stm32f4: Add support for SPI

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2019-07-27 11:57:14 -04:00
parent d79f99b188
commit 961d13ee1a
4 changed files with 69 additions and 0 deletions

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@ -7,6 +7,8 @@ config STM32F4_SELECT
default y
select HAVE_GPIO
select HAVE_GPIO_ADC
select HAVE_GPIO_SPI
select HAVE_GPIO_BITBANGING
config BOARD_DIRECTORY
string

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@ -16,6 +16,7 @@ src-y += generic/crc16_ccitt.c generic/alloc.c
src-y += generic/armcm_irq.c generic/armcm_timer.c
src-y += ../lib/stm32f4/system_stm32f4xx.c
src-$(CONFIG_HAVE_GPIO_ADC) += stm32f4/adc.c
src-$(CONFIG_HAVE_GPIO_SPI) += stm32f4/spi.c
src-$(CONFIG_SERIAL) += stm32f4/serial.c generic/serial_irq.c
# Add assembler build rules

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@ -29,4 +29,13 @@ uint32_t gpio_adc_sample(struct gpio_adc g);
uint16_t gpio_adc_read(struct gpio_adc g);
void gpio_adc_cancel_sample(struct gpio_adc g);
struct spi_config {
void *spidev;
uint32_t spi_cr1;
};
struct spi_config spi_setup(uint32_t bus, uint8_t mode, uint32_t rate);
void spi_prepare(struct spi_config config);
void spi_transfer(struct spi_config config, uint8_t receive_data
, uint8_t len, uint8_t *data);
#endif // gpio.h

57
src/stm32f4/spi.c Normal file
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@ -0,0 +1,57 @@
// SPI functions on STM32F4
//
// Copyright (C) 2019 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "command.h" // shutdown
#include "gpio.h" // spi_setup
#include "internal.h" // gpio_peripheral
#include "sched.h" // sched_shutdown
DECL_ENUMERATION("spi_bus", "spi2", 0);
DECL_CONSTANT_STR("BUS_PINS_spi2", "PB14,PB15,PB13");
struct spi_config
spi_setup(uint32_t bus, uint8_t mode, uint32_t rate)
{
if (bus)
shutdown("Invalid spi bus");
// Enable SPI
enable_pclock(SPI2_BASE);
gpio_peripheral(GPIO('B', 14), GPIO_FUNCTION, 5, 1);
gpio_peripheral(GPIO('B', 15), GPIO_FUNCTION, 5, 0);
gpio_peripheral(GPIO('B', 13), GPIO_FUNCTION, 5, 0);
// Calculate CR1 register
uint32_t pclk = get_pclock_frequency(SPI2_BASE);
uint32_t div = 0;
while ((pclk >> (div + 1)) > rate && div < 7)
div++;
uint32_t cr1 = ((mode << SPI_CR1_CPHA_Pos) | (div << SPI_CR1_BR_Pos)
| SPI_CR1_SPE | SPI_CR1_MSTR | SPI_CR1_SSM | SPI_CR1_SSI);
return (struct spi_config){ .spi_cr1 = cr1 };
}
void
spi_prepare(struct spi_config config)
{
SPI2->CR1 = config.spi_cr1;
}
void
spi_transfer(struct spi_config config, uint8_t receive_data,
uint8_t len, uint8_t *data)
{
while (len--) {
SPI2->DR = *data;
while (!(SPI2->SR & SPI_SR_RXNE))
;
uint8_t rdata = SPI2->DR;
if (receive_data)
*data = rdata;
data++;
}
}