1 /*
2  * Copyright (c) 2012-2014 The Linux Foundation. All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 and
6  * only version 2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11  * GNU General Public License for more details.
12  *
13  */
14 
15 #ifndef _LINUX_IOPOLL_H
16 #define _LINUX_IOPOLL_H
17 
18 #include <linux/kernel.h>
19 #include <linux/types.h>
20 #include <linux/ktime.h>
21 #include <linux/delay.h>
22 #include <linux/errno.h>
23 #include <linux/io.h>
24 
25 /**
26  * readx_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs
27  * @op: accessor function (takes @addr as its only argument)
28  * @addr: Address to poll
29  * @val: Variable to read the value into
30  * @cond: Break condition (usually involving @val)
31  * @sleep_us: Maximum time to sleep between reads in us (0
32  *            tight-loops).  Should be less than ~20ms since usleep_range
33  *            is used (see Documentation/timers/timers-howto.txt).
34  * @timeout_us: Timeout in us, 0 means never timeout
35  *
36  * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
37  * case, the last read value at @addr is stored in @val. Must not
38  * be called from atomic context if sleep_us or timeout_us are used.
39  *
40  * When available, you'll probably want to use one of the specialized
41  * macros defined below rather than this macro directly.
42  */
43 #define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us)	\
44 ({ \
45 	u64 __timeout_us = (timeout_us); \
46 	unsigned long __sleep_us = (sleep_us); \
47 	ktime_t __timeout = ktime_add_us(ktime_get(), __timeout_us); \
48 	might_sleep_if((__sleep_us) != 0); \
49 	for (;;) { \
50 		(val) = op(addr); \
51 		if (cond) \
52 			break; \
53 		if (__timeout_us && \
54 		    ktime_compare(ktime_get(), __timeout) > 0) { \
55 			(val) = op(addr); \
56 			break; \
57 		} \
58 		if (__sleep_us) \
59 			usleep_range((__sleep_us >> 2) + 1, __sleep_us); \
60 	} \
61 	(cond) ? 0 : -ETIMEDOUT; \
62 })
63 
64 /**
65  * readx_poll_timeout_atomic - Periodically poll an address until a condition is met or a timeout occurs
66  * @op: accessor function (takes @addr as its only argument)
67  * @addr: Address to poll
68  * @val: Variable to read the value into
69  * @cond: Break condition (usually involving @val)
70  * @delay_us: Time to udelay between reads in us (0 tight-loops).  Should
71  *            be less than ~10us since udelay is used (see
72  *            Documentation/timers/timers-howto.txt).
73  * @timeout_us: Timeout in us, 0 means never timeout
74  *
75  * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
76  * case, the last read value at @addr is stored in @val.
77  *
78  * When available, you'll probably want to use one of the specialized
79  * macros defined below rather than this macro directly.
80  */
81 #define readx_poll_timeout_atomic(op, addr, val, cond, delay_us, timeout_us) \
82 ({ \
83 	u64 __timeout_us = (timeout_us); \
84 	unsigned long __delay_us = (delay_us); \
85 	ktime_t __timeout = ktime_add_us(ktime_get(), __timeout_us); \
86 	for (;;) { \
87 		(val) = op(addr); \
88 		if (cond) \
89 			break; \
90 		if (__timeout_us && \
91 		    ktime_compare(ktime_get(), __timeout) > 0) { \
92 			(val) = op(addr); \
93 			break; \
94 		} \
95 		if (__delay_us) \
96 			udelay(__delay_us);	\
97 	} \
98 	(cond) ? 0 : -ETIMEDOUT; \
99 })
100 
101 
102 #define readb_poll_timeout(addr, val, cond, delay_us, timeout_us) \
103 	readx_poll_timeout(readb, addr, val, cond, delay_us, timeout_us)
104 
105 #define readb_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
106 	readx_poll_timeout_atomic(readb, addr, val, cond, delay_us, timeout_us)
107 
108 #define readw_poll_timeout(addr, val, cond, delay_us, timeout_us) \
109 	readx_poll_timeout(readw, addr, val, cond, delay_us, timeout_us)
110 
111 #define readw_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
112 	readx_poll_timeout_atomic(readw, addr, val, cond, delay_us, timeout_us)
113 
114 #define readl_poll_timeout(addr, val, cond, delay_us, timeout_us) \
115 	readx_poll_timeout(readl, addr, val, cond, delay_us, timeout_us)
116 
117 #define readl_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
118 	readx_poll_timeout_atomic(readl, addr, val, cond, delay_us, timeout_us)
119 
120 #define readq_poll_timeout(addr, val, cond, delay_us, timeout_us) \
121 	readx_poll_timeout(readq, addr, val, cond, delay_us, timeout_us)
122 
123 #define readq_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
124 	readx_poll_timeout_atomic(readq, addr, val, cond, delay_us, timeout_us)
125 
126 #define readb_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \
127 	readx_poll_timeout(readb_relaxed, addr, val, cond, delay_us, timeout_us)
128 
129 #define readb_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
130 	readx_poll_timeout_atomic(readb_relaxed, addr, val, cond, delay_us, timeout_us)
131 
132 #define readw_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \
133 	readx_poll_timeout(readw_relaxed, addr, val, cond, delay_us, timeout_us)
134 
135 #define readw_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
136 	readx_poll_timeout_atomic(readw_relaxed, addr, val, cond, delay_us, timeout_us)
137 
138 #define readl_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \
139 	readx_poll_timeout(readl_relaxed, addr, val, cond, delay_us, timeout_us)
140 
141 #define readl_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
142 	readx_poll_timeout_atomic(readl_relaxed, addr, val, cond, delay_us, timeout_us)
143 
144 #define readq_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \
145 	readx_poll_timeout(readq_relaxed, addr, val, cond, delay_us, timeout_us)
146 
147 #define readq_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
148 	readx_poll_timeout_atomic(readq_relaxed, addr, val, cond, delay_us, timeout_us)
149 
150 #endif /* _LINUX_IOPOLL_H */
151