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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
commit | ace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch) | |
tree | b2d64bc10158fdd5497876388cd68142ca374ed3 /Documentation/driver-api/fpga/fpga-mgr.rst | |
parent | Initial commit. (diff) | |
download | linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip |
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'Documentation/driver-api/fpga/fpga-mgr.rst')
-rw-r--r-- | Documentation/driver-api/fpga/fpga-mgr.rst | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/Documentation/driver-api/fpga/fpga-mgr.rst b/Documentation/driver-api/fpga/fpga-mgr.rst new file mode 100644 index 0000000000..49c0a95126 --- /dev/null +++ b/Documentation/driver-api/fpga/fpga-mgr.rst @@ -0,0 +1,162 @@ +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() or fpga_mgr_register_full(), 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_register(dev, "Altera SOCFPGA FPGA Manager", + &socfpga_fpga_ops, priv); + if (IS_ERR(mgr)) + return PTR_ERR(mgr); + + platform_set_drvdata(pdev, mgr); + + return 0; + } + + static int socfpga_fpga_remove(struct platform_device *pdev) + { + struct fpga_manager *mgr = platform_get_drvdata(pdev); + + fpga_mgr_unregister(mgr); + + return 0; + } + +Alternatively, the probe function could call one of the resource managed +register functions, devm_fpga_mgr_register() or devm_fpga_mgr_register_full(). +When these functions are used, the parameter syntax is the same, but the call +to fpga_mgr_unregister() should be removed. In the above example, the +socfpga_fpga_remove() function would not be required. + +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. .parse_header (optional, may be called once or multiple times) + 2. .write_init + 3. .write or .write_sg (may be called once or multiple times) + 4. .write_complete + +The .parse_header function will set header_size and data_size to +struct fpga_image_info. Before parse_header call, header_size is initialized +with initial_header_size. If flag skip_header of fpga_manager_ops is true, +.write function will get image buffer starting at header_size offset from the +beginning. If data_size is set, .write function will get data_size bytes of +the image buffer, otherwise .write will get data up to the end of image buffer. +This will not affect .write_sg, .write_sg will still get whole image in +sg_table form. If FPGA image is already mapped as a single contiguous buffer, +whole buffer will be passed into .parse_header. If image is in scatter-gather +form, core code will buffer up at least .initial_header_size before the first +call of .parse_header, if it is not enough, .parse_header should set desired +size into info->header_size and return -EAGAIN, then it will be called again +with greater part of image buffer on the input. + +The .write_init function will prepare the FPGA to receive the image data. The +buffer passed into .write_init will be at least info->header_size bytes 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 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. + +API for implementing a new FPGA Manager driver +---------------------------------------------- + +* ``fpga_mgr_states`` - Values for :c:expr:`fpga_manager->state`. +* struct fpga_manager - the FPGA manager struct +* struct fpga_manager_ops - Low level FPGA manager driver ops +* struct fpga_manager_info - Parameter structure for fpga_mgr_register_full() +* fpga_mgr_register_full() - Create and register an FPGA manager using the + fpga_mgr_info structure to provide the full flexibility of options +* fpga_mgr_register() - Create and register an FPGA manager using standard + arguments +* devm_fpga_mgr_register_full() - Resource managed version of + fpga_mgr_register_full() +* devm_fpga_mgr_register() - Resource managed version of fpga_mgr_register() +* 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 + +.. kernel-doc:: include/linux/fpga/fpga-mgr.h + :functions: fpga_manager_ops + +.. kernel-doc:: include/linux/fpga/fpga-mgr.h + :functions: fpga_manager_info + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_mgr_register_full + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_mgr_register + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: devm_fpga_mgr_register_full + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: devm_fpga_mgr_register + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_mgr_unregister |