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Update PRU UART documentation #708

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3018cf2
fix(linux): Remove PRU SW UART from TOC
jmenti May 14, 2026
cd1bacd
fix(linux): Enable PRU HW UART doc for am62x and am64x
jmenti May 14, 2026
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1 change: 0 additions & 1 deletion configs/AM335X/AM335X_linux_toc.txt
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Expand Up @@ -88,7 +88,6 @@ linux/Foundational_Components/PRU-ICSS/Linux_Drivers/RemoteProc
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/RPMsg
linux/Foundational_Components/PRU-ICSS/RPMsg_Quick_Start_Guide
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/PRU-ICSS_Ethernet
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pru-sw-uart
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pruss-uart
linux/Foundational_Components/PRU-ICSS-Hardware
linux/Foundational_Components/PRU-ICSS/PRU-EVMs
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1 change: 0 additions & 1 deletion configs/AM437X/AM437X_linux_toc.txt
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Expand Up @@ -89,7 +89,6 @@ linux/Foundational_Components/PRU-ICSS/Linux_Drivers/RemoteProc
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/RPMsg
linux/Foundational_Components/PRU-ICSS/RPMsg_Quick_Start_Guide
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/PRU-ICSS_Ethernet
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pru-sw-uart
linux/Foundational_Components/PRU-ICSS-Hardware
linux/Foundational_Components/PRU-ICSS/PRU-EVMs
linux/Foundational_Components/PRU-ICSS-Training
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1 change: 0 additions & 1 deletion configs/AM57X/AM57X_linux_toc.txt
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Expand Up @@ -94,7 +94,6 @@ linux/Foundational_Components/PRU-ICSS/Linux_Drivers/RemoteProc
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/RPMsg
linux/Foundational_Components/PRU-ICSS/RPMsg_Quick_Start_Guide
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/PRU-ICSS_Ethernet
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pru-sw-uart
linux/Foundational_Components/PRU-ICSS-Hardware
linux/Foundational_Components/PRU-ICSS/PRU-EVMs
linux/Foundational_Components/PRU-ICSS-Training
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1 change: 1 addition & 0 deletions configs/AM62X/AM62X_linux_toc.txt
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Expand Up @@ -108,6 +108,7 @@ linux/Foundational_Components_PRU_Subsystem
linux/Foundational_Components/PRU-ICSS-Linux-Drivers
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/RemoteProc
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/RPMsg
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pruss-uart
linux/Foundational_Components/PRU-ICSS/RPMsg_Quick_Start_Guide
linux/Foundational_Components/PRU-ICSS-Hardware
linux/Foundational_Components/PRU-ICSS/PRU-EVMs
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1 change: 1 addition & 0 deletions configs/AM64X/AM64X_linux_toc.txt
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Expand Up @@ -109,6 +109,7 @@ linux/Foundational_Components/PRU-ICSS/Linux_Drivers/RemoteProc
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/PRU_ICSSG_Ethernet
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/PRU_ICSSG_Ethernet_Switch
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/RPMsg
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pruss-uart
linux/Foundational_Components/PRU-ICSS/Linux_Drivers/PRU_ICSSG_XDP
linux/Foundational_Components/PRU-ICSS/RPMsg_Quick_Start_Guide
linux/Foundational_Components/PRU-ICSS-Hardware
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22 changes: 12 additions & 10 deletions source/linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pruss-uart.rst
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Expand Up @@ -3,27 +3,32 @@

.. rubric:: Introduction

As of Processor SDK v7.1, Linux supports the PRU UART peripheral within the
PRU-ICSS, which is based on the industry standard TL16C550.
The kernel driver is at drivers/tty/serial/8250/8250_pruss.c.
Linux supports the PRU HW UART peripheral within the

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[RedHat.Definitions] Define acronyms and abbreviations (such as 'UART') on first occurrence if they're likely to be unfamiliar.

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{"message": "[RedHat.Definitions] Define acronyms and abbreviations (such as 'UART') on first occurrence if they're likely to be unfamiliar.", "location": {"path": "source/linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pruss-uart.rst", "range": {"start": {"line": 6, "column": 27}}}, "severity": "INFO"}

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[RedHat.Definitions] Define acronyms and abbreviations (such as 'PRU') on first occurrence if they're likely to be unfamiliar.

