firewire: add fw_csr_string() helper function

The core (sysfs attributes), the firedtv driver, and possible future
drivers all read strings from some configuration ROM directory.  Factor
out the generic code from show_text_leaf() into a new helper function,
modified slightly to handle arbitrary buffer sizes.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 5 insertions, 34 deletions

diff --git a/drivers/media/dvb/firewire/firedtv-fw.c b/drivers/media/dvb/firewire/firedtv-fw.c
index 6223bf0..4253b7a 100644
--- a/drivers/media/dvb/firewire/firedtv-fw.c
+++ b/drivers/media/dvb/firewire/firedtv-fw.c
@@ -239,47 +239,18 @@ static const struct fw_address_region fcp_region = {
 };
 
 /* Adjust the template string if models with longer names appear. */
-#define MAX_MODEL_NAME_LEN ((int)DIV_ROUND_UP(sizeof("FireDTV ????"), 4))
-
-static size_t model_name(u32 *directory, __be32 *buffer)
-{
-	struct fw_csr_iterator ci;
-	int i, length, key, value, last_key = 0;
-	u32 *block = NULL;
-
-	fw_csr_iterator_init(&ci, directory);
-	while (fw_csr_iterator_next(&ci, &key, &value)) {
-		if (last_key == CSR_MODEL &&
-		    key == (CSR_DESCRIPTOR | CSR_LEAF))
-			block = ci.p - 1 + value;
-		last_key = key;
-	}
-
-	if (block == NULL)
-		return 0;
-
-	length = min((int)(block[0] >> 16) - 2, MAX_MODEL_NAME_LEN);
-	if (length <= 0)
-		return 0;
-
-	/* fast-forward to text string */
-	block += 3;
-
-	for (i = 0; i < length; i++)
-		buffer[i] = cpu_to_be32(block[i]);
-
-	return length * 4;
-}
+#define MAX_MODEL_NAME_LEN sizeof("FireDTV ????")
 
 static int node_probe(struct device *dev)
 {
 	struct firedtv *fdtv;
-	__be32 name[MAX_MODEL_NAME_LEN];
+	char name[MAX_MODEL_NAME_LEN];
 	int name_len, err;
 
-	name_len = model_name(fw_unit(dev)->directory, name);
+	name_len = fw_csr_string(fw_unit(dev)->directory, CSR_MODEL,
+				 name, sizeof(name));
 
-	fdtv = fdtv_alloc(dev, &backend, (char *)name, name_len);
+	fdtv = fdtv_alloc(dev, &backend, name, name_len >= 0 ? name_len : 0);
 	if (!fdtv)
 		return -ENOMEM;