xref: /openbmc/u-boot/include/wait_bit.h (revision a9707270)
1 /*
2  * Wait for bit with timeout and ctrlc
3  *
4  * (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
5  *
6  * SPDX-License-Identifier:	GPL-2.0+
7  */
8 
9 #ifndef __WAIT_BIT_H
10 #define __WAIT_BIT_H
11 
12 #include <common.h>
13 #include <console.h>
14 #include <linux/errno.h>
15 #include <asm/io.h>
16 
17 /**
18  * wait_for_bit()	waits for bit set/cleared in register
19  *
20  * Function polls register waiting for specific bit(s) change
21  * (either 0->1 or 1->0). It can fail under two conditions:
22  * - Timeout
23  * - User interaction (CTRL-C)
24  * Function succeeds only if all bits of masked register are set/cleared
25  * (depending on set option).
26  *
27  * @param prefix	Prefix added to timeout messagge (message visible only
28  *			with debug enabled)
29  * @param reg		Register that will be read (using readl())
30  * @param mask		Bit(s) of register that must be active
31  * @param set		Selects wait condition (bit set or clear)
32  * @param timeout_ms	Timeout (in miliseconds)
33  * @param breakable	Enables CTRL-C interruption
34  * @return		0 on success, -ETIMEDOUT or -EINTR on failure
35  */
36 static inline int wait_for_bit(const char *prefix, const u32 *reg,
37 			       const u32 mask, const bool set,
38 			       const unsigned int timeout_ms,
39 			       const bool breakable)
40 {
41 	u32 val;
42 	unsigned long start = get_timer(0);
43 
44 	while (1) {
45 		val = readl(reg);
46 
47 		if (!set)
48 			val = ~val;
49 
50 		if ((val & mask) == mask)
51 			return 0;
52 
53 		if (get_timer(start) > timeout_ms)
54 			break;
55 
56 		if (breakable && ctrlc()) {
57 			puts("Abort\n");
58 			return -EINTR;
59 		}
60 
61 		udelay(1);
62 	}
63 
64 	debug("%s: Timeout (reg=%p mask=%08x wait_set=%i)\n", prefix, reg, mask,
65 	      set);
66 
67 	return -ETIMEDOUT;
68 }
69 
70 
71 #endif
72