1FPGA Manager
2============
3
4Overview
5--------
6
7The FPGA manager core exports a set of functions for programming an FPGA with
8an image.  The API is manufacturer agnostic.  All manufacturer specifics are
9hidden away in a low level driver which registers a set of ops with the core.
10The FPGA image data itself is very manufacturer specific, but for our purposes
11it's just binary data.  The FPGA manager core won't parse it.
12
13The FPGA image to be programmed can be in a scatter gather list, a single
14contiguous buffer, or a firmware file.  Because allocating contiguous kernel
15memory for the buffer should be avoided, users are encouraged to use a scatter
16gather list instead if possible.
17
18The particulars for programming the image are presented in a structure (struct
19fpga_image_info).  This struct contains parameters such as pointers to the
20FPGA image as well as image-specific particulars such as whether the image was
21built for full or partial reconfiguration.
22
23How to support a new FPGA device
24--------------------------------
25
26To add another FPGA manager, write a driver that implements a set of ops.  The
27probe function calls fpga_mgr_register(), such as::
28
29	static const struct fpga_manager_ops socfpga_fpga_ops = {
30		.write_init = socfpga_fpga_ops_configure_init,
31		.write = socfpga_fpga_ops_configure_write,
32		.write_complete = socfpga_fpga_ops_configure_complete,
33		.state = socfpga_fpga_ops_state,
34	};
35
36	static int socfpga_fpga_probe(struct platform_device *pdev)
37	{
38		struct device *dev = &pdev->dev;
39		struct socfpga_fpga_priv *priv;
40		struct fpga_manager *mgr;
41		int ret;
42
43		priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
44		if (!priv)
45			return -ENOMEM;
46
47		/*
48		 * do ioremaps, get interrupts, etc. and save
49		 * them in priv
50		 */
51
52		mgr = devm_fpga_mgr_create(dev, "Altera SOCFPGA FPGA Manager",
53					   &socfpga_fpga_ops, priv);
54		if (!mgr)
55			return -ENOMEM;
56
57		platform_set_drvdata(pdev, mgr);
58
59		return fpga_mgr_register(mgr);
60	}
61
62	static int socfpga_fpga_remove(struct platform_device *pdev)
63	{
64		struct fpga_manager *mgr = platform_get_drvdata(pdev);
65
66		fpga_mgr_unregister(mgr);
67
68		return 0;
69	}
70
71
72The ops will implement whatever device specific register writes are needed to
73do the programming sequence for this particular FPGA.  These ops return 0 for
74success or negative error codes otherwise.
75
76The programming sequence is::
77 1. .write_init
78 2. .write or .write_sg (may be called once or multiple times)
79 3. .write_complete
80
81The .write_init function will prepare the FPGA to receive the image data.  The
82buffer passed into .write_init will be at most .initial_header_size bytes long;
83if the whole bitstream is not immediately available then the core code will
84buffer up at least this much before starting.
85
86The .write function writes a buffer to the FPGA. The buffer may be contain the
87whole FPGA image or may be a smaller chunk of an FPGA image.  In the latter
88case, this function is called multiple times for successive chunks. This interface
89is suitable for drivers which use PIO.
90
91The .write_sg version behaves the same as .write except the input is a sg_table
92scatter list. This interface is suitable for drivers which use DMA.
93
94The .write_complete function is called after all the image has been written
95to put the FPGA into operating mode.
96
97The ops include a .state function which will determine the state the FPGA is in
98and return a code of type enum fpga_mgr_states.  It doesn't result in a change
99in state.
100
101API for implementing a new FPGA Manager driver
102----------------------------------------------
103
104* ``fpga_mgr_states`` —  Values for :c:expr:`fpga_manager->state`.
105* struct fpga_manager —  the FPGA manager struct
106* struct fpga_manager_ops —  Low level FPGA manager driver ops
107* devm_fpga_mgr_create() —  Allocate and init a manager struct
108* fpga_mgr_register() —  Register an FPGA manager
109* fpga_mgr_unregister() —  Unregister an FPGA manager
110
111.. kernel-doc:: include/linux/fpga/fpga-mgr.h
112   :functions: fpga_mgr_states
113
114.. kernel-doc:: include/linux/fpga/fpga-mgr.h
115   :functions: fpga_manager
116
117.. kernel-doc:: include/linux/fpga/fpga-mgr.h
118   :functions: fpga_manager_ops
119
120.. kernel-doc:: drivers/fpga/fpga-mgr.c
121   :functions: devm_fpga_mgr_create
122
123.. kernel-doc:: drivers/fpga/fpga-mgr.c
124   :functions: fpga_mgr_register
125
126.. kernel-doc:: drivers/fpga/fpga-mgr.c
127   :functions: fpga_mgr_unregister
128