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// SPDX-License-Identifier: GPL-2.0
* System Trace Module (STM) infrastructure apis
* Copyright (C) 2014 Intel Corporation.
#ifndef _STM_H_
#define _STM_H_
#include <linux/device.h>
* enum stp_packet_type - STP packets that an STM driver sends
enum stp_packet_type {
* enum stp_packet_flags - STP packet modifiers
enum stp_packet_flags {
struct stp_policy;
struct stm_device;
* struct stm_data - STM device description and callbacks
* @name: device name
* @stm: internal structure, only used by stm class code
* @sw_start: first STP master available to software
* @sw_end: last STP master available to software
* @sw_nchannels: number of STP channels per master
* @sw_mmiosz: size of one channel's IO space, for mmap, optional
* @hw_override: masters in the STP stream will not match the ones
* assigned by software, but are up to the STM hardware
* @packet: callback that sends an STP packet
* @mmio_addr: mmap callback, optional
* @link: called when a new stm_source gets linked to us, optional
* @unlink: likewise for unlinking, again optional
* @set_options: set device-specific options on a channel
* Fill out this structure before calling stm_register_device() to create
* an STM device and stm_unregister_device() to destroy it. It will also be
* passed back to @packet(), @mmio_addr(), @link(), @unlink() and @set_options()
* callbacks.
* Normally, an STM device will have a range of masters available to software
* and the rest being statically assigned to various hardware trace sources.
* The former is defined by the the range [@sw_start..@sw_end] of the device
* description. That is, the lowest master that can be allocated to software
* writers is @sw_start and data from this writer will appear is @sw_start
* master in the STP stream.
* The @packet callback should adhere to the following rules:
* 1) it must return the number of bytes it consumed from the payload;
* 2) therefore, if it sent a packet that does not have payload (like FLAG),
* it must return zero;
* 3) if it does not support the requested packet type/flag combination,
* it must return -ENOTSUPP.
* The @unlink callback is called when there are no more active writers so
* that the master/channel can be quiesced.
struct stm_data {
const char *name;
struct stm_device *stm;
unsigned int sw_start;
unsigned int sw_end;
unsigned int sw_nchannels;
unsigned int sw_mmiosz;
unsigned int hw_override;
ssize_t (*packet)(struct stm_data *, unsigned int,
unsigned int, unsigned int,
unsigned int, unsigned int,
const unsigned char *);
phys_addr_t (*mmio_addr)(struct stm_data *, unsigned int,
unsigned int, unsigned int);
int (*link)(struct stm_data *, unsigned int,
unsigned int);
void (*unlink)(struct stm_data *, unsigned int,
unsigned int);
long (*set_options)(struct stm_data *, unsigned int,
unsigned int, unsigned int,
unsigned long);
int stm_register_device(struct device *parent, struct stm_data *stm_data,
struct module *owner);
void stm_unregister_device(struct stm_data *stm_data);
struct stm_source_device;
* struct stm_source_data - STM source device description and callbacks
* @name: device name, will be used for policy lookup
* @src: internal structure, only used by stm class code
* @nr_chans: number of channels to allocate
* @link: called when this source gets linked to an STM device
* @unlink: called when this source is about to get unlinked from its STM
* Fill in this structure before calling stm_source_register_device() to
* register a source device. Also pass it to unregister and write calls.
struct stm_source_data {
const char *name;
struct stm_source_device *src;
unsigned int percpu;
unsigned int nr_chans;
int (*link)(struct stm_source_data *data);
void (*unlink)(struct stm_source_data *data);
int stm_source_register_device(struct device *parent,
struct stm_source_data *data);
void stm_source_unregister_device(struct stm_source_data *data);
int notrace stm_source_write(struct stm_source_data *data, unsigned int chan,
const char *buf, size_t count);
#endif /* _STM_H_ */