xref: /openbmc/linux/include/linux/stm.h (revision d0b371e5)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * System Trace Module (STM) infrastructure apis
4  * Copyright (C) 2014 Intel Corporation.
5  */
6 
7 #ifndef _STM_H_
8 #define _STM_H_
9 
10 #include <linux/device.h>
11 
12 /**
13  * enum stp_packet_type - STP packets that an STM driver sends
14  */
15 enum stp_packet_type {
16 	STP_PACKET_DATA = 0,
17 	STP_PACKET_FLAG,
18 	STP_PACKET_USER,
19 	STP_PACKET_MERR,
20 	STP_PACKET_GERR,
21 	STP_PACKET_TRIG,
22 	STP_PACKET_XSYNC,
23 };
24 
25 /**
26  * enum stp_packet_flags - STP packet modifiers
27  */
28 enum stp_packet_flags {
29 	STP_PACKET_MARKED	= 0x1,
30 	STP_PACKET_TIMESTAMPED	= 0x2,
31 };
32 
33 struct stp_policy;
34 
35 struct stm_device;
36 
37 /**
38  * struct stm_data - STM device description and callbacks
39  * @name:		device name
40  * @stm:		internal structure, only used by stm class code
41  * @sw_start:		first STP master available to software
42  * @sw_end:		last STP master available to software
43  * @sw_nchannels:	number of STP channels per master
44  * @sw_mmiosz:		size of one channel's IO space, for mmap, optional
45  * @hw_override:	masters in the STP stream will not match the ones
46  *			assigned by software, but are up to the STM hardware
47  * @packet:		callback that sends an STP packet
48  * @mmio_addr:		mmap callback, optional
49  * @link:		called when a new stm_source gets linked to us, optional
50  * @unlink:		likewise for unlinking, again optional
51  * @set_options:	set device-specific options on a channel
52  *
53  * Fill out this structure before calling stm_register_device() to create
54  * an STM device and stm_unregister_device() to destroy it. It will also be
55  * passed back to @packet(), @mmio_addr(), @link(), @unlink() and @set_options()
56  * callbacks.
57  *
58  * Normally, an STM device will have a range of masters available to software
59  * and the rest being statically assigned to various hardware trace sources.
60  * The former is defined by the range [@sw_start..@sw_end] of the device
61  * description. That is, the lowest master that can be allocated to software
62  * writers is @sw_start and data from this writer will appear is @sw_start
63  * master in the STP stream.
64  *
65  * The @packet callback should adhere to the following rules:
66  *   1) it must return the number of bytes it consumed from the payload;
67  *   2) therefore, if it sent a packet that does not have payload (like FLAG),
68  *      it must return zero;
69  *   3) if it does not support the requested packet type/flag combination,
70  *      it must return -ENOTSUPP.
71  *
72  * The @unlink callback is called when there are no more active writers so
73  * that the master/channel can be quiesced.
74  */
75 struct stm_data {
76 	const char		*name;
77 	struct stm_device	*stm;
78 	unsigned int		sw_start;
79 	unsigned int		sw_end;
80 	unsigned int		sw_nchannels;
81 	unsigned int		sw_mmiosz;
82 	unsigned int		hw_override;
83 	ssize_t			(*packet)(struct stm_data *, unsigned int,
84 					  unsigned int, unsigned int,
85 					  unsigned int, unsigned int,
86 					  const unsigned char *);
87 	phys_addr_t		(*mmio_addr)(struct stm_data *, unsigned int,
88 					     unsigned int, unsigned int);
89 	int			(*link)(struct stm_data *, unsigned int,
90 					unsigned int);
91 	void			(*unlink)(struct stm_data *, unsigned int,
92 					  unsigned int);
93 	long			(*set_options)(struct stm_data *, unsigned int,
94 					       unsigned int, unsigned int,
95 					       unsigned long);
96 };
97 
98 int stm_register_device(struct device *parent, struct stm_data *stm_data,
99 			struct module *owner);
100 void stm_unregister_device(struct stm_data *stm_data);
101 
102 struct stm_source_device;
103 
104 /**
105  * struct stm_source_data - STM source device description and callbacks
106  * @name:	device name, will be used for policy lookup
107  * @src:	internal structure, only used by stm class code
108  * @nr_chans:	number of channels to allocate
109  * @link:	called when this source gets linked to an STM device
110  * @unlink:	called when this source is about to get unlinked from its STM
111  *
112  * Fill in this structure before calling stm_source_register_device() to
113  * register a source device. Also pass it to unregister and write calls.
114  */
115 struct stm_source_data {
116 	const char		*name;
117 	struct stm_source_device *src;
118 	unsigned int		percpu;
119 	unsigned int		nr_chans;
120 	int			(*link)(struct stm_source_data *data);
121 	void			(*unlink)(struct stm_source_data *data);
122 };
123 
124 int stm_source_register_device(struct device *parent,
125 			       struct stm_source_data *data);
126 void stm_source_unregister_device(struct stm_source_data *data);
127 
128 int notrace stm_source_write(struct stm_source_data *data, unsigned int chan,
129 			     const char *buf, size_t count);
130 
131 #endif /* _STM_H_ */
132