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SubjectRe: [PATCH v3 4/4] docs: fpga: document programming fpgas using regions
On Wed, Sep 26, 2018 at 9:12 AM Alan Tull <atull@kernel.org> wrote:
>
> Clarify the intention that interfaces and upper layers use
> regions rather than managers directly.
>
> Rearrange API documentation to better group the API functions
> used to create FPGA mgr/bridge/regions and the API used for
> programming FPGAs.
>
> Signed-off-by: Alan Tull <atull@kernel.org>
> Suggested-by: Federico Vaga <federico.vaga@cern.ch>

Acked-by: Moritz Fischer <mdf@kernel.org>
> ---
> v2: Add suggested-by
> s/a FPGA/an FPGA/
> document freeing the fpga_mgr_info on success path
> minor formatting fixes and suggested edits
> v3: no changes
> ---
> Documentation/driver-api/fpga/fpga-bridge.rst | 38 ++-----
> Documentation/driver-api/fpga/fpga-mgr.rst | 117 ++-------------------
> Documentation/driver-api/fpga/fpga-programming.rst | 107 +++++++++++++++++++
> Documentation/driver-api/fpga/fpga-region.rst | 92 ++++++++--------
> Documentation/driver-api/fpga/index.rst | 2 +
> Documentation/driver-api/fpga/intro.rst | 2 +-
> 6 files changed, 171 insertions(+), 187 deletions(-)
> create mode 100644 Documentation/driver-api/fpga/fpga-programming.rst
>
> diff --git a/Documentation/driver-api/fpga/fpga-bridge.rst b/Documentation/driver-api/fpga/fpga-bridge.rst
> index ebbcbde..71c5a40 100644
> --- a/Documentation/driver-api/fpga/fpga-bridge.rst
> +++ b/Documentation/driver-api/fpga/fpga-bridge.rst
> @@ -4,6 +4,12 @@ FPGA Bridge
> API to implement a new FPGA bridge
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> +* struct :c:type:`fpga_bridge` — The FPGA Bridge structure
> +* struct :c:type:`fpga_bridge_ops` — Low level Bridge driver ops
> +* :c:func:`devm_fpga_bridge_create()` — Allocate and init a bridge struct
> +* :c:func:`fpga_bridge_register()` — Register a bridge
> +* :c:func:`fpga_bridge_unregister()` — Unregister a bridge
> +
> .. kernel-doc:: include/linux/fpga/fpga-bridge.h
> :functions: fpga_bridge
>
> @@ -14,39 +20,7 @@ API to implement a new FPGA bridge
> :functions: devm_fpga_bridge_create
>
> .. kernel-doc:: drivers/fpga/fpga-bridge.c
> - :functions: fpga_bridge_create
> -
> -.. kernel-doc:: drivers/fpga/fpga-bridge.c
> - :functions: fpga_bridge_free
> -
> -.. kernel-doc:: drivers/fpga/fpga-bridge.c
> :functions: fpga_bridge_register
>
> .. kernel-doc:: drivers/fpga/fpga-bridge.c
> :functions: fpga_bridge_unregister
> -
> -API to control an FPGA bridge
> -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> -
> -You probably won't need these directly. FPGA regions should handle this.
> -
> -.. kernel-doc:: drivers/fpga/fpga-bridge.c
> - :functions: of_fpga_bridge_get
> -
> -.. kernel-doc:: drivers/fpga/fpga-bridge.c
> - :functions: fpga_bridge_get
> -
> -.. kernel-doc:: drivers/fpga/fpga-bridge.c
> - :functions: fpga_bridge_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_bridge_enable
> -
> -.. kernel-doc:: drivers/fpga/fpga-bridge.c
> - :functions: fpga_bridge_disable
> diff --git a/Documentation/driver-api/fpga/fpga-mgr.rst b/Documentation/driver-api/fpga/fpga-mgr.rst
> index db8885e..576f194 100644
> --- a/Documentation/driver-api/fpga/fpga-mgr.rst
> +++ b/Documentation/driver-api/fpga/fpga-mgr.rst
> @@ -98,67 +98,19 @@ The ops include a .state function which will determine the state the FPGA is in
> and return a code of type enum fpga_mgr_states. It doesn't result in a change
> in state.
