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1 | /* |
2 | * Copyright 2010 Benjamin Herrenschmidt, IBM Corp | |
3 | * <benh@kernel.crashing.org> | |
4 | * and David Gibson, IBM Corporation. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See | |
14 | * the GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write to the Free Software | |
18 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
19 | */ | |
20 | ||
21 | #ifndef _ASM_POWERPC_SCOM_H | |
22 | #define _ASM_POWERPC_SCOM_H | |
23 | ||
24 | #ifdef __KERNEL__ | |
25 | #ifndef __ASSEMBLY__ | |
26 | #ifdef CONFIG_PPC_SCOM | |
27 | ||
28 | /* | |
29 | * The SCOM bus is a sideband bus used for accessing various internal | |
30 | * registers of the processor or the chipset. The implementation details | |
31 | * differ between processors and platforms, and the access method as | |
32 | * well. | |
33 | * | |
34 | * This API allows to "map" ranges of SCOM register numbers associated | |
35 | * with a given SCOM controller. The later must be represented by a | |
36 | * device node, though some implementations might support NULL if there | |
37 | * is no possible ambiguity | |
38 | * | |
39 | * Then, scom_read/scom_write can be used to accesses registers inside | |
40 | * that range. The argument passed is a register number relative to | |
41 | * the beginning of the range mapped. | |
42 | */ | |
43 | ||
44 | typedef void *scom_map_t; | |
45 | ||
46 | /* Value for an invalid SCOM map */ | |
47 | #define SCOM_MAP_INVALID (NULL) | |
48 | ||
49 | /* The scom_controller data structure is what the platform passes | |
50 | * to the core code in scom_init, it provides the actual implementation | |
51 | * of all the SCOM functions | |
52 | */ | |
53 | struct scom_controller { | |
54 | scom_map_t (*map)(struct device_node *ctrl_dev, u64 reg, u64 count); | |
55 | void (*unmap)(scom_map_t map); | |
56 | ||
d7a88c7e BH |
57 | int (*read)(scom_map_t map, u64 reg, u64 *value); |
58 | int (*write)(scom_map_t map, u64 reg, u64 value); | |
ab814b93 BH |
59 | }; |
60 | ||
61 | extern const struct scom_controller *scom_controller; | |
62 | ||
63 | /** | |
64 | * scom_init - Initialize the SCOM backend, called by the platform | |
65 | * @controller: The platform SCOM controller | |
66 | */ | |
67 | static inline void scom_init(const struct scom_controller *controller) | |
68 | { | |
69 | scom_controller = controller; | |
70 | } | |
71 | ||
72 | /** | |
73 | * scom_map_ok - Test is a SCOM mapping is successful | |
74 | * @map: The result of scom_map to test | |
75 | */ | |
76 | static inline int scom_map_ok(scom_map_t map) | |
77 | { | |
78 | return map != SCOM_MAP_INVALID; | |
79 | } | |
80 | ||
81 | /** | |
82 | * scom_map - Map a block of SCOM registers | |
83 | * @ctrl_dev: Device node of the SCOM controller | |
84 | * some implementations allow NULL here | |
85 | * @reg: first SCOM register to map | |
86 | * @count: Number of SCOM registers to map | |
87 | */ | |
88 | ||
89 | static inline scom_map_t scom_map(struct device_node *ctrl_dev, | |
90 | u64 reg, u64 count) | |
91 | { | |
92 | return scom_controller->map(ctrl_dev, reg, count); | |
93 | } | |
94 | ||
95 | /** | |
96 | * scom_find_parent - Find the SCOM controller for a device | |
97 | * @dev: OF node of the device | |
98 | * | |
99 | * This is not meant for general usage, but in combination with | |
100 | * scom_map() allows to map registers not represented by the | |
101 | * device own scom-reg property. Useful for applying HW workarounds | |
102 | * on things not properly represented in the device-tree for example. | |
103 | */ | |
104 | struct device_node *scom_find_parent(struct device_node *dev); | |
105 | ||
106 | ||
107 | /** | |
108 | * scom_map_device - Map a device's block of SCOM registers | |
109 | * @dev: OF node of the device | |
110 | * @index: Register bank index (index in "scom-reg" property) | |
111 | * | |
112 | * This function will use the device-tree binding for SCOM which | |
113 | * is to follow "scom-parent" properties until it finds a node with | |
114 | * a "scom-controller" property to find the controller. It will then | |
115 | * use the "scom-reg" property which is made of reg/count pairs, | |
116 | * each of them having a size defined by the controller's #scom-cells | |
117 | * property | |
118 | */ | |
119 | extern scom_map_t scom_map_device(struct device_node *dev, int index); | |
120 | ||
121 | ||
122 | /** | |
123 | * scom_unmap - Unmap a block of SCOM registers | |
124 | * @map: Result of scom_map is to be unmapped | |
125 | */ | |
126 | static inline void scom_unmap(scom_map_t map) | |
127 | { | |
128 | if (scom_map_ok(map)) | |
129 | scom_controller->unmap(map); | |
130 | } | |
131 | ||
132 | /** | |
133 | * scom_read - Read a SCOM register | |
134 | * @map: Result of scom_map | |
135 | * @reg: Register index within that map | |
aaa63093 BH |
136 | * @value: Updated with the value read |
137 | * | |
138 | * Returns 0 (success) or a negative error code | |
ab814b93 | 139 | */ |
d7a88c7e | 140 | static inline int scom_read(scom_map_t map, u64 reg, u64 *value) |
ab814b93 | 141 | { |
aaa63093 BH |
142 | int rc; |
143 | ||
144 | rc = scom_controller->read(map, reg, value); | |
145 | if (rc) | |
146 | *value = 0xfffffffffffffffful; | |
147 | return rc; | |
ab814b93 BH |
148 | } |
149 | ||
150 | /** | |
151 | * scom_write - Write to a SCOM register | |
152 | * @map: Result of scom_map | |
153 | * @reg: Register index within that map | |
154 | * @value: Value to write | |
aaa63093 BH |
155 | * |
156 | * Returns 0 (success) or a negative error code | |
ab814b93 | 157 | */ |
d7a88c7e | 158 | static inline int scom_write(scom_map_t map, u64 reg, u64 value) |
ab814b93 | 159 | { |
aaa63093 | 160 | return scom_controller->write(map, reg, value); |
ab814b93 BH |
161 | } |
162 | ||
aaa63093 | 163 | |
ab814b93 BH |
164 | #endif /* CONFIG_PPC_SCOM */ |
165 | #endif /* __ASSEMBLY__ */ | |
166 | #endif /* __KERNEL__ */ | |
167 | #endif /* _ASM_POWERPC_SCOM_H */ |