1 /*
2  * Copyright 2006 Jake Moilanen <moilanen@austin.ibm.com>, IBM Corp.
3  * Copyright 2006-2007 Michael Ellerman, IBM Corp.
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU General Public License
7  * as published by the Free Software Foundation; version 2 of the
8  * License.
9  *
10  */
11 
12 #include <linux/device.h>
13 #include <linux/irq.h>
14 #include <linux/msi.h>
15 
16 #include <asm/rtas.h>
17 #include <asm/hw_irq.h>
18 #include <asm/ppc-pci.h>
19 
20 static int query_token, change_token;
21 
22 #define RTAS_QUERY_FN		0
23 #define RTAS_CHANGE_FN		1
24 #define RTAS_RESET_FN		2
25 #define RTAS_CHANGE_MSI_FN	3
26 #define RTAS_CHANGE_MSIX_FN	4
27 #define RTAS_CHANGE_32MSI_FN	5
28 
29 /* RTAS Helpers */
30 
31 static int rtas_change_msi(struct pci_dn *pdn, u32 func, u32 num_irqs)
32 {
33 	u32 addr, seq_num, rtas_ret[3];
34 	unsigned long buid;
35 	int rc;
36 
37 	addr = rtas_config_addr(pdn->busno, pdn->devfn, 0);
38 	buid = pdn->phb->buid;
39 
40 	seq_num = 1;
41 	do {
42 		if (func == RTAS_CHANGE_MSI_FN || func == RTAS_CHANGE_MSIX_FN ||
43 		    func == RTAS_CHANGE_32MSI_FN)
44 			rc = rtas_call(change_token, 6, 4, rtas_ret, addr,
45 					BUID_HI(buid), BUID_LO(buid),
46 					func, num_irqs, seq_num);
47 		else
48 			rc = rtas_call(change_token, 6, 3, rtas_ret, addr,
49 					BUID_HI(buid), BUID_LO(buid),
50 					func, num_irqs, seq_num);
51 
52 		seq_num = rtas_ret[1];
53 	} while (rtas_busy_delay(rc));
54 
55 	/*
56 	 * If the RTAS call succeeded, return the number of irqs allocated.
57 	 * If not, make sure we return a negative error code.
58 	 */
59 	if (rc == 0)
60 		rc = rtas_ret[0];
61 	else if (rc > 0)
62 		rc = -rc;
63 
64 	pr_debug("rtas_msi: ibm,change_msi(func=%d,num=%d), got %d rc = %d\n",
65 		 func, num_irqs, rtas_ret[0], rc);
66 
67 	return rc;
68 }
69 
70 static void rtas_disable_msi(struct pci_dev *pdev)
71 {
72 	struct pci_dn *pdn;
73 
74 	pdn = pci_get_pdn(pdev);
75 	if (!pdn)
76 		return;
77 
78 	/*
79 	 * disabling MSI with the explicit interface also disables MSI-X
80 	 */
81 	if (rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, 0) != 0) {
82 		/*
83 		 * may have failed because explicit interface is not
84 		 * present
85 		 */
86 		if (rtas_change_msi(pdn, RTAS_CHANGE_FN, 0) != 0) {
87 			pr_debug("rtas_msi: Setting MSIs to 0 failed!\n");
88 		}
89 	}
90 }
91 
92 static int rtas_query_irq_number(struct pci_dn *pdn, int offset)
93 {
94 	u32 addr, rtas_ret[2];
95 	unsigned long buid;
96 	int rc;
97 
98 	addr = rtas_config_addr(pdn->busno, pdn->devfn, 0);
99 	buid = pdn->phb->buid;
100 
101 	do {
102 		rc = rtas_call(query_token, 4, 3, rtas_ret, addr,
103 			       BUID_HI(buid), BUID_LO(buid), offset);
104 	} while (rtas_busy_delay(rc));
105 
106 	if (rc) {
107 		pr_debug("rtas_msi: error (%d) querying source number\n", rc);
108 		return rc;
109 	}
110 
111 	return rtas_ret[0];
112 }
113 
114 static void rtas_teardown_msi_irqs(struct pci_dev *pdev)
115 {
116 	struct msi_desc *entry;
117 
118 	list_for_each_entry(entry, &pdev->msi_list, list) {
119 		if (entry->irq == NO_IRQ)
120 			continue;
121 
122 		irq_set_msi_desc(entry->irq, NULL);
123 		irq_dispose_mapping(entry->irq);
124 	}
125 
126 	rtas_disable_msi(pdev);
127 }
128 
129 static int check_req(struct pci_dev *pdev, int nvec, char *prop_name)
130 {
131 	struct device_node *dn;
132 	struct pci_dn *pdn;
133 	const u32 *req_msi;
134 
135 	pdn = pci_get_pdn(pdev);
136 	if (!pdn)
137 		return -ENODEV;
138 
139 	dn = pdn->node;
140 
141 	req_msi = of_get_property(dn, prop_name, NULL);
142 	if (!req_msi) {
143 		pr_debug("rtas_msi: No %s on %s\n", prop_name, dn->full_name);
