lib: add fdelay_open_by_lun function

At CERN controls installations, devices of the same class are enumerated by a statically defined number known as LUN (logical unit number), that maps into geographical information via database entries. These are mapped through userspace programs and stored as tags in device node names. This patch adds a function to exploit this numbering

lib: add fdelay_open_by_lun function
At CERN controls installations, devices of the same class are enumerated by a statically defined number known as LUN (logical unit number), that maps into geographical information via database entries. These are mapped through userspace programs and stored as tags in device node names. This patch adds a function to exploit this numbering
50459535 · Juan David González Cobas · 537671c0 · 50459535 · 50459535
Commit 50459535 authored Jul 05, 2012 by Juan David González Cobas
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fdelay-init.c lib/fdelay-init.c +22 -0

fdelay-lib.h lib/fdelay-lib.h +1 -0

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--- a/lib/fdelay-init.c
+++ b/lib/fdelay-init.c
@@ -164,6 +164,28 @@ found:
 	return (void *)b;
 }

+/* Open one specific device by logical unit number (CERN/CO-like) */
+struct fdelay_board *fdelay_open_by_lun(int lun)
+{
+	ssize_t ret;
+	char dev_id_str[4];
+	char path_pattern[] = "/dev/fine-delay.%d";
+	char path[sizeof(path_pattern) + 1];
+	int dev_id;
+
+	ret = snprintf(path, sizeof(path), path_pattern, lun);
+	if (ret < 0 || ret >= sizeof(path)) {
+		errno = EINVAL;
+		return NULL;
+	}
+	ret = readlink(path, dev_id_str, sizeof(dev_id_str));
+	if (sscanf(dev_id_str, "%4x", &dev_id) != 1) {
+		errno = ENODEV;
+		return NULL;
+	}
+	return fdelay_open(-1, dev_id);
+}
+
 int fdelay_close(struct fdelay_board *userb)
 {
 	__define_board(b, userb);

--- a/lib/fdelay-lib.h
+++ b/lib/fdelay-lib.h
@@ -54,6 +54,7 @@ extern int fdelay_init(void);
 extern void fdelay_exit(void);

 extern struct fdelay_board *fdelay_open(int offset, int dev_id);
+extern struct fdelay_board *fdelay_open_by_lun(int lun);
 extern int fdelay_close(struct fdelay_board *);

 extern int fdelay_set_time(struct fdelay_board *b, struct fdelay_time *t);