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authorAlan Tull <atull@kernel.org>2017-11-15 14:20:12 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-11-28 16:30:37 +0100
commit5cf0c7f6502f26332b46fa87914553a4d6ae75ac (patch)
tree56814a3ec0bf179797e7d9fed89136954f937d3e /Documentation/fpga
parent9c1c4b2753fea36a072e78a5efc82fca0d13b455 (diff)
downloadlinux-5cf0c7f6502f26332b46fa87914553a4d6ae75ac.tar.bz2
fpga: mgr: API change to replace fpga load functions with single function
fpga-mgr has three methods for programming FPGAs, depending on whether the image is in a scatter gather list, a contiguous buffer, or a firmware file. This makes it difficult to write upper layers as the caller has to assume whether the FPGA image is in a sg table, as a single buffer, or a firmware file. This commit moves these parameters to struct fpga_image_info and adds a single function for programming fpgas. New functions: * fpga_mgr_load - given fpga manager and struct fpga_image_info, program the fpga. * fpga_image_info_alloc - alloc a struct fpga_image_info. * fpga_image_info_free - free a struct fpga_image_info. These three functions are unexported: * fpga_mgr_buf_load_sg * fpga_mgr_buf_load * fpga_mgr_firmware_load Also use devm_kstrdup to copy firmware_name so we aren't making assumptions about where it comes from when allocing/freeing the struct fpga_image_info. API documentation has been updated and a new document for FPGA region has been added. Signed-off-by: Alan Tull <atull@kernel.org> Acked-by: Moritz Fischer <mdf@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/fpga')
-rw-r--r--Documentation/fpga/fpga-mgr.txt119
-rw-r--r--Documentation/fpga/fpga-region.txt95
-rw-r--r--Documentation/fpga/overview.txt23
3 files changed, 169 insertions, 68 deletions
diff --git a/Documentation/fpga/fpga-mgr.txt b/Documentation/fpga/fpga-mgr.txt
index 78f197fadfd1..6ebc714f4b03 100644
--- a/Documentation/fpga/fpga-mgr.txt
+++ b/Documentation/fpga/fpga-mgr.txt
@@ -11,61 +11,53 @@ hidden away in a low level driver which registers a set of ops with the core.
The FPGA image data itself is very manufacturer specific, but for our purposes
it's just binary data. The FPGA manager core won't parse it.
+The FPGA image to be programmed can be in a scatter gather list, a single
+contiguous buffer, or a firmware file. Because allocating contiguous kernel
+memory for the buffer should be avoided, users are encouraged to use a scatter
+gather list instead if possible.
+
+The particulars for programming the image are presented in a structure (struct
+fpga_image_info). This struct contains parameters such as pointers to the
+FPGA image as well as image-specific particulars such as whether the image was
+built for full or partial reconfiguration.
API Functions:
==============
-To program the FPGA from a file or from a buffer:
--------------------------------------------------
-
- int fpga_mgr_buf_load(struct fpga_manager *mgr,
- struct fpga_image_info *info,
- const char *buf, size_t count);
-
-Load the FPGA from an image which exists as a contiguous buffer in
-memory. Allocating contiguous kernel memory for the buffer should be avoided,
-users are encouraged to use the _sg interface instead of this.
-
- int fpga_mgr_buf_load_sg(struct fpga_manager *mgr,
- struct fpga_image_info *info,
- struct sg_table *sgt);
+To program the FPGA:
+--------------------
-Load the FPGA from an image from non-contiguous in memory. Callers can
-construct a sg_table using alloc_page backed memory.
+ int fpga_mgr_load(struct fpga_manager *mgr,
+ struct fpga_image_info *info);
- int fpga_mgr_firmware_load(struct fpga_manager *mgr,
- struct fpga_image_info *info,
- const char *image_name);
-
-Load the FPGA from an image which exists as a file. The image file must be on
-the firmware search path (see the firmware class documentation). If successful,
+Load the FPGA from an image which is indicated in the info. If successful,
the FPGA ends up in operating mode. Return 0 on success or a negative error
code.
-A FPGA design contained in a FPGA image file will likely have particulars that
-affect how the image is programmed to the FPGA. These are contained in struct
-fpga_image_info. Currently the only such particular is a single flag bit
-indicating whether the image is for full or partial reconfiguration.
+To allocate or free a struct fpga_image_info:
+---------------------------------------------
+
+ struct fpga_image_info *fpga_image_info_alloc(struct device *dev);
+
+ void fpga_image_info_free(struct fpga_image_info *info);
To get/put a reference to a FPGA manager:
-----------------------------------------
struct fpga_manager *of_fpga_mgr_get(struct device_node *node);
struct fpga_manager *fpga_mgr_get(struct device *dev);
-
-Given a DT node or device, get an exclusive reference to a FPGA manager.
-
void fpga_mgr_put(struct fpga_manager *mgr);
-Release the reference.
+Given a DT node or device, get an exclusive reference to a FPGA manager.
+fpga_mgr_put releases the reference.
To register or unregister the low level FPGA-specific driver:
-------------------------------------------------------------
int fpga_mgr_register(struct device *dev, const char *name,
- const struct fpga_manager_ops *mops,
- void *priv);
+ const struct fpga_manager_ops *mops,
+ void *priv);
void fpga_mgr_unregister(struct device *dev);
@@ -78,59 +70,50 @@ How to write an image buffer to a supported FPGA
/* Include to get the API */
#include <linux/fpga/fpga-mgr.h>
-/* device node that specifies the FPGA manager to use */
-struct device_node *mgr_node = ...
-
-/* FPGA image is in this buffer. count is size of the buffer. */
-char *buf = ...
-int count = ...
