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/init.h>
13 #include <linux/module.h>
14 #include <linux/msi.h>
15 #include <linux/of_address.h>
16 #include <linux/of_irq.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 
28 struct 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 
41 static 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 
47 static inline u32 msi_readl(struct altera_msi *msi, const u32 reg)
48 {
49 	return readl_relaxed(msi->csr_base + reg);
50 }
51 
52 static 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 	u32 virq;
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 			virq = irq_find_mapping(msi->inner_domain, bit);
69 			if (virq)
70 				generic_handle_irq(virq);
71 			else
72 				dev_err(&msi->pdev->dev, "unexpected MSI\n");
73 		}
74 	}
75 
76 	chained_irq_exit(chip, desc);
77 }
78 
79 static struct irq_chip altera_msi_irq_chip = {
80 	.name = "Altera PCIe MSI",
81 	.irq_mask = pci_msi_mask_irq,
82 	.irq_unmask = pci_msi_unmask_irq,
83 };
84 
85 static struct msi_domain_info altera_msi_domain_info = {
86 	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
87 		     MSI_FLAG_PCI_MSIX),
88 	.chip	= &altera_msi_irq_chip,
89 };
90 
91 static void altera_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
92 {
93 	struct altera_msi *msi = irq_data_get_irq_chip_data(data);
94 	phys_addr_t addr = msi->vector_phy + (data->hwirq * sizeof(u32));
95 
96 	msg->address_lo = lower_32_bits(addr);
97 	msg->address_hi = upper_32_bits(addr);
98 	msg->data = data->hwirq;
99 
100 	dev_dbg(&msi->pdev->dev, "msi#%d address_hi %#x address_lo %#x\n",
101 		(int)data->hwirq, msg->address_hi, msg->address_lo);
102 }
103 
104 static int altera_msi_set_affinity(struct irq_data *irq_data,
105 				   const struct cpumask *mask, bool force)
106 {
107 	 return -EINVAL;
108 }
109 
110 static struct irq_chip altera_msi_bottom_irq_chip = {
111 	.name			= "Altera MSI",
112 	.irq_compose_msi_msg	= altera_compose_msi_msg,
113 	.irq_set_affinity	= altera_msi_set_affinity,
114 };
115 
116 static int altera_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
117 				   unsigned int nr_irqs, void *args)
118 {
119 	struct altera_msi *msi = domain->host_data;
120 	unsigned long bit;
121 	u32 mask;
122 
123 	WARN_ON(nr_irqs != 1);
124 	mutex_lock(&msi->lock);
125 
126 	bit = find_first_zero_bit(msi->used, msi->num_of_vectors);
127 	if (bit >= msi->num_of_vectors) {
128 		mutex_unlock(&msi->lock);
129 		return -ENOSPC;
130 	}
131 
132 	set_bit(bit, msi->used);
133 
134 	mutex_unlock(&msi->lock);
135 
136 	irq_domain_set_info(domain, virq, bit, &altera_msi_bottom_irq_chip,
137 			    domain->host_data, handle_simple_irq,
138 			    NULL, NULL);
139 
140 	mask = msi_readl(msi, MSI_INTMASK);
141 	mask |= 1 << bit;
142 	msi_writel(msi, mask, MSI_INTMASK);
143 
144 	return 0;
145 }
146 
147 static void altera_irq_domain_free(struct irq_domain *domain,
148 				   unsigned int virq, unsigned int nr_irqs)
149 {
150 	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
151 	struct altera_msi *msi = irq_data_get_irq_chip_data(d);
152 	u32 mask;
153 
154 	mutex_lock(&msi->lock);
155 
156 	if (!test_bit(d->hwirq, msi->used)) {
157 		dev_err(&msi->pdev->dev, "trying to free unused MSI#%lu\n",
158 			d->hwirq);
159 	} else {
160 		__clear_bit(d->hwirq, msi->used);
161 		mask = msi_readl(msi, MSI_INTMASK);
162 		mask &= ~(1 << d->hwirq);
163 		msi_writel(msi, mask, MSI_INTMASK);
164 	}
165 
166 	mutex_unlock(&msi->lock);
167 }
168 
169 static const struct irq_domain_ops msi_domain_ops = {
