ethlcd driver improvements

commit 27db3f541d69bc5ebae499d3ac6e5864e548612b
Author: Mariusz Bialonczyk <[email protected]>
Date:   Fri Mar 11 22:40:25 2011 +0100

    added helper function for sending data
    checking for correct device response
    added timeouts for socket (fixes LCDd hang up eg. when device disappear)

diff --git a/server/drivers/hd44780-ethlcd.c b/server/drivers/hd44780-ethlcd.c
index 0d3f117..0dd8dd3 100644
--- a/server/drivers/hd44780-ethlcd.c
+++ b/server/drivers/hd44780-ethlcd.c
@@ -16,16 +16,27 @@
  *
  */
 
-#include "hd44780-ethlcd.h"
-#include "hd44780-low.h"
-#include "shared/sockets.h"
-#include "report.h"
+/*
+ * Changes:
+ *  2008-08-20 Mariusz Bialonczyk <[email protected]>
+ *   - initial driver version
+ *  2010-05-10 Mariusz Bialonczyk <[email protected]>
+ *   - fix setting blocking mode
+ *  2011-03-11 Mariusz Bialonczyk <[email protected]>
+ *   - added helper function for sending data
+ *   - checking for correct device response
+ *   - added timeouts for socket (fixes LCDd hang up eg. when device disappear)
+ */
 
-#include <stdio.h>
 #include <string.h>
-#include <limits.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <sys/socket.h>
+
+#include "hd44780-ethlcd.h"
+#include "hd44780-low.h"
+#include "shared/sockets.h"
+#include "report.h"
 
 
 void ethlcd_HD44780_senddata(PrivateData *p, unsigned char displayID, unsigned char flags, unsigned char ch);
@@ -35,6 +46,9 @@ void ethlcd_HD44780_close(PrivateData *p);
 // fake pause function (pausing is handled by ethlcd device itself)
 void ethlcd_HD44780_uPause(PrivateData *p, int usecs) {}
 
+// helper function
+static void ethlcd_senddata(PrivateData *p, unsigned char *data, int length);
+
 
 /**
  * Initialize the driver.
@@ -46,6 +60,7 @@ int hd_init_ethlcd(Driver *drvthis)
 {
 	char hostname[256];
 	unsigned long flags = 0;
+	struct timeval tv;
 
 	PrivateData *p = (PrivateData*) drvthis->private_data;
 	HD44780_functions *hd44780_functions = p->hd44780_functions;
@@ -82,6 +97,22 @@ int hd_init_ethlcd(Driver *drvthis)
 		return -1;
 	}
 
+	//setting timeouts
+	tv.tv_sec = ETHLCD_TIMEOUT;
+	tv.tv_usec = 0;
+	if (setsockopt(p->sock, SOL_SOCKET, SO_RCVTIMEO, (void *) &tv, sizeof(struct timeval)) < 0)
+	{
+		report(RPT_ERR, "%s[%s]: Cannot set receive timeout: %s",
+			drvthis->name, ETHLCD_DRV_NAME, strerror(errno));
+		return -1;
+	}
+	if (setsockopt(p->sock, SOL_SOCKET, SO_SNDTIMEO, (void *) &tv, sizeof(struct timeval)) < 0)
+	{
+		report(RPT_ERR, "%s[%s]: Cannot set send timeout: %s",
+			drvthis->name, ETHLCD_DRV_NAME, strerror(errno));
+		return -1;
+	}
+
 	// Set up two-line, small character (5x8) mode
 	hd44780_functions->senddata(p, 0, RS_INSTR, FUNCSET | IF_4BIT | TWOLINE | SMALLCHAR);
 
@@ -105,7 +136,7 @@ int hd_init_ethlcd(Driver *drvthis)
  */
 void ethlcd_HD44780_senddata(PrivateData *p, unsigned char displayID, unsigned char flags, unsigned char ch)
 {
-	static char buff[2];
+	static unsigned char buff[2];
 
 	if (flags == RS_INSTR)
 		buff[0] = ETHLCD_SEND_INSTR;
@@ -113,8 +144,7 @@ void ethlcd_HD44780_senddata(PrivateData *p, unsigned char displayID, unsigned c
 		buff[0] = ETHLCD_SEND_DATA;
 	buff[1] = ch;
 
