Initial drop

Add some riscv code

Signed-off-by: Carlos Maiolino <[email protected]>

1 files changed, 58 insertions, 0 deletions

diff --git a/riscv/riscv-probe/libfemto/drivers/sifive_uart.c b/riscv/riscv-probe/libfemto/drivers/sifive_uart.c
new file mode 100644
index 0000000..9be877e
--- /dev/null
+++ b/riscv/riscv-probe/libfemto/drivers/sifive_uart.c
@@ -0,0 +1,58 @@
+// See LICENSE for license details.
+
+#include "femto.h"
+
+enum {
+    /* UART Registers */
+    UART_REG_TXFIFO = 0,
+    UART_REG_RXFIFO = 1,
+    UART_REG_TXCTRL = 2,
+    UART_REG_RXCTRL = 3,
+    UART_REG_IE     = 4,
+    UART_REG_IP     = 5,
+    UART_REG_DIV    = 6,
+
+    /* TXCTRL register */
+    UART_TXEN       = 1,
+    UART_TXSTOP     = 2,
+
+    /* RXCTRL register */
+    UART_RXEN       = 1,
+
+    /* IP register */
+    UART_IP_TXWM    = 1,
+    UART_IP_RXWM    = 2
+};
+
+static volatile int *uart;
+
+static void sifive_uart_init()
+{
+	uart = (int *)(void *)getauxval(SIFIVE_UART0_CTRL_ADDR);
+	uint32_t uart_freq = getauxval(UART0_CLOCK_FREQ);
+	uint32_t baud_rate = getauxval(UART0_BAUD_RATE);
+    uint32_t divisor = uart_freq / baud_rate - 1;
+    uart[UART_REG_DIV] = divisor;
+    uart[UART_REG_TXCTRL] = UART_TXEN;
+    uart[UART_REG_RXCTRL] = UART_RXEN;
+    uart[UART_REG_IE] = 0;
+}
+
+static int sifive_uart_getchar()
+{
+    int ch = uart[UART_REG_RXFIFO];
+    if (ch < 0) return -1;
+    return ch;
+}
+
+static int sifive_uart_putchar(int ch)
+{
+    while (uart[UART_REG_TXFIFO] < 0);
+    return uart[UART_REG_TXFIFO] = ch & 0xff;
+}
+
+console_device_t console_sifive_uart = {
+    sifive_uart_init,
+    sifive_uart_getchar,
+    sifive_uart_putchar
+};