pcie-altera-msi.c

  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/irqchip/irq-msi-lib.h>
 13#include <linux/irqdomain.h>
 14#include <linux/init.h>
 15#include <linux/module.h>
 16#include <linux/msi.h>
 17#include <linux/of_address.h>
 18#include <linux/of_pci.h>
 19#include <linux/pci.h>
 20#include <linux/platform_device.h>
 21#include <linux/slab.h>
 22
 23#define MSI_STATUS		0x0
 24#define MSI_ERROR		0x4
 25#define MSI_INTMASK		0x8
 26
 27#define MAX_MSI_VECTORS		32
 28
 29struct altera_msi {
 30	DECLARE_BITMAP(used, MAX_MSI_VECTORS);
 31	struct mutex		lock;	/* protect "used" bitmap */
 32	struct platform_device	*pdev;
 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
 77#define ALTERA_MSI_FLAGS_REQUIRED (MSI_FLAG_USE_DEF_DOM_OPS		| \
 78				   MSI_FLAG_USE_DEF_CHIP_OPS		| \
 79				   MSI_FLAG_NO_AFFINITY)
 80
 81#define ALTERA_MSI_FLAGS_SUPPORTED (MSI_GENERIC_FLAGS_MASK		| \
 82				    MSI_FLAG_PCI_MSIX)
 83
 84static const struct msi_parent_ops altera_msi_parent_ops = {
 85	.required_flags		= ALTERA_MSI_FLAGS_REQUIRED,
 86	.supported_flags	= ALTERA_MSI_FLAGS_SUPPORTED,
 87	.bus_select_token	= DOMAIN_BUS_PCI_MSI,
 88	.prefix			= "Altera-",
 89	.init_dev_msi_info	= msi_lib_init_dev_msi_info,
 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 struct irq_chip altera_msi_bottom_irq_chip = {
105	.name			= "Altera MSI",
106	.irq_compose_msi_msg	= altera_compose_msi_msg,
107};
108
109static int altera_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
110				   unsigned int nr_irqs, void *args)
111{
112	struct altera_msi *msi = domain->host_data;
113	unsigned long bit;
114	u32 mask;
115
116	WARN_ON(nr_irqs != 1);
117	mutex_lock(&msi->lock);
118
119	bit = find_first_zero_bit(msi->used, msi->num_of_vectors);
120	if (bit >= msi->num_of_vectors) {
121		mutex_unlock(&msi->lock);
122		return -ENOSPC;
123	}
124
125	set_bit(bit, msi->used);
126
127	mutex_unlock(&msi->lock);
128
129	irq_domain_set_info(domain, virq, bit, &altera_msi_bottom_irq_chip,
130			    domain->host_data, handle_simple_irq,
131			    NULL, NULL);
132
133	mask = msi_readl(msi, MSI_INTMASK);
134	mask |= 1 << bit;
135	msi_writel(msi, mask, MSI_INTMASK);
136
137	return 0;
138}
139
140static void altera_irq_domain_free(struct irq_domain *domain,
141				   unsigned int virq, unsigned int nr_irqs)
142{
143	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
144	struct altera_msi *msi = irq_data_get_irq_chip_data(d);
145	u32 mask;
146
147	mutex_lock(&msi->lock);
148
149	if (!test_bit(d->hwirq, msi->used)) {
150		dev_err(&msi->pdev->dev, "trying to free unused MSI#%lu\n",
151			d->hwirq);
152	} else {
153		__clear_bit(d->hwirq, msi->used);
154		mask = msi_readl(msi, MSI_INTMASK);
155		mask &= ~(1 << d->hwirq);
156		msi_writel(msi, mask, MSI_INTMASK);
157	}
158
159	mutex_unlock(&msi->lock);
160}
161
162static const struct irq_domain_ops msi_domain_ops = {
163	.alloc	= altera_irq_domain_alloc,
164	.free	= altera_irq_domain_free,
165};
166
167static int altera_allocate_domains(struct altera_msi *msi)
168{
169	struct irq_domain_info info = {
170		.fwnode		= dev_fwnode(&msi->pdev->dev),
171		.ops		= &msi_domain_ops,
172		.host_data	= msi,
173		.size		= msi->num_of_vectors,
174	};
175
176	msi->inner_domain = msi_create_parent_irq_domain(&info, &altera_msi_parent_ops);
177	if (!msi->inner_domain) {
178		dev_err(&msi->pdev->dev, "failed to create MSI domain\n");
179		return -ENOMEM;
180	}
181
182	return 0;
183}
184
185static void altera_free_domains(struct altera_msi *msi)
186{
187	irq_domain_remove(msi->inner_domain);
188}
189
190static void altera_msi_remove(struct platform_device *pdev)
191{
192	struct altera_msi *msi = platform_get_drvdata(pdev);
193
194	msi_writel(msi, 0, MSI_INTMASK);
195	irq_set_chained_handler_and_data(msi->irq, NULL, NULL);
196
197	altera_free_domains(msi);
198
199	platform_set_drvdata(pdev, NULL);
200}
201
202static int altera_msi_probe(struct platform_device *pdev)
203{
204	struct altera_msi *msi;
205	struct device_node *np = pdev->dev.of_node;
206	struct resource *res;
207	int ret;
208
209	msi = devm_kzalloc(&pdev->dev, sizeof(struct altera_msi),
210			   GFP_KERNEL);
211	if (!msi)
212		return -ENOMEM;
213
214	mutex_init(&msi->lock);
215	msi->pdev = pdev;
216
217	msi->csr_base = devm_platform_ioremap_resource_byname(pdev, "csr");
218	if (IS_ERR(msi->csr_base)) {
219		dev_err(&pdev->dev, "failed to map csr memory\n");
220		return PTR_ERR(msi->csr_base);
221	}
222
223	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
224					   "vector_slave");
225	msi->vector_base = devm_ioremap_resource(&pdev->dev, res);
226	if (IS_ERR(msi->vector_base))
227		return PTR_ERR(msi->vector_base);
228
229	msi->vector_phy = res->start;
230
231	if (of_property_read_u32(np, "num-vectors", &msi->num_of_vectors)) {
232		dev_err(&pdev->dev, "failed to parse the number of vectors\n");
233		return -EINVAL;
234	}
235
236	ret = altera_allocate_domains(msi);
237	if (ret)
238		return ret;
239
240	msi->irq = platform_get_irq(pdev, 0);
241	if (msi->irq < 0) {
242		ret = msi->irq;
243		goto err;
244	}
245
246	irq_set_chained_handler_and_data(msi->irq, altera_msi_isr, msi);
247	platform_set_drvdata(pdev, msi);
248
249	return 0;
250
251err:
252	altera_msi_remove(pdev);
253	return ret;
254}
255
256static const struct of_device_id altera_msi_of_match[] = {
257	{ .compatible = "altr,msi-1.0", NULL },
258	{ },
259};
260
261static struct platform_driver altera_msi_driver = {
262	.driver = {
263		.name = "altera-msi",
264		.of_match_table = altera_msi_of_match,
265	},
266	.probe = altera_msi_probe,
267	.remove = altera_msi_remove,
268};
269
270static int __init altera_msi_init(void)
271{
272	return platform_driver_register(&altera_msi_driver);
273}
274
275static void __exit altera_msi_exit(void)
276{
277	platform_driver_unregister(&altera_msi_driver);
278}
279
280subsys_initcall(altera_msi_init);
281MODULE_DEVICE_TABLE(of, altera_msi_of_match);
282module_exit(altera_msi_exit);
283MODULE_DESCRIPTION("Altera PCIe MSI support driver");
284MODULE_LICENSE("GPL v2");