144 		return -ENOENT;
145 	}
146 
147 	if (*req_msi < nvec) {
148 		pr_debug("rtas_msi: %s requests < %d MSIs\n", prop_name, nvec);
149 
150 		if (*req_msi == 0) /* Be paranoid */
151 			return -ENOSPC;
152 
153 		return *req_msi;
154 	}
155 
156 	return 0;
157 }
158 
159 static int check_req_msi(struct pci_dev *pdev, int nvec)
160 {
161 	return check_req(pdev, nvec, "ibm,req#msi");
162 }
163 
164 static int check_req_msix(struct pci_dev *pdev, int nvec)
165 {
166 	return check_req(pdev, nvec, "ibm,req#msi-x");
167 }
168 
169 /* Quota calculation */
170 
171 static struct device_node *find_pe_total_msi(struct pci_dev *dev, int *total)
172 {
173 	struct device_node *dn;
174 	const u32 *p;
175 
176 	dn = of_node_get(pci_device_to_OF_node(dev));
177 	while (dn) {
178 		p = of_get_property(dn, "ibm,pe-total-#msi", NULL);
179 		if (p) {
180 			pr_debug("rtas_msi: found prop on dn %s\n",
181 				dn->full_name);
182 			*total = *p;
183 			return dn;
184 		}
185 
186 		dn = of_get_next_parent(dn);
187 	}
188 
189 	return NULL;
190 }
191 
192 static struct device_node *find_pe_dn(struct pci_dev *dev, int *total)
193 {
194 	struct device_node *dn;
195 	struct eeh_dev *edev;
196 
197 	/* Found our PE and assume 8 at that point. */
198 
199 	dn = pci_device_to_OF_node(dev);
200 	if (!dn)
201 		return NULL;
202 
203 	/* Get the top level device in the PE */
204 	edev = of_node_to_eeh_dev(dn);
205 	if (edev->pe)
206 		edev = list_first_entry(&edev->pe->edevs, struct eeh_dev, list);
207 	dn = eeh_dev_to_of_node(edev);
208 	if (!dn)
209 		return NULL;
210 
211 	/* We actually want the parent */
212 	dn = of_get_parent(dn);
213 	if (!dn)
214 		return NULL;
215 
216 	/* Hardcode of 8 for old firmwares */
217 	*total = 8;
218 	pr_debug("rtas_msi: using PE dn %s\n", dn->full_name);
219 
220 	return dn;
221 }
222 
223 struct msi_counts {
224 	struct device_node *requestor;
225 	int num_devices;
226 	int request;
227 	int quota;
228 	int spare;
229 	int over_quota;
230 };
231 
232 static void *count_non_bridge_devices(struct device_node *dn, void *data)
233 {
234 	struct msi_counts *counts = data;
235 	const u32 *p;
236 	u32 class;
237 
238 	pr_debug("rtas_msi: counting %s\n", dn->full_name);
239 
240 	p = of_get_property(dn, "class-code", NULL);
241 	class = p ? *p : 0;
242 
243 	if ((class >> 8) != PCI_CLASS_BRIDGE_PCI)
244 		counts->num_devices++;
245 
246 	return NULL;
247 }
248 
249 static void *count_spare_msis(struct device_node *dn, void *data)
250 {
251 	struct msi_counts *counts = data;
252 	const u32 *p;
253 	int req;
254 
255 	if (dn == counts->requestor)
256 		req = counts->request;
257 	else {
258 		/* We don't know if a driver will try to use MSI or MSI-X,
259 		 * so we just have to punt and use the larger of the two. */
260 		req = 0;
261 		p = of_get_property(dn, "ibm,req#msi", NULL);
262 		if (p)
263 			req = *p;
264 
265 		p = of_get_property(dn, "ibm,req#msi-x", NULL);
266 		if (p)
267 			req = max(req, (int)*p);
268 	}
269 
270 	if (req < counts->quota)
271 		counts->spare += counts->quota - req;
272 	else if (req > counts->quota)
273 		counts->over_quota++;
274 
275 	return NULL;
276 }
277 
278 static int msi_quota_for_device(struct pci_dev *dev, int request)
279 {
280 	struct device_node *pe_dn;
281 	struct msi_counts counts;
282 	int total;
283 
284 	pr_debug("rtas_msi: calc quota for %s, request %d\n", pci_name(dev),
285 		  request);
286 
287 	pe_dn = find_pe_total_msi(dev, &total);
288 	if (!pe_dn)
289 		pe_dn = find_pe_dn(dev, &total);
290 
291 	if (!pe_dn) {
292 		pr_err("rtas_msi: couldn't find PE for %s\n", pci_name(dev));
