spi.c
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/*
* Copyright (C) 2015 Loci Controls Inc.
* 2016 Freie Universität 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_cc2538
* @ingroup drivers_periph_spi
* @{
*
* @file
* @brief Low-level SPI driver implementation
*
* @author Ian Martin <ian@locicontrols.com>
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
*
* @}
*/
#include "cpu.h"
#include "mutex.h"
#include "assert.h"
#include "periph/spi.h"
/**
* @brief Array holding one pre-initialized mutex for each SPI device
*/
static mutex_t locks[SPI_NUMOF];
static inline cc2538_ssi_t *dev(spi_t bus)
{
return spi_config[bus].dev;
}
static inline void poweron(spi_t bus)
{
SYS_CTRL_RCGCSSI |= (1 << bus);
SYS_CTRL_SCGCSSI |= (1 << bus);
SYS_CTRL_DCGCSSI |= (1 << bus);
}
static inline void poweroff(spi_t bus)
{
SYS_CTRL_RCGCSSI &= ~(1 << bus);
SYS_CTRL_SCGCSSI &= ~(1 << bus);
SYS_CTRL_DCGCSSI &= ~(1 << bus);
}
void spi_init(spi_t bus)
{
assert(bus <= SPI_NUMOF);
/* temporarily power on the device */
poweron(bus);
/* configure device to be a master and disable SSI operation mode */
dev(bus)->CR1 = 0;
/* configure system clock as SSI clock source */
dev(bus)->CC = SSI_SS_IODIV;
/* and power off the bus again */
poweroff(bus);
/* trigger SPI pin configuration */
spi_init_pins(bus);
}
void spi_init_pins(spi_t bus)
{
switch ((uintptr_t)spi_config[bus].dev) {
case (uintptr_t)SSI0:
IOC_PXX_SEL[spi_config[bus].mosi_pin] = SSI0_TXD;
IOC_PXX_SEL[spi_config[bus].sck_pin ] = SSI0_CLKOUT;
IOC_PXX_SEL[spi_config[bus].cs_pin ] = SSI0_FSSOUT;
IOC_SSIRXD_SSI0 = spi_config[bus].miso_pin;
break;
case (uintptr_t)SSI1:
IOC_PXX_SEL[spi_config[bus].mosi_pin] = SSI1_TXD;
IOC_PXX_SEL[spi_config[bus].sck_pin ] = SSI1_CLKOUT;
IOC_PXX_SEL[spi_config[bus].cs_pin ] = SSI1_FSSOUT;
IOC_SSIRXD_SSI1 = spi_config[bus].miso_pin;
break;
}
IOC_PXX_OVER[spi_config[bus].mosi_pin] = IOC_OVERRIDE_OE;
IOC_PXX_OVER[spi_config[bus].miso_pin] = IOC_OVERRIDE_DIS;
IOC_PXX_OVER[spi_config[bus].sck_pin ] = IOC_OVERRIDE_OE;
IOC_PXX_OVER[spi_config[bus].cs_pin ] = IOC_OVERRIDE_OE;
gpio_hardware_control(spi_config[bus].mosi_pin);
gpio_hardware_control(spi_config[bus].miso_pin);
gpio_hardware_control(spi_config[bus].sck_pin);
gpio_hardware_control(spi_config[bus].cs_pin);
}
int spi_acquire(spi_t bus, spi_cs_t cs, spi_mode_t mode, spi_clk_t clk)
{
/* lock the bus */
mutex_lock(&locks[bus]);
/* power on device */
poweron(bus);
/* configure SCR clock field, data-width and mode */
dev(bus)->CR0 = 0;
dev(bus)->CPSR = (spi_clk_config[clk].cpsr);
dev(bus)->CR0 = ((spi_clk_config[clk].scr << 8) | mode | SSI_CR0_DSS(8));
/* enable SSI device */
dev(bus)->CR1 = SSI_CR1_SSE;
return SPI_OK;
}
void spi_release(spi_t bus)
{
/* disable and power off device */
dev(bus)->CR1 = 0;
poweroff(bus);
/* and release lock... */
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);
}
if (!in_buf) {
for (size_t i = 0; i < len; i++) {
while (!(dev(bus)->SR & SSI_SR_TNF)) {}
dev(bus)->DR = out_buf[i];
}
/* flush RX FIFO while busy*/
while ((dev(bus)->SR & SSI_SR_BSY)) {
dev(bus)->DR;
}
}
else if (!out_buf) { /*TODO this case is currently untested */
size_t in_cnt = 0;
for (size_t i = 0; i < len; i++) {
while (!(dev(bus)->SR & SSI_SR_TNF)) {}
dev(bus)->DR = 0;
if (dev(bus)->SR & SSI_SR_RNE) {
in_buf[in_cnt++] = dev(bus)->DR;
}
}
/* get remaining bytes */
while (dev(bus)->SR & SSI_SR_RNE) {
in_buf[in_cnt++] = dev(bus)->DR;
}
}
else {
for (size_t i = 0; i < len; i++) {
while (!(dev(bus)->SR & SSI_SR_TNF)) {}
dev(bus)->DR = out_buf[i];
while (!(dev(bus)->SR & SSI_SR_RNE)){}
in_buf[i] = dev(bus)->DR;
}
/* wait until no more busy */
while ((dev(bus)->SR & SSI_SR_BSY)) {}
}
if ((!cont) && (cs != SPI_CS_UNDEF)) {
gpio_set((gpio_t)cs);
}
}