arch/powerpc/sysdev/msi_bitmap.c

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