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1FPGA Manager Core
2
3Alan Tull 2015
4
5Overview
6========
7
8The FPGA manager core exports a set of functions for programming an FPGA with
9an image. The API is manufacturer agnostic. All manufacturer specifics are
10hidden away in a low level driver which registers a set of ops with the core.
11The FPGA image data itself is very manufacturer specific, but for our purposes
12it's just binary data. The FPGA manager core won't parse it.
13
14
15API Functions:
16==============
17
18To program the FPGA from a file or from a buffer:
19-------------------------------------------------
20
21 int fpga_mgr_buf_load(struct fpga_manager *mgr, u32 flags,
22 const char *buf, size_t count);
23
24Load the FPGA from an image which exists as a buffer in memory.
25
26 int fpga_mgr_firmware_load(struct fpga_manager *mgr, u32 flags,
27 const char *image_name);
28
29Load the FPGA from an image which exists as a file. The image file must be on
30the firmware search path (see the firmware class documentation).
31
32For both these functions, flags == 0 for normal full reconfiguration or
33FPGA_MGR_PARTIAL_RECONFIG for partial reconfiguration. If successful, the FPGA
34ends up in operating mode. Return 0 on success or a negative error code.
35
36
37To get/put a reference to a FPGA manager:
38-----------------------------------------
39
40 struct fpga_manager *of_fpga_mgr_get(struct device_node *node);
41
42 void fpga_mgr_put(struct fpga_manager *mgr);
43
44Given a DT node, get an exclusive reference to a FPGA manager or release
45the reference.
46
47
48To register or unregister the low level FPGA-specific driver:
49-------------------------------------------------------------
50
51 int fpga_mgr_register(struct device *dev, const char *name,
52 const struct fpga_manager_ops *mops,
53 void *priv);
54
55 void fpga_mgr_unregister(struct device *dev);
56
57Use of these two functions is described below in "How To Support a new FPGA
58device."
59
60
61How to write an image buffer to a supported FPGA
62================================================
63/* Include to get the API */
64#include <linux/fpga/fpga-mgr.h>
65
66/* device node that specifies the FPGA manager to use */
67struct device_node *mgr_node = ...
68
69/* FPGA image is in this buffer. count is size of the buffer. */
70char *buf = ...
71int count = ...
72
73/* flags indicates whether to do full or partial reconfiguration */
74int flags = 0;
75
76int ret;
77
78/* Get exclusive control of FPGA manager */
79struct fpga_manager *mgr = of_fpga_mgr_get(mgr_node);
80
81/* Load the buffer to the FPGA */
82ret = fpga_mgr_buf_load(mgr, flags, buf, count);
83
84/* Release the FPGA manager */
85fpga_mgr_put(mgr);
86
87
88How to write an image file to a supported FPGA
89==============================================
90/* Include to get the API */
91#include <linux/fpga/fpga-mgr.h>
92
93/* device node that specifies the FPGA manager to use */
94struct device_node *mgr_node = ...
95
96/* FPGA image is in this file which is in the firmware search path */
97const char *path = "fpga-image-9.rbf"
98
99/* flags indicates whether to do full or partial reconfiguration */
100int flags = 0;
101
102int ret;
103
104/* Get exclusive control of FPGA manager */
105struct fpga_manager *mgr = of_fpga_mgr_get(mgr_node);
106
107/* Get the firmware image (path) and load it to the FPGA */
108ret = fpga_mgr_firmware_load(mgr, flags, path);
109
110/* Release the FPGA manager */
111fpga_mgr_put(mgr);
112
113
114How to support a new FPGA device
115================================
116To add another FPGA manager, write a driver that implements a set of ops. The
117probe function calls fpga_mgr_register(), such as:
118
119static const struct fpga_manager_ops socfpga_fpga_ops = {
120 .write_init = socfpga_fpga_ops_configure_init,
121 .write = socfpga_fpga_ops_configure_write,
122 .write_complete = socfpga_fpga_ops_configure_complete,
123 .state = socfpga_fpga_ops_state,
124};
125
126static int socfpga_fpga_probe(struct platform_device *pdev)
127{
128 struct device *dev = &pdev->dev;
129 struct socfpga_fpga_priv *priv;
130 int ret;
131
132 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
133 if (!priv)
134 return -ENOMEM;
135
136 /* ... do ioremaps, get interrupts, etc. and save
137 them in priv... */
138
139 return fpga_mgr_register(dev, "Altera SOCFPGA FPGA Manager",
140 &socfpga_fpga_ops, priv);
141}
142
143static int socfpga_fpga_remove(struct platform_device *pdev)
144{
145 fpga_mgr_unregister(&pdev->dev);
146
147 return 0;
148}
149
150
151The ops will implement whatever device specific register writes are needed to
152do the programming sequence for this particular FPGA. These ops return 0 for
153success or negative error codes otherwise.
