1// See LICENSE for license details.
2
3#include <string.h>
4#include "uart.h"
5#include "fdt.h"
6
7volatile uint32_t* uart;
8
9void uart_putchar(uint8_t ch)
10{
11#ifdef __riscv_atomic
12    int32_t r;
13    do {
14      __asm__ __volatile__ (
15        "amoor.w %0, %2, %1\n"
16        : "=r" (r), "+A" (uart[UART_REG_TXFIFO])
17        : "r" (ch));
18    } while (r < 0);
19#else
20    volatile uint32_t *tx = uart + UART_REG_TXFIFO;
21    while ((int32_t)(*tx) < 0);
22    *tx = ch;
23#endif
24}
25
26int uart_getchar()
27{
28  int32_t ch = uart[UART_REG_RXFIFO];
29  if (ch < 0) return -1;
30  return ch;
31}
32
33struct uart_scan
34{
35  int compat;
36  uint64_t reg;
37};
38
39static void uart_open(const struct fdt_scan_node *node, void *extra)
40{
41  struct uart_scan *scan = (struct uart_scan *)extra;
42  memset(scan, 0, sizeof(*scan));
43}
44
45static void uart_prop(const struct fdt_scan_prop *prop, void *extra)
46{
47  struct uart_scan *scan = (struct uart_scan *)extra;
48  if (!strcmp(prop->name, "compatible") && !strcmp((const char*)prop->value, "sifive,uart0")) {
49    scan->compat = 1;
50  } else if (!strcmp(prop->name, "reg")) {
51    fdt_get_address(prop->node->parent, prop->value, &scan->reg);
52  }
53}
54
55static void uart_done(const struct fdt_scan_node *node, void *extra)
56{
57  struct uart_scan *scan = (struct uart_scan *)extra;
58  if (!scan->compat || !scan->reg || uart) return;
59
60  // Enable Rx/Tx channels
61  uart = (void*)(uintptr_t)scan->reg;
62  uart[UART_REG_TXCTRL] = UART_TXEN;
63  uart[UART_REG_RXCTRL] = UART_RXEN;
64}
65
66void query_uart(uintptr_t fdt)
67{
68  struct fdt_cb cb;
69  struct uart_scan scan;
70
71  memset(&cb, 0, sizeof(cb));
72  cb.open = uart_open;
73  cb.prop = uart_prop;
74  cb.done = uart_done;
75  cb.extra = &scan;
76
77  fdt_scan(fdt, &cb);
78}
79