293 		goto out;
294 	}
295 
296 	pr_debug("rtas_msi: found PE %s\n", pe_dn->full_name);
297 
298 	memset(&counts, 0, sizeof(struct msi_counts));
299 
300 	/* Work out how many devices we have below this PE */
301 	traverse_pci_devices(pe_dn, count_non_bridge_devices, &counts);
302 
303 	if (counts.num_devices == 0) {
304 		pr_err("rtas_msi: found 0 devices under PE for %s\n",
305 			pci_name(dev));
306 		goto out;
307 	}
308 
309 	counts.quota = total / counts.num_devices;
310 	if (request <= counts.quota)
311 		goto out;
312 
313 	/* else, we have some more calculating to do */
314 	counts.requestor = pci_device_to_OF_node(dev);
315 	counts.request = request;
316 	traverse_pci_devices(pe_dn, count_spare_msis, &counts);
317 
318 	/* If the quota isn't an integer multiple of the total, we can
319 	 * use the remainder as spare MSIs for anyone that wants them. */
320 	counts.spare += total % counts.num_devices;
321 
322 	/* Divide any spare by the number of over-quota requestors */
323 	if (counts.over_quota)
324 		counts.quota += counts.spare / counts.over_quota;
325 
326 	/* And finally clamp the request to the possibly adjusted quota */
327 	request = min(counts.quota, request);
328 
329 	pr_debug("rtas_msi: request clamped to quota %d\n", request);
330 out:
331 	of_node_put(pe_dn);
332 
333 	return request;
334 }
335 
336 static int rtas_msi_check_device(struct pci_dev *pdev, int nvec, int type)
337 {
338 	int quota, rc;
339 
340 	if (type == PCI_CAP_ID_MSIX)
341 		rc = check_req_msix(pdev, nvec);
342 	else
343 		rc = check_req_msi(pdev, nvec);
344 
345 	if (rc)
346 		return rc;
347 
348 	quota = msi_quota_for_device(pdev, nvec);
349 
350 	if (quota && quota < nvec)
351 		return quota;
352 
353 	return 0;
354 }
355 
356 static int check_msix_entries(struct pci_dev *pdev)
357 {
358 	struct msi_desc *entry;
359 	int expected;
360 
361 	/* There's no way for us to express to firmware that we want
362 	 * a discontiguous, or non-zero based, range of MSI-X entries.
363 	 * So we must reject such requests. */
364 
365 	expected = 0;
366 	list_for_each_entry(entry, &pdev->msi_list, list) {
367 		if (entry->msi_attrib.entry_nr != expected) {
368 			pr_debug("rtas_msi: bad MSI-X entries.\n");
369 			return -EINVAL;
370 		}
371 		expected++;
372 	}
373 
374 	return 0;
375 }
376 
377 static void rtas_hack_32bit_msi_gen2(struct pci_dev *pdev)
378 {
379 	u32 addr_hi, addr_lo;
380 
381 	/*
382 	 * We should only get in here for IODA1 configs. This is based on the
383 	 * fact that we using RTAS for MSIs, we don't have the 32 bit MSI RTAS
384 	 * support, and we are in a PCIe Gen2 slot.
385 	 */
386 	dev_info(&pdev->dev,
387 		 "rtas_msi: No 32 bit MSI firmware support, forcing 32 bit MSI\n");
388 	pci_read_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_HI, &addr_hi);
389 	addr_lo = 0xffff0000 | ((addr_hi >> (48 - 32)) << 4);
390 	pci_write_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_LO, addr_lo);
391 	pci_write_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_HI, 0);
392 }
393 
394 static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec_in, int type)
395 {
396 	struct pci_dn *pdn;
397 	int hwirq, virq, i, rc;
398 	struct msi_desc *entry;
399 	struct msi_msg msg;
400 	int nvec = nvec_in;
401 	int use_32bit_msi_hack = 0;
402 
403 	pdn = pci_get_pdn(pdev);
404 	if (!pdn)
405 		return -ENODEV;
406 
407 	if (type == PCI_CAP_ID_MSIX && check_msix_entries(pdev))
408 		return -EINVAL;
409 
410 	/*
411 	 * Firmware currently refuse any non power of two allocation
412 	 * so we round up if the quota will allow it.
