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 	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 
77 static 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 
83 static 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 
89 static 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 
102 static int altera_msi_set_affinity(struct irq_data *irq_data,
103 				   const struct cpumask *mask, bool force)
104 {
105 	 return -EINVAL;
106 }
107 
108 static 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 
114 static 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 
145 static 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 
167 static const struct irq_domain_ops msi_domain_ops = {
168 	.alloc	= altera_irq_domain_alloc,
169 	.free	= altera_irq_domain_free,
170 };
171 
172 static 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 
194 static 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 
200 static int 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 	return 0;
211 }
212 
213 static int altera_msi_probe(struct platform_device *pdev)
214 {
215 	struct altera_msi *msi;
216 	struct device_node *np = pdev->dev.of_node;
217 	struct resource *res;
218 	int ret;
219 
220 	msi = devm_kzalloc(&pdev->dev, sizeof(struct altera_msi),
221 			   GFP_KERNEL);
222 	if (!msi)
223 		return -ENOMEM;
224 
225 	mutex_init(&msi->lock);
226 	msi->pdev = pdev;
227 
228 	msi->csr_base = devm_platform_ioremap_resource_byname(pdev, "csr");
229 	if (IS_ERR(msi->csr_base)) {
230 		dev_err(&pdev->dev, "failed to map csr memory\n");
231 		return PTR_ERR(msi->csr_base);
232 	}
233 
234 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
235 					   "vector_slave");
236 	msi->vector_base = devm_ioremap_resource(&pdev->dev, res);
237 	if (IS_ERR(msi->vector_base))
238 		return PTR_ERR(msi->vector_base);
239 
240 	msi->vector_phy = res->start;
241 
242 	if (of_property_read_u32(np, "num-vectors", &msi->num_of_vectors)) {
243 		dev_err(&pdev->dev, "failed to parse the number of vectors\n");
244 		return -EINVAL;
245 	}
246 
247 	ret = altera_allocate_domains(msi);
248 	if (ret)
249 		return ret;
250 
251 	msi->irq = platform_get_irq(pdev, 0);
252 	if (msi->irq < 0) {
253 		ret = msi->irq;
254 		goto err;
255 	}
256 
257 	irq_set_chained_handler_and_data(msi->irq, altera_msi_isr, msi);
258 	platform_set_drvdata(pdev, msi);
259 
260 	return 0;
261 
262 err:
263 	altera_msi_remove(pdev);
264 	return ret;
265 }
266 
267 static const struct of_device_id altera_msi_of_match[] = {
268 	{ .compatible = "altr,msi-1.0", NULL },
269 	{ },
270 };
271 
272 static struct platform_driver altera_msi_driver = {
273 	.driver = {
274 		.name = "altera-msi",
275 		.of_match_table = altera_msi_of_match,
276 	},
277 	.probe = altera_msi_probe,
278 	.remove = altera_msi_remove,
279 };
280 
281 static int __init altera_msi_init(void)
282 {
283 	return platform_driver_register(&altera_msi_driver);
284 }
285 
286 static void __exit altera_msi_exit(void)
287 {
288 	platform_driver_unregister(&altera_msi_driver);
289 }
290 
291 subsys_initcall(altera_msi_init);
292 MODULE_DEVICE_TABLE(of, altera_msi_of_match);
293 module_exit(altera_msi_exit);
294 MODULE_LICENSE("GPL v2");
295