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Diffstat (limited to 'include/avr/lock.h')
| -rw-r--r-- | include/avr/lock.h | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/include/avr/lock.h b/include/avr/lock.h new file mode 100644 index 0000000000..182f0f4cd8 --- /dev/null +++ b/include/avr/lock.h @@ -0,0 +1,243 @@ +/** + * @file avr/lock.h + * + * @brief Lock Bits API + * \par Introduction + * + * The Lockbit API allows a user to specify the lockbit settings for the + * specific AVR device they are compiling for. These lockbit settings will be + * placed in a special section in the ELF output file, after linking. + * + * Programming tools can take advantage of the lockbit information embedded in + * the ELF file, by extracting this information and determining if the lockbits + * need to be programmed after programming the Flash and EEPROM memories. + * This also allows a single ELF file to contain all the + * information needed to program an AVR. + * + * To use the Lockbit API, include the <avr/io.h> header file, which in turn + * automatically includes the individual I/O header file and the <avr/lock.h> + * file. These other two files provides everything necessary to set the AVR + * lockbits. + * + * \par Lockbit API + * + * Each I/O header file may define up to 3 macros that controls what kinds + * of lockbits are available to the user. + * + * If __LOCK_BITS_EXIST is defined, then two lock bits are available to the + * user and 3 mode settings are defined for these two bits. + * + * If __BOOT_LOCK_BITS_0_EXIST is defined, then the two BLB0 lock bits are + * available to the user and 4 mode settings are defined for these two bits. + * + * If __BOOT_LOCK_BITS_1_EXIST is defined, then the two BLB1 lock bits are + * available to the user and 4 mode settings are defined for these two bits. + * + * If __BOOT_LOCK_APPLICATION_TABLE_BITS_EXIST is defined then two lock bits + * are available to set the locking mode for the Application Table Section + * (which is used in the XMEGA family). + * + * If __BOOT_LOCK_APPLICATION_BITS_EXIST is defined then two lock bits are + * available to set the locking mode for the Application Section (which is used + * in the XMEGA family). + * + * If __BOOT_LOCK_BOOT_BITS_EXIST is defined then two lock bits are available + * to set the locking mode for the Boot Loader Section (which is used in the + * XMEGA family). + * + * The AVR lockbit modes have inverted values, logical 1 for an unprogrammed + * (disabled) bit and logical 0 for a programmed (enabled) bit. The defined + * macros for each individual lock bit represent this in their definition by a + * bit-wise inversion of a mask. For example, the LB_MODE_3 macro is defined + * as: + * \code + * #define LB_MODE_3 (0xFC) + * \endcode + * + * To combine the lockbit mode macros together to represent a whole byte, + * use the bitwise AND operator, like so: + * \code + * (LB_MODE_3 & BLB0_MODE_2) + * \endcode + * + * <avr/lock.h> also defines a macro that provides a default lockbit value: + * LOCKBITS_DEFAULT which is defined to be 0xFF. + * + * See the AVR device specific datasheet for more details about these + * lock bits and the available mode settings. + * + * A convenience macro, LOCKMEM, is defined as a GCC attribute for a + * custom-named section of ".lock". + * + * A convenience macro, LOCKBITS, is defined that declares a variable, __lock, + * of type unsigned char with the attribute defined by LOCKMEM. This variable + * allows the end user to easily set the lockbit data. + * + * \note If a device-specific I/O header file has previously defined LOCKMEM, + * then LOCKMEM is not redefined. If a device-specific I/O header file has + * previously defined LOCKBITS, then LOCKBITS is not