diff options
Diffstat (limited to 'uart')
| -rw-r--r-- | uart/uart.c | 213 | ||||
| -rw-r--r-- | uart/uart.h | 4 |
2 files changed, 217 insertions, 0 deletions
diff --git a/uart/uart.c b/uart/uart.c index 031cf74..2e5d68d 100644 --- a/uart/uart.c +++ b/uart/uart.c @@ -1,5 +1,218 @@ +#include <cm4.h> +#include <reg/gpio.h> +#include <reg/port.h> +#include <reg/sim.h> +#include <reg/uart.h> +#include <stddef.h> +#include <stdarg.h> + #include "uart.h" +#include "../asm.h" + +enum { + SBR_VAL = 39, + BRFA_VAL = 2, + SRBSZ = 1024, + FIFOSZ = 8, +}; + +static struct { + unsigned char buf[SRBSZ]; + int start, end; +} send_rb = { .start = 0, .end = 0 }; + +static inline size_t rb_store(void *_data, size_t size) +{ + unsigned char *data = _data; + size_t avail; + int start, end; + + start = send_rb.start; + end = send_rb.end; + avail = (start + sizeof send_rb.buf - end) % sizeof send_rb.buf - 1; + + if (size > avail) + size = avail; + + for (int i = 0; i < size; i++) + send_rb.buf[(end + i) % sizeof send_rb.buf] = data[i]; + send_rb.end = (end + size) % sizeof send_rb.buf; + + /* Enable Transmission Interrupt */ + CLI(); + SET_BIT(UART0_C2, C2_TIE); + STI(); + + return size; +} void uart_setup(void) { + /* Clock gating for UART0 */ + SET_BIT(SIM_SCGC4, SCGC4_UART0); + /* Disable TX and RX */ + SET_MASKED(UART0_C2, BV(C2_TE) | BV(C2_RE), 0); + /* Default settings */ + UART0_C1 = 0; + /* SBR and BRFA for baud rate */ + SET_MASKED(UART0_BDH, BDH_SBR_M, ((SBR_VAL & 0x1f00) >> 8) << BDH_SBR); + SET_MASKED(UART0_BDL, BDL_SBR_M, (SBR_VAL & 0xff) << BDL_SBR); + SET_MASKED(UART0_C4, C4_BRFA_M, BRFA_VAL << C4_BRFA); + /* flush and enable TX FIFO */ + UART0_CFIFO |= BV(CFIFO_TXFLUSH); + UART0_PFIFO |= BV(PFIFO_TXFE); + /* set watermark at 1 entry */ + SET_MASKED(UART0_TWFIFO, TWFIFO_TXWATER_M, 1 << TWFIFO_TXWATER); + /* NVIC enable interrupt */ + ISR_CLRPEND(45); + INTPRI(45) = 0xf0; + ISR_SETENA(45); + /* enable correct ALT MUX on TX pin */ + PORTB_PCR(17) = 3 << PCR_MUX; + /* enable TX */ + SET_MASKED(UART0_C2, BV(C2_TE), BV(C2_TE)); +} + +void uart_putchar(int c) +{ + static unsigned char buf[128]; + static size_t size = 0; + + if (c == '\n') + uart_putchar('\r'); + + buf[size++] = c; + + if (size >= sizeof buf || c == '\n') { + rb_store(buf, size); + size = 0; + } +} + +void uart_puts(const char *s) +{ + for (size_t i = 0; s[i]; i++) + uart_putchar(s[i]); + uart_putchar('\n'); +} + +static inline void putul(unsigned long n, int base) +{ + static const char *digits = "0123456789abcdef"; + int i; + char tmp[64]; + + if (base < 2 || base > 16) + return; + + if (n == 0) { + uart_putchar('0'); + return; + } + for (i = 0; n; i++) { + int res = n % base; + n = n / base; + tmp[i] = digits[res]; + } + + for (i -= 1; i >= 0; i--) + uart_putchar(tmp[i]); +} + +static inline void putl(long n) +{ + int i; + char tmp[64]; + + if (n < 0) { + uart_putchar('-'); + n *= -1; + } + + if (n == 0) { + uart_putchar('0'); + return; + } + + for (i = 0; n; i++) { + int res = n % 10; + n = n / 10; + tmp[i] = '0' + res; + } + + for (i -= 1; i >= 0; i--) + uart_putchar(tmp[i]); +} + +void uart_printf(const char *fmt, ...) +{ + va_list ap; + const char *p; + int ival; + unsigned uival; + long lival; + unsigned long ulival; + + va_start(ap, fmt); + for (p = fmt; *p; p++) { + if (*p != '%') { + uart_putchar(*p); + continue; + } + switch (*++p) { + case 'd': case 'i': + ival = va_arg(ap, int); + putl(ival); + break; + case 'o': case 'u': case 'x': + uival = va_arg(ap, unsigned); + switch (*p) { + case 'o': putul(uival, 8); break; + case 'u': putul(uival, 10); break; + case 'x': putul(uival, 16); break; + } + break; + case 'l': + switch (*++p) { + case 'd': case 'i': + lival = va_arg(ap, long); + putl(lival); + break; + case 'o': case 'u': case 'x': + ulival = va_arg(ap, unsigned long); + switch (*p) { + case 'o': putul(ulival, 8); break; + case 'u': putul(ulival, 10); break; + case 'x': putul(ulival, 16); break; + } + break; + } + } + } + va_end(ap); +} + +void uart0_isr(void) +{ + int avail, start, end, tosend; + + if (!GET_BIT(UART0_S1, S1_TDRE)) + return; + + avail = FIFOSZ - UART0_TCFIFO; + CLI(); + start = send_rb.start; + end = send_rb.end; + tosend = (end + sizeof send_rb.buf - start) % sizeof send_rb.buf; + if (tosend == 0) + UNSET_BIT(UART0_C2, C2_TIE); + STI(); + + if (tosend > avail) + tosend = avail; + + for (int i = 0; i < tosend; i++) + UART0_D = send_rb.buf[(start + i) % sizeof send_rb.buf]; + + send_rb.start = (start + tosend) % sizeof send_rb.buf; } diff --git a/uart/uart.h b/uart/uart.h index 984d704..2733bb7 100644 --- a/uart/uart.h +++ b/uart/uart.h @@ -2,5 +2,9 @@ #define UART_UART_H void uart_setup(void); +void uart_putchar(int c); +void uart_printf(const char *fmt, ...); +void uart_puts(const char *s); +void uart0_isr(void); #endif /* UART_UART_H */ |