1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * APM X-Gene MSI Driver
4  *
5  * Copyright (c) 2014, Applied Micro Circuits Corporation
6  * Author: Tanmay Inamdar <tinamdar@apm.com>
7  *	   Duc Dang <dhdang@apm.com>
8  */
9 #include <linux/cpu.h>
10 #include <linux/interrupt.h>
11 #include <linux/irqdomain.h>
12 #include <linux/module.h>
13 #include <linux/msi.h>
14 #include <linux/irqchip/chained_irq.h>
15 #include <linux/pci.h>
16 #include <linux/platform_device.h>
17 #include <linux/of_pci.h>
18 
19 #define MSI_IR0			0x000000
20 #define MSI_INT0		0x800000
21 #define IDX_PER_GROUP		8
22 #define IRQS_PER_IDX		16
23 #define NR_HW_IRQS		16
24 #define NR_MSI_VEC		(IDX_PER_GROUP * IRQS_PER_IDX * NR_HW_IRQS)
25 
26 struct xgene_msi_group {
27 	struct xgene_msi	*msi;
28 	int			gic_irq;
29 	u32			msi_grp;
30 };
31 
32 struct xgene_msi {
33 	struct device_node	*node;
34 	struct irq_domain	*inner_domain;
35 	struct irq_domain	*msi_domain;
36 	u64			msi_addr;
37 	void __iomem		*msi_regs;
38 	unsigned long		*bitmap;
39 	struct mutex		bitmap_lock;
40 	struct xgene_msi_group	*msi_groups;
41 	int			num_cpus;
42 };
43 
44 /* Global data */
45 static struct xgene_msi xgene_msi_ctrl;
46 
47 static struct irq_chip xgene_msi_top_irq_chip = {
48 	.name		= "X-Gene1 MSI",
49 	.irq_enable	= pci_msi_unmask_irq,
50 	.irq_disable	= pci_msi_mask_irq,
51 	.irq_mask	= pci_msi_mask_irq,
52 	.irq_unmask	= pci_msi_unmask_irq,
53 };
54 
55 static struct  msi_domain_info xgene_msi_domain_info = {
56 	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
57 		  MSI_FLAG_PCI_MSIX),
58 	.chip	= &xgene_msi_top_irq_chip,
59 };
60 
61 /*
62  * X-Gene v1 has 16 groups of MSI termination registers MSInIRx, where
63  * n is group number (0..F), x is index of registers in each group (0..7)
64  * The register layout is as follows:
65  * MSI0IR0			base_addr
66  * MSI0IR1			base_addr +  0x10000
67  * ...				...
68  * MSI0IR6			base_addr +  0x60000
69  * MSI0IR7			base_addr +  0x70000
70  * MSI1IR0			base_addr +  0x80000
71  * MSI1IR1			base_addr +  0x90000
72  * ...				...
73  * MSI1IR7			base_addr +  0xF0000
74  * MSI2IR0			base_addr + 0x100000
75  * ...				...
76  * MSIFIR0			base_addr + 0x780000
77  * MSIFIR1			base_addr + 0x790000
78  * ...				...
79  * MSIFIR7			base_addr + 0x7F0000
80  * MSIINT0			base_addr + 0x800000
81  * MSIINT1			base_addr + 0x810000
82  * ...				...
83  * MSIINTF			base_addr + 0x8F0000
84  *
85  * Each index register supports 16 MSI vectors (0..15) to generate interrupt.
86  * There are total 16 GIC IRQs assigned for these 16 groups of MSI termination
87  * registers.
88  *
89  * Each MSI termination group has 1 MSIINTn register (n is 0..15) to indicate
90  * the MSI pending status caused by 1 of its 8 index registers.
91  */
92 
93 /* MSInIRx read helper */
94 static u32 xgene_msi_ir_read(struct xgene_msi *msi,
95 				    u32 msi_grp, u32 msir_idx)
96 {
97 	return readl_relaxed(msi->msi_regs + MSI_IR0 +
98 			      (msi_grp << 19) + (msir_idx << 16));
99 }
100 
101 /* MSIINTn read helper */
102 static u32 xgene_msi_int_read(struct xgene_msi *msi, u32 msi_grp)
103 {
104 	return readl_relaxed(msi->msi_regs + MSI_INT0 + (msi_grp << 16));
105 }
106 
107 /*
108  * With 2048 MSI vectors supported, the MSI message can be constructed using
109  * following scheme:
110  * - Divide into 8 256-vector groups
111  *		Group 0: 0-255
112  *		Group 1: 256-511
113  *		Group 2: 512-767
114  *		...
