[PATCH] Add a "device" parameter for Dediprog.

[Stefan Tauner]

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, rebasing etc. by Stefan Tauner.

Signed-off-by: Nathan Laredo 
Signed-off-by: David Hendricks 
Signed-off-by: Stefan Tauner 
---
That looked way easier (because it was tested and acked on IRC),
than it was in the end, meh.
I have tested the various new input checks, but not the successful path.
Someone needs to write a manpage entry for this option (please).

This should be applied to r1627.
 dediprog.c |   40 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 35 insertions(+), 5 deletions(-)

diff --git a/dediprog.c b/dediprog.c
index a81cf83..c2b66cc 100644
--- a/dediprog.c
+++ b/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))
-				return dev;
+			    (dev->descriptor.idProduct == pid)) {
+				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;