1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * Copyright (c) 2012-2014 The Linux Foundation. All rights reserved.
4  */
5 
6 #ifndef _LINUX_IOPOLL_H
7 #define _LINUX_IOPOLL_H
8 
9 #include <linux/kernel.h>
10 #include <linux/types.h>
11 #include <linux/ktime.h>
12 #include <linux/delay.h>
13 #include <linux/errno.h>
14 #include <linux/io.h>
15 
16 /**
17  * read_poll_timeout - Periodically poll an address until a condition is
18  *			met or a timeout occurs
19  * @op: accessor function (takes @args as its arguments)
20  * @val: Variable to read the value into
21  * @cond: Break condition (usually involving @val)
22  * @sleep_us: Maximum time to sleep between reads in us (0
23  *            tight-loops).  Should be less than ~20ms since usleep_range
24  *            is used (see Documentation/timers/timers-howto.rst).
25  * @timeout_us: Timeout in us, 0 means never timeout
26  * @sleep_before_read: if it is true, sleep @sleep_us before read.
27  * @args: arguments for @op poll
28  *
29  * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
30  * case, the last read value at @args is stored in @val. Must not
31  * be called from atomic context if sleep_us or timeout_us are used.
32  *
33  * When available, you'll probably want to use one of the specialized
34  * macros defined below rather than this macro directly.
35  */
36 #define read_poll_timeout(op, val, cond, sleep_us, timeout_us, \
37 				sleep_before_read, args...) \
38 ({ \
39 	u64 __timeout_us = (timeout_us); \
40 	unsigned long __sleep_us = (sleep_us); \
41 	ktime_t __timeout = ktime_add_us(ktime_get(), __timeout_us); \
42 	might_sleep_if((__sleep_us) != 0); \
43 	if (sleep_before_read && __sleep_us) \
44 		usleep_range((__sleep_us >> 2) + 1, __sleep_us); \
45 	for (;;) { \
46 		(val) = op(args); \
47 		if (cond) \
48 			break; \
49 		if (__timeout_us && \
50 		    ktime_compare(ktime_get(), __timeout) > 0) { \
51 			(val) = op(args); \
52 			break; \
53 		} \
54 		if (__sleep_us) \
55 			usleep_range((__sleep_us >> 2) + 1, __sleep_us); \
56 		cpu_relax(); \
57 	} \
58 	(cond) ? 0 : -ETIMEDOUT; \
59 })
60 
61 /**
62  * read_poll_timeout_atomic - Periodically poll an address until a condition is
63  * 				met or a timeout occurs
64  * @op: accessor function (takes @args as its arguments)
65  * @val: Variable to read the value into
66  * @cond: Break condition (usually involving @val)
67  * @delay_us: Time to udelay between reads in us (0 tight-loops).  Should
68  *            be less than ~10us since udelay is used (see
69  *            Documentation/timers/timers-howto.rst).
70  * @timeout_us: Timeout in us, 0 means never timeout
71  * @delay_before_read: if it is true, delay @delay_us before read.
72  * @args: arguments for @op poll
73  *
74  * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
75  * case, the last read value at @args is stored in @val.
76  *
77  * This macro does not rely on timekeeping.  Hence it is safe to call even when
78  * timekeeping is suspended, at the expense of an underestimation of wall clock
79  * time, which is rather minimal with a non-zero delay_us.
80  *
81  * When available, you'll probably want to use one of the specialized
82  * macros defined below rather than this macro directly.
83  */
84 #define read_poll_timeout_atomic(op, val, cond, delay_us, timeout_us, \
85 					delay_before_read, args...) \
86 ({ \
87 	u64 __timeout_us = (timeout_us); \
88 	s64 __left_ns = __timeout_us * NSEC_PER_USEC; \
89 	unsigned long __delay_us = (delay_us); \
90 	u64 __delay_ns = __delay_us * NSEC_PER_USEC; \
91 	if (delay_before_read && __delay_us) { \
92 		udelay(__delay_us); \
93 		if (__timeout_us) \
94 			__left_ns -= __delay_ns; \
95 	} \
96 	for (;;) { \
97 		(val) = op(args); \
98 		if (cond) \
99 			break; \
100 		if (__timeout_us && __left_ns < 0) { \
101 			(val) = op(args); \
102 			break; \
103 		} \
104 		if (__delay_us) { \
105 			udelay(__delay_us); \
106 			if (__timeout_us) \
107 				__left_ns -= __delay_ns; \
108 		} \
109 		cpu_relax(); \
110 		if (__timeout_us) \
111 			__left_ns--; \
112 	} \
113 	(cond) ? 0 : -ETIMEDOUT; \
114 })
115 
116 /**
117  * readx_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs
118  * @op: accessor function (takes @addr as its only argument)
119  * @addr: Address to poll
120  * @val: Variable to read the value into
121  * @cond: Break condition (usually involving @val)
122  * @sleep_us: Maximum time to sleep between reads in us (0
123  *            tight-loops).  Should be less than ~20ms since usleep_range
124  *            is used (see Documentation/timers/timers-howto.rst).