115  *		Group 7: 1792-2047
116  * - Each 256-vector group is divided into 16 16-vector groups
117  *	As an example: 16 16-vector groups for 256-vector group 0-255 is
118  *		Group 0: 0-15
119  *		Group 1: 16-32
120  *		...
121  *		Group 15: 240-255
122  * - The termination address of MSI vector in 256-vector group n and 16-vector
123  *   group x is the address of MSIxIRn
124  * - The data for MSI vector in 16-vector group x is x
125  */
126 static u32 hwirq_to_reg_set(unsigned long hwirq)
127 {
128 	return (hwirq / (NR_HW_IRQS * IRQS_PER_IDX));
129 }
130 
131 static u32 hwirq_to_group(unsigned long hwirq)
132 {
133 	return (hwirq % NR_HW_IRQS);
134 }
135 
136 static u32 hwirq_to_msi_data(unsigned long hwirq)
137 {
138 	return ((hwirq / NR_HW_IRQS) % IRQS_PER_IDX);
139 }
140 
141 static void xgene_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
142 {
143 	struct xgene_msi *msi = irq_data_get_irq_chip_data(data);
144 	u32 reg_set = hwirq_to_reg_set(data->hwirq);
145 	u32 group = hwirq_to_group(data->hwirq);
146 	u64 target_addr = msi->msi_addr + (((8 * group) + reg_set) << 16);
147 
148 	msg->address_hi = upper_32_bits(target_addr);
149 	msg->address_lo = lower_32_bits(target_addr);
150 	msg->data = hwirq_to_msi_data(data->hwirq);
151 }
152 
153 /*
154  * X-Gene v1 only has 16 MSI GIC IRQs for 2048 MSI vectors.  To maintain
155  * the expected behaviour of .set_affinity for each MSI interrupt, the 16
156  * MSI GIC IRQs are statically allocated to 8 X-Gene v1 cores (2 GIC IRQs
157  * for each core).  The MSI vector is moved fom 1 MSI GIC IRQ to another
158  * MSI GIC IRQ to steer its MSI interrupt to correct X-Gene v1 core.  As a
159  * consequence, the total MSI vectors that X-Gene v1 supports will be
160  * reduced to 256 (2048/8) vectors.
161  */
162 static int hwirq_to_cpu(unsigned long hwirq)
163 {
164 	return (hwirq % xgene_msi_ctrl.num_cpus);
165 }
166 
167 static unsigned long hwirq_to_canonical_hwirq(unsigned long hwirq)
168 {
169 	return (hwirq - hwirq_to_cpu(hwirq));
170 }
171 
172 static int xgene_msi_set_affinity(struct irq_data *irqdata,
173 				  const struct cpumask *mask, bool force)
174 {
175 	int target_cpu = cpumask_first(mask);
176 	int curr_cpu;
177 
178 	curr_cpu = hwirq_to_cpu(irqdata->hwirq);
179 	if (curr_cpu == target_cpu)
180 		return IRQ_SET_MASK_OK_DONE;
181 
182 	/* Update MSI number to target the new CPU */
183 	irqdata->hwirq = hwirq_to_canonical_hwirq(irqdata->hwirq) + target_cpu;
184 
185 	return IRQ_SET_MASK_OK;
186 }
187 
188 static struct irq_chip xgene_msi_bottom_irq_chip = {
189 	.name			= "MSI",
190 	.irq_set_affinity       = xgene_msi_set_affinity,
191 	.irq_compose_msi_msg	= xgene_compose_msi_msg,
192 };
193 
194 static int xgene_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
195 				  unsigned int nr_irqs, void *args)
196 {
197 	struct xgene_msi *msi = domain->host_data;
198 	int msi_irq;
199 
200 	mutex_lock(&msi->bitmap_lock);
201 
