1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Altera PCIe MSI support
4 *
5 * Author: Ley Foon Tan <lftan@altera.com>
6 *
7 * Copyright Altera Corporation (C) 2013-2015. All rights reserved
8 */
9
10#include <linux/interrupt.h>
11#include <linux/irqchip/chained_irq.h>
12#include <linux/irqdomain.h>
13#include <linux/init.h>
14#include <linux/module.h>
15#include <linux/msi.h>
16#include <linux/of_address.h>
17#include <linux/of_pci.h>
18#include <linux/pci.h>
19#include <linux/platform_device.h>
20#include <linux/slab.h>
21
22#define MSI_STATUS		0x0
23#define MSI_ERROR		0x4
24#define MSI_INTMASK		0x8
25
26#define MAX_MSI_VECTORS		32
27
28struct altera_msi {
29	DECLARE_BITMAP(used, MAX_MSI_VECTORS);
30	struct mutex		lock;	/* protect "used" bitmap */
31	struct platform_device	*pdev;
32	struct irq_domain	*msi_domain;
33	struct irq_domain	*inner_domain;
34	void __iomem		*csr_base;
35	void __iomem		*vector_base;
36	phys_addr_t		vector_phy;
37	u32			num_of_vectors;
38	int			irq;
39};
40
41static inline void msi_writel(struct altera_msi *msi, const u32 value,
42			      const u32 reg)
43{
44	writel_relaxed(value, msi->csr_base + reg);
45}
46
47static inline u32 msi_readl(struct altera_msi *msi, const u32 reg)
48{
49	return readl_relaxed(msi->csr_base + reg);
50}
51
52static void altera_msi_isr(struct irq_desc *desc)
53{
54	struct irq_chip *chip = irq_desc_get_chip(desc);
55	struct altera_msi *msi;
56	unsigned long status;
57	u32 bit;
58	int ret;
59
60	chained_irq_enter(chip, desc);
61	msi = irq_desc_get_handler_data(desc);
62
63	while ((status = msi_readl(msi, MSI_STATUS)) != 0) {
64		for_each_set_bit(bit, &status, msi->num_of_vectors) {
65			/* Dummy read from vector to clear the interrupt */
66			readl_relaxed(msi->vector_base + (bit * sizeof(u32)));
67
68			ret = generic_handle_domain_irq(msi->inner_domain, bit);
69			if (ret)
70				dev_err_ratelimited(&msi->pdev->dev, "unexpected MSI\n");
71		}
72	}
73
74	chained_irq_exit(chip, desc);
75}
76
77static struct irq_chip altera_msi_irq_chip = {
78	.name = "Altera PCIe MSI",
79	.irq_mask = pci_msi_mask_irq,
80	.irq_unmask = pci_msi_unmask_irq,
81};
82
83static struct msi_domain_info altera_msi_domain_info = {
84	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
85		     MSI_FLAG_PCI_MSIX),
86	.chip	= &altera_msi_irq_chip,
87};
88
89static void altera_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
90{
91	struct altera_msi *msi = irq_data_get_irq_chip_data(data);
92	phys_addr_t addr = msi->vector_phy + (data->hwirq * sizeof(u32));
93
94	msg->address_lo = lower_32_bits(addr);
95	msg->address_hi = upper_32_bits(addr);
96	msg->data = data->hwirq;
97
98	dev_dbg(&msi->pdev->dev, "msi#%d address_hi %#x address_lo %#x\n",
99		(int)data->hwirq, msg->address_hi, msg->address_lo);
100}
101
102static int altera_msi_set_affinity(struct irq_data *irq_data,
103				   const struct cpumask *mask, bool force)
104{
105	 return -EINVAL;
106}
107
108static struct irq_chip altera_msi_bottom_irq_chip = {
109	.name			= "Altera MSI",
110	.irq_compose_msi_msg	= altera_compose_msi_msg,
111	.irq_set_affinity	= altera_msi_set_affinity,
112};
113
114static int altera_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
115				   unsigned int nr_irqs, void *args)
116{
117	struct altera_msi *msi = domain->host_data;
118	unsigned long bit;
119	u32 mask;
120
121	WARN_ON(nr_irqs != 1);
122	mutex_lock(&msi->lock);
123
124	bit = find_first_zero_bit(msi->used, msi->num_of_vectors);
125	if (bit >= msi->num_of_vectors) {
126		mutex_unlock(&msi->lock);
127		return -ENOSPC;
128	}
129
130	set_bit(bit, msi->used);
131
132	mutex_unlock(&msi->lock);
133
134	irq_domain_set_info(domain, virq, bit, &altera_msi_bottom_irq_chip,
135			    domain->host_data, handle_simple_irq,
136			    NULL, NULL);
137
138	mask = msi_readl(msi, MSI_INTMASK);
139	mask |= 1 << bit;
140	msi_writel(msi, mask, MSI_INTMASK);
141
142	return 0;
143}
144
145static void altera_irq_domain_free(struct irq_domain *domain,
