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kernel/linux-rt-4.4.41/Documentation/arm/keystone/knav-qmss.txt 2.84 KB
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  * Texas Instruments Keystone Navigator Queue Management SubSystem driver
  
  Driver source code path
    drivers/soc/ti/knav_qmss.c
    drivers/soc/ti/knav_qmss_acc.c
  
  The QMSS (Queue Manager Sub System) found on Keystone SOCs is one of
  the main hardware sub system which forms the backbone of the Keystone
  multi-core Navigator. QMSS consist of queue managers, packed-data structure
  processors(PDSP), linking RAM, descriptor pools and infrastructure
  Packet DMA.
  The Queue Manager is a hardware module that is responsible for accelerating
  management of the packet queues. Packets are queued/de-queued by writing or
  reading descriptor address to a particular memory mapped location. The PDSPs
  perform QMSS related functions like accumulation, QoS, or event management.
  Linking RAM registers are used to link the descriptors which are stored in
  descriptor RAM. Descriptor RAM is configurable as internal or external memory.
  The QMSS driver manages the PDSP setups, linking RAM regions,
  queue pool management (allocation, push, pop and notify) and descriptor
  pool management.
  
  knav qmss driver provides a set of APIs to drivers to open/close qmss queues,
  allocate descriptor pools, map the descriptors, push/pop to queues etc. For
  details of the available APIs, please refers to include/linux/soc/ti/knav_qmss.h
  
  DT documentation is available at
  Documentation/devicetree/bindings/soc/ti/keystone-navigator-qmss.txt
  
  Accumulator QMSS queues using PDSP firmware
  ============================================
  The QMSS PDSP firmware support accumulator channel that can monitor a single
  queue or multiple contiguous queues. drivers/soc/ti/knav_qmss_acc.c is the
  driver that interface with the accumulator PDSP. This configures
  accumulator channels defined in DTS (example in DT documentation) to monitor
  1 or 32 queues per channel. More description on the firmware is available in
  CPPI/QMSS Low Level Driver document (docs/CPPI_QMSS_LLD_SDS.pdf) at
  	git://git.ti.com/keystone-rtos/qmss-lld.git
  
  k2_qmss_pdsp_acc48_k2_le_1_0_0_9.bin firmware supports upto 48 accumulator
  channels. This firmware is available under ti-keystone folder of
  firmware.git at
     git://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git
  
  To use copy the firmware image to lib/firmware folder of the initramfs or
  ubifs file system and provide a sym link to k2_qmss_pdsp_acc48_k2_le_1_0_0_9.bin
  in the file system and boot up the kernel. User would see
  
   "firmware file ks2_qmss_pdsp_acc48.bin downloaded for PDSP"
  
  in the boot up log if loading of firmware to PDSP is successful.
  
  Use of accumulated queues requires the firmware image to be present in the
  file system. The driver doesn't acc queues to the supported queue range if
  PDSP is not running in the SoC. The API call fails if there is a queue open
  request to an acc queue and PDSP is not running. So make sure to copy firmware
  to file system before using these queue types.