202 	msi_irq = bitmap_find_next_zero_area(msi->bitmap, NR_MSI_VEC, 0,
203 					     msi->num_cpus, 0);
204 	if (msi_irq < NR_MSI_VEC)
205 		bitmap_set(msi->bitmap, msi_irq, msi->num_cpus);
206 	else
207 		msi_irq = -ENOSPC;
208 
209 	mutex_unlock(&msi->bitmap_lock);
210 
211 	if (msi_irq < 0)
212 		return msi_irq;
213 
214 	irq_domain_set_info(domain, virq, msi_irq,
215 			    &xgene_msi_bottom_irq_chip, domain->host_data,
216 			    handle_simple_irq, NULL, NULL);
217 
218 	return 0;
219 }
220 
221 static void xgene_irq_domain_free(struct irq_domain *domain,
222 				  unsigned int virq, unsigned int nr_irqs)
223 {
224 	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
225 	struct xgene_msi *msi = irq_data_get_irq_chip_data(d);
226 	u32 hwirq;
227 
228 	mutex_lock(&msi->bitmap_lock);
229 
230 	hwirq = hwirq_to_canonical_hwirq(d->hwirq);
231 	bitmap_clear(msi->bitmap, hwirq, msi->num_cpus);
232 
233 	mutex_unlock(&msi->bitmap_lock);
234 
235 	irq_domain_free_irqs_parent(domain, virq, nr_irqs);
236 }
237 
238 static const struct irq_domain_ops msi_domain_ops = {
239 	.alloc  = xgene_irq_domain_alloc,
240 	.free   = xgene_irq_domain_free,
241 };
242 
243 static int xgene_allocate_domains(struct xgene_msi *msi)
244 {
245 	msi->inner_domain = irq_domain_add_linear(NULL, NR_MSI_VEC,
246 						  &msi_domain_ops, msi);
247 	if (!msi->inner_domain)
248 		return -ENOMEM;
249 
250 	msi->msi_domain = pci_msi_create_irq_domain(of_node_to_fwnode(msi->node),
251 						    &xgene_msi_domain_info,
252 						    msi->inner_domain);
253 
254 	if (!msi->msi_domain) {
255 		irq_domain_remove(msi->inner_domain);
256 		return -ENOMEM;
257 	}
258 
259 	return 0;
260 }
261 
262 static void xgene_free_domains(struct xgene_msi *msi)
263 {
264 	if (msi->msi_domain)
265 		irq_domain_remove(msi->msi_domain);
266 	if (msi->inner_domain)
267 		irq_domain_remove(msi->inner_domain);
268 }
269 
270 static int xgene_msi_init_allocator(struct xgene_msi *xgene_msi)
271 {
272 	xgene_msi->bitmap = bitmap_zalloc(NR_MSI_VEC, GFP_KERNEL);
273 	if (!xgene_msi->bitmap)
274 		return -ENOMEM;
275 
276 	mutex_init(&xgene_msi->bitmap_lock);
277 
278 	xgene_msi->msi_groups = kcalloc(NR_HW_IRQS,
279 					sizeof(struct xgene_msi_group),
280 					GFP_KERNEL);
281 	if (!xgene_msi->msi_groups)
282 		return -ENOMEM;
283 
284 	return 0;
285 }
286 
287 static void xgene_msi_isr(struct irq_desc *desc)
288 {
289 	struct irq_chip *chip = irq_desc_get_chip(desc);
290 	struct xgene_msi_group *msi_groups;
291 	struct xgene_msi *xgene_msi;
292 	int msir_index, msir_val, hw_irq, ret;
293 	u32 intr_index, grp_select, msi_grp;
294 
295 	chained_irq_enter(chip, desc);
296 
297 	msi_groups = irq_desc_get_handler_data(desc);
298 	xgene_msi = msi_groups->msi;
299 	msi_grp = msi_groups->msi_grp;
300 
301 	/*
302 	 * MSIINTn (n is 0..F) indicates if there is a pending MSI interrupt
303 	 * If bit x of this register is set (x is 0..7), one or more interrupts
304 	 * corresponding to MSInIRx is set.
