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 elopes
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/*
* Copyright (C) 2014-2016 Freie Universitรคt Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup cpu_nrf5x_common
* @ingroup drivers_periph_spi
* @{
*
* @file
* @brief Low-level SPI driver implementation
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
* @author Frank Holtz <frank-riot2015@holtznet.de>
* @author Jan Wagner <mail@jwagner.eu>
*
* @}
*/
#include "cpu.h"
#include "mutex.h"
#include "assert.h"
#include "periph/spi.h"
#include "periph/gpio.h"
#ifdef SPI_NUMOF
/**
* @brief array holding one pre-initialized mutex for each SPI device
*/
static mutex_t locks[SPI_NUMOF];
static inline NRF_SPI_Type *dev(spi_t bus)
{
return spi_config[bus].dev;
}
void spi_init(spi_t bus)
{
assert(bus < SPI_NUMOF);
/* initialize mutex */
mutex_init(&locks[bus]);
/* initialize pins */
spi_init_pins(bus);
}
void spi_init_pins(spi_t bus)
{
/* set pin direction */
gpio_init(spi_config[bus].sclk, GPIO_OUT);
gpio_init(spi_config[bus].mosi, GPIO_OUT);
gpio_init(spi_config[bus].miso, GPIO_IN);
/* select pins for the SPI device */
SPI_SCKSEL = spi_config[bus].sclk;
SPI_MOSISEL = spi_config[bus].mosi;
SPI_MISOSEL = spi_config[bus].miso;
}
int spi_acquire(spi_t bus, spi_cs_t cs, spi_mode_t mode, spi_clk_t clk)
{
mutex_lock(&locks[bus]);
#ifdef CPU_FAM_NRF51
/* power on the bus (NRF51 only) */
dev(bus)->POWER = 1;
#endif
/* configure bus */
dev(bus)->CONFIG = mode;
dev(bus)->FREQUENCY = clk;
/* enable the bus */
dev(bus)->ENABLE = 1;
return SPI_OK;
}
void spi_release(spi_t bus)
{
/* power off everything */
dev(bus)->ENABLE = 0;
#ifdef CPU_FAM_NRF51
dev(bus)->POWER = 0;
#endif
mutex_unlock(&locks[bus]);
}
void spi_transfer_bytes(spi_t bus, spi_cs_t cs, bool cont,
const void *out, void *in, size_t len)
{
const uint8_t *out_buf = out;
uint8_t *in_buf = in;
assert(out_buf || in_buf);
if (cs != SPI_CS_UNDEF) {
gpio_clear((gpio_t)cs);
}
for (int i = 0; i < (int)len; i++) {
uint8_t tmp = (out_buf) ? out_buf[i] : 0;
dev(bus)->EVENTS_READY = 0;
dev(bus)->TXD = (uint8_t)tmp;
while (dev(bus)->EVENTS_READY != 1);
tmp = (uint8_t)dev(bus)->RXD;
if (in_buf) {
in_buf[i] = tmp;
}
}
if ((cs != SPI_CS_UNDEF) && (!cont)) {
gpio_set((gpio_t)cs);
}
}
#endif /* SPI_NUMOF */
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