rpi4-osdev/part14-spi-ethernet/lib/spi.c

101 lines
2.5 KiB
C
Raw Normal View History

#include "../include/io.h"
#include "../include/fb.h"
// SPI
struct Spi0Regs {
volatile unsigned int cs;
volatile unsigned int fifo;
volatile unsigned int clock;
volatile unsigned int data_length;
volatile unsigned int ltoh;
volatile unsigned int dc;
};
#define REGS_SPI0 ((struct Spi0Regs *)(PERIPHERAL_BASE + 0x00204000))
// CS Register
#define CS_LEN_LONG (1 << 25)
#define CS_DMA_LEN (1 << 24)
#define CS_CSPOL2 (1 << 23)
#define CS_CSPOL1 (1 << 22)
#define CS_CSPOL0 (1 << 21)
#define CS_RXF (1 << 20)
#define CS_RXR (1 << 19)
#define CS_TXD (1 << 18)
#define CS_RXD (1 << 17)
#define CS_DONE (1 << 16)
#define CS_LEN (1 << 13)
#define CS_REN (1 << 12)
#define CS_ADCS (1 << 11)
#define CS_INTR (1 << 10)
#define CS_INTD (1 << 9)
#define CS_DMAEN (1 << 8)
#define CS_TA (1 << 7)
#define CS_CSPOL (1 << 6)
#define CS_CLEAR_RX (1 << 5)
#define CS_CLEAR_TX (1 << 4)
#define CS_CPOL__SHIFT 3
#define CS_CPHA__SHIFT 2
#define CS_CS (1 << 0)
#define CS_CS__SHIFT 0
void spi_init() {
gpio_useAsAlt0(7); //CS1
gpio_initOutputPinWithPullNone(8); //CS0
gpio_useAsAlt0(9); //MISO
gpio_useAsAlt0(10); //MOSI
gpio_useAsAlt0(11); //SCLK
}
void spi_chip_select(unsigned char chip_select) {
gpio_setPinOutputBool(8, chip_select);
}
void spi_send_recv(unsigned char *sbuffer, unsigned char *rbuffer, unsigned int size) {
REGS_SPI0->data_length = size;
REGS_SPI0->cs = REGS_SPI0->cs | CS_CLEAR_RX | CS_CLEAR_TX | CS_TA;
unsigned int read_count = 0;
unsigned int write_count = 0;
while(read_count < size || write_count < size) {
while(write_count < size && REGS_SPI0->cs & CS_TXD) {
if (sbuffer) {
REGS_SPI0->fifo = *sbuffer++;
} else {
REGS_SPI0->fifo = 0;
}
write_count++;
}
while(read_count < size && REGS_SPI0->cs & CS_RXD) {
unsigned int data = REGS_SPI0->fifo;
if (rbuffer) {
*rbuffer++ = data;
}
read_count++;
}
}
while(!(REGS_SPI0->cs & CS_DONE)) {
while(REGS_SPI0->cs & CS_RXD) {
unsigned int r = REGS_SPI0->fifo;
debughex(r);
}
}
REGS_SPI0->cs = (REGS_SPI0->cs & ~CS_TA);
}
void spi_send(unsigned char *data, unsigned int size) {
spi_send_recv(data, 0, size);
}
void spi_recv(unsigned char *data, unsigned int size) {
spi_send_recv(0, data, size);
}