset, msi;
97 	int idx;
98 	int retry = 0;
99 
100 	write_offset = dcr_read(msic->dcr_host, MSIC_WRITE_OFFSET_REG);
101 	pr_devel("axon_msi: original write_offset 0x%x\n", write_offset);
102 
103 	/* write_offset doesn't wrap properly, so we have to mask it */
104 	write_offset &= MSIC_FIFO_SIZE_MASK;
105 
106 	while (msic->read_offset != write_offset && retry < 100) {
107 		idx  = msic->read_offset / sizeof(__le32);
108 		msi  = le32_to_cpu(msic->fifo_virt[idx]);
109 		msi &= 0xFFFF;
110 
111 		pr_devel("axon_msi: woff %x roff %x msi %x\n",
112 			  write_offset, msic->read_offset, msi);
113 
114 		if (msi < nr_irqs && irq_get_chip_data(msi) == msic) {
115 			generic_handle_irq(msi);
116 			msic->fifo_virt[idx] = cpu_to_le32(0xffffffff);
117 		} else {
118 			/*
119 			 * Reading the MSIC_WRITE_OFFSET_REG does not
120 			 * reliably flush the outstanding DMA to the
121 			 * FIFO buffer. Here we were reading stale
122 			 * data, so we need to retry.
123 			 */
124 			udelay(1);
125 			retry++;
126 			pr_devel("axon_msi: invalid irq 0x%x!\n", msi);
127 			continue;
128 		}
129 
130 		if (retry) {
131 			pr_devel("axon_msi: late irq 0x%x, retry %d\n",
132 				 msi, retry);
133 			retry = 0;
134 		}
135 
136 		msic->read_offset += MSIC_FIFO_ENTRY_SIZE;
137 		msic->read_offset &= MSIC_FIFO_SIZE_MASK;
138 	}
139 
140 	if (retry) {
141 		printk(KERN_WARNING "axon_msi: irq timed out\n");
142 
143 		msic->read_offset += MSIC_FIFO_ENTRY_SIZE;
144 		msic->read_offset &= MSIC_FIFO_SIZE_MASK;
145 	}
146 
147 	chip->irq_eoi(&desc->irq_data);
148 }
149 
150 static struct axon_msic *find_msi_translator(struct pci_dev *dev)
151 {
152 	struct irq_domain *irq_domain;
153 	struct device_node *dn, *tmp;
154 	const phandle *ph;
155 	struct axon_msic *msic = NULL;
156 
157 	dn = of_node_get(pci_device_to_OF_node(dev));
158 	if (!dn) {
159 		dev_dbg(&dev->dev, "axon_msi: no pci_dn found\n");
160 		return NULL;
161 	}
162 
163 	for (; dn; dn = of_get_next_parent(dn)) {
164 		ph = of_get_property(dn, "msi-translator", NULL);
165 		if (ph)
166 			break;
167 	}
168 
169 	if (!ph) {
170 		dev_dbg(&dev->dev,
171 			"axon_msi: no msi-translator property found\n");
172 		goto out_error;
173 	}
174 
175 	tmp = dn;
176 	dn = of_find_node_by_phandle(*ph);
177 	of_node_put(tmp);
178 	if (!dn) {
179 		dev_dbg(&dev->dev,
180 			"axon_msi: msi-translator doesn't point to a node\n");
181 		goto out_error;
182 	}
183 
184 	irq_domain = irq_find_host(dn);
185 	if (!irq_domain) {
186 		dev_dbg(&dev->dev, "axon_msi: no irq_domain found for node %pOF\n",
187 			dn);
188 		goto out_error;
189 	}
190 
191 	msic = irq_domain->host_data;
192 
193 out_error:
194 	of_node_put(dn);
195 
196 	return msic;
197 }
198 
199 static int setup_msi_msg_address(struct pci_dev *dev, struct msi_msg *msg)
200 {
201 	struct device_node *dn;
202 	struct msi_desc *entry;
203 	int len;
204 	const u32 *prop;
205 
206 	dn = of_node_get(pci_device_to_OF_node(dev));
207 	if (!dn) {
208 		dev_dbg(&dev->dev, "axon_msi: no pci_dn found\n");
209 		return -ENODEV;
210 	}
211 
212 	entry = first_pci_msi_entry(dev);
213 
214 	for (; dn; dn = of_get_next_parent(dn)) {
215 		if (entry->msi_attrib.is_64) {
216 			prop = of_get_property(dn, "msi-address-64", &len);
217 			if (prop)
218 				break;
219 		}
220 
221 		prop = of_get_property(dn, "msi-address-32", &len);
222 		if (prop)
223 			break;
224 	}
225 
226 	if (!prop) {
227 		dev_dbg(&dev->dev,
228 			"axon_msi: no msi-address-(32|64) properties found\n");
