source: rtems/cpukit/score/cpu/avr/avr/lock.h @ 04a62dce

4.104.11
Last change on this file since 04a62dce was 04a62dce, checked in by Joel Sherrill <joel.sherrill@…>, on Aug 6, 2009 at 2:52:07 PM

2009-08-05 Josh Switnicki <josh.switnicki@…>

  • Makefile.am: added AVR specific Header files to score/cpu/avr/avr. These are from avr-libc 1.6 and assumed to exist by AVR applications.
  • preinstall.am: Regenerated.
  • Property mode set to 100644
File size: 8.3 KB
Line 
1/* Copyright (c) 2007, Atmel Corporation
2   All rights reserved.
3
4   Redistribution and use in source and binary forms, with or without
5   modification, are permitted provided that the following conditions are met:
6
7   * Redistributions of source code must retain the above copyright
8     notice, this list of conditions and the following disclaimer.
9
10   * Redistributions in binary form must reproduce the above copyright
11     notice, this list of conditions and the following disclaimer in
12     the documentation and/or other materials provided with the
13     distribution.
14
15   * Neither the name of the copyright holders nor the names of
16     contributors may be used to endorse or promote products derived
17     from this software without specific prior written permission.
18
19  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
20  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
23  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  POSSIBILITY OF SUCH DAMAGE. */
30
31/* $Id$ */
32
33/* avr/lock.h - Lock Bits API */
34
35#ifndef _AVR_LOCK_H_
36#define _AVR_LOCK_H_  1
37
38
39/** \file */
40/** \defgroup avr_lock <avr/lock.h>: Lockbit Support
41
42    \par Introduction
43
44    The Lockbit API allows a user to specify the lockbit settings for the
45    specific AVR device they are compiling for. These lockbit settings will be
46    placed in a special section in the ELF output file, after linking.
47
48    Programming tools can take advantage of the lockbit information embedded in
49    the ELF file, by extracting this information and determining if the lockbits
50    need to be programmed after programming the Flash and EEPROM memories.
51    This also allows a single ELF file to contain all the
52    information needed to program an AVR.
53
54    To use the Lockbit API, include the <avr/io.h> header file, which in turn
55    automatically includes the individual I/O header file and the <avr/lock.h>
56    file. These other two files provides everything necessary to set the AVR
57    lockbits.
58   
59    \par Lockbit API
60   
61    Each I/O header file may define up to 3 macros that controls what kinds
62    of lockbits are available to the user.
63   
64    If __LOCK_BITS_EXIST is defined, then two lock bits are available to the
65    user and 3 mode settings are defined for these two bits.
66   
67    If __BOOT_LOCK_BITS_0_EXIST is defined, then the two BLB0 lock bits are
68    available to the user and 4 mode settings are defined for these two bits.
69   
70    If __BOOT_LOCK_BITS_1_EXIST is defined, then the two BLB1 lock bits are
71    available to the user and 4 mode settings are defined for these two bits.
72
73    If __BOOT_LOCK_APPLICATION_TABLE_BITS_EXIST is defined then two lock bits
74    are available to set the locking mode for the Application Table Section
75    (which is used in the XMEGA family).
76   
77    If __BOOT_LOCK_APPLICATION_BITS_EXIST is defined then two lock bits are
78    available to set the locking mode for the Application Section (which is used
79    in the XMEGA family).
80   
81    If __BOOT_LOCK_BOOT_BITS_EXIST is defined then two lock bits are available
82    to set the locking mode for the Boot Loader Section (which is used in the
83    XMEGA family).
84
85    The AVR lockbit modes have inverted values, logical 1 for an unprogrammed
86    (disabled) bit and logical 0 for a programmed (enabled) bit. The defined
87    macros for each individual lock bit represent this in their definition by a
88    bit-wise inversion of a mask. For example, the LB_MODE_3 macro is defined
89    as:
90    \code
91    #define LB_MODE_3  (0xFC)
92`   \endcode
93   
94    To combine the lockbit mode macros together to represent a whole byte,
95    use the bitwise AND operator, like so:
96    \code
97    (LB_MODE_3 & BLB0_MODE_2)
98    \endcode
99   
100    <avr/lock.h> also defines a macro that provides a default lockbit value:
101    LOCKBITS_DEFAULT which is defined to be 0xFF.
102
