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#include <string.h>
#include "uart.h"
#include "fdt.h"
volatile uint32_t* uart;
void uart_putchar(uint8_t ch)
{
#ifdef __riscv_atomic
int32_t r;
do {
__asm__ __volatile__ (
"amoor.w %0, %2, %1\n"
: "=r" (r), "+A" (uart[UART_REG_TXFIFO])
: "r" (ch));
} while (r < 0);
#else
volatile uint32_t *tx = uart + UART_REG_TXFIFO;
while ((int32_t)(*tx) < 0);
*tx = ch;
#endif
}
int uart_getchar()
{
int32_t ch = uart[UART_REG_RXFIFO];
if (ch < 0) return -1;
return ch;
}
struct uart_scan
{
int compat;
uint64_t reg;
};
static void uart_open(const struct fdt_scan_node *node, void *extra)
{
struct uart_scan *scan = (struct uart_scan *)extra;
memset(scan, 0, sizeof(*scan));
}
static void uart_prop(const struct fdt_scan_prop *prop, void *extra)
{
struct uart_scan *scan = (struct uart_scan *)extra;
if (!strcmp(prop->name, "compatible") && !strcmp((const char*)prop->value, "sifive,uart0")) {
scan->compat = 1;
} else if (!strcmp(prop->name, "reg")) {
fdt_get_address(prop->node->parent, prop->value, &scan->reg);
}
}
static void uart_done(const struct fdt_scan_node *node, void *extra)
{
struct uart_scan *scan = (struct uart_scan *)extra;
if (!scan->compat || !scan->reg || uart) return;
// Enable Rx/Tx channels
uart = (void*)(uintptr_t)scan->reg;
uart[UART_REG_TXCTRL] = UART_TXEN;
uart[UART_REG_RXCTRL] = UART_RXEN;
}
void query_uart(uintptr_t fdt)
{
struct fdt_cb cb;
struct uart_scan scan;
memset(&cb, 0, sizeof(cb));
cb.open = uart_open;
cb.prop = uart_prop;
cb.done = uart_done;
cb.extra = &scan;
fdt_scan(fdt, &cb);
}
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