125  * @timeout_us: Timeout in us, 0 means never timeout
126  *
127  * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
128  * case, the last read value at @addr is stored in @val. Must not
129  * be called from atomic context if sleep_us or timeout_us are used.
130  *
131  * When available, you'll probably want to use one of the specialized
132  * macros defined below rather than this macro directly.
133  */
134 #define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us)	\
135 	read_poll_timeout(op, val, cond, sleep_us, timeout_us, false, addr)
136 
137 /**
138  * readx_poll_timeout_atomic - Periodically poll an address until a condition is met or a timeout occurs
139  * @op: accessor function (takes @addr as its only argument)
140  * @addr: Address to poll
141  * @val: Variable to read the value into
142  * @cond: Break condition (usually involving @val)
143  * @delay_us: Time to udelay between reads in us (0 tight-loops).  Should
144  *            be less than ~10us since udelay is used (see
145  *            Documentation/timers/timers-howto.rst).
146  * @timeout_us: Timeout in us, 0 means never timeout
147  *
148  * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
149  * case, the last read value at @addr is stored in @val.
150  *
151  * When available, you'll probably want to use one of the specialized
152  * macros defined below rather than this macro directly.
153  */
154 #define readx_poll_timeout_atomic(op, addr, val, cond, delay_us, timeout_us) \
155 	read_poll_timeout_atomic(op, val, cond, delay_us, timeout_us, false, addr)
156 
157 #define readb_poll_timeout(addr, val, cond, delay_us, timeout_us) \
158 	readx_poll_timeout(readb, addr, val, cond, delay_us, timeout_us)
159 
160 #define readb_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
161 	readx_poll_timeout_atomic(readb, addr, val, cond, delay_us, timeout_us)
162 
163 #define readw_poll_timeout(addr, val, cond, delay_us, timeout_us) \
164 	readx_poll_timeout(readw, addr, val, cond, delay_us, timeout_us)
165 
166 #define readw_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
167 	readx_poll_timeout_atomic(readw, addr, val, cond, delay_us, timeout_us)
168 
169 #define readl_poll_timeout(addr, val, cond, delay_us, timeout_us) \
170 	readx_poll_timeout(readl, addr, val, cond, delay_us, timeout_us)
171 
172 #define readl_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
173 	readx_poll_timeout_atomic(readl, addr, val, cond, delay_us, timeout_us)
174 
175 #define readq_poll_timeout(addr, val, cond, delay_us, timeout_us) \
176 	readx_poll_timeout(readq, addr, val, cond, delay_us, timeout_us)
177 
178 #define readq_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
179 	readx_poll_timeout_atomic(readq, addr, val, cond, delay_us, timeout_us)
180 
181 #define readb_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \
182 	readx_poll_timeout(readb_relaxed, addr, val, cond, delay_us, timeout_us)
183 
184 #define readb_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
185 	readx_poll_timeout_atomic(readb_relaxed, addr, val, cond, delay_us, timeout_us)
186 
187 #define readw_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \
188 	readx_poll_timeout(readw_relaxed, addr, val, cond, delay_us, timeout_us)
189 
190 #define readw_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
191 	readx_poll_timeout_atomic(readw_relaxed, addr, val, cond, delay_us, timeout_us)
192 
193 #define readl_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \
194 	readx_poll_timeout(readl_relaxed, addr, val, cond, delay_us, timeout_us)
195 
196 #define readl_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
197 	readx_poll_timeout_atomic(readl_relaxed, addr, val, cond, delay_us, timeout_us)
198 
199 #define readq_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \
200 	readx_poll_timeout(readq_relaxed, addr, val, cond, delay_us, timeout_us)
201 
202 #define readq_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
203 	readx_poll_timeout_atomic(readq_relaxed, addr, val, cond, delay_us, timeout_us)
204 
205 #endif /* _LINUX_IOPOLL_H */
206