1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
|
/*
* Copyright (c) 2015 Google, Inc
* Written by Simon Glass <sjg@chromium.org>
* Copyright (c) 2016, NVIDIA CORPORATION.
*
* SPDX-License-Identifier: GPL-2.0+
*/
#ifndef _CLK_H_
#define _CLK_H_
#include <linux/errno.h>
#include <linux/types.h>
/**
* A clock is a hardware signal that oscillates autonomously at a specific
* frequency and duty cycle. Most hardware modules require one or more clock
* signal to drive their operation. Clock signals are typically generated
* externally to the HW module consuming them, by an entity this API calls a
* clock provider. This API provides a standard means for drivers to enable and
* disable clocks, and to set the rate at which they oscillate.
*
* A driver that implements UCLASS_CLOCK is a clock provider. A provider will
* often implement multiple separate clocks, since the hardware it manages
* often has this capability. clock_uclass.h describes the interface which
* clock providers must implement.
*
* Clock consumers/clients are the HW modules driven by the clock signals. This
* header file describes the API used by drivers for those HW modules.
*/
struct udevice;
/**
* struct clk - A handle to (allowing control of) a single clock.
*
* Clients provide storage for clock handles. The content of the structure is
* managed solely by the clock API and clock drivers. A clock struct is
* initialized by "get"ing the clock struct. The clock struct is passed to all
* other clock APIs to identify which clock signal to operate upon.
*
* @dev: The device which implements the clock signal.
* @id: The clock signal ID within the provider.
*
* Currently, the clock API assumes that a single integer ID is enough to
* identify and configure any clock signal for any clock provider. If this
* assumption becomes invalid in the future, the struct could be expanded to
* either (a) add more fields to allow clock providers to store additional
* information, or (b) replace the id field with an opaque pointer, which the
* provider would dynamically allocated during its .of_xlate op, and process
* during is .request op. This may require the addition of an extra op to clean
* up the allocation.
*/
struct clk {
struct udevice *dev;
/*
* Written by of_xlate. We assume a single id is enough for now. In the
* future, we might add more fields here.
*/
unsigned long id;
};
#if CONFIG_IS_ENABLED(OF_CONTROL) && CONFIG_IS_ENABLED(CLK)
struct phandle_2_cell;
int clk_get_by_index_platdata(struct udevice *dev, int index,
struct phandle_2_cell *cells, struct clk *clk);
/**
* clock_get_by_index - Get/request a clock by integer index.
*
* This looks up and requests a clock. The index is relative to the client
* device; each device is assumed to have n clocks associated with it somehow,
* and this function finds and requests one of them. The mapping of client
* device clock indices to provider clocks may be via device-tree properties,
* board-provided mapping tables, or some other mechanism.
*
* @dev: The client device.
* @index: The index of the clock to request, within the client's list of
* clocks.
* @clock A pointer to a clock struct to initialize.
* @return 0 if OK, or a negative error code.
*/
int clk_get_by_index(struct udevice *dev, int index, struct clk *clk);
/**
* clock_get_by_name - Get/request a clock by name.
*
* This looks up and requests a clock. The name is relative to the client
* device; each device is assumed to have n clocks associated with it somehow,
* and this function finds and requests one of them. The mapping of client
* device clock names to provider clocks may be via device-tree properties,
* board-provided mapping tables, or some other mechanism.
*
* @dev: The client device.
* @name: The name of the clock to request, within the client's list of
* clocks.
* @clock: A pointer to a clock struct to initialize.
* @return 0 if OK, or a negative error code.
*/
int clk_get_by_name(struct udevice *dev, const char *name, struct clk *clk);
#else
static inline int clk_get_by_index(struct udevice *dev, int index,
struct clk *clk)
{
return -ENOSYS;
}
static inline int clk_get_by_name(struct udevice *dev, const char *name,
struct clk *clk)
{
return -ENOSYS;
}
#endif
/**
* clk_request - Request a clock by provider-specific ID.
*
* This requests a clock using a provider-specific ID. Generally, this function
* should not be used, since clk_get_by_index/name() provide an interface that
* better separates clients from intimate knowledge of clock providers.
* However, this function may be useful in core SoC-specific code.
*
* @dev: The clock provider device.
* @clock: A pointer to a clock struct to initialize. The caller must
* have already initialized any field in this struct which the
* clock provider uses to identify the clock.
* @return 0 if OK, or a negative error code.
*/
int clk_request(struct udevice *dev, struct clk *clk);
/**
* clock_free - Free a previously requested clock.
*
* @clock: A clock struct that was previously successfully requested by
* clk_request/get_by_*().
* @return 0 if OK, or a negative error code.
*/
int clk_free(struct clk *clk);
/**
* clk_get_rate() - Get current clock rate.
*
* @clk: A clock struct that was previously successfully requested by
* clk_request/get_by_*().
* @return clock rate in Hz, or -ve error code.
*/
ulong clk_get_rate(struct clk *clk);
/**
* clk_set_rate() - Set current clock rate.
*
* @clk: A clock struct that was previously successfully requested by
* clk_request/get_by_*().
* @rate: New clock rate in Hz.
* @return new rate, or -ve error code.
*/
ulong clk_set_rate(struct clk *clk, ulong rate);
/**
* clk_enable() - Enable (turn on) a clock.
*
* @clk: A clock struct that was previously successfully requested by
* clk_request/get_by_*().
* @return zero on success, or -ve error code.
*/
int clk_enable(struct clk *clk);
/**
* clk_disable() - Disable (turn off) a clock.
*
* @clk: A clock struct that was previously successfully requested by
* clk_request/get_by_*().
* @return zero on success, or -ve error code.
*/
int clk_disable(struct clk *clk);
int soc_clk_dump(void);
#endif
|
