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Linux/arch/powerpc/sysdev/msi_bitmap.c

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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 
 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 
 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 
 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  **/
 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 
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 
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 
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 
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 
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 

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