Signed-off-by: Marc Reilly <marc@xxxxxxxxxxxxxxx>
---
fs/devfs.c | 41 +++++++++++++++++++++++++++++++++++++++++
include/driver.h | 1 +
2 files changed, 42 insertions(+), 0 deletions(-)
diff --git a/fs/devfs.c b/fs/devfs.c
index 7019c8d..c1196d1 100644
--- a/fs/devfs.c
+++ b/fs/devfs.c
@@ -38,6 +38,47 @@
static LIST_HEAD(cdev_list);
+/**
+ * Allocates a unique name for a cdev based on existing cdevs.
+ *
+ * @param template Starting point for the name of the device.
+ * The name can optionally contain a "%d" marker to designate where the
+ * device number should be inserted into the device string. If no marker
+ * is specified then one is appended.
+ *
+ * @param prefid Preferred device id. Any id less than zero will default
+ * to start from 0.
+ */
+char *make_cdev_name(const char *template, int prefid)
+{
+ char *name = 0;
+ char *temp;
+ int id;
+ struct cdev *cdev;
+
+ /* if there is no template for number, append one */
+ if (!strstr(template, "%d"))
+ temp = asprintf("%s%%d", template);
+ else
+ temp = strdup(template);
+
+ id = (prefid < 0) ? 0 : prefid;
+
+ do {
+ free(name);
+ name = asprintf(temp, id);
+
+ cdev = cdev_by_name(name);
+ if (cdev && (id == prefid))
+ printf("WARN: preferred device name %s already used\n",
+ name);
+ ++id;
+ } while (cdev);
+
+ free(temp);
+ return name;
+}
+
struct cdev *cdev_by_name(const char *filename)
{
struct cdev *cdev;
diff --git a/include/driver.h b/include/driver.h
index b9edca0..1712637 100644
--- a/include/driver.h
+++ b/include/driver.h
@@ -313,6 +313,7 @@ struct cdev {
int devfs_create(struct cdev *);
int devfs_remove(struct cdev *);
+char *make_cdev_name(const char *template, int prefid);
struct cdev *cdev_by_name(const char *filename);
ssize_t cdev_read(struct cdev *cdev, void *buf, size_t count, ulong offset, ulong flags);
ssize_t cdev_write(struct cdev *cdev, const void *buf, size_t count, ulong offset, ulong flags);
--
1.7.1
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