Add a "device" parameter for Dediprog

This patch adds a "device" parameter for Dediprog which enables use of
multiple dediprogs connected to a single machine. Very handy for test racks.

Example usage:
flashrom -p dediprog:device=0
flashrom -p dediprog:device=1
etc...

The patch was originally written by Nathan Laredo.
Thanks to David Hendricks for submitting it upstream.
Additional error handling, man page etc. by Stefan Tauner.

Corresponding to flashrom svn r1628.

Signed-off-by: Nathan Laredo <nil@google.com>
Signed-off-by: David Hendricks <dhendrix@google.com>
Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>

dediprog.c

@@ -19,6 +19,7 @@
 
 #include <stdio.h>
 #include <string.h>
+#include <errno.h>
 #include <usb.h>
 #include "flash.h"
 #include "chipdrivers.h"
@@ -46,7 +47,8 @@ static void print_hex(void *buf, size_t len)
 #endif
 
 /* Might be useful for other USB devices as well. static for now. */
-static struct usb_device *get_device_by_vid_pid(uint16_t vid, uint16_t pid)
+/* device parameter allows user to specify one device of multiple installed */
+static struct usb_device *get_device_by_vid_pid(uint16_t vid, uint16_t pid, unsigned int device)
 {
 	struct usb_bus *bus;
 	struct usb_device *dev;
@@ -54,8 +56,11 @@ static struct usb_device *get_device_by_vid_pid(uint16_t vid, uint16_t pid)
 	for (bus = usb_get_busses(); bus; bus = bus->next)
 		for (dev = bus->devices; dev; dev = dev->next)
 			if ((dev->descriptor.idVendor == vid) &&
-			    (dev->descriptor.idProduct == pid))
+			    (dev->descriptor.idProduct == pid)) {
-				return dev;
+				if (device == 0)
+					return dev;
+				device--;
+			}
 
 	return NULL;
 }
@@ -777,8 +782,9 @@ static int dediprog_shutdown(void *data)
 int dediprog_init(void)
 {
 	struct usb_device *dev;
-	char *voltage;
+	char *voltage, *device;
 	int millivolt = 3500;
+	long usedevice = 0;
 	int ret;
 
 	msg_pspew("%s\n", __func__);
@@ -792,11 +798,35 @@ int dediprog_init(void)
 		msg_pinfo("Setting voltage to %i mV\n", millivolt);
 	}
 
+	device = extract_programmer_param("device");
+	if (device) {
+		char *dev_suffix;
+		errno = 0;
+		usedevice = strtol(device, &dev_suffix, 10);
+		if (errno != 0 || device == dev_suffix) {
+			msg_perr("Error: Could not convert 'device'.\n");
+			free(device);
+			return 1;
+		}
+		if (usedevice < 0 || usedevice > UINT_MAX) {
+			msg_perr("Error: Value for 'device' is out of range.\n");
+			free(device);
+			return 1;
+		}
+		if (strlen(dev_suffix) > 0) {
+			msg_perr("Error: Garbage following 'device' value.\n");
+			free(device);
+			return 1;
+		}
+		msg_pinfo("Using device %li.\n", usedevice);
+	}
+	free(device);
+
 	/* Here comes the USB stuff. */
 	usb_init();
 	usb_find_busses();
 	usb_find_devices();
-	dev = get_device_by_vid_pid(0x0483, 0xdada);
+	dev = get_device_by_vid_pid(0x0483, 0xdada, (unsigned int) usedevice);
 	if (!dev) {
 		msg_perr("Could not find a Dediprog SF100 on USB!\n");
 		return 1;

flashrom.8

@@ -1,4 +1,4 @@
-.TH FLASHROM 8 "Feb 15, 2012"
+.TH FLASHROM 8 "Dec, 2012"
 .SH NAME
 flashrom \- detect, read, write, verify and erase flash chips
 .SH SYNOPSIS
@@ -651,6 +651,15 @@ where
 can be
 .BR 0V ", " 1.8V ", " 2.5V ", " 3.5V
 or the equivalent in mV.
+.sp
+An optional
+.B device
+parameter specifies which of multiple connected Dediprog devices should be used.
+Please be aware that the order depends on libusb's usb_get_busses() function and that the numbering starts
+at 0.
+Usage example to select the second device:
+.sp
+.B "  flashrom \-p dediprog:device=1"
 .SS
 .BR "rayer_spi " programmer
 The default I/O base address used for the parallel port is 0x378 and you can use