TRINATH KARRI
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pcie tlp preparation in linux driver
pcie tlp preparation in linux driver
- Thread starter TRINATH KARRI
- Start date
Hey there! PCIe TLP (Transaction Layer Packet) preparation in Linux driver refers to the process of preparing and transmitting PCIe packets through the PCIe bus in a driver implementation.
To prepare TLPs in a Linux driver, you typically need to follow these steps:
1. Allocate memory for the TLP packet: Use the appropriate APIs (e.g., kmalloc) to allocate memory for the TLP packet data structure.
2. Fill in the TLP packet fields: Set the necessary fields in the TLP packet, such as the transaction type, address, and data.
3. Prepare the TLP packet for transmission: Depending on the driver and hardware specific implementation, you may need to perform additional steps to prepare the TLP packet for transmission. This could involve setting flags, calculating checksums, or performing other hardware-specific operations.
4. Send the TLP packet: Use the appropriate APIs or functions to send the TLP packet, typically through the device's PCIe bus interface.
It's important to note that the exact implementation of PCIe TLP preparation can vary depending on the specific driver and hardware you are working with. Therefore, you should consult the documentation and resources specific to your driver and hardware for more detailed guidance.
If you have any further questions or need more specific help, just let me know, dude!
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TRINATH KARRI
Member
which driver in u-boot is responsible ?
In U-Boot, the driver responsible for PCIe TLP preparation depends on the specific hardware platform and the PCIe controller being used. U-Boot typically provides a generic PCIe driver framework that can be used as a starting point for specific platform implementations.
The PCIe driver in U-Boot is responsible for handling PCIe configuration and initialization, including TLP preparation and transmission. However, the exact implementation can vary depending on the hardware platform and the specific PCIe controller chipset.
To find the specific driver responsible for PCIe TLP preparation in your U-Boot configuration, you'll need to consult the U-Boot source code and documentation of your hardware platform. Look for the PCIe driver or controller-specific driver in the U-Boot source tree, and examine its implementation to understand how it handles TLP preparation.
Keep in mind that U-Boot is a versatile and highly customizable bootloader, so different hardware platforms may have different implementations and drivers for PCIe functionality. If you're working with a specific hardware platform, it's best to refer to the documentation and resources provided by the platform manufacturer or community for more specific guidance.
If you have any more questions or need further assistance, just ride the wave and let me know, man!
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TRINATH KARRI
Member
low level pci drivers in linux
In Linux, low-level PCI drivers are responsible for managing the interaction between the kernel and PCI devices. These drivers handle tasks such as device detection, resource allocation, configuration, and communication with the PCI bus.
The low-level PCI drivers in Linux are typically implemented as part of the kernel's PCI subsystem. They provide a standardized interface for accessing and controlling PCI devices across different hardware architectures.
Some of the key components and drivers related to low-level PCI functionality in Linux include:
1. PCI Core: The PCI Core driver provides a generic interface and infrastructure for PCI device enumeration, configuration, and resource management.
2. PCI Bus Driver: The PCI bus driver implements the bus-specific operations for a particular hardware architecture. It handles low-level communication with the PCI bus and facilitates device enumeration and configuration.
3. PCI Device Driver: Device-specific drivers are responsible for managing individual PCI devices. They interact with the PCI Core and handle device-specific operations such as device initialization, power management, and interrupt handling.
4. PCI Driver Framework: Linux provides a framework that simplifies the development of PCI device drivers. This framework includes functions and data structures to register and manage PCI drivers, allowing for easier integration of drivers into the kernel.
It's important to note that low-level PCI drivers in Linux can vary depending on the hardware architecture and specific PCI controller used in a system. So, the implementation and drivers may differ from platform to platform.
For more detailed information and specific driver implementations, you can refer to the Linux kernel source code and documentation, which provide insights into the low-level PCI driver development process.
If you have further questions or need additional assistance, don't hesitate to ask, dude!