103    See the AVR device specific datasheet for more details about these
104    lock bits and the available mode settings.
105   
106    A convenience macro, LOCKMEM, is defined as a GCC attribute for a
107    custom-named section of ".lock".
108   
109    A convenience macro, LOCKBITS, is defined that declares a variable, __lock,
110    of type unsigned char with the attribute defined by LOCKMEM. This variable
111    allows the end user to easily set the lockbit data.
112
113    \note If a device-specific I/O header file has previously defined LOCKMEM,
114    then LOCKMEM is not redefined. If a device-specific I/O header file has
115    previously defined LOCKBITS, then LOCKBITS is not redefined. LOCKBITS is
116    currently known to be defined in the I/O header files for the XMEGA devices.
117
118    \par API Usage Example
119   
120    Putting all of this together is easy:
121   
122    \code
123    #include <avr/io.h>
124
125    LOCKBITS = (LB_MODE_1 & BLB0_MODE_3 & BLB1_MODE_4);
126
127    int main(void)
128    {
129        return 0;
130    }
131    \endcode
132   
133    Or:
134   
135    \code
136    #include <avr/io.h>
137
138    unsigned char __lock __attribute__((section (".lock"))) =
139        (LB_MODE_1 & BLB0_MODE_3 & BLB1_MODE_4);
140
141    int main(void)
142    {
143        return 0;
144    }
145    \endcode
146   
147   
148   
149    However there are a number of caveats that you need to be aware of to
150    use this API properly.
151   
152    Be sure to include <avr/io.h> to get all of the definitions for the API.
153    The LOCKBITS macro defines a global variable to store the lockbit data. This
154    variable is assigned to its own linker section. Assign the desired lockbit
155    values immediately in the variable initialization.
156   
157    The .lock section in the ELF file will get its values from the initial
158    variable assignment ONLY. This means that you can NOT assign values to
159    this variable in functions and the new values will not be put into the
160    ELF .lock section.
161   
162    The global variable is declared in the LOCKBITS macro has two leading
163    underscores, which means that it is reserved for the "implementation",
164    meaning the library, so it will not conflict with a user-named variable.
165   
166    You must initialize the lockbit variable to some meaningful value, even
167    if it is the default value. This is because the lockbits default to a
168    logical 1, meaning unprogrammed. Normal uninitialized data defaults to all
169    locgial zeros. So it is vital that all lockbits are initialized, even with
170    default data. If they are not, then the lockbits may not programmed to the
171    desired settings and can possibly put your device into an unrecoverable
172    state.
173   
174    Be sure to have the -mmcu=<em>device</em> flag in your compile command line and
175    your linker command line to have the correct device selected and to have
176    the correct I/O header file included when you include <avr/io.h>.
177
178    You can print out the contents of the .lock section in the ELF file by
179    using this command line:
180    \code
181    avr-objdump -s -j .lock <ELF file>
182    \endcode
183
184*/
185
186
187#ifndef __ASSEMBLER__
188
189#ifndef LOCKMEM
190#define LOCKMEM  __attribute__((section (".lock")))
191#endif
192
193#ifndef LOCKBITS
194#define LOCKBITS unsigned char __lock LOCKMEM
195#endif
196
197#endif  /* !__ASSEMBLER */
198
199
200/* Lock Bit Modes */
201#if defined(__LOCK_BITS_EXIST)
202#define LB_MODE_1  (0xFF)
203#define LB_MODE_2  (0xFE)
204#define LB_MODE_3  (0xFC)
205#endif
206
207#if defined(__BOOT_LOCK_BITS_0_EXIST)
208#define BLB0_MODE_1  (0xFF)
209#define BLB0_MODE_2  (0xFB)
210#define BLB0_MODE_3  (0xF3)
211#define BLB0_MODE_4  (0xF7)
212#endif
213
214#if defined(__BOOT_LOCK_BITS_1_EXIST)
215#define BLB1_MODE_1  (0xFF)
216#define BLB1_MODE_2  (0xEF)
217#define BLB1_MODE_3  (0xCF)
218#define BLB1_MODE_4  (0xDF)
219#endif
220
221#if defined(__BOOT_LOCK_APPLICATION_TABLE_BITS_EXIST)
222#define BLBAT0 ~_BV(2)
223#define BLBAT1 ~_BV(3)
224#endif
225
226#if defined(__BOOT_LOCK_APPLICATION_BITS_EXIST)
227#define BLBA0 ~_BV(4)
228#define BLBA1 ~_BV(5)
229#endif
230
231#if defined(__BOOT_LOCK_BOOT_BITS_EXIST)
232#define BLBB0 ~_BV(6)
233#define BLBB1 ~_BV(7)
234#endif
235
236
237#define LOCKBITS_DEFAULT (0xFF)
238
239#endif /* _AVR_LOCK_H_ */
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