shell: Shell subsystem reimplementation

New shell support features like:
- multi-instance
- command tree
- static and dynamic commands
- multiline
- help print function
- smart tab (autocompletion)
- meta-keys
- history, wildcards etc.
- generic transport (initially, uart present)

Signed-off-by: Jakub Rzeszutko <jakub.rzeszutko@nordicsemi.no>
Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
Signed-off-by: Piotr Zięcik <piotr.ziecik@nordicsemi.no>

subsys/shell/shell_uart.c

@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2018 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <shell/shell_uart.h>
+#include <uart.h>
+
+static void timer_handler(struct k_timer *timer)
+{
+	struct shell_uart *sh_uart =
+			CONTAINER_OF(timer, struct shell_uart, timer);
+
+	if (uart_poll_in(sh_uart->dev, sh_uart->rx) == 0) {
+		sh_uart->rx_cnt = 1;
+		sh_uart->handler(SHELL_TRANSPORT_EVT_RX_RDY, sh_uart->context);
+	}
+}
+
+
+static int init(const struct shell_transport *transport,
+		const void *config,
+		shell_transport_handler_t evt_handler,
+		void *context)
+{
+	struct shell_uart *sh_uart = (struct shell_uart *)transport->ctx;
+
+	sh_uart->dev = device_get_binding(CONFIG_UART_CONSOLE_ON_DEV_NAME);
+	sh_uart->handler = evt_handler;
+	sh_uart->context = context;
+
+	k_timer_init(&sh_uart->timer, timer_handler, NULL);
+
+	k_timer_start(&sh_uart->timer, 20, 20);
+
+	return 0;
+}
+
+static int uninit(const struct shell_transport *transport)
+{
+	return 0;
+}
+
+static int enable(const struct shell_transport *transport, bool blocking)
+{
+	return 0;
+}
+
+static int write(const struct shell_transport *transport,
+		 const void *data, size_t length, size_t *cnt)
+{
+	struct shell_uart *sh_uart = (struct shell_uart *)transport->ctx;
+	const u8_t *data8 = (const u8_t *)data;
+
+	for (size_t i = 0; i < length; i++) {
+		uart_poll_out(sh_uart->dev, data8[i]);
+	}
+
+	*cnt = length;
+
+	sh_uart->handler(SHELL_TRANSPORT_EVT_TX_RDY, sh_uart->context);
+
+	return 0;
+}
+
+static int read(const struct shell_transport *transport,
+		void *data, size_t length, size_t *cnt)
+{
+	struct shell_uart *sh_uart = (struct shell_uart *)transport->ctx;
+
+	if (sh_uart->rx_cnt) {
+		memcpy(data, sh_uart->rx, 1);
+		sh_uart->rx_cnt = 0;
+		*cnt = 1;
+	} else {
+		*cnt = 0;
+	}
+
+	return 0;
+}
+
+const struct shell_transport_api shell_uart_transport_api = {
+	.init = init,
+	.uninit = uninit,
+	.enable = enable,
+	.write = write,
+	.read = read
+};