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1 /*
2  * Copyright 2006-2008, Michael Ellerman, IBM Corporation.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License
6  * as published by the Free Software Foundation; version 2 of the
7  * License.
8  *
9  */
10 
11 #include <linux/slab.h>
12 #include <linux/kernel.h>
13 #include <linux/bitmap.h>
14 #include <asm/msi_bitmap.h>
15 #include <asm/setup.h>
16 
msi_bitmap_alloc_hwirqs(struct msi_bitmap * bmp,int num)17 int msi_bitmap_alloc_hwirqs(struct msi_bitmap *bmp, int num)
18 {
19 	unsigned long flags;
20 	int offset, order = get_count_order(num);
21 
22 	spin_lock_irqsave(&bmp->lock, flags);
23 	/*
24 	 * This is fast, but stricter than we need. We might want to add
25 	 * a fallback routine which does a linear search with no alignment.
26 	 */
27 	offset = bitmap_find_free_region(bmp->bitmap, bmp->irq_count, order);
28 	spin_unlock_irqrestore(&bmp->lock, flags);
29 
30 	pr_debug("msi_bitmap: allocated 0x%x (2^%d) at offset 0x%x\n",
31 		 num, order, offset);
32 
33 	return offset;
34 }
35 
msi_bitmap_free_hwirqs(struct msi_bitmap * bmp,unsigned int offset,unsigned int num)36 void msi_bitmap_free_hwirqs(struct msi_bitmap *bmp, unsigned int offset,
37 			    unsigned int num)
38 {
39 	unsigned long flags;
40 	int order = get_count_order(num);
41 
42 	pr_debug("msi_bitmap: freeing 0x%x (2^%d) at offset 0x%x\n",
43 		 num, order, offset);
44 
45 	spin_lock_irqsave(&bmp->lock, flags);
46 	bitmap_release_region(bmp->bitmap, offset, order);
47 	spin_unlock_irqrestore(&bmp->lock, flags);
48 }
49 
msi_bitmap_reserve_hwirq(struct msi_bitmap * bmp,unsigned int hwirq)50 void msi_bitmap_reserve_hwirq(struct msi_bitmap *bmp, unsigned int hwirq)
51 {
52 	unsigned long flags;
53 
54 	pr_debug("msi_bitmap: reserving hwirq 0x%x\n", hwirq);
55 
56 	spin_lock_irqsave(&bmp->lock, flags);
57 	bitmap_allocate_region(bmp->bitmap, hwirq, 0);
58 	spin_unlock_irqrestore(&bmp->lock, flags);
59 }
60 
61 /**
62  * msi_bitmap_reserve_dt_hwirqs - Reserve irqs specified in the device tree.
63  * @bmp: pointer to the MSI bitmap.
64  *
65  * Looks in the device tree to see if there is a property specifying which
66  * irqs can be used for MSI. If found those irqs reserved in the device tree
67  * are reserved in the bitmap.
68  *
69  * Returns 0 for success, < 0 if there was an error, and > 0 if no property
70  * was found in the device tree.
71  **/
msi_bitmap_reserve_dt_hwirqs(struct msi_bitmap * bmp)72 int msi_bitmap_reserve_dt_hwirqs(struct msi_bitmap *bmp)
73 {
74 	int i, j, len;
75 	const u32 *p;
76 
77 	if (!bmp->of_node)
78 		return 1;
79 
80 	p = of_get_property(bmp->of_node, "msi-available-ranges", &len);
81 	if (!p) {
82 		pr_debug("msi_bitmap: no msi-available-ranges property " \
83 			 "found on %s\n", bmp->of_node->full_name);
84 		return 1;
85 	}
86 
87 	if (len % (2 * sizeof(u32)) != 0) {
88 		printk(KERN_WARNING "msi_bitmap: Malformed msi-available-ranges"
89 		       " property on %s\n", bmp->of_node->full_name);
90 		return -EINVAL;
91 	}
92 
93 	bitmap_allocate_region(bmp->bitmap, 0, get_count_order(bmp->irq_count));
94 
95 	spin_lock(&bmp->lock);
96 
97 	/* Format is: (<u32 start> <u32 count>)+ */
98 	len /= 2 * sizeof(u32);
99 	for (i = 0; i < len; i++, p += 2) {
100 		for (j = 0; j < *(p + 1); j++)
101 			bitmap_release_region(bmp->bitmap, *p + j, 0);
102 	}
103 
104 	spin_unlock(&bmp->lock);
105 
106 	return 0;
107 }
108 
msi_bitmap_alloc(struct msi_bitmap * bmp,unsigned int irq_count,struct device_node * of_node)109 int msi_bitmap_alloc(struct msi_bitmap *bmp, unsigned int irq_count,
110 		     struct device_node *of_node)
111 {
112 	int size;
113 
114 	if (!irq_count)
115 		return -EINVAL;
116 
117 	size = BITS_TO_LONGS(irq_count) * sizeof(long);
118 	pr_debug("msi_bitmap: allocator bitmap size is 0x%x bytes\n", size);
119 
120 	bmp->bitmap = zalloc_maybe_bootmem(size, GFP_KERNEL);
121 	if (!bmp->bitmap) {
122 		pr_debug("msi_bitmap: ENOMEM allocating allocator bitmap!\n");