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TRINATH KARRI
Member
in uboot which drivers are low level pci drivers
In U-Boot, the low-level PCI drivers are responsible for handling the interaction between the bootloader and PCI devices. They provide essential functionality such as device detection, configuration, and initialization during the early boot process before handing control over to the Linux kernel.
In U-Boot, the low-level PCI driver implementation primarily depends on the specific hardware platform and the PCI controller being used. Here are a few key components and drivers that can be considered low-level PCI drivers in U-Boot:
1. PCI subsystem: U-Boot's PCI subsystem provides a generic framework for handling PCI devices. It includes core functionality for enumeration, configuration, and initialization of PCI devices.
2. PCI controller drivers: These drivers are responsible for controlling the PCI host controller on the specific hardware platform. They handle low-level operations, such as communication with the PCI bus, and provide the necessary interfaces for device detection and configuration.
3. Board-specific PCI drivers: Some hardware platforms require board-specific drivers to support PCI functionality. These drivers provide platform-specific routines for initializing and configuring the PCI devices on the board.
It's important to note that the implementation of low-level PCI drivers in U-Boot can vary significantly based on the specific hardware platform and the level of PCI support provided by U-Boot for that platform.
To determine the exact low-level PCI drivers used in your U-Boot configuration, you should refer to the U-Boot source code and documentation provided by the platform manufacturer or community for your specific hardware platform.
If you have any further questions or need more guidance, feel free to ask, dude!
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TRINATH KARRI
Member
iATU3:
INDEX 0x00000003
LOWER PHYS 0x40000000
UPPER PHYS 0x00000040
LOWER BUS 0x40000000
UPPER BUS 0x00000000
LIMIT 0x7fffffff
CR1 0x00000000
CR2 0x80000000
INDEX 0x00000003
LOWER PHYS 0x40000000
UPPER PHYS 0x00000040
LOWER BUS 0x40000000
UPPER BUS 0x00000000
LIMIT 0x7fffffff
CR1 0x00000000
CR2 0x80000000
The information you provided appears to be a configuration for iATU3 (Internal Address Translation Unit 3). It specifies the settings for the address translation and mapping of a PCI region.
Let's break down the values:
- INDEX: Specifies the index or identification number for the iATU3 configuration. In this case, it is set to 0x00000003.
- LOWER PHYS: Represents the lower 32 bits of the physical address range. In this example, it is set to 0x40000000.
- UPPER PHYS: Represents the upper 32 bits of the physical address range. Here, it is set to 0x00000040.
- LOWER BUS: Specifies the lower 32 bits of the bus address range. In this case, it is set to 0x40000000.
- UPPER BUS: Specifies the upper 32 bits of the bus address range. It is set to 0x00000000.
- LIMIT: Represents the limit or end address of the mapping range. In this example, it is set to 0x7fffffff.
- CR1: Indicates the value of Control Register 1 associated with this configuration. It is set to 0x00000000 in this case.
- CR2: Represents the value of Control Register 2 associated with this configuration. Here, it is set to 0x80000000.
Please note that without specific context or further information, it's challenging to provide precise details regarding the purpose or usage of this configuration. The values you shared are specific to your system and its PCI setup.
If you need further assistance or have more questions, feel free to ask, dude!
OP
TRINATH KARRI
Member
They are Address Translation unit registers for ls1046
Ah, got it! The values you provided are the Address Translation Unit (ATU) registers for the LS1046 SoC (System-on-Chip). These registers are used to configure the address translation and mapping for the PCI controller on the LS1046 platform.
The LS1046 is based on the ARM architecture and is commonly used in networking and embedded systems. The ATU registers allow for flexible mapping and translation of addresses between the PCI bus and the physical memory space.
Here is a breakdown of the LS1046 ATU register values you provided:
- INDEX: Specifies the index or identification number for the ATU configuration. In this case, it is set to 0x00000003.
- LOWER PHYS: Represents the lower 32 bits of the physical address range. The value 0x40000000 indicates a starting physical address of 0x40000000.
- UPPER PHYS: Represents the upper 32 bits of the physical address range. In this case, it is set to 0x00000040.
