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RIOT/cpu/rpx0xx/periph/spi.c
Frank Engelhardt 6353181c74 cpu/rpx0xx: add spi functionality
2023-05-01 12:13:15 +02:00

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/*
* Copyright (C) 2023 Frank Engelhardt
*
* 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_rpx0xx
* @{
*
* @file
* @brief Implementation of SPI.
*
* @author Frank Engelhardt <frank@f9e.de>
*
* @}
*/
#include "assert.h"
#include "bitarithm.h"
#include "cpu.h"
#include "mutex.h"
#include "periph/gpio.h"
#include "periph/spi.h"
#define ENABLE_DEBUG 0
#include "debug.h"
/**
* @brief Allocate one lock per SPI device.
*/
static mutex_t locks[SPI_NUMOF];
/**
* @brief Save the clock prescaler values for faster bus acquisition.
*/
typedef struct {
spi_clk_t clk;
uint8_t cpsdvsr;
uint8_t scr;
} _pl022_clk_t;
static _pl022_clk_t pl022_clk[SPI_NUMOF];
gpio_t spi_pin_clk(spi_t spi)
{
assert((unsigned)spi < SPI_NUMOF);
return spi_config[spi].clk_pin;
}
gpio_t spi_pin_miso(spi_t spi)
{
assert((unsigned)spi < SPI_NUMOF);
return spi_config[spi].miso_pin;
}
gpio_t spi_pin_mosi(spi_t spi)
{
assert((unsigned)spi < SPI_NUMOF);
return spi_config[spi].mosi_pin;
}
static void _poweron(spi_t spi)
{
uint32_t reset_bit_mask = (spi_config[spi].dev == SPI0)
? RESETS_RESET_spi0_Msk
: RESETS_RESET_spi1_Msk;
periph_reset(reset_bit_mask);
periph_reset_done(reset_bit_mask);
}
static void _poweroff(spi_t spi)
{
uint32_t reset_bit_mask = (spi_config[spi].dev == SPI0)
? RESETS_RESET_spi0_Msk
: RESETS_RESET_spi1_Msk;
periph_reset(reset_bit_mask);
}
void spi_init(spi_t spi)
{
DEBUG("[rpx0xx] Call spi_init(spi=%" PRIdFAST8 ")", spi);
assert((unsigned)spi < SPI_NUMOF);
/* initialize device lock */
mutex_init(&locks[spi]);
/* trigger pin initialization */
spi_init_pins(spi);
/* clock prescaler values must be calculated */
pl022_clk[spi].clk = 0xff;
}
void spi_init_pins(spi_t spi)
{
DEBUG("[rpx0xx] Call spi_init_pins(spi=%" PRIdFAST8 ")", spi);
assert((unsigned)spi < SPI_NUMOF);
const gpio_pad_ctrl_t mosi_pad_config = {
/* SPI should typically draw less than 2 mA */
.drive_strength = DRIVE_STRENGTH_2MA,
};
const gpio_io_ctrl_t mosi_io_config = {
.function_select = FUNCTION_SELECT_SPI,
};
const gpio_pad_ctrl_t clk_pad_config = {
/* SPI should typically draw less than 2 mA */
.drive_strength = DRIVE_STRENGTH_2MA,
};
const gpio_io_ctrl_t clk_io_config = {
.function_select = FUNCTION_SELECT_SPI,
};
const gpio_pad_ctrl_t miso_pad_config = {
.input_enable = 1,
.schmitt_trig_enable = 1,
};
const gpio_io_ctrl_t miso_io_config = {
.function_select = FUNCTION_SELECT_SPI,
};
if (gpio_is_valid(spi_config[spi].mosi_pin)) {
gpio_set_pad_config(spi_config[spi].mosi_pin, mosi_pad_config);
gpio_set_io_config(spi_config[spi].mosi_pin, mosi_io_config);
}
if (gpio_is_valid(spi_config[spi].clk_pin)) {
gpio_set_pad_config(spi_config[spi].clk_pin, clk_pad_config);
gpio_set_io_config(spi_config[spi].clk_pin, clk_io_config);
}
if (gpio_is_valid(spi_config[spi].miso_pin)) {
gpio_set_pad_config(spi_config[spi].miso_pin, miso_pad_config);
gpio_set_io_config(spi_config[spi].miso_pin, miso_io_config);
}
/* allow access to the bus */
mutex_unlock(&locks[spi]);
}
void spi_deinit_pins(spi_t spi)
{
DEBUG("[rpx0xx] Call spi_deinit_pins(spi=%" PRIdFAST8 ")\n", spi);
