1 /* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause */
2 /*
3 * Copyright (C) 2018, STMicroelectronics - All Rights Reserved
4 */
5
6 #ifndef _HWSPINLOCK_H_
7 #define _HWSPINLOCK_H_
8
9 #include <linux/errno.h>
10
11 /**
12 * Implement a hwspinlock uclass.
13 * Hardware spinlocks are used to perform hardware protection of
14 * critical sections and synchronisation between multiprocessors.
15 */
16
17 struct udevice;
18
19 /**
20 * struct hwspinlock - A handle to (allowing control of) a single hardware
21 * spinlock.
22 *
23 * @dev: The device which implements the hardware spinlock.
24 * @id: The hardware spinlock ID within the provider.
25 */
26 struct hwspinlock {
27 struct udevice *dev;
28 unsigned long id;
29 };
30
31 #if CONFIG_IS_ENABLED(DM_HWSPINLOCK)
32
33 /**
34 * hwspinlock_get_by_index - Get a hardware spinlock by integer index
35 *
36 * This looks up and request a hardware spinlock. The index is relative to the
37 * client device; each device is assumed to have n hardware spinlock associated
38 * with it somehow, and this function finds and requests one of them.
39 *
40 * @dev: The client device.
41 * @index: The index of the hardware spinlock to request, within the
42 * client's list of hardware spinlock.
43 * @hws: A pointer to a hardware spinlock struct to initialize.
44 * Return: 0 if OK, or a negative error code.
45 */
46 int hwspinlock_get_by_index(struct udevice *dev,
47 int index, struct hwspinlock *hws);
48
49 /**
50 * Lock the hardware spinlock
51 *
52 * @hws: A hardware spinlock struct that previously requested by
53 * hwspinlock_get_by_index
54 * @timeout: Timeout value in msecs
55 * @return: 0 if OK, -ETIMEDOUT if timeout, -ve on other errors
56 */
57 int hwspinlock_lock_timeout(struct hwspinlock *hws, unsigned int timeout);
58
59 /**
60 * Unlock the hardware spinlock
61 *
62 * @hws: A hardware spinlock struct that previously requested by
63 * hwspinlock_get_by_index
64 * @return: 0 if OK, -ve on error
65 */
66 int hwspinlock_unlock(struct hwspinlock *hws);
67
68 #else
69
hwspinlock_get_by_index(struct udevice * dev,int index,struct hwspinlock * hws)70 static inline int hwspinlock_get_by_index(struct udevice *dev,
71 int index,
72 struct hwspinlock *hws)
73 {
74 return -ENOSYS;
75 }
76
hwspinlock_lock_timeout(struct hwspinlock * hws,int timeout)77 static inline int hwspinlock_lock_timeout(struct hwspinlock *hws,
78 int timeout)
79 {
80 return -ENOSYS;
81 }
82
hwspinlock_unlock(struct hwspinlock * hws)83 static inline int hwspinlock_unlock(struct hwspinlock *hws)
84 {
85 return -ENOSYS;
86 }
87
88 #endif /* CONFIG_DM_HWSPINLOCK */
89
90 struct ofnode_phandle_args;
91
92 /**
93 * struct hwspinlock_ops - Driver model hwspinlock operations
94 *
95 * The uclass interface is implemented by all hwspinlock devices which use
96 * driver model.
97 */
98 struct hwspinlock_ops {
99 /**
100 * of_xlate - Translate a client's device-tree (OF) hardware specifier.
101 *
102 * The hardware core calls this function as the first step in
103 * implementing a client's hwspinlock_get_by_*() call.
104 *
105 * @hws: The hardware spinlock struct to hold the translation
106 * result.
107 * @args: The hardware spinlock specifier values from device tree.
108 * @return 0 if OK, or a negative error code.
109 */
110 int (*of_xlate)(struct hwspinlock *hws,
111 struct ofnode_phandle_args *args);
112
113 /**
114 * Lock the hardware spinlock
115 *
116 * @dev: hwspinlock Device
117 * @index: index of the lock to be used
118 * @return 0 if OK, -ve on error
119 */
120 int (*lock)(struct udevice *dev, int index);
121
122 /**
123 * Unlock the hardware spinlock
124 *
125 * @dev: hwspinlock Device
126 * @index: index of the lock to be unlocked
127 * @return 0 if OK, -ve on error
128 */
129 int (*unlock)(struct udevice *dev, int index);
130
131 /**
132 * Relax - optional
133 * Platform-specific relax method, called by hwspinlock core
134 * while spinning on a lock, between two successive call to
135 * lock
136 *
137 * @dev: hwspinlock Device
138 */
139 void (*relax)(struct udevice *dev);
140 };
141
142 #endif /* _HWSPINLOCK_H_ */
143