knav-qmss.rst (3049B)
1====================================================================== 2Texas Instruments Keystone Navigator Queue Management SubSystem driver 3====================================================================== 4 5Driver source code path 6 drivers/soc/ti/knav_qmss.c 7 drivers/soc/ti/knav_qmss_acc.c 8 9The QMSS (Queue Manager Sub System) found on Keystone SOCs is one of 10the main hardware sub system which forms the backbone of the Keystone 11multi-core Navigator. QMSS consist of queue managers, packed-data structure 12processors(PDSP), linking RAM, descriptor pools and infrastructure 13Packet DMA. 14The Queue Manager is a hardware module that is responsible for accelerating 15management of the packet queues. Packets are queued/de-queued by writing or 16reading descriptor address to a particular memory mapped location. The PDSPs 17perform QMSS related functions like accumulation, QoS, or event management. 18Linking RAM registers are used to link the descriptors which are stored in 19descriptor RAM. Descriptor RAM is configurable as internal or external memory. 20The QMSS driver manages the PDSP setups, linking RAM regions, 21queue pool management (allocation, push, pop and notify) and descriptor 22pool management. 23 24knav qmss driver provides a set of APIs to drivers to open/close qmss queues, 25allocate descriptor pools, map the descriptors, push/pop to queues etc. For 26details of the available APIs, please refers to include/linux/soc/ti/knav_qmss.h 27 28DT documentation is available at 29Documentation/devicetree/bindings/soc/ti/keystone-navigator-qmss.txt 30 31Accumulator QMSS queues using PDSP firmware 32============================================ 33The QMSS PDSP firmware support accumulator channel that can monitor a single 34queue or multiple contiguous queues. drivers/soc/ti/knav_qmss_acc.c is the 35driver that interface with the accumulator PDSP. This configures 36accumulator channels defined in DTS (example in DT documentation) to monitor 371 or 32 queues per channel. More description on the firmware is available in 38CPPI/QMSS Low Level Driver document (docs/CPPI_QMSS_LLD_SDS.pdf) at 39 40 git://git.ti.com/keystone-rtos/qmss-lld.git 41 42k2_qmss_pdsp_acc48_k2_le_1_0_0_9.bin firmware supports upto 48 accumulator 43channels. This firmware is available under ti-keystone folder of 44firmware.git at 45 46 git://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git 47 48To use copy the firmware image to lib/firmware folder of the initramfs or 49ubifs file system and provide a sym link to k2_qmss_pdsp_acc48_k2_le_1_0_0_9.bin 50in the file system and boot up the kernel. User would see 51 52 "firmware file ks2_qmss_pdsp_acc48.bin downloaded for PDSP" 53 54in the boot up log if loading of firmware to PDSP is successful. 55 56Use of accumulated queues requires the firmware image to be present in the 57file system. The driver doesn't acc queues to the supported queue range if 58PDSP is not running in the SoC. The API call fails if there is a queue open 59request to an acc queue and PDSP is not running. So make sure to copy firmware 60to file system before using these queue types.