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