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>
diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index 9d0dfcb..a39e434 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -59,6 +59,67 @@
}
EXPORT_SYMBOL(fw_csr_iterator_next);
+static u32 *search_leaf(u32 *directory, int search_key)
+{
+ struct fw_csr_iterator ci;
+ int last_key = 0, key, value;
+
+ fw_csr_iterator_init(&ci, directory);
+ while (fw_csr_iterator_next(&ci, &key, &value)) {
+ if (last_key == search_key &&
+ key == (CSR_DESCRIPTOR | CSR_LEAF))
+ return ci.p - 1 + value;
+ last_key = key;
+ }
+ return NULL;
+}
+
+static int textual_leaf_to_string(u32 *block, char *buf, size_t size)
+{
+ unsigned int quadlets, length;
+
+ if (!size || !buf)
+ return -EINVAL;
+
+ quadlets = min(block[0] >> 16, 256u);
+ if (quadlets < 2)
+ return -ENODATA;
+
+ if (block[1] != 0 || block[2] != 0)
+ /* unknown language/character set */
+ return -ENODATA;
+
+ block += 3;
+ quadlets -= 2;
+ for (length = 0; length < quadlets * 4 && length + 1 < size; length++) {
+ char c = block[length / 4] >> (24 - 8 * (length % 4));
+ if (c == '\0')
+ break;
+ buf[length] = c;
+ }
+ buf[length] = '\0';
+ return length;
+}
+
+/**
+ * fw_csr_string - reads a string from the configuration ROM
+ * @directory: device or unit directory;
+ * fw_device->config_rom+5 or fw_unit->directory
+ * @key: the key of the preceding directory entry
+ * @buf: where to put the string
+ * @size: size of @buf, in bytes
+ *
+ * Returns string length (>= 0) or error code (< 0).
+ */
+int fw_csr_string(u32 *directory, int key, char *buf, size_t size)
+{
+ u32 *leaf = search_leaf(directory, key);
+ if (!leaf)
+ return -ENOENT;
+ return textual_leaf_to_string(leaf, buf, size);
+}
+EXPORT_SYMBOL(fw_csr_string);
+
static bool is_fw_unit(struct device *dev);
static int match_unit_directory(u32 *directory, u32 match_flags,
@@ -226,10 +287,10 @@
{
struct config_rom_attribute *attr =
container_of(dattr, struct config_rom_attribute, attr);
- struct fw_csr_iterator ci;
- u32 *dir, *block = NULL, *p, *end;
- int length, key, value, last_key = 0, ret = -ENOENT;
- char *b;
+ u32 *dir;
+ size_t bufsize;
+ char dummy_buf[2];
+ int ret;
down_read(&fw_device_rwsem);
@@ -238,40 +299,23 @@
else
dir = fw_device(dev)->config_rom + 5;
- fw_csr_iterator_init(&ci, dir);
- while (fw_csr_iterator_next(&ci, &key, &value)) {
- if (attr->key == last_key &&
- key == (CSR_DESCRIPTOR | CSR_LEAF))
- block = ci.p - 1 + value;
- last_key = key;
+ if (buf) {
+ bufsize = PAGE_SIZE - 1;
+ } else {
+ buf = dummy_buf;
+ bufsize = 1;
}
- if (block == NULL)
- goto out;
+ ret = fw_csr_string(dir, attr->key, buf, bufsize);
- length = min(block[0] >> 16, 256U);
- if (length < 3)
- goto out;
-
- if (block[1] != 0 || block[2] != 0)
- /* Unknown encoding. */
- goto out;
-
- if (buf == NULL) {
- ret = length * 4;
- goto out;
+ if (ret >= 0) {
+ /* Strip trailing whitespace and add newline. */
+ while (ret > 0 && isspace(buf[ret - 1]))
+ ret--;
+ strcpy(buf + ret, "\n");
+ ret++;
}
- b = buf;
- end = &block[length + 1];
- for (p = &block[3]; p < end; p++, b += 4)
- * (u32 *) b = (__force u32) __cpu_to_be32(*p);
-
- /* Strip trailing whitespace and add newline. */
- while (b--, (isspace(*b) || *b == '\0') && b > buf);
- strcpy(b + 1, "\n");
- ret = b + 2 - buf;
- out:
up_read(&fw_device_rwsem);
return ret;