redefined. LOCKBITS is + * currently known to be defined in the I/O header files for the XMEGA devices. + * + * \par API Usage Example + * + * Putting all of this together is easy: + * + * \code + * #include <avr/io.h> + * + * LOCKBITS = (LB_MODE_1 & BLB0_MODE_3 & BLB1_MODE_4); + * + * int main(void) + * { + * return 0; + * } + * \endcode + * + * Or: + * + * \code + * #include <avr/io.h> + * + * unsigned char __lock __attribute__((section (".lock"))) = + * (LB_MODE_1 & BLB0_MODE_3 & BLB1_MODE_4); + * + * int main(void) + * { + * return 0; + * } + * \endcode + * + * + * + * However there are a number of caveats that you need to be aware of to + * use this API properly. + * + * Be sure to include <avr/io.h> to get all of the definitions for the API. + * The LOCKBITS macro defines a global variable to store the lockbit data. This + * variable is assigned to its own linker section. Assign the desired lockbit + * values immediately in the variable initialization. + * + * The .lock section in the ELF file will get its values from the initial + * variable assignment ONLY. This means that you can NOT assign values to + * this variable in functions and the new values will not be put into the + * ELF .lock section. + * + * The global variable is declared in the LOCKBITS macro has two leading + * underscores, which means that it is reserved for the "implementation", + * meaning the library, so it will not conflict with a user-named variable. + * + * You must initialize the lockbit variable to some meaningful value, even + * if it is the default value. This is because the lockbits default to a + * logical 1, meaning unprogrammed. Normal uninitialized data defaults to all + * locgial zeros. So it is vital that all lockbits are initialized, even with + * default data. If they are not, then the lockbits may not programmed to the + * desired settings and can possibly put your device into an unrecoverable + * state. + * + * Be sure to have the -mmcu=<em>device</em> flag in your compile command line and + * your linker command line to have the correct device selected and to have + * the correct I/O header file included when you include <avr/io.h>. + * + * You can print out the contents of the .lock section in the ELF file by + * using this command line: + * \code + * avr-objdump -s -j .lock <ELF file> + * \endcode + */ + +/* + * Copyright (c) 2007, Atmel Corporation + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * * Neither the name of the copyright holders nor the names of + * contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#ifndef _AVR_LOCK_H_ +#define _AVR_LOCK_H_ 1 + +/** + * @defgroup avr_lock Lockbit Support + * + * @ingroup avr + */ +/**@{*/ + +#ifndef __ASSEMBLER__ + +#ifndef LOCKMEM +#define LOCKMEM __attribute__((section (".lock"))) +#endif + +#ifndef LOCKBITS +#define LOCKBITS unsigned char __lock LOCKMEM +#endif + +#endif /* !__ASSEMBLER */ + + +/* Lock Bit Modes */ +#if defined(__LOCK_BITS_EXIST) +#define LB_MODE_1 (0xFF) +#define LB_MODE_2 (0xFE) +#define LB_MODE_3 (0xFC) +#endif + +#if defined(__BOOT_LOCK_BITS_0_EXIST) +#define BLB0_MODE_1 (0xFF) +#define BLB0_MODE_2 (0xFB) +#define BLB0_MODE_3 (0xF3) +#define BLB0_MODE_4 (0xF7) +#endif + +#if defined(__BOOT_LOCK_BITS_1_EXIST) +#define BLB1_MODE_1 (0xFF) +#define BLB1_MODE_2 (0xEF) +#define BLB1_MODE_3 (0xCF) +#define BLB1_MODE_4 (0xDF) +#endif + +#if defined(__BOOT_LOCK_APPLICATION_TABLE_BITS_EXIST) +#define BLBAT0 ~_BV(2) +#define BLBAT1 ~_BV(3) +#endif + +#if defined(__BOOT_LOCK_APPLICATION_BITS_EXIST) +#define BLBA0 ~_BV(4) +#define BLBA1 ~_BV(5) +#endif + +#if defined(__BOOT_LOCK_BOOT_BITS_EXIST) +#define BLBB0 ~_BV(6) +#define BLBB1 ~_BV(7) +#endif + + +#define LOCKBITS_DEFAULT (0xFF) + +/**@}*/ +#endif /* _AVR_LOCK_H_ */ |