1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * MSI support for PPC4xx SoCs using High Speed Transfer Assist (HSTA) for
4 * generation of the interrupt.
5 *
6 * Copyright © 2013 Alistair Popple <alistair@popple.id.au> IBM Corporation
7 */
8
9#include <linux/kernel.h>
10#include <linux/interrupt.h>
11#include <linux/msi.h>
12#include <linux/of.h>
13#include <linux/of_platform.h>
14#include <linux/pci.h>
15#include <linux/semaphore.h>
16#include <asm/msi_bitmap.h>
17#include <asm/ppc-pci.h>
18
19struct ppc4xx_hsta_msi {
20	struct device *dev;
21
22	/* The ioremapped HSTA MSI IO space */
23	u32 __iomem *data;
24
25	/* Physical address of HSTA MSI IO space */
26	u64 address;
27	struct msi_bitmap bmp;
28
29	/* An array mapping offsets to hardware IRQs */
30	int *irq_map;
31
32	/* Number of hwirqs supported */
33	int irq_count;
34};
35static struct ppc4xx_hsta_msi ppc4xx_hsta_msi;
36
37static int hsta_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
38{
39	struct msi_msg msg;
40	struct msi_desc *entry;
41	int irq, hwirq;
42	u64 addr;
43
44	/* We don't support MSI-X */
45	if (type == PCI_CAP_ID_MSIX) {
46		pr_debug("%s: MSI-X not supported.\n", __func__);
47		return -EINVAL;
48	}
49
50	for_each_pci_msi_entry(entry, dev) {
51		irq = msi_bitmap_alloc_hwirqs(&ppc4xx_hsta_msi.bmp, 1);
52		if (irq < 0) {
53			pr_debug("%s: Failed to allocate msi interrupt\n",
54				 __func__);
55			return irq;
56		}
57
58		hwirq = ppc4xx_hsta_msi.irq_map[irq];
59		if (!hwirq) {
60			pr_err("%s: Failed mapping irq %d\n", __func__, irq);
61			return -EINVAL;
62		}
63
64		/*
65		 * HSTA generates interrupts on writes to 128-bit aligned
66		 * addresses.
67		 */
68		addr = ppc4xx_hsta_msi.address + irq*0x10;
69		msg.address_hi = upper_32_bits(addr);
70		msg.address_lo = lower_32_bits(addr);
71
72		/* Data is not used by the HSTA. */
73		msg.data = 0;
74
75		pr_debug("%s: Setup irq %d (0x%0llx)\n", __func__, hwirq,
76			 (((u64) msg.address_hi) << 32) | msg.address_lo);
77
78		if (irq_set_msi_desc(hwirq, entry)) {
79			pr_err(
80			"%s: Invalid hwirq %d specified in device tree\n",
81			__func__, hwirq);
82			msi_bitmap_free_hwirqs(&ppc4xx_hsta_msi.bmp, irq, 1);
83			return -EINVAL;
84		}
85		pci_write_msi_msg(hwirq, &msg);
86	}
87
88	return 0;
89}
90
91static int hsta_find_hwirq_offset(int hwirq)
92{
93	int irq;
94
95	/* Find the offset given the hwirq */
96	for (irq = 0; irq < ppc4xx_hsta_msi.irq_count; irq++)
97		if (ppc4xx_hsta_msi.irq_map[irq] == hwirq)
98			return irq;
99
100	return -EINVAL;
101}
102
103static void hsta_teardown_msi_irqs(struct pci_dev *dev)
104{
105	struct msi_desc *entry;
106	int irq;
107
108	for_each_pci_msi_entry(entry, dev) {
109		if (!entry->irq)
110			continue;
111
112		irq = hsta_find_hwirq_offset(entry->irq);
113
114		/* entry->irq should always be in irq_map */
115		BUG_ON(irq < 0);
116		irq_set_msi_desc(entry->irq, NULL);
117		msi_bitmap_free_hwirqs(&ppc4xx_hsta_msi.bmp, irq, 1);
118		pr_debug("%s: Teardown IRQ %u (index %u)\n", __func__,
119			 entry->irq, irq);
120	}
121}
122
123static int hsta_msi_probe(struct platform_device *pdev)
124{
125	struct device *dev = &pdev->dev;
126	struct resource *mem;
127	int irq, ret, irq_count;
128	struct pci_controller *phb;
129
130	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
131	if (!mem) {
132		dev_err(dev, "Unable to get mmio space\n");
133		return -EINVAL;
134	}
135
136	irq_count = of_irq_count(dev->of_node);
137	if (!irq_count) {
138		dev_err(dev, "Unable to find IRQ range\n");
139		return -EINVAL;
140	}
141
142	ppc4xx_hsta_msi.dev = dev;
143	ppc4xx_hsta_msi.address = mem->start;
144	ppc4xx_hsta_msi.data = ioremap(mem->start, resource_size(mem));
145	ppc4xx_hsta_msi.irq_count = irq_count;
146	if (!ppc4xx_hsta_msi.data) {
147		dev_err(dev, "Unable to map memory\n");
148		return -ENOMEM;
149	}
150
151	ret = msi_bitmap_alloc(&ppc4xx_hsta_msi.bmp, irq_count, dev->of_node);
152	if (ret)
153		goto out;
154
155	ppc4xx_hsta_msi.irq_map = kmalloc_array(irq_count, sizeof(int),
156						GFP_KERNEL);
157	if (!ppc4xx_hsta_msi.irq_map) {
158		ret = -ENOMEM;
159		goto out1;
160	}
161
162	/* Setup a mapping from irq offsets to hardware irq numbers */
163	for (irq = 0; irq < irq_count; irq++) {
164		ppc4xx_hsta_msi.irq_map[irq] =
165			irq_of_parse_and_map(dev->of_node, irq);
166		if (!ppc4xx_hsta_msi.irq_map[irq]) {
167			dev_err(dev, "Unable to map IRQ\n");
168			ret = -EINVAL;
169			goto out2;
170		}
171	}
172
173	list_for_each_entry(phb, &hose_list, list_node) {
174		phb->controller_ops.setup_msi_irqs = hsta_setup_msi_irqs;
175		phb->controller_ops.teardown_msi_irqs = hsta_teardown_msi_irqs;
176	}
177	return 0;
178
179out2:
180	kfree(ppc4xx_hsta_msi.irq_map);
181
182out1:
183	msi_bitmap_free(&ppc4xx_hsta_msi.bmp);
184
185out:
186	iounmap(ppc4xx_hsta_msi.data);
187	return ret;
188}
189
190static const struct of_device_id hsta_msi_ids[] = {
191	{
192		.compatible = "ibm,hsta-msi",
193	},
194	{}
195};
196
197static struct platform_driver hsta_msi_driver = {
198	.probe = hsta_msi_probe,
199	.driver = {
200		.name = "hsta-msi",
201		.of_match_table = hsta_msi_ids,
202	},
203};
204
205static int hsta_msi_init(void)
206{
207	return platform_driver_register(&hsta_msi_driver);
208}
209subsys_initcall(hsta_msi_init);
210