154
155The programming sequence is:
156 1. .write_init
157 2. .write (may be called once or multiple times)
158 3. .write_complete
159
160The .write_init function will prepare the FPGA to receive the image data.
161
162The .write function writes a buffer to the FPGA. The buffer may be contain the
163whole FPGA image or may be a smaller chunk of an FPGA image. In the latter
164case, this function is called multiple times for successive chunks.
165
166The .write_complete function is called after all the image has been written
167to put the FPGA into operating mode.
168
169The ops include a .state function which will read the hardware FPGA manager and
170return a code of type enum fpga_mgr_states. It doesn't result in a change in
171hardware state.
1FPGA Manager Core
2
3Alan Tull 2015
4
5Overview
6========
7
8The FPGA manager core exports a set of functions for programming an FPGA with
9an image. The API is manufacturer agnostic. All manufacturer specifics are
10hidden away in a low level driver which registers a set of ops with the core.
11The FPGA image data itself is very manufacturer specific, but for our purposes
12it's just binary data. The FPGA manager core won't parse it.
13
14The FPGA image to be programmed can be in a scatter gather list, a single
15contiguous buffer, or a firmware file. Because allocating contiguous kernel
16memory for the buffer should be avoided, users are encouraged to use a scatter
17gather list instead if possible.
18
19The particulars for programming the image are presented in a structure (struct
20fpga_image_info). This struct contains parameters such as pointers to the
21FPGA image as well as image-specific particulars such as whether the image was
22built for full or partial reconfiguration.
23
24API Functions:
25==============
26
27To program the FPGA:
28--------------------
29
30 int fpga_mgr_load(struct fpga_manager *mgr,
31 struct fpga_image_info *info);
32
33Load the FPGA from an image which is indicated in the info. If successful,
34the FPGA ends up in operating mode. Return 0 on success or a negative error
35code.
36
37To allocate or free a struct fpga_image_info:
38---------------------------------------------
39
40 struct fpga_image_info *fpga_image_info_alloc(struct device *dev);
41
42 void fpga_image_info_free(struct fpga_image_info *info);
43
44To get/put a reference to a FPGA manager:
45-----------------------------------------
46
47 struct fpga_manager *of_fpga_mgr_get(struct device_node *node);
48 struct fpga_manager *fpga_mgr_get(struct device *dev);
49 void fpga_mgr_put(struct fpga_manager *mgr);
50
51Given a DT node or device, get a reference to a FPGA manager. This pointer
52can be saved until you are ready to program the FPGA. fpga_mgr_put releases
53the reference.
54
55
56To get exclusive control of a FPGA manager:
57-------------------------------------------
58
59 int fpga_mgr_lock(struct fpga_manager *mgr);
60 void fpga_mgr_unlock(struct fpga_manager *mgr);
61
62The user should call fpga_mgr_lock and verify that it returns 0 before
63attempting to program the FPGA. Likewise, the user should call
64fpga_mgr_unlock when done programming the FPGA.
65
66
67To register or unregister the low level FPGA-specific driver:
68-------------------------------------------------------------
69
70 int fpga_mgr_register(struct device *dev, const char *name,
71 const struct fpga_manager_ops *mops,
72 void *priv);
73
74 void fpga_mgr_unregister(struct device *dev);
75
76Use of these two functions is described below in "How To Support a new FPGA
77device."