>
> -How to write an image buffer to a supported FPGA
> -------------------------------------------------
> -
> -Some sample code::
> -
> - #include <linux/fpga/fpga-mgr.h>
> -
> - struct fpga_manager *mgr;
> - struct fpga_image_info *info;
> - int ret;
> -
> - /*
> - * Get a reference to FPGA manager. The manager is not locked, so you can
> - * hold onto this reference without it preventing programming.
> - *
> - * This example uses the device node of the manager. Alternatively, use
> - * fpga_mgr_get(dev) instead if you have the device.
> - */
> - mgr = of_fpga_mgr_get(mgr_node);
> -
> - /* struct with information about the FPGA image to program. */
> - info = fpga_image_info_alloc(dev);
> -
> - /* flags indicates whether to do full or partial reconfiguration */
> - info->flags = FPGA_MGR_PARTIAL_RECONFIG;
> -
> - /*
> - * 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) {
> -
> - info->sgt = [your scatter gather table]
> -
> - } else if (image is in a buffer) {
> -
> - info->buf = [your image buffer]
> - info->count = [image buffer size]
> -
> - } else if (image is in a firmware file) {
> -
> - info->firmware_name = devm_kstrdup(dev, firmware_name, GFP_KERNEL);
> -
> - }
> -
> - /* Get exclusive control of FPGA manager */
> - ret = fpga_mgr_lock(mgr);
> -
> - /* Load the buffer to the FPGA */
> - ret = fpga_mgr_buf_load(mgr, &info, buf, count);
> -
> - /* Release the FPGA manager */
> - fpga_mgr_unlock(mgr);
> - fpga_mgr_put(mgr);
> -
> - /* Deallocate the image info if you're done with it */
> - fpga_image_info_free(info);
> -
> API for implementing a new FPGA Manager driver
> ----------------------------------------------
>
> +* ``fpga_mgr_states`` — Values for :c:member:`fpga_manager->state`.
> +* struct :c:type:`fpga_manager` — the FPGA manager struct
> +* struct :c:type:`fpga_manager_ops` — Low level FPGA manager driver ops
> +* :c:func:`devm_fpga_mgr_create` — Allocate and init a manager struct
> +* :c:func:`fpga_mgr_register` — Register an FPGA manager
> +* :c:func:`fpga_mgr_unregister` — Unregister an FPGA manager
> +
> +.. kernel-doc:: include/linux/fpga/fpga-mgr.h
> + :functions: fpga_mgr_states
> +
> .. kernel-doc:: include/linux/fpga/fpga-mgr.h
> :functions: fpga_manager
>
> @@ -169,56 +121,7 @@ API for implementing a new FPGA Manager driver
> :functions: devm_fpga_mgr_create
>
> .. kernel-doc:: drivers/fpga/fpga-mgr.c
> - :functions: fpga_mgr_create
> -
> -.. kernel-doc:: drivers/fpga/fpga-mgr.c
> - :functions: fpga_mgr_free
> -
> -.. kernel-doc:: drivers/fpga/fpga-mgr.c
> :functions: fpga_mgr_register
>
> .. kernel-doc:: drivers/fpga/fpga-mgr.c
> :functions: fpga_mgr_unregister
> -
> -API for programming an FPGA
> ----------------------------
> -
> -FPGA Manager flags
> -
> -.. kernel-doc:: include/linux/fpga/fpga-mgr.h
> - :doc: FPGA Manager flags
> -
> -.. kernel-doc:: include/linux/fpga/fpga-mgr.h
> - :functions: fpga_image_info
> -
> -.. kernel-doc:: include/linux/fpga/fpga-mgr.h
> - :functions: fpga_mgr_states
> -
> -.. kernel-doc:: drivers/fpga/fpga-mgr.c
> - :functions: fpga_image_info_alloc
> -
> -.. kernel-doc:: drivers/fpga/fpga-mgr.c
> - :functions: fpga_image_info_free
> -
> -.. kernel-doc:: drivers/fpga/fpga-mgr.c
> - :functions: of_fpga_mgr_get
> -
> -.. kernel-doc:: drivers/fpga/fpga-mgr.c
> - :functions: fpga_mgr_get
> -
> -.. kernel-doc:: drivers/fpga/fpga-mgr.c
> - :functions: fpga_mgr_put
> -
> -.. kernel-doc:: drivers/fpga/fpga-mgr.c
> - :functions: fpga_mgr_lock
> -
> -.. kernel-doc:: drivers/fpga/fpga-mgr.c
> - :functions: fpga_mgr_unlock
> -
> -.. kernel-doc:: include/linux/fpga/fpga-mgr.h
> - :functions: fpga_mgr_states
> -
> -Note - use :c:func:`fpga_region_program_fpga()` instead of :c:func:`fpga_mgr_load()`
> -
> -.. kernel-doc:: drivers/fpga/fpga-mgr.c
> - :functions: fpga_mgr_load