/* lock mutex to block usage of the SPI bus */
mutex_lock(&locks[spi]);
assert((unsigned)spi < SPI_NUMOF);
if (gpio_is_valid(spi_config[spi].mosi_pin)) {
gpio_reset_all_config(spi_config[spi].mosi_pin);
}
if (gpio_is_valid(spi_config[spi].miso_pin)) {
gpio_reset_all_config(spi_config[spi].miso_pin);
}
if (gpio_is_valid(spi_config[spi].clk_pin)) {
gpio_reset_all_config(spi_config[spi].clk_pin);
}
}
int spi_init_cs(spi_t spi, spi_cs_t cs)
{
DEBUG("[rpx0xx] Call spi_init_cs(spi=%" PRIdFAST8 ", cs=%" PRIu32 ")\n",
spi, cs);
if (spi >= SPI_NUMOF) {
return SPI_NODEV;
}
if (!gpio_is_valid(cs)) {
return SPI_NOCS;
}
gpio_init((gpio_t)cs, GPIO_OUT);
gpio_set((gpio_t)cs);
return SPI_OK;
}
int spi_deinit_cs(spi_t spi, spi_cs_t cs)
{
DEBUG("[rpx0xx] Call spi_deinit_cs(spi=%" PRIdFAST8 ", cs=%" PRIu32 ")\n",
spi, cs);
if (spi >= SPI_NUMOF) {
return SPI_NODEV;
}
if (!gpio_is_valid(cs)) {
return SPI_NOCS;
}
gpio_reset_all_config((gpio_t)cs);
return SPI_OK;
}
static inline void _check_best_clk_result(uint16_t target_dvsr,
uint16_t cur_dvsr,
uint16_t scr,
uint8_t cpsdvsr,
uint16_t *best_diff,
uint16_t *best_scr,
uint8_t *best_cpsdvsr)
{
uint16_t diff = (target_dvsr > cur_dvsr)
? target_dvsr - cur_dvsr
: cur_dvsr - target_dvsr;
if (diff < *best_diff) {
*best_diff = diff;
*best_cpsdvsr = cpsdvsr;
*best_scr = scr;
}
}
static void _calc_pl022_clk(_pl022_clk_t *pl022_clk, spi_clk_t clk)
{
uint16_t dvsr = CLOCK_PERIPH / clk;
/* The divisor must be split into two 8-bit divisors, cpsdvsr and scr,
* dvsr = cpsdvsr*scr. cpsdvsr must be an even number greater than 0. */
uint8_t cpsdvsr = 2, best_cpsdvsr = 2;
uint16_t scr = 256, best_scr = 256;
uint16_t best_diff = dvsr;
uint16_t cur_dvsr = scr * cpsdvsr;
/* Come from above with cpsdvsr and from below with scr.
* Check all intermediate combinations and use the best. */
_check_best_clk_result(dvsr, cur_dvsr, scr, cpsdvsr, &best_diff,
&best_scr, &best_cpsdvsr);
while (scr > 0 && cpsdvsr < 254 && best_diff != 0) {
while (dvsr > cur_dvsr && cpsdvsr < 254) {
cpsdvsr += 2;
cur_dvsr += 2 * scr;
_check_best_clk_result(dvsr, cur_dvsr, scr, cpsdvsr, &best_diff,
&best_scr, &best_cpsdvsr);
}
while (dvsr < cur_dvsr && scr > 0) {
scr -= 1;
cur_dvsr -= cpsdvsr;
_check_best_clk_result(dvsr, cur_dvsr, scr, cpsdvsr, &best_diff,
&best_scr, &best_cpsdvsr);
}
}
uint32_t resulting_clk_hz = CLOCK_PERIPH / (best_cpsdvsr * best_scr);
pl022_clk->clk = clk;
pl022_clk->cpsdvsr = best_cpsdvsr;
/* For scr, +1 is added internally. */
pl022_clk->scr = (best_scr - 1);
DEBUG("[rpx0xx] Values for spi clock divider registers CPSDVSR=%" PRIu16
", SCR=%" PRIu16 ". Resulting clock is %" PRIu32 " Hz.\n",
best_cpsdvsr, best_scr - 1, resulting_clk_hz);
}
void spi_acquire(spi_t spi, spi_cs_t cs, spi_mode_t mode, spi_clk_t clk)
{
DEBUG("[rpx0xx] Call spi_acquire(spi=%" PRIuFAST8 ", cs=%" PRIu32
", mode=%" PRIu16 ", clk=%" PRIu32 ")\n", spi, cs, mode, clk);
assert((unsigned)spi < SPI_NUMOF);
assert(clk == SPI_CLK_100KHZ || clk == SPI_CLK_10MHZ || clk == SPI_CLK_1MHZ
|| clk == SPI_CLK_400KHZ || clk == SPI_CLK_5MHZ);
(void)cs;
/* lock bus */
mutex_lock(&locks[spi]);
_poweron(spi);
SPI0_Type *dev = spi_config[spi].dev;
io_reg_write_dont_corrupt(&dev->SSPCR0,
0x7 << SPI0_SSPCR0_DSS_Pos,
SPI0_SSPCR0_DSS_Msk);
/* uncomment the following line for debug loopback mode */
