diag: transport: Add support for UART connection to host PC

Add the option to connect to a host PC connected via a UART cable.
Configure the UART via the following command line option:
-u <uart device name[@baudrate]>
The device name is typically /dev/ttyMSM1 and the baud rate 115200.

Signed-off-by: Eyal Ilsar <eilsar@codeaurora.org>
[bjorn: Moved code to uart.c, modified initialization from main,
	made uart register iself as client]
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Makefile

@@ -3,7 +3,7 @@ DIAG := diag
 CFLAGS := -Wall -g -O2
 LDFLAGS := -ludev
 
-SRCS := diag.c diag_cntl.c hdlc.c mbuf.c peripheral.c socket.c util.c watch.c
+SRCS := diag.c diag_cntl.c hdlc.c mbuf.c peripheral.c socket.c uart.c util.c watch.c
 OBJS := $(SRCS:.c=.o)
 
 $(DIAG): $(OBJS)

diag.c

@@ -232,25 +232,32 @@ static void usage(void)
 	fprintf(stderr,
 		"User space application for diag interface\n"
 		"\n"
-		"usage: diag [-hs]\n"
+		"usage: diag [-hsu]\n"
 		"\n"
 		"options:\n"
 		"   -h   show this usage\n"
 		"   -s   <socket address[:port]>\n"
+		"   -u   <uart device name[@baudrate]>\n"
 	);
+
 	exit(1);
 }
 
 int main(int argc, char **argv)
 {
-	char *host_address = "";
+	char *host_address = NULL;
 	int host_port = DEFAULT_SOCKET_PORT;
+	char *uartdev = NULL;
+	int baudrate = DEFAULT_BAUD_RATE;
 	char *token;
 	int ret;
 	int c;
 
+	if (argc == 1)
+		usage();
+
 	for (;;) {
-		c = getopt(argc, argv, "hs:");
+		c = getopt(argc, argv, "hs:u:");
 		if (c < 0)
 			break;
 		switch (c) {
@@ -260,6 +267,12 @@ int main(int argc, char **argv)
 			if (token)
 				host_port = atoi(token);
 			break;
+		case 'u':
+			uartdev = strtok(strdup(optarg), "@");
+			token = strtok(NULL, "");
+			if (token)
+				baudrate = atoi(token);
+			break;
 		default:
 		case 'h':
 			usage();
@@ -267,9 +280,17 @@ int main(int argc, char **argv)
 		}
 	}
 
-	ret = diag_sock_connect(host_address, host_port);
-	if (ret < 0)
-		err(1, "failed to connect to client");
+	if (host_address) {
+		ret = diag_sock_connect(host_address, host_port);
+		if (ret < 0)
+			err(1, "failed to connect to client");
+	} else if (uartdev) {
+		ret = diag_uart_open(uartdev, baudrate);
+		if (ret < 0)
+			errx(1, "failed to open uart\n");
+	} else {
+		errx(1, "no configured connection mode\n");
+	}
 
 	peripheral_init();
 

diag.h

@@ -35,6 +35,7 @@
 #include "list.h"
 
 #define DEFAULT_SOCKET_PORT 2500
+#define DEFAULT_BAUD_RATE 115200
 
 #define BIT(x) (1 << (x))
 
@@ -89,6 +90,7 @@ int diag_cmd_recv(int fd, void *data);
 int diag_data_recv(int fd, void *data);
 
 int diag_sock_connect(const char *hostname, unsigned short port);
+int diag_uart_open(const char *uartname, unsigned int baudrate);
 
 void diag_client_add(struct diag_client *client);
 int diag_client_handle_command(struct diag_client *client, uint8_t *data, size_t len);

uart.c

@@ -0,0 +1,151 @@
+/*
+ * Copyright (c) 2016-2017, The Linux Foundation. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ *       copyright notice, this list of conditions and the following
+ *       disclaimer in the documentation and/or other materials provided
+ *       with the distribution.
+ *     * Neither the name of The Linux Foundation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
+ * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include <sys/ioctl.h>
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <termios.h>
+#include <unistd.h>
+
+#include "diag.h"
+#include "hdlc.h"
+#include "watch.h"
+
+#define APPS_BUF_SIZE 4096
+
+static unsigned int check_baudrate(unsigned int baudrate)
+{
+	switch (baudrate)
+	{
+	case 9600:
+		return B9600;
+	case 19200:
+		return B19200;
+	case 38400:
+		return B38400;
+	case 115200:
+		return B115200;
+	default:
+		warn("Illegal baud rate %u!", baudrate);
+		return 0;
+	}
+}
+
+static int diag_uart_recv(int fd, void* data)
+{
+	struct diag_client *client = (struct diag_client *)data;
+	uint8_t buf[APPS_BUF_SIZE] = { 0 };
+	size_t msglen;
+	size_t len;
+	ssize_t n;
+	void *msg;
+	void *ptr;
+
+	n = read(client->fd, buf, sizeof(buf));
+	if ((n < 0) && (errno != EAGAIN)) {
+		warn("Failed to read from fd=%d\n", client->fd);
+		return n;
+	}
+
+	ptr = buf;
+	len = n;
+
+	for (;;) {
+		msg = hdlc_decode_one(&ptr, &len, &msglen);
+		if (!msg)
+			break;
+
+		diag_client_handle_command(client, msg, msglen);
+	}
+
+	return 0;
+}
+
+int diag_uart_open(const char *uartname, unsigned int baudrate)
+{
+	struct diag_client *client;
+	int ret;
+	int fd;
+	struct termios options, options_save;
+
+	baudrate = check_baudrate(baudrate);
+	if (baudrate == 0)
+		return -EINVAL;
+
+	fd = open(uartname, O_RDWR | O_NOCTTY | O_NONBLOCK);
+	if (fd < 0)
+		return -errno;
+
+	ret = tcflush(fd, TCIOFLUSH);
+	if (ret < 0)
+		return -errno;
+
+	ret = fcntl(fd, F_SETFL, 0);
+	if (ret < 0)
+		return -errno;
+
+	ret = ioctl(fd, TCGETS, &options_save);
+	if (ret < 0)
+		return -errno;
+
+	options = options_save;
+	options.c_cc[VTIME]    = 0;   /* inter-character timer unused */
+	options.c_cc[VMIN]     = 4;   /* blocking read until 4 chars received */
+	options.c_cflag &= ~PARENB;
+	options.c_cflag &= ~CSTOPB;
+	options.c_cflag &= ~CSIZE;
+	options.c_cflag |= (CS8 | CLOCAL | CREAD);
+	options.c_iflag = 0;
+	options.c_oflag = 0;
+	options.c_lflag = 0;
+	options.c_cflag = (options.c_cflag & ~CBAUD) | (baudrate & CBAUD);
+
+	ret = ioctl(fd, TCSETS, &options); // TODO: need to call ioctl(ret, TCSETS, &options_save) to revert to original state
+	if (ret < 0)
+		return -errno;
+
+	printf("Connected to %s@%d\n", uartname, baudrate);
+
+	client = calloc(1, sizeof(*client));
+	if (!client)
+		err(1, "failed to allocate client context\n");
+
+	client->fd = fd;
+	client->name = "UART client";
+
+	watch_add_readfd(ret, diag_uart_recv, client);
+	watch_add_writeq(client->fd, &client->outq);
+
+	diag_client_add(client);
+
+	return fd;
+}