1FPGA Region 2=========== 3 4Overview 5-------- 6 7This document is meant to be a brief overview of the FPGA region API usage. A 8more conceptual look at regions can be found in the Device Tree binding 9document [#f1]_. 10 11For the purposes of this API document, let's just say that a region associates 12an FPGA Manager and a bridge (or bridges) with a reprogrammable region of an 13FPGA or the whole FPGA. The API provides a way to register a region and to 14program a region. 15 16Currently the only layer above fpga-region.c in the kernel is the Device Tree 17support (of-fpga-region.c) described in [#f1]_. The DT support layer uses regions 18to program the FPGA and then DT to handle enumeration. The common region code 19is intended to be used by other schemes that have other ways of accomplishing 20enumeration after programming. 21 22An fpga-region can be set up to know the following things: 23 24 * which FPGA manager to use to do the programming 25 26 * which bridges to disable before programming and enable afterwards. 27 28Additional info needed to program the FPGA image is passed in the struct 29fpga_image_info including: 30 31 * pointers to the image as either a scatter-gather buffer, a contiguous 32 buffer, or the name of firmware file 33 34 * flags indicating specifics such as whether the image is for partial 35 reconfiguration. 36 37How to add a new FPGA region 38---------------------------- 39 40An example of usage can be seen in the probe function of [#f2]_. 41 42.. [#f1] ../devicetree/bindings/fpga/fpga-region.txt 43.. [#f2] ../../drivers/fpga/of-fpga-region.c 44 45API to add a new FPGA region 46---------------------------- 47 48* struct fpga_region — The FPGA region struct 49* devm_fpga_region_create() — Allocate and init a region struct 50* fpga_region_register() — Register an FPGA region 51* fpga_region_unregister() — Unregister an FPGA region 52 53The FPGA region's probe function will need to get a reference to the FPGA 54Manager it will be using to do the programming. This usually would happen 55during the region's probe function. 56 57* fpga_mgr_get() — Get a reference to an FPGA manager, raise ref count 58* of_fpga_mgr_get() — Get a reference to an FPGA manager, raise ref count, 59 given a device node. 60* fpga_mgr_put() — Put an FPGA manager 61 62The FPGA region will need to specify which bridges to control while programming 63the FPGA. The region driver can build a list of bridges during probe time 64(:c:expr:`fpga_region->bridge_list`) or it can have a function that creates 65the list of bridges to program just before programming 66(:c:expr:`fpga_region->get_bridges`). The FPGA bridge framework supplies the 67following APIs to handle building or tearing down that list. 68 69* fpga_bridge_get_to_list() — Get a ref of an FPGA bridge, add it to a 70 list 71* of_fpga_bridge_get_to_list() — Get a ref of an FPGA bridge, add it to a 72 list, given a device node 73* fpga_bridges_put() — Given a list of bridges, put them 74 75.. kernel-doc:: include/linux/fpga/fpga-region.h 76 :functions: fpga_region 77 78.. kernel-doc:: drivers/fpga/fpga-region.c 79 :functions: devm_fpga_region_create 80 81.. kernel-doc:: drivers/fpga/fpga-region.c 82 :functions: fpga_region_register 83 84.. kernel-doc:: drivers/fpga/fpga-region.c 85 :functions: fpga_region_unregister 86 87.. kernel-doc:: drivers/fpga/fpga-mgr.c 88 :functions: fpga_mgr_get 89 90.. kernel-doc:: drivers/fpga/fpga-mgr.c 91 :functions: of_fpga_mgr_get 92 93.. kernel-doc:: drivers/fpga/fpga-mgr.c 94 :functions: fpga_mgr_put 95 96.. kernel-doc:: drivers/fpga/fpga-bridge.c 97 :functions: fpga_bridge_get_to_list 98 99.. kernel-doc:: drivers/fpga/fpga-bridge.c 100 :functions: of_fpga_bridge_get_to_list 101 102.. kernel-doc:: drivers/fpga/fpga-bridge.c 103 :functions: fpga_bridges_put 104