170 	.alloc	= altera_irq_domain_alloc,
171 	.free	= altera_irq_domain_free,
172 };
173 
174 static int altera_allocate_domains(struct altera_msi *msi)
175 {
176 	struct fwnode_handle *fwnode = of_node_to_fwnode(msi->pdev->dev.of_node);
177 
178 	msi->inner_domain = irq_domain_add_linear(NULL, msi->num_of_vectors,
179 					     &msi_domain_ops, msi);
180 	if (!msi->inner_domain) {
181 		dev_err(&msi->pdev->dev, "failed to create IRQ domain\n");
182 		return -ENOMEM;
183 	}
184 
185 	msi->msi_domain = pci_msi_create_irq_domain(fwnode,
186 				&altera_msi_domain_info, msi->inner_domain);
187 	if (!msi->msi_domain) {
188 		dev_err(&msi->pdev->dev, "failed to create MSI domain\n");
189 		irq_domain_remove(msi->inner_domain);
190 		return -ENOMEM;
191 	}
192 
193 	return 0;
194 }
195 
196 static void altera_free_domains(struct altera_msi *msi)
197 {
198 	irq_domain_remove(msi->msi_domain);
199 	irq_domain_remove(msi->inner_domain);
200 }
201 
202 static int altera_msi_remove(struct platform_device *pdev)
203 {
204 	struct altera_msi *msi = platform_get_drvdata(pdev);
205 
206 	msi_writel(msi, 0, MSI_INTMASK);
207 	irq_set_chained_handler(msi->irq, NULL);
208 	irq_set_handler_data(msi->irq, NULL);
209 
210 	altera_free_domains(msi);
211 
212 	platform_set_drvdata(pdev, NULL);
213 	return 0;
214 }
215 
216 static int altera_msi_probe(struct platform_device *pdev)
217 {
218 	struct altera_msi *msi;
219 	struct device_node *np = pdev->dev.of_node;
220 	struct resource *res;
221 	int ret;
222 
223 	msi = devm_kzalloc(&pdev->dev, sizeof(struct altera_msi),
224 			   GFP_KERNEL);
225 	if (!msi)
226 		return -ENOMEM;
227 
228 	mutex_init(&msi->lock);
229 	msi->pdev = pdev;
230 
231 	msi->csr_base = devm_platform_ioremap_resource_byname(pdev, "csr");
232 	if (IS_ERR(msi->csr_base)) {
233 		dev_err(&pdev->dev, "failed to map csr memory\n");
234 		return PTR_ERR(msi->csr_base);
235 	}
236 
237 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
238 					   "vector_slave");
239 	msi->vector_base = devm_ioremap_resource(&pdev->dev, res);
240 	if (IS_ERR(msi->vector_base)) {
241 		dev_err(&pdev->dev, "failed to map vector_slave memory\n");
242 		return PTR_ERR(msi->vector_base);
243 	}
244 
245 	msi->vector_phy = res->start;
246 
247 	if (of_property_read_u32(np, "num-vectors", &msi->num_of_vectors)) {
248 		dev_err(&pdev->dev, "failed to parse the number of vectors\n");
249 		return -EINVAL;
250 	}
251 
252 	ret = altera_allocate_domains(msi);
253 	if (ret)
254 		return ret;
255 
256 	msi->irq = platform_get_irq(pdev, 0);
257 	if (msi->irq < 0) {
258 		ret = msi->irq;
259 		goto err;
260 	}
261 
262 	irq_set_chained_handler_and_data(msi->irq, altera_msi_isr, msi);
263 	platform_set_drvdata(pdev, msi);
264 
265 	return 0;
266 
267 err:
268 	altera_msi_remove(pdev);
269 	return ret;
270 }
271 
272 static const struct of_device_id altera_msi_of_match[] = {
273 	{ .compatible = "altr,msi-1.0", NULL },
274 	{ },
275 };
276 
277 static struct platform_driver altera_msi_driver = {
278 	.driver = {
279 		.name = "altera-msi",
280 		.of_match_table = altera_msi_of_match,
281 	},
282 	.probe = altera_msi_probe,
283 	.remove = altera_msi_remove,
284 };
285 
286 static int __init altera_msi_init(void)
287 {
288 	return platform_driver_register(&altera_msi_driver);
289 }
290 
291 static void __exit altera_msi_exit(void)
292 {
293 	platform_driver_unregister(&altera_msi_driver);
294 }
295 
296 subsys_initcall(altera_msi_init);
297 MODULE_DEVICE_TABLE(of, altera_msi_of_match);
298 module_exit(altera_msi_exit);
299 MODULE_LICENSE("GPL v2");
300