229 		return -ENOENT;
230 	}
231 
232 	switch (len) {
233 	case 8:
234 		msg->address_hi = prop[0];
235 		msg->address_lo = prop[1];
236 		break;
237 	case 4:
238 		msg->address_hi = 0;
239 		msg->address_lo = prop[0];
240 		break;
241 	default:
242 		dev_dbg(&dev->dev,
243 			"axon_msi: malformed msi-address-(32|64) property\n");
244 		of_node_put(dn);
245 		return -EINVAL;
246 	}
247 
248 	of_node_put(dn);
249 
250 	return 0;
251 }
252 
253 static int axon_msi_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
254 {
255 	unsigned int virq, rc;
256 	struct msi_desc *entry;
257 	struct msi_msg msg;
258 	struct axon_msic *msic;
259 
260 	msic = find_msi_translator(dev);
261 	if (!msic)
262 		return -ENODEV;
263 
264 	rc = setup_msi_msg_address(dev, &msg);
265 	if (rc)
266 		return rc;
267 
268 	for_each_pci_msi_entry(entry, dev) {
269 		virq = irq_create_direct_mapping(msic->irq_domain);
270 		if (!virq) {
271 			dev_warn(&dev->dev,
272 				 "axon_msi: virq allocation failed!\n");
273 			return -1;
274 		}
275 		dev_dbg(&dev->dev, "axon_msi: allocated virq 0x%x\n", virq);
276 
277 		irq_set_msi_desc(virq, entry);
278 		msg.data = virq;
279 		pci_write_msi_msg(virq, &msg);
280 	}
281 
282 	return 0;
283 }
284 
285 static void axon_msi_teardown_msi_irqs(struct pci_dev *dev)
286 {
287 	struct msi_desc *entry;
288 
289 	dev_dbg(&dev->dev, "axon_msi: tearing down msi irqs\n");
290 
291 	for_each_pci_msi_entry(entry, dev) {
292 		if (!entry->irq)
293 			continue;
294 
295 		irq_set_msi_desc(entry->irq, NULL);
296 		irq_dispose_mapping(entry->irq);
297 	}
298 }
299 
300 static struct irq_chip msic_irq_chip = {
301 	.irq_mask	= pci_msi_mask_irq,
302 	.irq_unmask	= pci_msi_unmask_irq,
303 	.irq_shutdown	= pci_msi_mask_irq,
304 	.name		= "AXON-MSI",
305 };
306 
307 static int msic_host_map(struct irq_domain *h, unsigned int virq,
308 			 irq_hw_number_t hw)
309 {
310 	irq_set_chip_data(virq, h->host_data);
311 	irq_set_chip_and_handler(virq, &msic_irq_chip, handle_simple_irq);
312 
313 	return 0;
314 }
315 
316 static const struct irq_domain_ops msic_host_ops = {
317 	.map	= msic_host_map,
318 };
319 
320 static void axon_msi_shutdown(struct platform_device *device)
321 {
322 	struct axon_msic *msic = dev_get_drvdata(&device->dev);
323 	u32 tmp;
324 
325 	pr_devel("axon_msi: disabling %pOF\n",
326 		 irq_domain_get_of_node(msic->irq_domain));
327 	tmp  = dcr_read(msic->dcr_host, MSIC_CTRL_REG);
328 	tmp &= ~MSIC_CTRL_ENABLE & ~MSIC_CTRL_IRQ_ENABLE;
329 	msic_dcr_write(msic, MSIC_CTRL_REG, tmp);
330 }
331 
332 static int axon_msi_probe(struct platform_device *device)
333 {
334 	struct device_node *dn = device->dev.of_node;
335 	struct axon_msic *msic;
336 	unsigned int virq;
337 	int dcr_base, dcr_len;
338 
339 	pr_devel("axon_msi: setting up dn %pOF\n", dn);
340 
341 	msic = kzalloc(sizeof(*msic), GFP_KERNEL);
342 	if (!msic) {
343 		printk(KERN_ERR "axon_msi: couldn't allocate msic for %pOF\n",
344 		       dn);
345 		goto out;
346 	}
347 
348 	dcr_base = dcr_resource_start(dn, 0);
349 	dcr_len = dcr_resource_len(dn, 0);
350 
351 	if (dcr_base == 0 || dcr_len == 0) {
352 		printk(KERN_ERR
353 		       "axon_msi: couldn't parse dcr properties on %pOF\n",
354 			dn);
355 		goto out_free_msic;
356 	}
357 
358 	msic->dcr_host = dcr_map(dn, dcr_base, dcr_len);
359 	if (!DCR_MAP_OK(msic->dcr_host)) {
360 		printk(KERN_ERR "axon_msi: dcr_map failed for %pOF\n",
361 		       dn);
362 		goto out_free_msic;
363 	}
364 
365 	msic->fifo_virt = dma_alloc_coherent(&device->dev, MSIC_FIFO_SIZE_BYTES,
