61 lines
3.0 KiB
ReStructuredText
61 lines
3.0 KiB
ReStructuredText
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======================================================================
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Texas Instruments Keystone Navigator Queue Management SubSystem driver
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======================================================================
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Driver source code path
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drivers/soc/ti/knav_qmss.c
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drivers/soc/ti/knav_qmss_acc.c
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The QMSS (Queue Manager Sub System) found on Keystone SOCs is one of
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the main hardware sub system which forms the backbone of the Keystone
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multi-core Navigator. QMSS consist of queue managers, packed-data structure
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processors(PDSP), linking RAM, descriptor pools and infrastructure
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Packet DMA.
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The Queue Manager is a hardware module that is responsible for accelerating
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management of the packet queues. Packets are queued/de-queued by writing or
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reading descriptor address to a particular memory mapped location. The PDSPs
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perform QMSS related functions like accumulation, QoS, or event management.
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Linking RAM registers are used to link the descriptors which are stored in
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descriptor RAM. Descriptor RAM is configurable as internal or external memory.
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The QMSS driver manages the PDSP setups, linking RAM regions,
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queue pool management (allocation, push, pop and notify) and descriptor
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pool management.
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knav qmss driver provides a set of APIs to drivers to open/close qmss queues,
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allocate descriptor pools, map the descriptors, push/pop to queues etc. For
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details of the available APIs, please refers to include/linux/soc/ti/knav_qmss.h
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DT documentation is available at
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Documentation/devicetree/bindings/soc/ti/keystone-navigator-qmss.txt
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Accumulator QMSS queues using PDSP firmware
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============================================
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The QMSS PDSP firmware support accumulator channel that can monitor a single
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queue or multiple contiguous queues. drivers/soc/ti/knav_qmss_acc.c is the
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driver that interface with the accumulator PDSP. This configures
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accumulator channels defined in DTS (example in DT documentation) to monitor
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1 or 32 queues per channel. More description on the firmware is available in
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CPPI/QMSS Low Level Driver document (docs/CPPI_QMSS_LLD_SDS.pdf) at
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git://git.ti.com/keystone-rtos/qmss-lld.git
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k2_qmss_pdsp_acc48_k2_le_1_0_0_9.bin firmware supports upto 48 accumulator
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channels. This firmware is available under ti-keystone folder of
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firmware.git at
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git://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git
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To use copy the firmware image to lib/firmware folder of the initramfs or
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ubifs file system and provide a sym link to k2_qmss_pdsp_acc48_k2_le_1_0_0_9.bin
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in the file system and boot up the kernel. User would see
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"firmware file ks2_qmss_pdsp_acc48.bin downloaded for PDSP"
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in the boot up log if loading of firmware to PDSP is successful.
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Use of accumulated queues requires the firmware image to be present in the
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file system. The driver doesn't acc queues to the supported queue range if
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PDSP is not running in the SoC. The API call fails if there is a queue open
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request to an acc queue and PDSP is not running. So make sure to copy firmware
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to file system before using these queue types.
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