Linux kernel mirror (for testing)
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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * NSC/Cyrix CPU indexed register access. Must be inlined instead of
4 * macros to ensure correct access ordering
5 * Access order is always 0x22 (=offset), 0x23 (=value)
6 *
7 * When using the old macros a line like
8 * setCx86(CX86_CCR2, getCx86(CX86_CCR2) | 0x88);
9 * gets expanded to:
10 * do {
11 * outb((CX86_CCR2), 0x22);
12 * outb((({
13 * outb((CX86_CCR2), 0x22);
14 * inb(0x23);
15 * }) | 0x88), 0x23);
16 * } while (0);
17 *
18 * which in fact violates the access order (= 0x22, 0x22, 0x23, 0x23).
19 */
20
21static inline u8 getCx86(u8 reg)
22{
23 outb(reg, 0x22);
24 return inb(0x23);
25}
26
27static inline void setCx86(u8 reg, u8 data)
28{
29 outb(reg, 0x22);
30 outb(data, 0x23);
31}
32
33#define getCx86_old(reg) ({ outb((reg), 0x22); inb(0x23); })
34
35#define setCx86_old(reg, data) do { \
36 outb((reg), 0x22); \
37 outb((data), 0x23); \
38} while (0)
39