rt2x00: Driver requiring firmware should select crc algo
The driver should select what CRC algorithm is required
when performing a checksum on the firmware.
rt61pci & rt73usb require crc-itu-t
rt2800pci & rt2800usb require crc-ccitt
Legacy 2800pci/usb driver uses crc-itu-t + bit order reversion,
but that is just inefficient especially since the end result is
the same as a different algorithm which is also available as library. ;)
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2x00firmware.c b/drivers/net/wireless/rt2x00/rt2x00firmware.c
index 442ff80..4f9fe56 100644
--- a/drivers/net/wireless/rt2x00/rt2x00firmware.c
+++ b/drivers/net/wireless/rt2x00/rt2x00firmware.c
@@ -23,6 +23,7 @@
Abstract: rt2x00 firmware loading routines.
*/
+#include <linux/crc-ccitt.h>
#include <linux/crc-itu-t.h>
#include <linux/kernel.h>
#include <linux/module.h>
@@ -37,7 +38,6 @@
char *fw_name;
int retval;
u16 crc;
- u16 tmp;
/*
* Read correct firmware from harddisk.
@@ -64,17 +64,37 @@
}
/*
- * Validate the firmware using 16 bit CRC.
- * The last 2 bytes of the firmware are the CRC
- * so substract those 2 bytes from the CRC checksum,
- * and set those 2 bytes to 0 when calculating CRC.
+ * Perform crc validation on the firmware.
+ * The last 2 bytes in the firmware array are the crc checksum itself,
+ * this means that we should never pass those 2 bytes to the crc
+ * algorithm.
*/
- tmp = 0;
- crc = crc_itu_t(0, fw->data, fw->size - 2);
- crc = crc_itu_t(crc, (u8 *)&tmp, 2);
+ if (test_bit(DRIVER_REQUIRE_FIRMWARE_CRC_ITU_T, &rt2x00dev->flags)) {
+ /*
+ * Use the crc itu-t algorithm.
+ * Use 0 for the last 2 bytes to complete the checksum.
+ */
+ crc = crc_itu_t(0, fw->data, fw->size - 2);
+ crc = crc_itu_t_byte(crc, 0);
+ crc = crc_itu_t_byte(crc, 0);
+ } else if (test_bit(DRIVER_REQUIRE_FIRMWARE_CCITT, &rt2x00dev->flags)) {
+ /*
+ * Use the crc ccitt algorithm.
+ * This will return the same value as the legacy driver which
+ * used bit ordering reversion on the both the firmware bytes
+ * before input input as well as on the final output.
+ * Obviously using crc ccitt directly is much more efficient.
+ */
+ crc = crc_ccitt(~0, fw->data, fw->size - 2);
+ } else {
+ ERROR(rt2x00dev, "No checksum algorithm selected "
+ "for firmware validation.\n");
+ retval = -ENOENT;
+ goto exit;
+ }
if (crc != (fw->data[fw->size - 2] << 8 | fw->data[fw->size - 1])) {
- ERROR(rt2x00dev, "Firmware CRC error.\n");
+ ERROR(rt2x00dev, "Firmware checksum error.\n");
retval = -ENOENT;
goto exit;
}
@@ -96,6 +116,9 @@
{
int retval;
+ if (!test_bit(DRIVER_REQUIRE_FIRMWARE, &rt2x00dev->flags))
+ return 0;
+
if (!rt2x00dev->fw) {
retval = rt2x00lib_request_firmware(rt2x00dev);
if (retval)