RISCV32IM-MCU-Eval软核

#include <stdint.h> #define DEFAULT_BAUDRATE (115200) #define NS16550_BASE (0x62300000ULL) #define NS16550_CLOCK_RATE (1000ULL * CLOCK_KHZ) enum __attribute__ ((__packed__)) ier_t { IER_ERBI = (1<<0), IER_ETBEI = (1<<1), IER_ELSI = (1<<2), IER_EDSSI = (1<<3), IER_SLEEP = (1<<4), // 16650 only }; enum __attribute__ ((__packed__)) iir_t { IIR_IP = 1, IIR_NONE = 1, IIR_RLSI = 6, IIR_RDAI = 4, IIR_CTOI = 0xc, IIR_THRI = 2, IIR_MSRI = 0, IIR_F64E = 0x20, IIR_FE = 0xc0, }; enum __attribute__ ((__packed__)) fcr_t { FCR_FE = 1, FCR_RXFR = 2, FCR_TXFR = 4, FCR_DMS = 8, FCR_F64E = 0x20, FCR_RT1 = 0, FCR_RT4 = 0x40, FCR_RT8 = 0x80, FCR_RT14 = 0xc0, FCR_RT16 = 0x40, FCR_RT32 = 0x80, FCR_RT56 = 0xc0, }; enum __attribute__ ((__packed__)) lcr_t { LCR_WLS5 = 0, LCR_WLS6 = 1, LCR_WLS7 = 2, LCR_WLS8 = 3, LCR_STB = 4, LCR_PEN = 8, LCR_EPS = 0x10, LCR_SP = 0x20, LCR_BC = 0x40, LCR_DLAB = 0x80, }; enum __attribute__ ((__packed__)) mcr_t { MCR_DTR = 1, MCR_RTS = 2, MCR_OUT1 = 4, MCR_OUT2 = 8, MCR_LOOP = 0x10, MCR_AFE = 0x20, }; enum __attribute__ ((__packed__)) lsr_t { LSR_DR = 1, LSR_OE = 2, LSR_PE = 4, LSR_FE = 8, LSR_BI = 0x10, LSR_THRE = 0x20, LSR_TEMT = 0x40, LSR_RXFE = 0x80, }; enum __attribute__ ((__packed__)) msr_t { MSR_DCTS = 1, MSR_DDSR = 2, MSR_TERI = 4, MSR_DDCD = 8, MSR_CTS = 0x10, MSR_DSR = 0x20, MSR_RI = 0x40, MSR_DCD = 0x80, }; struct __attribute__ ((aligned (4))) ns16550_pio { // 0x000 union __attribute__ ((aligned (4))) { const volatile uint8_t rbr; volatile uint8_t thr; volatile uint8_t dll; }; // 0x004 union __attribute__ ((aligned (4))) { volatile uint8_t dlm; volatile enum ier_t ier; }; // 0x008 union __attribute__ ((aligned (4))) { const volatile enum iir_t iir; volatile enum fcr_t fcr; }; // 0x00c volatile enum lcr_t lcr __attribute__ ((aligned (4))); // 0x010 volatile enum mcr_t mcr __attribute__ ((aligned (4))); // 0x014 volatile enum lsr_t lsr __attribute__ ((aligned (4))); // 0x018 volatile uint8_t msr __attribute__ ((aligned (4))); // 0x01c volatile uint8_t scr __attribute__ ((aligned (4))); }; static struct ns16550_pio * pio = (void*)NS16550_BASE; __attribute__ ((constructor)) static int ns16550_init(void) { uint32_t divisor; pio->ier = 0; divisor = NS16550_CLOCK_RATE / (16 * DEFAULT_BAUDRATE); pio->lcr |= LCR_DLAB; pio->dll = divisor & 0xff; pio->dlm = (divisor >> 8) & 0xff; pio->lcr &= ~LCR_DLAB; pio->lcr = LCR_WLS8; pio->fcr = FCR_FE; pio->mcr = MCR_RTS; return 0; } int ns16550_rxready(void) { return ((pio->lsr & LSR_DR) != 0); } int ns16550_rxchar(void) { while ((pio->lsr & LSR_DR) == 0) ; // nothing return pio->rbr; } int ns16550_txchar(int c) { while ((pio->lsr & LSR_THRE) == 0) ; // nothing pio->thr = c; return c; } void ns16550_flush(void) { while ((pio->lsr & LSR_TEMT) == 0) ; // nothing } int _read(int file, char *ptr, int len) { int count = 0; while (ns16550_rxready() && (count < len)) { *ptr++ = ns16550_rxchar(); count++; } return count; } int _write(int file, char *ptr, int len) { int todo; for (todo = 0; todo < len; todo++) { ns16550_txchar (*ptr++); } return len; }