> diff --git a/Documentation/driver-api/fpga/fpga-programming.rst b/Documentation/driver-api/fpga/fpga-programming.rst
> new file mode 100644
> index 0000000..b5484df
> --- /dev/null
> +++ b/Documentation/driver-api/fpga/fpga-programming.rst
> @@ -0,0 +1,107 @@
> +In-kernel API for FPGA Programming
> +==================================
> +
> +Overview
> +--------
> +
> +The in-kernel API for FPGA programming is a combination of APIs from
> +FPGA manager, bridge, and regions. The actual function used to
> +trigger FPGA programming is :c:func:`fpga_region_program_fpga()`.
> +
> +:c:func:`fpga_region_program_fpga()` uses functionality supplied by
> +the FPGA manager and bridges. It will:
> +
> + * lock the region's mutex
> + * lock the mutex of 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 using info passed in :c:member:`fpga_region->info`.
> + * re-enable the bridges
> + * release the locks
> +
> +The struct fpga_image_info specifies what FPGA image to program. It is
> +allocated/freed by :c:func:`fpga_image_info_alloc()` and freed with
> +:c:func:`fpga_image_info_free()`
> +
> +How to program an FPGA using a region
> +-------------------------------------
> +
> +When the FPGA region driver probed, it was given a pointer to an FPGA manager
> +driver so it knows which manager to use. The region also either has a list of
> +bridges to control during programming or it has a pointer to a function that
> +will generate that list. Here's some sample code of what to do next::
> +
> + #include <linux/fpga/fpga-mgr.h>
> + #include <linux/fpga/fpga-region.h>
> +
> + struct fpga_image_info *info;
> + int ret;
> +
> + /*
> + * First, alloc the struct with information about the FPGA image to
> + * program.
> + */
> + info = fpga_image_info_alloc(dev);
> + if (!info)
> + return -ENOMEM;
> +
> + /* Set flags as needed, such as: */
> + info->flags = FPGA_MGR_PARTIAL_RECONFIG;
> +
> + /*
> + * Indicate where the FPGA image is. This is pseudo-code; you're
> + * going to use one of these three.
> + */
> + if (image is in a scatter gather table) {
> +
> + info->sgt = [your scatter gather table]
> +
> + } else if (image is in a buffer) {
> +
> + info->buf = [your image buffer]
> + info->count = [image buffer size]
> +
> + } else if (image is in a firmware file) {
> +
> + info->firmware_name = devm_kstrdup(dev, firmware_name,
> + GFP_KERNEL);
> +
> + }
> +
> + /* Add info to region and do the programming */
> + region->info = info;
> + ret = fpga_region_program_fpga(region);
> +
> + /* Deallocate the image info if you're done with it */
> + region->info = NULL;
> + fpga_image_info_free(info);
> +
> + if (ret)
> + return ret;
> +
> + /* Now enumerate whatever hardware has appeared in the FPGA. */
> +
> +API for programming an FPGA
> +---------------------------
> +
> +* :c:func:`fpga_region_program_fpga` — Program an FPGA
> +* :c:type:`fpga_image_info` — Specifies what FPGA image to program
> +* :c:func:`fpga_image_info_alloc()` — Allocate an FPGA image info struct
> +* :c:func:`fpga_image_info_free()` — Free an FPGA image info struct
> +
> +.. kernel-doc:: drivers/fpga/fpga-region.c
> + :functions: fpga_region_program_fpga
> +
> +FPGA Manager flags
> +
> +.. kernel-doc:: include/linux/fpga/fpga-mgr.h
> + :doc: FPGA Manager flags
> +
> +.. kernel-doc:: include/linux/fpga/fpga-mgr.h
> + :functions: fpga_image_info
> +
> +.. kernel-doc:: drivers/fpga/fpga-mgr.c
> + :functions: fpga_image_info_alloc
> +
> +.. kernel-doc:: drivers/fpga/fpga-mgr.c
> + :functions: fpga_image_info_free
> diff --git a/Documentation/driver-api/fpga/fpga-region.rst b/Documentation/driver-api/fpga/fpga-region.rst
> index dc9f75c..0529b2d 100644
> --- a/Documentation/driver-api/fpga/fpga-region.rst
> +++ b/Documentation/driver-api/fpga/fpga-region.rst
> @@ -34,41 +34,6 @@ fpga_image_info including:
> * flags indicating specifics such as whether the image is for partial
> reconfiguration.
