source: rtems-docs/user/bsps/bsps-riscv.rst @ 5973f92

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Last change on this file since 5973f92 was 5973f92, checked in by Sebastian Huber <sebastian.huber@…>, on 01/22/19 at 11:58:09

user: Stub documentation for griscv BSP

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1.. SPDX-License-Identifier: CC-BY-SA-4.0
2
3.. Copyright (C) 2018 embedded brains GmbH
4
5riscv (RISC-V)
6**************
7
8riscv
9=====
10
11This BSP offers 13 variants:
12
13* rv32i
14
15* rv32iac
16
17* rv32im
18
19* rv32imac
20
21* rv32imafc
22
23* rv32imafd
24
25* rv32imafdc
26
27* rv64imac
28
29* rv64imac_medany
30
31* rv64imafd
32
33* rv64imafd_medany
34
35* rv64imafdc
36
37* rv64imafdc_medany
38
39Each variant corresponds to a GCC multilib.  A particular variant reflects an
40ISA with ABI and code model choice.
41
42The basic hardware initialization is not performed by the BSP.  A boot loader
43with device tree support must be used to start the BSP, e.g. BBL.  The BSP must
44be started im machine mode.
45
46The reference platform for this BSP is the Qemu `virt` machine.
47
48Build Configuration Options
49---------------------------
50
51The following options are available at the configure command line.
52
53``BSP_PRESS_KEY_FOR_RESET``
54    If defined to a non-zero value, then print a message and wait until pressed
55    before resetting board when application terminates.
56
57``BSP_RESET_BOARD_AT_EXIT``
58    If defined to a non-zero value, then reset the board when the application
59    terminates.
60
61``BSP_PRINT_EXCEPTION_CONTEXT``
62    If defined to a non-zero value, then print the exception context when an
63    unexpected exception occurs.
64
65``BSP_FDT_BLOB_SIZE_MAX``
66    The maximum size of the device tree blob in bytes (default is 65536).
67
68``BSP_CONSOLE_BAUD``
69    The default baud for console driver devices (default 115200).
70
71``RISCV_MAXIMUM_EXTERNAL_INTERRUPTS``
72     The maximum number of external interrupts supported by the BSP (default
73     64).
74
75``RISCV_ENABLE_HTIF_SUPPORT``
76     Enables the HTIF support if defined to a non-zero value, otherwise it is
77     disabled (disabled by default).
78
79``RISCV_CONSOLE_MAX_NS16550_DEVICES``
80     The maximum number of NS16550 devices supported by the console driver (2
81     by default).
82
83``RISCV_RAM_REGION_BEGIN``
84     The begin of the RAM region for linker command file (default is 0x70000000
85     for 64-bit with -mcmodel=medlow and 0x80000000 for all other).
86
87``RISCV_RAM_REGION_SIZE``
88     The size of the RAM region for linker command file (default 64MiB).
89
90Interrupt Controller
91--------------------
92
93Exactly one Core Local Interruptor (CLINT) and exactly one Platform-Level
94Interrupt Controller (PLIC) are supported.  The maximum number of external
95interrupts supported by the BSP is defined by the
96``RISCV_MAXIMUM_EXTERNAL_INTERRUPTS`` BSP option.
97
98Clock Driver
99------------
100
101The clock driver uses the CLINT timer.
102
103Console Driver
104--------------
105
106The console driver supports devices compatible to
107
108* "ucb,htif0" (depending on the ``RISCV_ENABLE_HTIF_SUPPORT`` BSP option),
109
110* "ns16550a" (see ``RISCV_CONSOLE_MAX_NS16550_DEVICES`` BSP option), and
111
112* "ns16750" (see ``RISCV_CONSOLE_MAX_NS16550_DEVICES`` BSP option).
113
114They are initialized according to the device tree.  The console driver does not
115configure the pins or peripheral clocks.  The console device is selected
116according to the device tree "/chosen/stdout-path" property value.
117
118griscv
119======
120
121This RISC-V BSP supports chips using the
122`GRLIB <https://www.gaisler.com/products/grlib/grlib.pdf>`_.
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