drivers: esp32: Add minimal UART driver based on ROM routines
This is a minimal driver enabling console output during the port
bringup. While the driver works, only one of the three UART devices
are supported, and there isn't any way to change any parameters or
use interrupts. This will most likely be superceded by a proper
driver after the port has matured.
Signed-off-by: Leandro Pereira <leandro.pereira@intel.com>
diff --git a/drivers/serial/uart_esp32.c b/drivers/serial/uart_esp32.c
new file mode 100644
index 0000000..70c42db
--- /dev/null
+++ b/drivers/serial/uart_esp32.c
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2017 Intel Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <uart.h>
+#include <rom/uart.h>
+#include <rom/ets_sys.h>
+#include <errno.h>
+
+static unsigned char esp32_uart_tx(struct device *dev,
+ unsigned char c)
+{
+ ARG_UNUSED(dev);
+
+ uart_tx_one_char(c);
+
+ return 0;
+}
+
+static int esp32_uart_rx(struct device *dev, unsigned char *p_char)
+{
+ ARG_UNUSED(dev);
+
+ switch (uart_rx_one_char(p_char)) {
+ case OK:
+ return 0;
+ case PENDING:
+ return -EINPROGRESS;
+ case BUSY:
+ return -EBUSY;
+ case CANCEL:
+ return -ECANCELED;
+ default:
+ return -EIO;
+ }
+}
+
+static int esp32_uart_init(struct device *dev)
+{
+ ARG_UNUSED(dev);
+
+ return 0;
+}
+
+
+static const struct uart_driver_api esp32_uart_api = {
+ .poll_in = &esp32_uart_rx,
+ .poll_out = &esp32_uart_tx,
+ .err_check = NULL,
+#ifdef CONFIG_UART_INTERRUPT_DRIVEN
+
+#error "Interrupt-driven ESP32 UART not implemented yet"
+
+#endif
+};
+
+DEVICE_AND_API_INIT(esp32_uart, "ROMUART",
+ esp32_uart_init, NULL, NULL,
+ PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
+ &esp32_uart_api);
