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/*
ChibiOS/RT - Copyright (C) 2006-2007 Giovanni Di Sirio.
This file is part of ChibiOS/RT.
ChibiOS/RT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
ChibiOS/RT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @file ports/ARM7-LPC214x/lpc214x_ssp.c
* @brief LPC214x SSP driver code.
* @addtogroup LPC214x_SSP
* @{
*/
#include <ch.h>
#include "lpc214x.h"
#include "lpc214x_ssp.h"
#if LPC214x_SSP_USE_MUTEX
static Semaphore me;
#endif
/**
* @brief Aquires access to the SSP bus.
* @note This function also handles the mutual exclusion on the SSP bus if
* the @p LPC214x_SSP_USE_MUTEX option is enabled.
*/
void sspAcquireBus(void) {
#if LPC214x_SSP_USE_MUTEX
chSemWait(&me);
#endif
IO0CLR = 1 << 20;
}
/**
* @brief Releases the SSP bus.
* @note This function also handles the mutual exclusion on the SSP bus if
* the @p LPC214x_SSP_USE_MUTEX option is enabled.
*/
void sspReleaseBus(void) {
IO0SET = 1 << 20;
#if LPC214x_SSP_USE_MUTEX
chSemSignal(&me);
#endif
}
/**
* @brief Synchronous SSP transfer.
* @param[in] in pointer to the incoming data buffer, if this parameter is set
* to @p NULL then the incoming data is discarded
* @param[out] out pointer to the outgoing data buffer, if this parameter is
* set to @p NULL then 0xFF bytes will be output
* @param[in] n the number of bytes to be transferred
* @note The transfer is performed in a software loop and is not interrupt
* driven for performance reasons, this function should be invoked
* by a low priority thread in order to "play nice" with the
* rest of the system. This kind of peripheral would really need a
* dedicated DMA channel.
*/
void sspRW(uint8_t *in, uint8_t *out, size_t n) {
int icnt, ocnt;
SSP *ssp = SSPBase;
icnt = ocnt = n;
while (icnt) {
if (ssp->SSP_SR & SR_RNE) {
if (in)
*in++ = ssp->SSP_DR;
else
ssp->SSP_DR;
icnt--;
continue; /* Priority over transmission. */
}
if (ocnt && (ssp->SSP_SR & SR_TNF)) {
if (out)
ssp->SSP_DR = *out++;
else
ssp->SSP_DR = 0xFF;
ocnt--;
}
}
}
/**
* @brief SSP setup.
* @param[in] cpsr the value for the @p CPSR register
* @param[in] cr0 the value for the @p CR0 register
* @param[in] cr1 the value for the @p CR1 register
*/
void lpc214x_ssp_setup(int cpsr, int cr0, int cr1) {
SSP *ssp = SSPBase;
ssp->SSP_CR1 = 0;
ssp->SSP_CR0 = cr0;
ssp->SSP_CPSR = cpsr;
ssp->SSP_CR1 = cr1 | CR1_SSE;
}
/**
* @brief SSP subsystem initialization.
*/
void lpc214x_ssp_init(void) {
/* Enables the SPI1 clock */
PCONP = (PCONP & PCALL) | PCSPI1;
/* Clock = PCLK / 2 (fastest). */
lpc214x_ssp_setup(2, CR0_DSS8BIT | CR0_FRFSPI | CR0_CLOCKRATE(0), 0);
#if LPC214x_SSP_USE_MUTEX
chSemInit(&me, 1);
#endif
}
/** @} */
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