- LOWER BUS: Specifies the lower 32 bits of the bus address range. The value 0x40000000 indicates a starting bus address of 0x40000000.
- UPPER BUS: Specifies the upper 32 bits of the bus address range. It is set to 0x00000000, indicating no translation of the upper bits.
- LIMIT: Represents the limit or end address of the mapping range. In this example, it is set to 0x7fffffff, indicating a mapping range up to 0x7fffffff.
- CR1: Control Register 1 associated with this ATU configuration. The value 0x00000000 indicates specific configuration options or flags.
- CR2: Control Register 2 associated with this ATU configuration. The value 0x80000000 indicates additional configuration options or flags.
Keep in mind that the interpretation and usage of these registers can vary based on the specific platform and hardware configuration. It's important to refer to the documentation and resources specific to the LS1046 SoC for further details on the usage and purpose of these registers.
Let me know if there's anything else I can help you with, dude!
OP
TRINATH KARRI
Member
Give me an example for PCIe outbound configuration taking an example address
Sure thing, dude! Let's say we want to configure a PCIe outbound translation window in U-Boot for the LS1046 SoC with an example address.
Here's an example configuration using the address range from 0x10000000 to 0x1FFFFFFF:
Code:
#define PCIE_OUTBOUND_BASE 0x10000000
#define PCIE_OUTBOUND_SIZE 0x10000000
#define PCIE_ATU_REGION_INDEX 1
struct fsl_pcie *pcie = /* Get a pointer to your PCIe controller */;
struct fsl_pcie_addr translation_addr;
/* Configure the address translation */
translation_addr.cfg0 = PCIE_OUTBOUND_BASE;
translation_addr.cfg1 = PCIE_OUTBOUND_SIZE;
translation_addr.cfg2 = PCIE_ATU_REGION_INDEX;
/* Configure the outbound region */
fsl_pcie_init_outbound_region(pcie, &translation_addr);
/* Enable the outbound translation region */
fsl_pcie_enable_outbound_translation(pcie, PCIE_ATU_REGION_INDEX);In this example, we define
PCIE_OUTBOUND_BASE as the base address of the outbound translation window (0x10000000 in this case) and PCIE_OUTBOUND_SIZE as the size of the window (0x10000000, or 256MB in this case). PCIE_ATU_REGION_INDEX is the index of the translation region (1 in this case).We then initialize the
translation_addr structure with the configuration values. Finally, we use the fsl_pcie_init_outbound_region function to configure the outbound region with the provided address translation, and fsl_pcie_enable_outbound_translation to enable the outbound translation region specified by the index.Remember to adapt this example to match your specific platform and hardware configuration, and consult the U-Boot documentation and LS1046 SoC documentation for further information and specific details.
If you have any more questions or need further assistance, just let me know, dude!
OP
TRINATH KARRI
Member
explain how address is translated
When it comes to address translation in PCIe, the process involves mapping addresses between the host system (e.g., CPU) and the device connected via the PCIe bus. This mapping ensures that access to the device's memory and registers can be done efficiently and accurately.
The translation process generally involves two key components: the Address Translation Unit (ATU) on the host side and the Device Memory Space on the device side.
On the host side:
1. The host system generates a transaction with a target address to be sent over the PCIe bus.
2. The host's ATU (Address Translation Unit) checks if the address falls within any configured outbound regions. Outbound regions are preconfigured translation windows that specify address mappings.
3. If a match is found, the ATU replaces the original address in the transaction with the translated address specified by the configured outbound region.
4. The transaction is sent over the PCIe bus with the translated address to the target device.
On the device side:
1. The target device receives the transaction over the PCIe bus.
2. The device's memory space is divided into various regions, including memory-mapped I/O registers and device memory regions.
3. The device decodes the translated address to identify the appropriate target memory location or register within its memory space.
4. The device performs the requested operation (read or write) at the specified memory location or register.
5. The device's response is transmitted back to the host.
Address translation enables a seamless and transparent communication between the host and the device, allowing them to interact as if they were connected directly. The ATU on the host and the memory space on the device work together to ensure that the correct memory locations or registers are accessed.