+struct fpga_manager *mgr;
+struct fpga_image_info *info;
+int ret;
/* struct with information about the FPGA image to program. */
-struct fpga_image_info info;
+info = fpga_image_info_alloc(dev);
/* flags indicates whether to do full or partial reconfiguration */
-info.flags = 0;
-
-int ret;
+info->flags = FPGA_MGR_PARTIAL_RECONFIG;
-/* Get exclusive control of FPGA manager */
-struct fpga_manager *mgr = of_fpga_mgr_get(mgr_node);
+/*
+ * At this point, indicate where the image is. This is pseudo-code; you're
+ * going to use one of these three.
+ */
+if (image is in a scatter gather table) {
-/* Load the buffer to the FPGA */
-ret = fpga_mgr_buf_load(mgr, &info, buf, count);
-
-/* Release the FPGA manager */
-fpga_mgr_put(mgr);
+ info->sgt = [your scatter gather table]
+} else if (image is in a buffer) {
-How to write an image file to a supported FPGA
-==============================================
-/* Include to get the API */
-#include <linux/fpga/fpga-mgr.h>
+ info->buf = [your image buffer]
+ info->count = [image buffer size]
-/* device node that specifies the FPGA manager to use */
-struct device_node *mgr_node = ...
+} else if (image is in a firmware file) {
-/* FPGA image is in this file which is in the firmware search path */
-const char *path = "fpga-image-9.rbf"
+ info->firmware_name = devm_kstrdup(dev, firmware_name, GFP_KERNEL);
-/* struct with information about the FPGA image to program. */
-struct fpga_image_info info;
-
-/* flags indicates whether to do full or partial reconfiguration */
-info.flags = 0;
-
-int ret;
+}
-/* Get exclusive control of FPGA manager */
-struct fpga_manager *mgr = of_fpga_mgr_get(mgr_node);
+/*
+ * Get a reference to FPGA manager. This example uses the device node of the
+ * manager. You could use fpga_mgr_get() instead if you have the device instead
+ * of the device node.
+ */
+mgr = of_fpga_mgr_get(mgr_node);
-/* Get the firmware image (path) and load it to the FPGA */
-ret = fpga_mgr_firmware_load(mgr, &info, path);
+/* Load the buffer to the FPGA */
+ret = fpga_mgr_buf_load(mgr, &info, buf, count);
/* Release the FPGA manager */
fpga_mgr_put(mgr);
+/* Deallocate the image info if you're done with it */
+fpga_image_info_free(info);
How to support a new FPGA device
================================
diff --git a/Documentation/fpga/fpga-region.txt b/Documentation/fpga/fpga-region.txt
new file mode 100644
index 000000000000..139a02ba1ff6
--- /dev/null
+++ b/Documentation/fpga/fpga-region.txt
@@ -0,0 +1,95 @@
+FPGA Regions
+
+Alan Tull 2017
+
+CONTENTS
+ - Introduction
+ - The FPGA region API
+ - Usage example
+
+Introduction
+============
+
+This document is meant to be an brief overview of the FPGA region API usage. A
+more conceptual look at regions can be found in [1].
+
+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 [1]. 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 [2] 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 if for partial
+ reconfiguration.
+
+===================
+The FPGA region API
+===================
+
+To register or unregister a region:
+-----------------------------------
+
+ int fpga_region_register(struct device *dev,
+ struct fpga_region *region);
+ int fpga_region_unregister(struct fpga_region *region);
+
+An example of usage can be seen in the probe function of [3]
+
+To program an FPGA:
+-------------------
+ int fpga_region_program_fpga(struct fpga_region *region);
+
+This function operates on info passed in the fpga_image_info
+(region->info).
+
+This function will attempt to:
+ * lock the region's mutex
+ * lock the region's FPGA manager
+ * build a list of FPGA bridges if a method has been specified to do so
+ * disable the bridges
+ * program the FPGA
+ * re-enable the bridges
+ * release the locks
+
+=============
+Usage example
+=============
+
+First, allocate the info struct:
+
+ info = fpga_image_info_alloc(dev);
+ if (!info)
+ return -ENOMEM;
+
+Set flags as needed, i.e.
+
+ info->flags |= FPGA_MGR_PARTIAL_RECONFIG;
+
+Point to your FPGA image, such as:
+
+ info->sgt = &sgt;
+
+Add info to region and do the programming:
+
+ region->info = info;
+ ret = fpga_region_program_fpga(region);
+
+Then enumerate whatever hardware has appeared in the FPGA.
+
+--
+[1] ../devicetree/bindings/fpga/fpga-region.txt
+[2] ./fpga-mgr.txt
+[3] ../../drivers/fpga/of-fpga-region.c
diff --git a/Documentation/fpga/overview.txt b/Documentation/fpga/overview.txt
new file mode 100644
index 000000000000..0f1236e7e675
--- /dev/null
+++ b/Documentation/fpga/overview.txt
@@ -0,0 +1,23 @@
+Linux kernel FPGA support
+
+Alan Tull 2017
+
+The main point of this project has been to separate the out the upper layers
+that know when to reprogram a FPGA from the lower layers that know how to
+reprogram a specific FPGA device. The intention is to make this manufacturer
+agnostic, understanding that of course the FPGA images are very device specific
+themselves.
+
+The framework in the kernel includes:
+* low level FPGA manager drivers that know how to program a specific device
+* the fpga-mgr framework they are registered with
+* low level FPGA bridge drivers for hard/soft bridges which are intended to
+ be disable during FPGA programming
+* the fpga-bridge framework they are registered with
+* the fpga-region framework which associates and controls managers and bridges
+ as reconfigurable regions
+* the of-fpga-region support for reprogramming FPGAs when device tree overlays
+ are applied.
+
+I would encourage you the user to add code that creates FPGA regions rather
+that trying to control managers and bridges separately.