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