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 = 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		ret = fpga_mgr_register(mgr);
60		if (ret)
61			fpga_mgr_free(mgr);
62
63		return ret;
64	}
65
66	static int socfpga_fpga_remove(struct platform_device *pdev)
67	{
68		struct fpga_manager *mgr = platform_get_drvdata(pdev);
69
70		fpga_mgr_unregister(mgr);
71
72		return 0;
73	}
74
75
76The ops will implement whatever device specific register writes are needed to
77do the programming sequence for this particular FPGA.  These ops return 0 for
78success or negative error codes otherwise.
79
80The programming sequence is::
81 1. .write_init
82 2. .write or .write_sg (may be called once or multiple times)
83 3. .write_complete
84
85The .write_init function will prepare the FPGA to receive the image data.  The
86buffer passed into .write_init will be at most .initial_header_size bytes long;
87if the whole bitstream is not immediately available then the core code will
88buffer up at least this much before starting.
89
90The .write function writes a buffer to the FPGA. The buffer may be contain the
91whole FPGA image or may be a smaller chunk of an FPGA image.  In the latter
92case, this function is called multiple times for successive chunks. This interface
93is suitable for drivers which use PIO.
94
95The .write_sg version behaves the same as .write except the input is a sg_table
96scatter list. This interface is suitable for drivers which use DMA.
97
98The .write_complete function is called after all the image has been written
99to put the FPGA into operating mode.
100
101The ops include a .state function which will determine the state the FPGA is in
102and return a code of type enum fpga_mgr_states.  It doesn't result in a change
103in state.
104
105How to write an image buffer to a supported FPGA
106------------------------------------------------
107
108Some sample code::
109
110	#include <linux/fpga/fpga-mgr.h>
111
112	struct fpga_manager *mgr;
113	struct fpga_image_info *info;
114	int ret;
115
116	/*
117	 * Get a reference to FPGA manager.  The manager is not locked, so you can
118	 * hold onto this reference without it preventing programming.
119	 *
120	 * This example uses the device node of the manager.  Alternatively, use
121	 * fpga_mgr_get(dev) instead if you have the device.
122	 */
123	mgr = of_fpga_mgr_get(mgr_node);
124
125	/* struct with information about the FPGA image to program. */
126	info = fpga_image_info_alloc(dev);
127
128	/* flags indicates whether to do full or partial reconfiguration */
129	info->flags = FPGA_MGR_PARTIAL_RECONFIG;
130
131	/*
132	 * At this point, indicate where the image is. This is pseudo-code; you're
133	 * going to use one of these three.
134	 */
135	if (image is in a scatter gather table) {
136
137		info->sgt = [your scatter gather table]
138
139	} else if (image is in a buffer) {
140
141		info->buf = [your image buffer]
142		info->count = [image buffer size]
143
144	} else if (image is in a firmware file) {
145
146		info->firmware_name = devm_kstrdup(dev, firmware_name, GFP_KERNEL);
147
148	}
149
150	/* Get exclusive control of FPGA manager */
151	ret = fpga_mgr_lock(mgr);
152
153	/* Load the buffer to the FPGA */
154	ret = fpga_mgr_buf_load(mgr, &info, buf, count);
155
156	/* Release the FPGA manager */
157	fpga_mgr_unlock(mgr);
158	fpga_mgr_put(mgr);
159
160	/* Deallocate the image info if you're done with it */
161	fpga_image_info_free(info);
162
163API for implementing a new FPGA Manager driver
164----------------------------------------------
165
166.. kernel-doc:: include/linux/fpga/fpga-mgr.h
167   :functions: fpga_manager
168
169.. kernel-doc:: include/linux/fpga/fpga-mgr.h
170   :functions: fpga_manager_ops
171
172.. kernel-doc:: drivers/fpga/fpga-mgr.c
173   :functions: fpga_mgr_create
174
175.. kernel-doc:: drivers/fpga/fpga-mgr.c
176   :functions: fpga_mgr_free
177
178.. kernel-doc:: drivers/fpga/fpga-mgr.c
179   :functions: fpga_mgr_register
180
181.. kernel-doc:: drivers/fpga/fpga-mgr.c
182   :functions: fpga_mgr_unregister
183
184API for programming an FPGA
185---------------------------
186
187.. kernel-doc:: include/linux/fpga/fpga-mgr.h
188   :functions: fpga_image_info
189
190.. kernel-doc:: include/linux/fpga/fpga-mgr.h
191   :functions: fpga_mgr_states
192
193.. kernel-doc:: drivers/fpga/fpga-mgr.c
194   :functions: fpga_image_info_alloc
195
196.. kernel-doc:: drivers/fpga/fpga-mgr.c
197   :functions: fpga_image_info_free
198
199.. kernel-doc:: drivers/fpga/fpga-mgr.c
200   :functions: of_fpga_mgr_get
201
202.. kernel-doc:: drivers/fpga/fpga-mgr.c
203   :functions: fpga_mgr_get
204
205.. kernel-doc:: drivers/fpga/fpga-mgr.c
206   :functions: fpga_mgr_put
207
208.. kernel-doc:: drivers/fpga/fpga-mgr.c
209   :functions: fpga_mgr_lock
210
211.. kernel-doc:: drivers/fpga/fpga-mgr.c
212   :functions: fpga_mgr_unlock
213
214.. kernel-doc:: include/linux/fpga/fpga-mgr.h
215   :functions: fpga_mgr_states
216
217Note - use :c:func:`fpga_region_program_fpga()` instead of :c:func:`fpga_mgr_load()`
218
219.. kernel-doc:: drivers/fpga/fpga-mgr.c
220   :functions: fpga_mgr_load
221