>
> -How to program an FPGA using a region
> --------------------------------------
> -
> -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);
> -
> -:c:func:`fpga_region_program_fpga()` 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
> -
> -Then you will want to enumerate whatever hardware has appeared in the FPGA.
> -
> How to add a new FPGA region
> ----------------------------
>
> @@ -77,15 +42,36 @@ 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 program an FPGA
> -----------------------
> -
> -.. kernel-doc:: drivers/fpga/fpga-region.c
> - :functions: fpga_region_program_fpga
> -
> API to add a new FPGA region
> ----------------------------
>
> +* struct :c:type:`fpga_region` — The FPGA region struct
> +* :c:func:`devm_fpga_region_create` — Allocate and init a region struct
> +* :c:func:`fpga_region_register` — Register an FPGA region
> +* :c:func:`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.
> +
> +* :c:func:`fpga_mgr_get` — Get a reference to an FPGA manager, raise ref count
> +* :c:func:`of_fpga_mgr_get` — Get a reference to an FPGA manager, raise ref count,
> + given a device node.
> +* :c:func:`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:member:`fpga_region->bridge_list`) or it can have a function that creates
> +the list of bridges to program just before programming
> +(:c:member:`fpga_region->get_bridges`). The FPGA bridge framework supplies the
> +following APIs to handle building or tearing down that list.
> +
> +* :c:func:`fpga_bridge_get_to_list` — Get a ref of an FPGA bridge, add it to a
> + list
> +* :c:func:`of_fpga_bridge_get_to_list` — Get a ref of an FPGA bridge, add it to a
> + list, given a device node
> +* :c:func:`fpga_bridges_put` — Given a list of bridges, put them
> +
> .. kernel-doc:: include/linux/fpga/fpga-region.h
> :functions: fpga_region
>
> @@ -93,13 +79,25 @@ API to add a new FPGA region
> :functions: devm_fpga_region_create
>
> .. kernel-doc:: drivers/fpga/fpga-region.c
> - :functions: fpga_region_create
> -
> -.. kernel-doc:: drivers/fpga/fpga-region.c
> - :functions: fpga_region_free
> -
> -.. 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
> diff --git a/Documentation/driver-api/fpga/index.rst b/Documentation/driver-api/fpga/index.rst
> index c51e5eb..31a4773 100644
> --- a/Documentation/driver-api/fpga/index.rst
> +++ b/Documentation/driver-api/fpga/index.rst
> @@ -11,3 +11,5 @@ FPGA Subsystem
> fpga-mgr
> fpga-bridge
> fpga-region
> + fpga-programming
> +
> diff --git a/Documentation/driver-api/fpga/intro.rst b/Documentation/driver-api/fpga/intro.rst
> index 50d1cab..f54c7da 100644
> --- a/Documentation/driver-api/fpga/intro.rst
> +++ b/Documentation/driver-api/fpga/intro.rst
> @@ -44,7 +44,7 @@ FPGA Region
> -----------
>
> If you are adding a new interface to the FPGA framework, add it on top
> -of an FPGA region to allow the most reuse of your interface.
> +of an FPGA region.
>
> The FPGA Region framework (fpga-region.c) associates managers and
> bridges as reconfigurable regions. A region may refer to the whole
> --
> 2.7.4
>

Thanks,
Moritz

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