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/******************************************************************************
* The MIT License
*
* Copyright (c) 2010 LeafLabs, LLC.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy,
* modify, merge, publish, distribute, sublicense, and/or sell copies
* of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*****************************************************************************/
/**
* @file bkp.c
* @brief Backup register support.
*/
#include "bkp.h"
#include "pwr.h"
#include "rcc.h"
#include "bitband.h"
static inline __io uint32* data_register(uint8 reg);
bkp_dev bkp = {
.regs = BKP_BASE,
};
/** Backup device. */
const bkp_dev *BKP = &bkp;
/**
* @brief Initialize backup interface.
*
* Enables the power and backup interface clocks, and resets the
* backup device.
*/
void bkp_init(void) {
/* Don't call pwr_init(), or you'll reset the device. We just
* need the clock. */
rcc_clk_enable(RCC_PWR);
rcc_clk_enable(RCC_BKP);
rcc_reset_dev(RCC_BKP);
}
/**
* Enable write access to the backup registers. Backup interface must
* be initialized for subsequent register writes to work.
* @see bkp_init()
*/
void bkp_enable_writes(void) {
*bb_perip(&PWR_BASE->CR, PWR_CR_DBP) = 1;
}
/**
* Disable write access to the backup registers.
*/
void bkp_disable_writes(void) {
*bb_perip(&PWR_BASE->CR, PWR_CR_DBP) = 0;
}
/**
* Read a value from given backup data register.
* @param reg Data register to read, from 1 to BKP_NR_DATA_REGS (10 on
* medium-density devices, 42 on high-density devices).
*/
uint16 bkp_read(uint8 reg) {
__io uint32* dr = data_register(reg);
if (!dr) {
ASSERT(0); /* nonexistent register */
return 0;
}
return (uint16)*dr;
}
/**
* @brief Write a value to given data register.
*
* Write access to backup registers must be enabled.
*
* @param reg Data register to write, from 1 to BKP_NR_DATA_REGS (10
* on medium-density devices, 42 on high-density devices).
* @param val Value to write into the register.
* @see bkp_enable_writes()
*/
void bkp_write(uint8 reg, uint16 val) {
__io uint32* dr = data_register(reg);
if (!dr) {
ASSERT(0); /* nonexistent register */
return;
}
*dr = (uint32)val;
}
/*
* Data register memory layout is not contiguous. It's split up from
* 1--NR_LOW_DRS, beginning at BKP_BASE->DR1, through to
* (NR_LOW_DRS+1)--BKP_NR_DATA_REGS, beginning at BKP_BASE->DR11.
*/
#define NR_LOW_DRS 10
static inline __io uint32* data_register(uint8 reg) {
if (reg < 1 || reg > BKP_NR_DATA_REGS) {
return 0;
}
#if BKP_NR_DATA_REGS == NR_LOW_DRS
return (uint32*)BKP_BASE + reg;
#else
if (reg <= NR_LOW_DRS) {
return (uint32*)BKP_BASE + reg;
} else {
return (uint32*)&(BKP_BASE->DR11) + (reg - NR_LOW_DRS - 1);
}
#endif
}
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