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{"message": "[RedHat.Definitions] Define acronyms and abbreviations (such as 'PRU') on first occurrence if they're likely to be unfamiliar.", "location": {"path": "source/linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pruss-uart.rst", "range": {"start": {"line": 6, "column": 20}}}, "severity": "INFO"}

.. ifconfig:: CONFIG_part_variant in ('AM62X')

Programmable Real-Time Unit Subsystem (PRUSS)

.. ifconfig:: CONFIG_part_variant in ('AM64X')

.. rubric:: Support Devices
Programmable Real-Time Unit and Industrial Communication Subsystem - Gigabit (PRU-ICSSG)

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[RedHat.Definitions] Define acronyms and abbreviations (such as 'PRU') on first occurrence if they're likely to be unfamiliar.

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{"message": "[RedHat.Definitions] Define acronyms and abbreviations (such as 'PRU') on first occurrence if they're likely to be unfamiliar.", "location": {"path": "source/linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pruss-uart.rst", "range": {"start": {"line": 14, "column": 82}}}, "severity": "INFO"}
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Suggested change
Programmable Real-Time Unit and Industrial Communication Subsystem - Gigabit (PRU-ICSSG)
Programmable Real-Time Unit (PRU) and Industrial Communication Subsystem - Gigabit (ICSSG) or PRU-ICSSG


- |__PART_FAMILY_DEVICE_NAMES__|
.. ifconfig:: CONFIG_part_variant in ('AM335X', 'AM437X', 'AM57XX')

Programmable Real-Time Unit Subsystem and Industrial Communication Subsystem (PRU-ICSS)

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[RedHat.Definitions] Define acronyms and abbreviations (such as 'ICSS') on first occurrence if they're likely to be unfamiliar.

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{"message": "[RedHat.Definitions] Define acronyms and abbreviations (such as 'ICSS') on first occurrence if they're likely to be unfamiliar.", "location": {"path": "source/linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pruss-uart.rst", "range": {"start": {"line": 18, "column": 86}}}, "severity": "INFO"}
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Is it actually Programmable Real-Time Unit Subsystem or was this also supposed to just be Programmable Real-Time Unit?


which is based on the industry standard TL16C550.

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[RedHat.PassiveVoice] 'is based' is passive voice. In general, use active voice. Consult the style guide for acceptable use of passive voice.

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{"message": "[RedHat.PassiveVoice] 'is based' is passive voice. In general, use active voice. Consult the style guide for acceptable use of passive voice.", "location": {"path": "source/linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pruss-uart.rst", "range": {"start": {"line": 20, "column": 7}}}, "severity": "INFO"}

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[RedHat.TermsSuggestions] Depending on the context, consider using 'that' or ', which' rather than 'which'.

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{"message": "[RedHat.TermsSuggestions] Depending on the context, consider using 'that' or ', which' rather than 'which'.", "location": {"path": "source/linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pruss-uart.rst", "range": {"start": {"line": 20, "column": 1}}}, "severity": "INFO"}
The kernel driver is at drivers/tty/serial/8250/8250_pruss.c.

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[RedHat.Slash] Use either 'or' or 'and' in 'drivers/tty'

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{"message": "[RedHat.Slash] Use either 'or' or 'and' in 'drivers/tty'", "location": {"path": "source/linux/Foundational_Components/PRU-ICSS/Linux_Drivers/pruss-uart.rst", "range": {"start": {"line": 21, "column": 25}}}, "severity": "WARNING"}
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If you want this to flow better consider adding a replacement variable definition for those platforms instead. Currently this will appear as a broken up sentence. Optionally you could restructure this so the user doesn't have to follow a few sentence fragments.

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The kernel driver is at drivers/tty/serial/8250/8250_pruss.c.
The kernel driver is at :file:`drivers/tty/serial/8250/8250_pruss.c`.


.. rubric:: Supported Driver Features

- Baud rates up to 12Mbps
- Hardware flow control


.. rubric:: Unsupported Driver Features

- DMA support


.. rubric:: Kernel Config

The PRUSS UART Linux kernel driver depends on the PRU-ICSS kernel drivers. So
Expand Down Expand Up @@ -61,7 +66,6 @@
status = "okay";
};


.. rubric:: Driver Usage

Once the driver is probed, kernel log shows the following message.
Expand All @@ -78,5 +82,3 @@

The index in ttyS1 could vary depending on the serial alias configuration
in the device tree.


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