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
 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	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
 79static 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
 85static 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
 91static 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
104static int altera_msi_set_affinity(struct irq_data *irq_data,
105				   const struct cpumask *mask, bool force)
106{
107	 return -EINVAL;
108}
109
110static 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
116static 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
147static 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
169static const struct irq_domain_ops msi_domain_ops = {
170	.alloc	= altera_irq_domain_alloc,
171	.free	= altera_irq_domain_free,
172};
173
174static 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
196static 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
202static 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_and_data(msi->irq, NULL, NULL);
208
209	altera_free_domains(msi);
210
211	platform_set_drvdata(pdev, NULL);
212	return 0;
213}
214
215static int altera_msi_probe(struct platform_device *pdev)
216{
217	struct altera_msi *msi;
218	struct device_node *np = pdev->dev.of_node;
219	struct resource *res;
220	int ret;
221
222	msi = devm_kzalloc(&pdev->dev, sizeof(struct altera_msi),
223			   GFP_KERNEL);
224	if (!msi)
225		return -ENOMEM;
226
227	mutex_init(&msi->lock);
228	msi->pdev = pdev;
229
230	msi->csr_base = devm_platform_ioremap_resource_byname(pdev, "csr");
231	if (IS_ERR(msi->csr_base)) {
232		dev_err(&pdev->dev, "failed to map csr memory\n");
233		return PTR_ERR(msi->csr_base);
234	}
235
236	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
237					   "vector_slave");
238	msi->vector_base = devm_ioremap_resource(&pdev->dev, res);
239	if (IS_ERR(msi->vector_base))
240		return PTR_ERR(msi->vector_base);
241
242	msi->vector_phy = res->start;
243
244	if (of_property_read_u32(np, "num-vectors", &msi->num_of_vectors)) {
245		dev_err(&pdev->dev, "failed to parse the number of vectors\n");
246		return -EINVAL;
247	}
248
249	ret = altera_allocate_domains(msi);
250	if (ret)
251		return ret;
252
253	msi->irq = platform_get_irq(pdev, 0);
254	if (msi->irq < 0) {
255		ret = msi->irq;
256		goto err;
257	}
258
259	irq_set_chained_handler_and_data(msi->irq, altera_msi_isr, msi);
260	platform_set_drvdata(pdev, msi);
261
262	return 0;
263
264err:
265	altera_msi_remove(pdev);
266	return ret;
267}
268
269static const struct of_device_id altera_msi_of_match[] = {
270	{ .compatible = "altr,msi-1.0", NULL },
271	{ },
272};
273
274static struct platform_driver altera_msi_driver = {
275	.driver = {
276		.name = "altera-msi",
277		.of_match_table = altera_msi_of_match,
278	},
279	.probe = altera_msi_probe,
280	.remove = altera_msi_remove,
281};
282
283static int __init altera_msi_init(void)
284{
285	return platform_driver_register(&altera_msi_driver);
286}
287
288static void __exit altera_msi_exit(void)
289{
290	platform_driver_unregister(&altera_msi_driver);
291}
292
293subsys_initcall(altera_msi_init);
294MODULE_DEVICE_TABLE(of, altera_msi_of_match);
295module_exit(altera_msi_exit);
296MODULE_LICENSE("GPL v2");