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_NO_AFFINITY | 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 struct irq_chip altera_msi_bottom_irq_chip = {
103	.name			= "Altera MSI",
104	.irq_compose_msi_msg	= altera_compose_msi_msg,
105};
106
107static int altera_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
108				   unsigned int nr_irqs, void *args)
109{
110	struct altera_msi *msi = domain->host_data;
111	unsigned long bit;
112	u32 mask;
113
114	WARN_ON(nr_irqs != 1);
115	mutex_lock(&msi->lock);
116
117	bit = find_first_zero_bit(msi->used, msi->num_of_vectors);
118	if (bit >= msi->num_of_vectors) {
119		mutex_unlock(&msi->lock);
120		return -ENOSPC;
121	}
122
123	set_bit(bit, msi->used);
124
125	mutex_unlock(&msi->lock);
126
127	irq_domain_set_info(domain, virq, bit, &altera_msi_bottom_irq_chip,
128			    domain->host_data, handle_simple_irq,
129			    NULL, NULL);
130
131	mask = msi_readl(msi, MSI_INTMASK);
132	mask |= 1 << bit;
133	msi_writel(msi, mask, MSI_INTMASK);
134
135	return 0;
136}
137
138static void altera_irq_domain_free(struct irq_domain *domain,
139				   unsigned int virq, unsigned int nr_irqs)
140{
141	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
142	struct altera_msi *msi = irq_data_get_irq_chip_data(d);
143	u32 mask;
144
145	mutex_lock(&msi->lock);
146
147	if (!test_bit(d->hwirq, msi->used)) {
148		dev_err(&msi->pdev->dev, "trying to free unused MSI#%lu\n",
149			d->hwirq);
150	} else {
151		__clear_bit(d->hwirq, msi->used);
152		mask = msi_readl(msi, MSI_INTMASK);
153		mask &= ~(1 << d->hwirq);
154		msi_writel(msi, mask, MSI_INTMASK);
155	}
156
157	mutex_unlock(&msi->lock);
158}
159
160static const struct irq_domain_ops msi_domain_ops = {
161	.alloc	= altera_irq_domain_alloc,
162	.free	= altera_irq_domain_free,
163};
164
165static int altera_allocate_domains(struct altera_msi *msi)
166{
167	struct fwnode_handle *fwnode = of_node_to_fwnode(msi->pdev->dev.of_node);
168
169	msi->inner_domain = irq_domain_add_linear(NULL, msi->num_of_vectors,
170					     &msi_domain_ops, msi);
171	if (!msi->inner_domain) {
172		dev_err(&msi->pdev->dev, "failed to create IRQ domain\n");
173		return -ENOMEM;
174	}
175
176	msi->msi_domain = pci_msi_create_irq_domain(fwnode,
177				&altera_msi_domain_info, msi->inner_domain);
178	if (!msi->msi_domain) {
179		dev_err(&msi->pdev->dev, "failed to create MSI domain\n");
180		irq_domain_remove(msi->inner_domain);
181		return -ENOMEM;
182	}
183
184	return 0;
185}
186
187static void altera_free_domains(struct altera_msi *msi)
188{
189	irq_domain_remove(msi->msi_domain);
190	irq_domain_remove(msi->inner_domain);
191}
192
193static void altera_msi_remove(struct platform_device *pdev)
194{
195	struct altera_msi *msi = platform_get_drvdata(pdev);
196
197	msi_writel(msi, 0, MSI_INTMASK);
198	irq_set_chained_handler_and_data(msi->irq, NULL, NULL);
199
200	altera_free_domains(msi);
201
202	platform_set_drvdata(pdev, NULL);
203}
204
205static int altera_msi_probe(struct platform_device *pdev)
206{
207	struct altera_msi *msi;
208	struct device_node *np = pdev->dev.of_node;
209	struct resource *res;
210	int ret;
211
212	msi = devm_kzalloc(&pdev->dev, sizeof(struct altera_msi),
213			   GFP_KERNEL);
214	if (!msi)
215		return -ENOMEM;
216
217	mutex_init(&msi->lock);
218	msi->pdev = pdev;
219
220	msi->csr_base = devm_platform_ioremap_resource_byname(pdev, "csr");
221	if (IS_ERR(msi->csr_base)) {
222		dev_err(&pdev->dev, "failed to map csr memory\n");
223		return PTR_ERR(msi->csr_base);
224	}
225
226	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
227					   "vector_slave");
228	msi->vector_base = devm_ioremap_resource(&pdev->dev, res);
229	if (IS_ERR(msi->vector_base))
230		return PTR_ERR(msi->vector_base);
231
232	msi->vector_phy = res->start;
233
234	if (of_property_read_u32(np, "num-vectors", &msi->num_of_vectors)) {
235		dev_err(&pdev->dev, "failed to parse the number of vectors\n");
236		return -EINVAL;
237	}
238
239	ret = altera_allocate_domains(msi);
240	if (ret)
241		return ret;
242
243	msi->irq = platform_get_irq(pdev, 0);
244	if (msi->irq < 0) {
245		ret = msi->irq;
246		goto err;
247	}
248
249	irq_set_chained_handler_and_data(msi->irq, altera_msi_isr, msi);
250	platform_set_drvdata(pdev, msi);
251
252	return 0;
253
254err:
255	altera_msi_remove(pdev);
256	return ret;
257}
258
259static const struct of_device_id altera_msi_of_match[] = {
260	{ .compatible = "altr,msi-1.0", NULL },
261	{ },
262};
263
264static struct platform_driver altera_msi_driver = {
265	.driver = {
266		.name = "altera-msi",
267		.of_match_table = altera_msi_of_match,
268	},
269	.probe = altera_msi_probe,
270	.remove = altera_msi_remove,
271};
272
273static int __init altera_msi_init(void)
274{
275	return platform_driver_register(&altera_msi_driver);
276}
277
278static void __exit altera_msi_exit(void)
279{
280	platform_driver_unregister(&altera_msi_driver);
281}
282
283subsys_initcall(altera_msi_init);
284MODULE_DEVICE_TABLE(of, altera_msi_of_match);
285module_exit(altera_msi_exit);
286MODULE_DESCRIPTION("Altera PCIe MSI support driver");
287MODULE_LICENSE("GPL v2");