366 					     &msic->fifo_phys, GFP_KERNEL);
367 	if (!msic->fifo_virt) {
368 		printk(KERN_ERR "axon_msi: couldn't allocate fifo for %pOF\n",
369 		       dn);
370 		goto out_free_msic;
371 	}
372 
373 	virq = irq_of_parse_and_map(dn, 0);
374 	if (!virq) {
375 		printk(KERN_ERR "axon_msi: irq parse and map failed for %pOF\n",
376 		       dn);
377 		goto out_free_fifo;
378 	}
379 	memset(msic->fifo_virt, 0xff, MSIC_FIFO_SIZE_BYTES);
380 
381 	/* We rely on being able to stash a virq in a u16, so limit irqs to < 65536 */
382 	msic->irq_domain = irq_domain_add_nomap(dn, 65536, &msic_host_ops, msic);
383 	if (!msic->irq_domain) {
384 		printk(KERN_ERR "axon_msi: couldn't allocate irq_domain for %pOF\n",
385 		       dn);
386 		goto out_free_fifo;
387 	}
388 
389 	irq_set_handler_data(virq, msic);
390 	irq_set_chained_handler(virq, axon_msi_cascade);
391 	pr_devel("axon_msi: irq 0x%x setup for axon_msi\n", virq);
392 
393 	/* Enable the MSIC hardware */
394 	msic_dcr_write(msic, MSIC_BASE_ADDR_HI_REG, msic->fifo_phys >> 32);
395 	msic_dcr_write(msic, MSIC_BASE_ADDR_LO_REG,
396 				  msic->fifo_phys & 0xFFFFFFFF);
397 	msic_dcr_write(msic, MSIC_CTRL_REG,
398 			MSIC_CTRL_IRQ_ENABLE | MSIC_CTRL_ENABLE |
399 			MSIC_CTRL_FIFO_SIZE);
400 
401 	msic->read_offset = dcr_read(msic->dcr_host, MSIC_WRITE_OFFSET_REG)
402 				& MSIC_FIFO_SIZE_MASK;
403 
404 	dev_set_drvdata(&device->dev, msic);
405 
406 	cell_pci_controller_ops.setup_msi_irqs = axon_msi_setup_msi_irqs;
407 	cell_pci_controller_ops.teardown_msi_irqs = axon_msi_teardown_msi_irqs;
408 
409 	axon_msi_debug_setup(dn, msic);
410 
411 	printk(KERN_DEBUG "axon_msi: setup MSIC on %pOF\n", dn);
412 
413 	return 0;
414 
415 out_free_fifo:
416 	dma_free_coherent(&device->dev, MSIC_FIFO_SIZE_BYTES, msic->fifo_virt,
417 			  msic->fifo_phys);
418 out_free_msic:
419 	kfree(msic);
420 out:
421 
422 	return -1;
423 }
424 
425 static const struct of_device_id axon_msi_device_id[] = {
426 	{
427 		.compatible	= "ibm,axon-msic"
428 	},
429 	{}
430 };
431 
432 static struct platform_driver axon_msi_driver = {
433 	.probe		= axon_msi_probe,
434 	.shutdown	= axon_msi_shutdown,
435 	.driver = {
436 		.name = "axon-msi",
437 		.of_match_table = axon_msi_device_id,
438 	},
439 };
440 
441 static int __init axon_msi_init(void)
442 {
443 	return platform_driver_register(&axon_msi_driver);
444 }
445 subsys_initcall(axon_msi_init);
446 
447 
448 #ifdef DEBUG
449 static int msic_set(void *data, u64 val)
450 {
451 	struct axon_msic *msic = data;
452 	out_le32(msic->trigger, val);
453 	return 0;
454 }
455 
456 static int msic_get(void *data, u64 *val)
457 {
458 	*val = 0;
459 	return 0;
460 }
461 
462 DEFINE_SIMPLE_ATTRIBUTE(fops_msic, msic_get, msic_set, "%llu\n");
463 
464 void axon_msi_debug_setup(struct device_node *dn, struct axon_msic *msic)
465 {
466 	char name[8];
467 	u64 addr;
468 
469 	addr = of_translate_address(dn, of_get_property(dn, "reg", NULL));
470 	if (addr == OF_BAD_ADDR) {
471 		pr_devel("axon_msi: couldn't translate reg property\n");
472 		return;
473 	}
474 
475 	msic->trigger = ioremap(addr, 0x4);
476 	if (!msic->trigger) {
477 		pr_devel("axon_msi: ioremap failed\n");
478 		return;
479 	}
480 
481 	snprintf(name, sizeof(name), "msic_%d", of_node_to_nid(dn));
482 
483 	if (!debugfs_create_file(name, 0600, powerpc_debugfs_root,
484 				 msic, &fops_msic)) {
485 		pr_devel("axon_msi: debugfs_create_file failed!\n");
486 		return;
487 	}
488 }
489 #endif /* DEBUG */
490