查看“HDP Linux driver”的源代码

== Article purpose ==
This article introduces the '''Hardware Debug Port''' which allows the observation of internal signals. By using multiplexers, up to 16 signals of each of 8-bit output can be observed. The article explains:

* How to configure, use and debug the driver
* The driver structure, and where the source code can be found.

== Short description ==

* 8 output signals
* One of 16 internal signals with individual control
* 8 software-programmable signals for pinout agnostic code debugging
* Output disabling by security signal

[[File:HDP_overview.png|thumb|center|766px|alt=Alternate text|HDP Block Diagram]]

== Configuration ==
=== Kernel configuration ===
The '''HDP''' is enabled and ready to be used in all STM32MPU Embedded Software Distributions, via the Linux<sup>&reg;</sup> kernel configuration '''CONFIG_STM32_HDP''', set to disabled by default.
 Symbol: '''STM32_HDP'''
 Location:
   Device Drivers
   [*] SOC (System On Chip) specific Drivers
     [*] STMicroelectronics STM32MP157 Hardware Debug Port (HDP) pin control 

Please refer to the [[Menuconfig or how to configure kernel]] article for instructions on modifying the configuration, and recompiling the Linux kernel image in the Distribution Package context.

=== Device tree ===
Refer to the [[HDP device tree configuration]] article when configuring the HDP Linux kernel driver.

== How to trace and debug ==

=== How to monitor ===

==== How to monitor with debugfs ====

'''sysfs''' entry can be used to browse HDP registers.

  {{Board$}} /sys/kernel/debug/hdp# ls
   ctrl  gpoclr  gposet  gpoval  mux  val

See the HDP chapter in the reference manual <ref>[[STM32MP15 resources#Reference manuals|STM32MP15 reference manuals]]</ref> for further register details.

== Source code location ==
The HDP Linux driver source code is composed of:
* “<Linux kernel directory>/drivers/soc/st/stm32_hdp.c”  to handle common resources: registers, clock.
{{Info|Please note that the upstreaming of the HDP Linux driver source code is in progress}}

==References==
<references />

<noinclude>
[[Category:Embedded trace and debug]]
{{PublicationRequestId | 10412 | 2019-01-24 | PhilipS}}
{{ArticleBasedOnModel | Linux driver article model}}
</noinclude>