146				   unsigned int virq, unsigned int nr_irqs)
147{
148	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
149	struct altera_msi *msi = irq_data_get_irq_chip_data(d);
150	u32 mask;
151
152	mutex_lock(&msi->lock);
153
154	if (!test_bit(d->hwirq, msi->used)) {
155		dev_err(&msi->pdev->dev, "trying to free unused MSI#%lu\n",
156			d->hwirq);
157	} else {
158		__clear_bit(d->hwirq, msi->used);
159		mask = msi_readl(msi, MSI_INTMASK);
160		mask &= ~(1 << d->hwirq);
161		msi_writel(msi, mask, MSI_INTMASK);
162	}
163
164	mutex_unlock(&msi->lock);
165}
166
167static const struct irq_domain_ops msi_domain_ops = {
168	.alloc	= altera_irq_domain_alloc,
169	.free	= altera_irq_domain_free,
170};
171
172static int altera_allocate_domains(struct altera_msi *msi)
173{
174	struct fwnode_handle *fwnode = of_node_to_fwnode(msi->pdev->dev.of_node);
175
176	msi->inner_domain = irq_domain_add_linear(NULL, msi->num_of_vectors,
177					     &msi_domain_ops, msi);
178	if (!msi->inner_domain) {
179		dev_err(&msi->pdev->dev, "failed to create IRQ domain\n");
180		return -ENOMEM;
181	}
182
183	msi->msi_domain = pci_msi_create_irq_domain(fwnode,
184				&altera_msi_domain_info, msi->inner_domain);
185	if (!msi->msi_domain) {
186		dev_err(&msi->pdev->dev, "failed to create MSI domain\n");
187		irq_domain_remove(msi->inner_domain);
188		return -ENOMEM;
189	}
190
191	return 0;
192}
193
194static void altera_free_domains(struct altera_msi *msi)
195{
196	irq_domain_remove(msi->msi_domain);
197	irq_domain_remove(msi->inner_domain);
198}
199
200static void altera_msi_remove(struct platform_device *pdev)
201{
202	struct altera_msi *msi = platform_get_drvdata(pdev);
203
204	msi_writel(msi, 0, MSI_INTMASK);
205	irq_set_chained_handler_and_data(msi->irq, NULL, NULL);
206
207	altera_free_domains(msi);
208
209	platform_set_drvdata(pdev, NULL);
210}
211
212static int altera_msi_probe(struct platform_device *pdev)
213{
214	struct altera_msi *msi;
215	struct device_node *np = pdev->dev.of_node;
216	struct resource *res;
217	int ret;
218
219	msi = devm_kzalloc(&pdev->dev, sizeof(struct altera_msi),
220			   GFP_KERNEL);
221	if (!msi)
222		return -ENOMEM;
223
224	mutex_init(&msi->lock);
225	msi->pdev = pdev;
226
227	msi->csr_base = devm_platform_ioremap_resource_byname(pdev, "csr");
228	if (IS_ERR(msi->csr_base)) {
229		dev_err(&pdev->dev, "failed to map csr memory\n");
230		return PTR_ERR(msi->csr_base);
231	}
232
233	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
234					   "vector_slave");
235	msi->vector_base = devm_ioremap_resource(&pdev->dev, res);
236	if (IS_ERR(msi->vector_base))
237		return PTR_ERR(msi->vector_base);
238
239	msi->vector_phy = res->start;
240
241	if (of_property_read_u32(np, "num-vectors", &msi->num_of_vectors)) {
242		dev_err(&pdev->dev, "failed to parse the number of vectors\n");
243		return -EINVAL;
244	}
245
246	ret = altera_allocate_domains(msi);
247	if (ret)
248		return ret;
249
250	msi->irq = platform_get_irq(pdev, 0);
251	if (msi->irq < 0) {
252		ret = msi->irq;
253		goto err;
254	}
255
256	irq_set_chained_handler_and_data(msi->irq, altera_msi_isr, msi);
257	platform_set_drvdata(pdev, msi);
258
259	return 0;
260
261err:
262	altera_msi_remove(pdev);
263	return ret;
264}
265
266static const struct of_device_id altera_msi_of_match[] = {
267	{ .compatible = "altr,msi-1.0", NULL },
268	{ },
269};
270
271static struct platform_driver altera_msi_driver = {
272	.driver = {
273		.name = "altera-msi",
274		.of_match_table = altera_msi_of_match,
275	},
276	.probe = altera_msi_probe,
277	.remove_new = altera_msi_remove,
278};
279
280static int __init altera_msi_init(void)
281{
282	return platform_driver_register(&altera_msi_driver);
283}
284
285static void __exit altera_msi_exit(void)
286{
287	platform_driver_unregister(&altera_msi_driver);
288}
289
290subsys_initcall(altera_msi_init);
291MODULE_DEVICE_TABLE(of, altera_msi_of_match);
292module_exit(altera_msi_exit);
293MODULE_LICENSE("GPL v2");
294