413 	 */
414 	if (type == PCI_CAP_ID_MSIX) {
415 		int m = roundup_pow_of_two(nvec);
416 		int quota = msi_quota_for_device(pdev, m);
417 
418 		if (quota >= m)
419 			nvec = m;
420 	}
421 
422 	/*
423 	 * Try the new more explicit firmware interface, if that fails fall
424 	 * back to the old interface. The old interface is known to never
425 	 * return MSI-Xs.
426 	 */
427 again:
428 	if (type == PCI_CAP_ID_MSI) {
429 		if (pdn->force_32bit_msi) {
430 			rc = rtas_change_msi(pdn, RTAS_CHANGE_32MSI_FN, nvec);
431 			if (rc < 0) {
432 				/*
433 				 * We only want to run the 32 bit MSI hack below if
434 				 * the max bus speed is Gen2 speed
435 				 */
436 				if (pdev->bus->max_bus_speed != PCIE_SPEED_5_0GT)
437 					return rc;
438 
439 				use_32bit_msi_hack = 1;
440 			}
441 		} else
442 			rc = -1;
443 
444 		if (rc < 0)
445 			rc = rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, nvec);
446 
447 		if (rc < 0) {
448 			pr_debug("rtas_msi: trying the old firmware call.\n");
449 			rc = rtas_change_msi(pdn, RTAS_CHANGE_FN, nvec);
450 		}
451 
452 		if (use_32bit_msi_hack && rc > 0)
453 			rtas_hack_32bit_msi_gen2(pdev);
454 	} else
455 		rc = rtas_change_msi(pdn, RTAS_CHANGE_MSIX_FN, nvec);
456 
457 	if (rc != nvec) {
458 		if (nvec != nvec_in) {
459 			nvec = nvec_in;
460 			goto again;
461 		}
462 		pr_debug("rtas_msi: rtas_change_msi() failed\n");
463 		return rc;
464 	}
465 
466 	i = 0;
467 	list_for_each_entry(entry, &pdev->msi_list, list) {
468 		hwirq = rtas_query_irq_number(pdn, i++);
469 		if (hwirq < 0) {
470 			pr_debug("rtas_msi: error (%d) getting hwirq\n", rc);
471 			return hwirq;
472 		}
473 
474 		virq = irq_create_mapping(NULL, hwirq);
475 
476 		if (virq == NO_IRQ) {
477 			pr_debug("rtas_msi: Failed mapping hwirq %d\n", hwirq);
478 			return -ENOSPC;
479 		}
480 
481 		dev_dbg(&pdev->dev, "rtas_msi: allocated virq %d\n", virq);
482 		irq_set_msi_desc(virq, entry);
483 
484 		/* Read config space back so we can restore after reset */
485 		read_msi_msg(virq, &msg);
486 		entry->msg = msg;
487 	}
488 
489 	return 0;
490 }
491 
492 static void rtas_msi_pci_irq_fixup(struct pci_dev *pdev)
493 {
494 	/* No LSI -> leave MSIs (if any) configured */
495 	if (pdev->irq == NO_IRQ) {
496 		dev_dbg(&pdev->dev, "rtas_msi: no LSI, nothing to do.\n");
497 		return;
498 	}
499 
500 	/* No MSI -> MSIs can't have been assigned by fw, leave LSI */
501 	if (check_req_msi(pdev, 1) && check_req_msix(pdev, 1)) {
502 		dev_dbg(&pdev->dev, "rtas_msi: no req#msi/x, nothing to do.\n");
503 		return;
504 	}
505 
506 	dev_dbg(&pdev->dev, "rtas_msi: disabling existing MSI.\n");
507 	rtas_disable_msi(pdev);
508 }
509 
510 static int rtas_msi_init(void)
511 {
512 	query_token  = rtas_token("ibm,query-interrupt-source-number");
513 	change_token = rtas_token("ibm,change-msi");
514 
515 	if ((query_token == RTAS_UNKNOWN_SERVICE) ||
516 			(change_token == RTAS_UNKNOWN_SERVICE)) {
517 		pr_debug("rtas_msi: no RTAS tokens, no MSI support.\n");
518 		return -1;
519 	}
520 
521 	pr_debug("rtas_msi: Registering RTAS MSI callbacks.\n");
522 
523 	WARN_ON(ppc_md.setup_msi_irqs);
524 	ppc_md.setup_msi_irqs = rtas_setup_msi_irqs;
525 	ppc_md.teardown_msi_irqs = rtas_teardown_msi_irqs;
526 	ppc_md.msi_check_device = rtas_msi_check_device;
527 
528 	WARN_ON(ppc_md.pci_irq_fixup);
529 	ppc_md.pci_irq_fixup = rtas_msi_pci_irq_fixup;
530 
531 	return 0;
532 }
533 arch_initcall(rtas_msi_init);
534 
535