226 lines
6.4 KiB
ReStructuredText
226 lines
6.4 KiB
ReStructuredText
FPGA Manager
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============
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Overview
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--------
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The FPGA manager core exports a set of functions for programming an FPGA with
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an image. The API is manufacturer agnostic. All manufacturer specifics are
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hidden away in a low level driver which registers a set of ops with the core.
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The FPGA image data itself is very manufacturer specific, but for our purposes
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it's just binary data. The FPGA manager core won't parse it.
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The FPGA image to be programmed can be in a scatter gather list, a single
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contiguous buffer, or a firmware file. Because allocating contiguous kernel
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memory for the buffer should be avoided, users are encouraged to use a scatter
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gather list instead if possible.
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The particulars for programming the image are presented in a structure (struct
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fpga_image_info). This struct contains parameters such as pointers to the
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FPGA image as well as image-specific particulars such as whether the image was
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built for full or partial reconfiguration.
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How to support a new FPGA device
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--------------------------------
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To add another FPGA manager, write a driver that implements a set of ops. The
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probe function calls fpga_mgr_register(), such as::
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static const struct fpga_manager_ops socfpga_fpga_ops = {
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.write_init = socfpga_fpga_ops_configure_init,
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.write = socfpga_fpga_ops_configure_write,
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.write_complete = socfpga_fpga_ops_configure_complete,
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.state = socfpga_fpga_ops_state,
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};
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static int socfpga_fpga_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct socfpga_fpga_priv *priv;
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struct fpga_manager *mgr;
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int ret;
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priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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/*
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* do ioremaps, get interrupts, etc. and save
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* them in priv
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*/
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mgr = fpga_mgr_create(dev, "Altera SOCFPGA FPGA Manager",
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&socfpga_fpga_ops, priv);
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if (!mgr)
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return -ENOMEM;
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platform_set_drvdata(pdev, mgr);
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ret = fpga_mgr_register(mgr);
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if (ret)
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fpga_mgr_free(mgr);
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return ret;
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}
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static int socfpga_fpga_remove(struct platform_device *pdev)
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{
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struct fpga_manager *mgr = platform_get_drvdata(pdev);
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fpga_mgr_unregister(mgr);
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return 0;
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}
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The ops will implement whatever device specific register writes are needed to
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do the programming sequence for this particular FPGA. These ops return 0 for
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success or negative error codes otherwise.
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The programming sequence is::
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1. .write_init
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2. .write or .write_sg (may be called once or multiple times)
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3. .write_complete
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The .write_init function will prepare the FPGA to receive the image data. The
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buffer passed into .write_init will be at most .initial_header_size bytes long;
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if the whole bitstream is not immediately available then the core code will
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buffer up at least this much before starting.
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The .write function writes a buffer to the FPGA. The buffer may be contain the
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whole FPGA image or may be a smaller chunk of an FPGA image. In the latter
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case, this function is called multiple times for successive chunks. This interface
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is suitable for drivers which use PIO.
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The .write_sg version behaves the same as .write except the input is a sg_table
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scatter list. This interface is suitable for drivers which use DMA.
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The .write_complete function is called after all the image has been written
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to put the FPGA into operating mode.
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The ops include a .state function which will determine the state the FPGA is in
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and return a code of type enum fpga_mgr_states. It doesn't result in a change
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in state.
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How to write an image buffer to a supported FPGA
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------------------------------------------------
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Some sample code::
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#include <linux/fpga/fpga-mgr.h>
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struct fpga_manager *mgr;
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struct fpga_image_info *info;
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int ret;
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/*
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* Get a reference to FPGA manager. The manager is not locked, so you can
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* hold onto this reference without it preventing programming.
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*
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* This example uses the device node of the manager. Alternatively, use
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* fpga_mgr_get(dev) instead if you have the device.
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*/
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mgr = of_fpga_mgr_get(mgr_node);
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/* struct with information about the FPGA image to program. */
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info = fpga_image_info_alloc(dev);
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/* flags indicates whether to do full or partial reconfiguration */
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info->flags = FPGA_MGR_PARTIAL_RECONFIG;
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/*
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* At this point, indicate where the image is. This is pseudo-code; you're
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* going to use one of these three.
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*/
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if (image is in a scatter gather table) {
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info->sgt = [your scatter gather table]
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} else if (image is in a buffer) {
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info->buf = [your image buffer]
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info->count = [image buffer size]
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} else if (image is in a firmware file) {
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info->firmware_name = devm_kstrdup(dev, firmware_name, GFP_KERNEL);
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}
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/* Get exclusive control of FPGA manager */
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ret = fpga_mgr_lock(mgr);
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/* Load the buffer to the FPGA */
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ret = fpga_mgr_buf_load(mgr, &info, buf, count);
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/* Release the FPGA manager */
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fpga_mgr_unlock(mgr);
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fpga_mgr_put(mgr);
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/* Deallocate the image info if you're done with it */
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fpga_image_info_free(info);
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API for implementing a new FPGA Manager driver
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----------------------------------------------
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.. kernel-doc:: include/linux/fpga/fpga-mgr.h
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:functions: fpga_manager
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.. kernel-doc:: include/linux/fpga/fpga-mgr.h
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:functions: fpga_manager_ops
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: fpga_mgr_create
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: fpga_mgr_free
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: fpga_mgr_register
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: fpga_mgr_unregister
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API for programming an FPGA
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---------------------------
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FPGA Manager flags
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.. kernel-doc:: include/linux/fpga/fpga-mgr.h
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:doc: FPGA Manager flags
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.. kernel-doc:: include/linux/fpga/fpga-mgr.h
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:functions: fpga_image_info
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.. kernel-doc:: include/linux/fpga/fpga-mgr.h
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:functions: fpga_mgr_states
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: fpga_image_info_alloc
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: fpga_image_info_free
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: of_fpga_mgr_get
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: fpga_mgr_get
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: fpga_mgr_put
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: fpga_mgr_lock
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: fpga_mgr_unlock
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.. kernel-doc:: include/linux/fpga/fpga-mgr.h
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:functions: fpga_mgr_states
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Note - use :c:func:`fpga_region_program_fpga()` instead of :c:func:`fpga_mgr_load()`
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: fpga_mgr_load
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