Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 109 insertions, 0 deletions

diff --git a/Documentation/driver-api/fpga/fpga-region.rst b/Documentation/driver-api/fpga/fpga-region.rst
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+FPGA Region
+===========
+
+Overview
+--------
+
+This document is meant to be a brief overview of the FPGA region API usage.  A
+more conceptual look at regions can be found in the Device Tree binding
+document [#f1]_.
+
+For the purposes of this API document, let's just say that a region associates
+an FPGA Manager and a bridge (or bridges) with a reprogrammable region of an
+FPGA or the whole FPGA.  The API provides a way to register a region and to
+program a region.
+
+Currently the only layer above fpga-region.c in the kernel is the Device Tree
+support (of-fpga-region.c) described in [#f1]_.  The DT support layer uses regions
+to program the FPGA and then DT to handle enumeration.  The common region code
+is intended to be used by other schemes that have other ways of accomplishing
+enumeration after programming.
+
+An fpga-region can be set up to know the following things:
+
+ * which FPGA manager to use to do the programming
+
+ * which bridges to disable before programming and enable afterwards.
+
+Additional info needed to program the FPGA image is passed in the struct
+fpga_image_info including:
+
+ * pointers to the image as either a scatter-gather buffer, a contiguous
+   buffer, or the name of firmware file
+
+ * flags indicating specifics such as whether the image is for partial
+   reconfiguration.
+
+How to add a new FPGA region
+----------------------------
+
+An example of usage can be seen in the probe function of [#f2]_.
+
+.. [#f1] ../devicetree/bindings/fpga/fpga-region.txt
+.. [#f2] ../../drivers/fpga/of-fpga-region.c
+
+API to add a new FPGA region
+----------------------------
+
+* struct fpga_region - The FPGA region struct
+* struct fpga_region_info - Parameter structure for fpga_region_register_full()
+* fpga_region_register_full() -  Create and register an FPGA region using the
+  fpga_region_info structure to provide the full flexibility of options
+* fpga_region_register() -  Create and register an FPGA region using standard
+  arguments
+* fpga_region_unregister() -  Unregister an FPGA region
+
+The FPGA region's probe function will need to get a reference to the FPGA
+Manager it will be using to do the programming.  This usually would happen
+during the region's probe function.
+
+* fpga_mgr_get() - Get a reference to an FPGA manager, raise ref count
+* of_fpga_mgr_get() -  Get a reference to an FPGA manager, raise ref count,
+  given a device node.
+* fpga_mgr_put() - Put an FPGA manager
+
+The FPGA region will need to specify which bridges to control while programming
+the FPGA.  The region driver can build a list of bridges during probe time
+(:c:expr:`fpga_region->bridge_list`) or it can have a function that creates
+the list of bridges to program just before programming
+(:c:expr:`fpga_region->get_bridges`).  The FPGA bridge framework supplies the
+following APIs to handle building or tearing down that list.
+
+* fpga_bridge_get_to_list() - Get a ref of an FPGA bridge, add it to a
+  list
+* of_fpga_bridge_get_to_list() - Get a ref of an FPGA bridge, add it to a
+  list, given a device node
+* fpga_bridges_put() - Given a list of bridges, put them
+
+.. kernel-doc:: include/linux/fpga/fpga-region.h
+   :functions: fpga_region
+
+.. kernel-doc:: include/linux/fpga/fpga-region.h
+   :functions: fpga_region_info
+
+.. kernel-doc:: drivers/fpga/fpga-region.c
+   :functions: fpga_region_register_full
+
+.. kernel-doc:: drivers/fpga/fpga-region.c
+   :functions: fpga_region_register
+
+.. kernel-doc:: drivers/fpga/fpga-region.c
+   :functions: fpga_region_unregister
+
+.. kernel-doc:: drivers/fpga/fpga-mgr.c
+   :functions: fpga_mgr_get
+
+.. kernel-doc:: drivers/fpga/fpga-mgr.c
+   :functions: of_fpga_mgr_get
+
+.. kernel-doc:: drivers/fpga/fpga-mgr.c
+   :functions: fpga_mgr_put
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: fpga_bridge_get_to_list
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: of_fpga_bridge_get_to_list
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: fpga_bridges_put