]> git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blame - include/asm-generic/getorder.h
dmaengine: imx-sdma: fix size check for sdma script_number
[mirror_ubuntu-bionic-kernel.git] / include / asm-generic / getorder.h
CommitLineData
b2441318 1/* SPDX-License-Identifier: GPL-2.0 */
5b17e1cd
AB
2#ifndef __ASM_GENERIC_GETORDER_H
3#define __ASM_GENERIC_GETORDER_H
fd4fd5aa 4
fd4fd5aa
SR
5#ifndef __ASSEMBLY__
6
38f33230 7#include <linux/compiler.h>
d66acc39
DH
8#include <linux/log2.h>
9
e0891a98
DH
10/**
11 * get_order - Determine the allocation order of a memory size
12 * @size: The size for which to get the order
13 *
14 * Determine the allocation order of a particular sized block of memory. This
15 * is on a logarithmic scale, where:
16 *
17 * 0 -> 2^0 * PAGE_SIZE and below
18 * 1 -> 2^1 * PAGE_SIZE to 2^0 * PAGE_SIZE + 1
19 * 2 -> 2^2 * PAGE_SIZE to 2^1 * PAGE_SIZE + 1
20 * 3 -> 2^3 * PAGE_SIZE to 2^2 * PAGE_SIZE + 1
21 * 4 -> 2^4 * PAGE_SIZE to 2^3 * PAGE_SIZE + 1
22 * ...
23 *
24 * The order returned is used to find the smallest allocation granule required
25 * to hold an object of the specified size.
26 *
27 * The result is undefined if the size is 0.
e0891a98 28 */
28040ade
QC
29static inline __attribute_const__ int get_order(unsigned long size)
30{
31 if (__builtin_constant_p(size)) {
32 if (!size)
33 return BITS_PER_LONG - PAGE_SHIFT;
34
35 if (size < (1UL << PAGE_SHIFT))
36 return 0;
37
38 return ilog2((size) - 1) - PAGE_SHIFT + 1;
39 }
40
41 size--;
42 size >>= PAGE_SHIFT;
43#if BITS_PER_LONG == 32
44 return fls(size);
45#else
46 return fls64(size);
47#endif
48}
fd4fd5aa
SR
49
50#endif /* __ASSEMBLY__ */
fd4fd5aa 51
5b17e1cd 52#endif /* __ASM_GENERIC_GETORDER_H */