Re: [PATCH 10/14] documentation: fpga: move fpga-mgr.txt to driver-api

[Randy Dunlap]

On 05/16/2018 04:50 PM, Alan Tull wrote:
> Move Documentation/fpga/fpga-mgr.txt to driver-api/fpga/fpga-mgr.rst
> and:
>  - Add to driver-api/fpga/index.rst
>  - Format changes so documentation builds cleanly.
>  - Minor rewrites that make the doc flow better as ReST documentation.
>    - Such as moving API reference to end of doc
>  - Change API reference section to refer to kernel-doc documentation in
>    fpga-mgr.c driver code rather than statically defining each function.
> 
> Signed-off-by: Alan Tull <atull@xxxxxxxxxx>
> ---
>  Documentation/driver-api/fpga/fpga-mgr.rst | 220 +++++++++++++++++++++++++++++
>  Documentation/driver-api/fpga/index.rst    |   1 +
>  Documentation/fpga/fpga-mgr.txt            | 218 ----------------------------
>  3 files changed, 221 insertions(+), 218 deletions(-)
>  create mode 100644 Documentation/driver-api/fpga/fpga-mgr.rst
>  delete mode 100644 Documentation/fpga/fpga-mgr.txt
> 
> diff --git a/Documentation/driver-api/fpga/fpga-mgr.rst b/Documentation/driver-api/fpga/fpga-mgr.rst
> new file mode 100644
> index 0000000..bcf2dd2
> --- /dev/null
> +++ b/Documentation/driver-api/fpga/fpga-mgr.rst
> @@ -0,0 +1,220 @@
> +FPGA Manager
> +============
> +
> +Overview
> +--------
> +
> +The FPGA manager core exports a set of functions for programming an FPGA with
> +an image.  The API is manufacturer agnostic.  All manufacturer specifics are
> +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.
> +
> +How to support a new FPGA device
> +--------------------------------
> +
> +To add another FPGA manager, write a driver that implements a set of ops.  The
> +probe function calls fpga_mgr_register(), such as::
> +
> +	static const struct fpga_manager_ops socfpga_fpga_ops = {
> +		.write_init = socfpga_fpga_ops_configure_init,
> +		.write = socfpga_fpga_ops_configure_write,
> +		.write_complete = socfpga_fpga_ops_configure_complete,
> +		.state = socfpga_fpga_ops_state,
> +	};
> +
> +	static int socfpga_fpga_probe(struct platform_device *pdev)
> +	{
> +		struct device *dev = &pdev->dev;
> +		struct socfpga_fpga_priv *priv;
> +		struct fpga_manager *mgr;
> +		int ret;
> +
> +		priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +		if (!priv)
> +			return -ENOMEM;
> +
> +		/*
> +		 * do ioremaps, get interrupts, etc. and save
> +		 * them in priv
> +		 */
> +
> +		mgr = fpga_mgr_create(dev, "Altera SOCFPGA FPGA Manager",
> +				      &socfpga_fpga_ops, priv);
> +		if (!mgr)
> +			return -ENOMEM;
> +
> +		platform_set_drvdata(pdev, mgr);
> +
> +		ret = fpga_mgr_register(mgr);
> +		if (ret)
> +			fpga_mgr_free(mgr);
> +
> +		return ret;
> +	}
> +
> +	static int socfpga_fpga_remove(struct platform_device *pdev)
> +	{
> +		struct fpga_manager *mgr = platform_get_drvdata(pdev);
> +
> +		fpga_mgr_unregister(mgr);
> +
> +		return 0;
> +	}
> +
> +
> +The ops will implement whatever device specific register writes are needed to
> +do the programming sequence for this particular FPGA.  These ops return 0 for
> +success or negative error codes otherwise.
> +
> +The programming sequence is::
> + 1. .write_init
> + 2. .write or .write_sg (may be called once or multiple times)
> + 3. .write_complete
> +
> +The .write_init function will prepare the FPGA to receive the image data.  The
> +buffer passed into .write_init will be atmost .initial_header_size bytes long,

                                          at most                           long;

> +if the whole bitstream is not immediately available then the core code will
> +buffer up at least this much before starting.
> +
> +The .write function writes a buffer to the FPGA. The buffer may be contain the
> +whole FPGA image or may be a smaller chunk of an FPGA image.  In the latter
> +case, this function is called multiple times for successive chunks. This interface
> +is suitable for drivers which use PIO.
> +
> +The .write_sg version behaves the same as .write except the input is a sg_table
> +scatter list. This interface is suitable for drivers which use DMA.
> +
> +The .write_complete function is called after all the image has been written
> +to put the FPGA into operating mode.
> +
> +The ops include a .state function which will read the hardware FPGA manager and

                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ??

> +return a code of type enum fpga_mgr_states.  It doesn't result in a change in
> +hardware 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
> +----------------------------------------------
> +
> +.. kernel-doc:: include/linux/fpga/fpga-mgr.h
> +   :functions: fpga_manager
> +
> +.. kernel-doc:: include/linux/fpga/fpga-mgr.h
> +   :functions: fpga_manager_ops
> +
> +.. 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 a FPGA
> +--------------------------
> +
> +.. 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


-- 
~Randy