305 	 */
306 	grp_select = xgene_msi_int_read(xgene_msi, msi_grp);
307 	while (grp_select) {
308 		msir_index = ffs(grp_select) - 1;
309 		/*
310 		 * Calculate MSInIRx address to read to check for interrupts
311 		 * (refer to termination address and data assignment
312 		 * described in xgene_compose_msi_msg() )
313 		 */
314 		msir_val = xgene_msi_ir_read(xgene_msi, msi_grp, msir_index);
315 		while (msir_val) {
316 			intr_index = ffs(msir_val) - 1;
317 			/*
318 			 * Calculate MSI vector number (refer to the termination
319 			 * address and data assignment described in
320 			 * xgene_compose_msi_msg function)
321 			 */
322 			hw_irq = (((msir_index * IRQS_PER_IDX) + intr_index) *
323 				 NR_HW_IRQS) + msi_grp;
324 			/*
325 			 * As we have multiple hw_irq that maps to single MSI,
326 			 * always look up the virq using the hw_irq as seen from
327 			 * CPU0
328 			 */
329 			hw_irq = hwirq_to_canonical_hwirq(hw_irq);
330 			ret = generic_handle_domain_irq(xgene_msi->inner_domain, hw_irq);
331 			WARN_ON_ONCE(ret);
332 			msir_val &= ~(1 << intr_index);
333 		}
334 		grp_select &= ~(1 << msir_index);
335 
336 		if (!grp_select) {
337 			/*
338 			 * We handled all interrupts happened in this group,
339 			 * resample this group MSI_INTx register in case
340 			 * something else has been made pending in the meantime
341 			 */
342 			grp_select = xgene_msi_int_read(xgene_msi, msi_grp);
343 		}
344 	}
345 
346 	chained_irq_exit(chip, desc);
347 }
348 
349 static enum cpuhp_state pci_xgene_online;
350 
351 static void xgene_msi_remove(struct platform_device *pdev)
352 {
353 	struct xgene_msi *msi = platform_get_drvdata(pdev);
354 
355 	if (pci_xgene_online)
356 		cpuhp_remove_state(pci_xgene_online);
357 	cpuhp_remove_state(CPUHP_PCI_XGENE_DEAD);
358 
359 	kfree(msi->msi_groups);
360 
361 	bitmap_free(msi->bitmap);
362 	msi->bitmap = NULL;
363 
364 	xgene_free_domains(msi);
365 }
366 
367 static int xgene_msi_hwirq_alloc(unsigned int cpu)
368 {
369 	struct xgene_msi *msi = &xgene_msi_ctrl;
370 	struct xgene_msi_group *msi_group;
371 	cpumask_var_t mask;
372 	int i;
373 	int err;
374 
375 	for (i = cpu; i < NR_HW_IRQS; i += msi->num_cpus) {
376 		msi_group = &msi->msi_groups[i];
377 		if (!msi_group->gic_irq)
378 			continue;
379 
380 		irq_set_chained_handler_and_data(msi_group->gic_irq,
381 			xgene_msi_isr, msi_group);
382 
383 		/*
384 		 * Statically allocate MSI GIC IRQs to each CPU core.
385 		 * With 8-core X-Gene v1, 2 MSI GIC IRQs are allocated
386 		 * to each core.