-	sock_send(p->sock, buff, 2);	//send data to device
-	sock_recv(p->sock, &buff, 1);	//wait for reply
+	ethlcd_senddata(p, buff, 2);
 }
 
 
@@ -126,15 +156,12 @@ void ethlcd_HD44780_senddata(PrivateData *p, unsigned char displayID, unsigned c
 unsigned char ethlcd_HD44780_scankeypad(PrivateData *p)
 {
 	unsigned char readval;
-	static char buff[2];
+	static unsigned char buff[2];
 
 	buff[0] = ETHLCD_GET_BUTTONS;
 
-	sock_send(p->sock, buff, 1);	//send data to device
-	sock_recv(p->sock, &buff, 2);	//wait for answer
+	ethlcd_senddata(p, buff, 1);
 
-	if (buff[0] != ETHLCD_GET_BUTTONS)  //check if this is true reply for our packet
-		return 0;
 	//answer should be in second byte on bits 0-6 in negative logic:
 	readval = buff[1];
 
@@ -159,7 +186,7 @@ unsigned char ethlcd_HD44780_scankeypad(PrivateData *p)
  */
 void ethlcd_HD44780_backlight(PrivateData *p, unsigned char state)
 {
-	static char buff[2];
+	static unsigned char buff[2];
 
 	buff[0] = ETHLCD_SET_BACKLIGHT;
 
@@ -173,8 +200,7 @@ void ethlcd_HD44780_backlight(PrivateData *p, unsigned char state)
 	else
 		buff[1] = ETHLCD_BACKLIGHT_OFF;
 
-	sock_send(p->sock, buff, 2);	//send data to device
-	sock_recv(p->sock, &buff, 1);	//wait for reply
+	ethlcd_senddata(p, buff, 2);
 }
 
 
@@ -186,3 +212,49 @@ void ethlcd_HD44780_close(PrivateData *p)
 {
 	sock_close(p->sock);
 }
+
+
+/**
+ * Send the data to ethlcd device.
+ * \param p       Pointer to driver's private data structure.
+ * \param data    Pointer to buffer with data to send.
+ * \param length  Number of bytes to send.
+ */
+static void ethlcd_senddata(PrivateData *p, unsigned char *data, int length)
+{
+	int response_len, len;
+	unsigned char cmd;
+
+	/* Send data to device */
+	cmd = data[0];	//storing command byte for verification
+	len = sock_send(p->sock, data, length);
+	if (len <= 0)
+	{
+		p->hd44780_functions->drv_report(RPT_ERR, "%s: Write to socket failed: %s. Exiting",
+			ETHLCD_DRV_NAME, strerror(errno));
+		exit (-1);
+	}
+
+	/* Check if this is a command with reply */
+	if (cmd == ETHLCD_GET_BUTTONS)
+		response_len = 2;
+	else
+		response_len = 1;
+
+	/* Wait for reply */
+	len = sock_recv(p->sock, data, response_len);
+	if (len <= 0)
+	{
+		p->hd44780_functions->drv_report(RPT_ERR, "%s: Read from socket failed: %s. Exiting",
+			ETHLCD_DRV_NAME, strerror(errno));
+		exit (-1);
+	}
+
+	/* Check reply */
+	if (data[0] != cmd)
+	{
+		p->hd44780_functions->drv_report(RPT_ERR, "%s: Invalid device response (want 0x%02X, got 0x%02X). Exiting",
+			ETHLCD_DRV_NAME, cmd, data[0]);
+		exit (-1);
+	}
+}
diff --git a/server/drivers/hd44780-ethlcd.h b/server/drivers/hd44780-ethlcd.h
index dc3875b..6de5456 100644
--- a/server/drivers/hd44780-ethlcd.h
+++ b/server/drivers/hd44780-ethlcd.h
@@ -6,8 +6,9 @@
 // initialise this particular driver
 int hd_init_ethlcd(Driver *drvthis);
 
-#define ETHLCD_DRV_NAME "ethlcd"
-#define DEFAULT_ETHLCD_PORT 2425
+#define ETHLCD_DRV_NAME      "ethlcd"
+#define DEFAULT_ETHLCD_PORT  2425
+#define ETHLCD_TIMEOUT       5
 
 // ethlcd protocol constants:
 #define ETHLCD_SEND_INSTR               0x01