feat(drivers/imx_uart): add driver

Signed-off-by: David Cerdeira <davidmcerdeira@gmail.com>

Author: DavidMCerdeira

src/platform/drivers/imx_uart/imx_uart.c

@@ -0,0 +1,36 @@
+/**
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ */
+
+#include <drivers/imx_uart.h>
+#include <fences.h>
+
+#define IMX_UART_STAT2_TXDC   (1 << 3)
+#define IMX_UART_STAT2_TXFULL (1 << 4)
+
+void uart_init(volatile struct imx_uart* uart)
+{
+    UNUSED_ARG(uart);
+    return;
+}
+
+void uart_enable(volatile struct imx_uart* uart)
+{
+    UNUSED_ARG(uart);
+    return;
+}
+
+void uart_putc(volatile struct imx_uart* uart, int8_t c)
+{
+    while (uart->ts & IMX_UART_STAT2_TXFULL) { }
+    uart->txd = (uint32_t)c;
+    while (!(uart->stat2 & IMX_UART_STAT2_TXDC)) { }
+}
+
+void uart_puts(volatile struct imx_uart* uart, int8_t const* str)
+{
+    while (*str) {
+        uart_putc(uart, *str++);
+    }
+}

src/platform/drivers/imx_uart/inc/drivers/imx_uart.h

@@ -0,0 +1,39 @@
+/**
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ */
+
+#ifndef IMX_UART_H
+#define IMX_UART_H
+
+#include <stdint.h>
+
+struct imx_uart {
+    uint32_t rxd;            /* 0x0 */
+    uint32_t reserved1[0xf]; /* (0x40 - 0x4)  / 4 */
+    uint32_t txd;            /* 0x40*/
+    uint32_t reserved2[0xf]; /* (0x80 - 0x44) / 4 */
+    uint32_t cr1;            /* 0x80 */
+    uint32_t cr2;            /* 0x84 */
+    uint32_t cr3;            /* 0x88 */
+    uint32_t cr4;            /* 0x8c */
+    uint32_t fcr;            /* 0x90 */
+    uint32_t stat1;          /* 0x94 */
+    uint32_t stat2;          /* 0x98 */
+    uint32_t esc;            /* 0x9c */
+    uint32_t tim;            /* 0xa0 */
+    uint32_t bir;            /* 0xa4 */
+    uint32_t bmr;            /* 0xa8 */
+    uint32_t brc;            /* 0xac */
+    uint32_t onems;          /* 0xb0 */
+    uint32_t ts;             /* 0xb4 */
+};
+
+typedef volatile struct imx_uart bao_uart_t;
+
+void uart_enable(volatile struct imx_uart* uart);
+void uart_init(volatile struct imx_uart* uart);
+void uart_puts(volatile struct imx_uart* uart, const int8_t* str);
+void uart_putc(volatile struct imx_uart* uart, int8_t str);
+
+#endif /* IMX_UART_H */

src/platform/drivers/imx_uart/objects.mk

@@ -0,0 +1,4 @@
+## SPDX-License-Identifier: Apache-2.0
+## Copyright (c) Bao Project and Contributors. All rights reserved.
+
+drivers-objs-y+=imx_uart/imx_uart.o