387 		 */
388 		if (alloc_cpumask_var(&mask, GFP_KERNEL)) {
389 			cpumask_clear(mask);
390 			cpumask_set_cpu(cpu, mask);
391 			err = irq_set_affinity(msi_group->gic_irq, mask);
392 			if (err)
393 				pr_err("failed to set affinity for GIC IRQ");
394 			free_cpumask_var(mask);
395 		} else {
396 			pr_err("failed to alloc CPU mask for affinity\n");
397 			err = -EINVAL;
398 		}
399 
400 		if (err) {
401 			irq_set_chained_handler_and_data(msi_group->gic_irq,
402 							 NULL, NULL);
403 			return err;
404 		}
405 	}
406 
407 	return 0;
408 }
409 
410 static int xgene_msi_hwirq_free(unsigned int cpu)
411 {
412 	struct xgene_msi *msi = &xgene_msi_ctrl;
413 	struct xgene_msi_group *msi_group;
414 	int i;
415 
416 	for (i = cpu; i < NR_HW_IRQS; i += msi->num_cpus) {
417 		msi_group = &msi->msi_groups[i];
418 		if (!msi_group->gic_irq)
419 			continue;
420 
421 		irq_set_chained_handler_and_data(msi_group->gic_irq, NULL,
422 						 NULL);
423 	}
424 	return 0;
425 }
426 
427 static const struct of_device_id xgene_msi_match_table[] = {
428 	{.compatible = "apm,xgene1-msi"},
429 	{},
430 };
431 
432 static int xgene_msi_probe(struct platform_device *pdev)
433 {
434 	struct resource *res;
435 	int rc, irq_index;
436 	struct xgene_msi *xgene_msi;
437 	int virt_msir;
438 	u32 msi_val, msi_idx;
439 
440 	xgene_msi = &xgene_msi_ctrl;
441 
442 	platform_set_drvdata(pdev, xgene_msi);
443 
444 	xgene_msi->msi_regs = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
445 	if (IS_ERR(xgene_msi->msi_regs)) {
446 		rc = PTR_ERR(xgene_msi->msi_regs);
447 		goto error;
448 	}
449 	xgene_msi->msi_addr = res->start;
450 	xgene_msi->node = pdev->dev.of_node;
451 	xgene_msi->num_cpus = num_possible_cpus();
452 
453 	rc = xgene_msi_init_allocator(xgene_msi);
454 	if (rc) {
455 		dev_err(&pdev->dev, "Error allocating MSI bitmap\n");
456 		goto error;
457 	}
458 
459 	rc = xgene_allocate_domains(xgene_msi);
460 	if (rc) {
461 		dev_err(&pdev->dev, "Failed to allocate MSI domain\n");
462 		goto error;
463 	}
464 
465 	for (irq_index = 0; irq_index < NR_HW_IRQS; irq_index++) {
466 		virt_msir = platform_get_irq(pdev, irq_index);
467 		if (virt_msir < 0) {
468 			rc = virt_msir;
469 			goto error;
470 		}
471 		xgene_msi->msi_groups[irq_index].gic_irq = virt_msir;
472 		xgene_msi->msi_groups[irq_index].msi_grp = irq_index;
473 		xgene_msi->msi_groups[irq_index].msi = xgene_msi;
474 	}
475 
476 	/*
477 	 * MSInIRx registers are read-to-clear; before registering
478 	 * interrupt handlers, read all of them to clear spurious
479 	 * interrupts that may occur before the driver is probed.
480 	 */
481 	for (irq_index = 0; irq_index < NR_HW_IRQS; irq_index++) {
482 		for (msi_idx = 0; msi_idx < IDX_PER_GROUP; msi_idx++)
483 			xgene_msi_ir_read(xgene_msi, irq_index, msi_idx);
484 
485 		/* Read MSIINTn to confirm */
486 		msi_val = xgene_msi_int_read(xgene_msi, irq_index);
487 		if (msi_val) {
488 			dev_err(&pdev->dev, "Failed to clear spurious IRQ\n");
489 			rc = -EINVAL;
490 			goto error;
491 		}
492 	}
493 
494 	rc = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "pci/xgene:online",
495 			       xgene_msi_hwirq_alloc, NULL);
496 	if (rc < 0)
497 		goto err_cpuhp;
498 	pci_xgene_online = rc;
499 	rc = cpuhp_setup_state(CPUHP_PCI_XGENE_DEAD, "pci/xgene:dead", NULL,
500 			       xgene_msi_hwirq_free);
501 	if (rc)
502 		goto err_cpuhp;
503 
504 	dev_info(&pdev->dev, "APM X-Gene PCIe MSI driver loaded\n");
505 
506 	return 0;
507 
508 err_cpuhp:
509 	dev_err(&pdev->dev, "failed to add CPU MSI notifier\n");
510 error:
511 	xgene_msi_remove(pdev);
512 	return rc;
513 }
514 
515 static struct platform_driver xgene_msi_driver = {
516 	.driver = {
517 		.name = "xgene-msi",
518 		.of_match_table = xgene_msi_match_table,
519 	},
520 	.probe = xgene_msi_probe,
521 	.remove_new = xgene_msi_remove,
522 };
523 
524 static int __init xgene_pcie_msi_init(void)
525 {
526 	return platform_driver_register(&xgene_msi_driver);
527 }
528 subsys_initcall(xgene_pcie_msi_init);
529