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
44typedef 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 */
53struct scom_controller {
54	scom_map_t (*map)(struct device_node *ctrl_dev, u64 reg, u64 count);
55	void (*unmap)(scom_map_t map);
56
57	u64 (*read)(scom_map_t map, u32 reg);
58	void (*write)(scom_map_t map, u32 reg, u64 value);
59};
60
61extern 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 */
67static 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 */
76static 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
89static 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 */
104struct 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 */
119extern 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 */
126static 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
136 */
137static inline u64 scom_read(scom_map_t map, u32 reg)
138{
139	return scom_controller->read(map, reg);
140}
141
142/**
143 * scom_write - Write to a SCOM register
144 * @map: Result of scom_map
145 * @reg: Register index within that map
146 * @value: Value to write
147 */
148static inline void scom_write(scom_map_t map, u32 reg, u64 value)
149{
150	scom_controller->write(map, reg, value);
151}
152
153#endif /* CONFIG_PPC_SCOM */
154#endif /* __ASSEMBLY__ */
155#endif /* __KERNEL__ */
156#endif /* _ASM_POWERPC_SCOM_H */
157