/* io_reg_atomic_set(&dev->SSPCR1, SPI0_SSPCR1_LBM_Msk); */
/* set SPI mode */
switch (mode) {
case SPI_MODE_0:
io_reg_atomic_clear(&dev->SSPCR0, SPI0_SSPCR0_SPO_Msk);
io_reg_atomic_clear(&dev->SSPCR0, SPI0_SSPCR0_SPH_Msk);
break;
case SPI_MODE_1:
io_reg_atomic_clear(&dev->SSPCR0, SPI0_SSPCR0_SPO_Msk);
io_reg_atomic_set(&dev->SSPCR0, SPI0_SSPCR0_SPH_Msk);
break;
case SPI_MODE_2:
io_reg_atomic_set(&dev->SSPCR0, SPI0_SSPCR0_SPO_Msk);
io_reg_atomic_clear(&dev->SSPCR0, SPI0_SSPCR0_SPH_Msk);
break;
case SPI_MODE_3:
io_reg_atomic_set(&dev->SSPCR0, SPI0_SSPCR0_SPO_Msk);
io_reg_atomic_set(&dev->SSPCR0, SPI0_SSPCR0_SPH_Msk);
break;
}
/* set clock speed */
if (clk != pl022_clk[spi].clk) {
_calc_pl022_clk(&pl022_clk[spi], clk);
}
io_reg_write_dont_corrupt(&dev->SSPCPSR,
pl022_clk[spi].cpsdvsr << SPI0_SSPCPSR_CPSDVSR_Pos,
SPI0_SSPCPSR_CPSDVSR_Msk);
io_reg_write_dont_corrupt(&dev->SSPCR0,
pl022_clk[spi].scr << SPI0_SSPCR0_SCR_Pos,
SPI0_SSPCR0_SCR_Msk);
/* enable SPI */
io_reg_atomic_set(&dev->SSPCR1, SPI0_SSPCR1_SSE_Msk);
}
void spi_release(spi_t spi)
{
DEBUG("[rpx0xx] Call spi_release(spi=%" PRIdFAST8 ")\n", spi);
assert((unsigned)spi < SPI_NUMOF);
SPI0_Type *dev = spi_config[spi].dev;
/* disable SPI */
io_reg_atomic_clear(&dev->SSPCR1, SPI0_SSPCR1_SSE_Msk);
_poweroff(spi);
mutex_unlock(&locks[spi]);
}
static inline void _wait_for_end(spi_t spi)
{
DEBUG("[rpx0xx] Call _wait_for_end(spi=%" PRIdFAST8 ")\n", spi);
SPI0_Type *dev = spi_config[spi].dev;
while (!(dev->SSPSR & SPI0_SSPSR_TFE_Msk)) {}
while (dev->SSPSR & SPI0_SSPSR_BSY_Msk) {}
}
static void _transfer_no_dma(spi_t spi, const void *out, void *in, size_t len)
{
DEBUG("[rpx0xx] Call _transfer_no_dma(spi=%" PRIdFAST8
", out=%p, in=%p, len=%" PRIu16 ")\n",
spi, out, in, len);
const uint8_t *outbuf = out;
uint8_t *inbuf = in;
SPI0_Type *dev = spi_config[spi].dev;
/* transfer data, use shortpath if only sending data */
if (!inbuf) {
for (size_t i = 0; i < len; i++) {
while (!(dev->SSPSR & SPI0_SSPSR_TFE_Msk)) {}
dev->SSPDR = outbuf[i];
}
/* wait until everything is finished and empty the receive buffer */
while (!(dev->SSPSR & SPI0_SSPSR_TFE_Msk)) {}
while (dev->SSPSR & SPI0_SSPSR_BSY_Msk) {}
while (dev->SSPSR & SPI0_SSPSR_RNE_Msk) {
dev->SSPDR;
}
}
else if (!outbuf) {
for (size_t i = 0; i < len; i++) {
while (!(dev->SSPSR & SPI0_SSPSR_TFE_Msk)) {}
dev->SSPDR = 0;
while (!(dev->SSPSR & SPI0_SSPSR_RNE_Msk)) {}
inbuf[i] = dev->SSPDR & 0xffUL;
}
}
else {
for (size_t i = 0; i < len; i++) {
while (!(dev->SSPSR & SPI0_SSPSR_TFE_Msk)) {}
dev->SSPDR = outbuf[i];
while (!(dev->SSPSR & SPI0_SSPSR_RNE_Msk)) {}
inbuf[i] = dev->SSPDR & 0xffUL;
}
}
_wait_for_end(spi);
}
void spi_transfer_bytes(spi_t spi, spi_cs_t cs, bool cont,
const void *out, void *in, size_t len)
{
DEBUG("[rpx0xx] Call spi_transfer_bytes(spi=%" PRIdFAST8
", out=%p, in=%p, len=%" PRIu16 ")\n",
spi, out, in, len);
/* make sure at least one input or one output buffer is given */
assert(out || in);
/* activate the given chip select line */
if (gpio_is_valid(cs)) {
gpio_clear((gpio_t)cs);
}
_transfer_no_dma(spi, out, in, len);
/* release the chip select if not specified differently */
if ((!cont) && gpio_is_valid(cs)) {
gpio_set((gpio_t)cs);
}
}
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