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 #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 */