123 		return -ENOMEM;
124 	}
125 
126 	/* We zalloc'ed the bitmap, so all irqs are free by default */
127 	spin_lock_init(&bmp->lock);
128 	bmp->of_node = of_node_get(of_node);
129 	bmp->irq_count = irq_count;
130 
131 	return 0;
132 }
133 
msi_bitmap_free(struct msi_bitmap * bmp)134 void msi_bitmap_free(struct msi_bitmap *bmp)
135 {
136 	/* we can't free the bitmap we don't know if it's bootmem etc. */
137 	of_node_put(bmp->of_node);
138 	bmp->bitmap = NULL;
139 }
140 
141 #ifdef CONFIG_MSI_BITMAP_SELFTEST
142 
143 #define check(x)	\
144 	if (!(x)) printk("msi_bitmap: test failed at line %d\n", __LINE__);
145 
test_basics(void)146 void __init test_basics(void)
147 {
148 	struct msi_bitmap bmp;
149 	int i, size = 512;
150 
151 	/* Can't allocate a bitmap of 0 irqs */
152 	check(msi_bitmap_alloc(&bmp, 0, NULL) != 0);
153 
154 	/* of_node may be NULL */
155 	check(0 == msi_bitmap_alloc(&bmp, size, NULL));
156 
157 	/* Should all be free by default */
158 	check(0 == bitmap_find_free_region(bmp.bitmap, size,
159 					   get_count_order(size)));
160 	bitmap_release_region(bmp.bitmap, 0, get_count_order(size));
161 
162 	/* With no node, there's no msi-available-ranges, so expect > 0 */
163 	check(msi_bitmap_reserve_dt_hwirqs(&bmp) > 0);
164 
165 	/* Should all still be free */
166 	check(0 == bitmap_find_free_region(bmp.bitmap, size,
167 					   get_count_order(size)));
168 	bitmap_release_region(bmp.bitmap, 0, get_count_order(size));
169 
170 	/* Check we can fill it up and then no more */
171 	for (i = 0; i < size; i++)
172 		check(msi_bitmap_alloc_hwirqs(&bmp, 1) >= 0);
173 
174 	check(msi_bitmap_alloc_hwirqs(&bmp, 1) < 0);
175 
176 	/* Should all be allocated */
177 	check(bitmap_find_free_region(bmp.bitmap, size, 0) < 0);
178 
179 	/* And if we free one we can then allocate another */
180 	msi_bitmap_free_hwirqs(&bmp, size / 2, 1);
181 	check(msi_bitmap_alloc_hwirqs(&bmp, 1) == size / 2);
182 
183 	msi_bitmap_free(&bmp);
184 
185 	/* Clients may check bitmap == NULL for "not-allocated" */
186 	check(bmp.bitmap == NULL);
187 
188 	kfree(bmp.bitmap);
189 }
190 
test_of_node(void)191 void __init test_of_node(void)
192 {
193 	u32 prop_data[] = { 10, 10, 25, 3, 40, 1, 100, 100, 200, 20 };
194 	const char *expected_str = "0-9,20-24,28-39,41-99,220-255";
195 	char *prop_name = "msi-available-ranges";
196 	char *node_name = "/fakenode";
197 	struct device_node of_node;
198 	struct property prop;
199 	struct msi_bitmap bmp;
200 	int size = 256;
201 	DECLARE_BITMAP(expected, size);
202 
203 	/* There should really be a struct device_node allocator */
204 	memset(&of_node, 0, sizeof(of_node));
205 	kref_init(&of_node.kref);
206 	of_node.full_name = node_name;
207 
208 	check(0 == msi_bitmap_alloc(&bmp, size, &of_node));
209 
210 	/* No msi-available-ranges, so expect > 0 */
211 	check(msi_bitmap_reserve_dt_hwirqs(&bmp) > 0);
212 
213 	/* Should all still be free */
214 	check(0 == bitmap_find_free_region(bmp.bitmap, size,
215 					   get_count_order(size)));
216 	bitmap_release_region(bmp.bitmap, 0, get_count_order(size));
217 
218 	/* Now create a fake msi-available-ranges property */
219 
220 	/* There should really .. oh whatever */
221 	memset(&prop, 0, sizeof(prop));
222 	prop.name = prop_name;
223 	prop.value = &prop_data;
224 	prop.length = sizeof(prop_data);
225 
226 	of_node.properties = &prop;
227 
228 	/* msi-available-ranges, so expect == 0 */
229 	check(msi_bitmap_reserve_dt_hwirqs(&bmp) == 0);
230 
231 	/* Check we got the expected result */
232 	check(0 == bitmap_parselist(expected_str, expected, size));
233 	check(bitmap_equal(expected, bmp.bitmap, size));
234 
235 	msi_bitmap_free(&bmp);
236 	kfree(bmp.bitmap);
237 }
238 
msi_bitmap_selftest(void)239 int __init msi_bitmap_selftest(void)
240 {
241 	printk(KERN_DEBUG "Running MSI bitmap self-tests ...\n");
242 
243 	test_basics();
244 	test_of_node();
245 
246 	return 0;
247 }
248 late_initcall(msi_bitmap_selftest);
249 #endif /* CONFIG_MSI_BITMAP_SELFTEST */
250