It's important to note that the specific implementation and details of address translation may vary depending on the PCIe endpoint and the platform. Different systems and devices may employ unique mechanisms or additional layers of translation for optimized performance or additional functionality.
If you have further questions or need clarification, feel free to ask, dude!
OP
TRINATH KARRI
Member
explain with an example address not source code
Sure thing, dude! Let's dive into an example to illustrate how address translation works in PCIe.
Let's consider a scenario where we have a PCIe device, such as a graphics card, connected to our host system. The host system wants to read data from a specific memory location on the device.
1. Host System:
- The host system initiates a read operation by generating a transaction with a specific target address, let's say 0x12345678.
- The host's PCIe controller receives the transaction and passes it through the Address Translation Unit (ATU).
2. Address Translation (Host Side):
- The ATU in the host's PCIe controller checks its configuration to see if any outbound translation regions have been set up.
- Let's assume that an outbound region is configured with a base address of 0x10000000 and a size of 0x01000000.
- The ATU compares the target address (0x12345678) with the configured outbound region(s).
- If the target address falls within the range of the outbound region, the ATU translates the address accordingly.
- In our example, the address translation unit determines that the translated address is 0x02345678.
3. Transaction over PCIe:
- The PCIe controller forwards the transaction with the translated address (0x02345678) onto the PCIe bus.
- The transaction travels across the bus and reaches the target device (graphics card) connected via PCIe.
4. Device-Side Mapping:
- The device-side PCIe controller receives the transaction and delivers it to the target device.
- On the device, the device's memory space is structured into various regions.
- The device uses its memory decoding mechanisms to identify the translated address (0x02345678).
- Based on the translated address, the device locates the corresponding memory location or register within its memory space.
5. Data Transfer:
- Assuming the transaction was a read operation, the device retrieves the data from the specified memory location.
- The data is sent back to the host system over the PCIe bus.
That's the basic flow of address translation in PCIe. The host system initiates a transaction, the address is translated by the host's ATU, and the transaction is passed through the PCIe bus to the target device. The device uses its memory decoding to locate the appropriate memory location or register and performs the requested operation.
The specifics of the address translation process and the memory decoding mechanisms vary depending on the PCIe configuration, the device, and the host system.
If you have any more questions or need further clarification, feel free to ask, dude!
OP
TRINATH KARRI
Member
"Let's assume that an outbound region is configured with a base address of 0x10000000 and a size of 0x01000000." what is the need for outbound region here
Apologies if the need for outbound regions wasn't clear, dude. Let me explain why outbound regions are important in address translation.
The purpose of outbound regions in address translation is to define specific memory ranges on the host system that will be mapped to corresponding memory or register spaces on the device connected via PCIe. Outbound regions allow the host to communicate with the device by translating the host's memory addresses to device-specific addresses.
In our example, the outbound region is configured with a base address of 0x10000000 and a size of 0x01000000. This means that the host system can access a specific range of memory addresses (starting from 0x10000000) within this size limit (0x01000000) on the PCIe device.
When the host system initiates a transaction with a target address, the host's ATU checks if the target address falls within the configured outbound region(s). If it does, the ATU performs the address translation by replacing the original address with the translated address specific to the configured outbound region.
The outbound region serves a few purposes:
1. Address Isolation: The outbound region ensures that the host system can only access specific memory ranges or registers on the device. It prevents unintentional access to memory locations outside the defined range.
2. Memory/Register Mapping: The outbound region establishes the mapping between the host system's memory addresses and the device's memory or register spaces. The translation allows the host system to communicate with the device using device-specific memory addresses.
3. Memory Space Partitioning: By configuring multiple outbound regions, different parts of the device's memory space can be mapped to different memory regions on the host system. This allows for efficient management and utilization of device resources.
Overall, the outbound regions play a critical role in facilitating address translation and communication between the host system and the device connected via PCIe. They provide a mechanism to map host system memory addresses to the device's memory or register spaces, ensuring controlled access and effective communication.
If you have any more questions or need further clarification, feel free to ask, dude!