78
79
80How to write an image buffer to a supported FPGA
81================================================
82#include <linux/fpga/fpga-mgr.h>
83
84struct fpga_manager *mgr;
85struct fpga_image_info *info;
86int ret;
87
88/*
89 * Get a reference to FPGA manager. The manager is not locked, so you can
90 * hold onto this reference without it preventing programming.
91 *
92 * This example uses the device node of the manager. Alternatively, use
93 * fpga_mgr_get(dev) instead if you have the device.
94 */
95mgr = of_fpga_mgr_get(mgr_node);
96
97/* struct with information about the FPGA image to program. */
98info = fpga_image_info_alloc(dev);
99
100/* flags indicates whether to do full or partial reconfiguration */
101info->flags = FPGA_MGR_PARTIAL_RECONFIG;
102
103/*
104 * At this point, indicate where the image is. This is pseudo-code; you're
105 * going to use one of these three.
106 */
107if (image is in a scatter gather table) {
108
109 info->sgt = [your scatter gather table]
110
111} else if (image is in a buffer) {
112
113 info->buf = [your image buffer]
114 info->count = [image buffer size]
115
116} else if (image is in a firmware file) {
117
118 info->firmware_name = devm_kstrdup(dev, firmware_name, GFP_KERNEL);
119
120}
121
122/* Get exclusive control of FPGA manager */
123ret = fpga_mgr_lock(mgr);
124
125/* Load the buffer to the FPGA */
126ret = fpga_mgr_buf_load(mgr, &info, buf, count);
127
128/* Release the FPGA manager */
129fpga_mgr_unlock(mgr);
130fpga_mgr_put(mgr);
131
132/* Deallocate the image info if you're done with it */
133fpga_image_info_free(info);
134
135How to support a new FPGA device
136================================
137To add another FPGA manager, write a driver that implements a set of ops. The
138probe function calls fpga_mgr_register(), such as:
139
140static const struct fpga_manager_ops socfpga_fpga_ops = {
141 .write_init = socfpga_fpga_ops_configure_init,
142 .write = socfpga_fpga_ops_configure_write,
143 .write_complete = socfpga_fpga_ops_configure_complete,
144 .state = socfpga_fpga_ops_state,
145};
146
147static int socfpga_fpga_probe(struct platform_device *pdev)
148{
149 struct device *dev = &pdev->dev;
150 struct socfpga_fpga_priv *priv;
151 int ret;
152
153 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
154 if (!priv)
155 return -ENOMEM;
156
157 /* ... do ioremaps, get interrupts, etc. and save
158 them in priv... */
159
160 return fpga_mgr_register(dev, "Altera SOCFPGA FPGA Manager",
161 &socfpga_fpga_ops, priv);
162}
163
164static int socfpga_fpga_remove(struct platform_device *pdev)
165{
166 fpga_mgr_unregister(&pdev->dev);
167
168 return 0;
169}
170
171
172The ops will implement whatever device specific register writes are needed to
173do the programming sequence for this particular FPGA. These ops return 0 for
174success or negative error codes otherwise.
175
176The programming sequence is:
177 1. .write_init
178 2. .write or .write_sg (may be called once or multiple times)
179 3. .write_complete
180
181The .write_init function will prepare the FPGA to receive the image data. The
182buffer passed into .write_init will be atmost .initial_header_size bytes long,
183if the whole bitstream is not immediately available then the core code will
184buffer up at least this much before starting.
185
186The .write function writes a buffer to the FPGA. The buffer may be contain the
187whole FPGA image or may be a smaller chunk of an FPGA image. In the latter
188case, this function is called multiple times for successive chunks. This interface
189is suitable for drivers which use PIO.
190
191The .write_sg version behaves the same as .write except the input is a sg_table
192scatter list. This interface is suitable for drivers which use DMA.
193
194The .write_complete function is called after all the image has been written
195to put the FPGA into operating mode.
196
197The ops include a .state function which will read the hardware FPGA manager and
198return a code of type enum fpga_mgr_states. It doesn't result in a change in
199hardware state.