p54: improve eeprom parser
Christian Lamparter [Mon, 16 Aug 2010 23:16:58 +0000 (01:16 +0200)]
Like other vendors, p54* devices have a checksum for
the EEPROM descriptor data. This patch enhances the
parser code to generate and verify the data fields,
before initializing the radio-chip on the card.

Note:
If you have to bootstrap an alternative EEPROM image
for your device and you don't know how to generate a
valid crc ccitt checksum, you should take a look at:
http://git.kernel.org/?p=linux/kernel/git/chr/p54tools.git

The "checksum" utility loads a binary p54 EEPROM blob
(use the -f switch, to skip the check) and applies
the correct crc automatically.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/p54/Kconfig
drivers/net/wireless/p54/eeprom.c

index b0342a5..60a930e 100644 (file)
@@ -2,6 +2,7 @@ config P54_COMMON
        tristate "Softmac Prism54 support"
        depends on MAC80211 && EXPERIMENTAL
        select FW_LOADER
+       select CRC_CCITT
        ---help---
          This is common code for isl38xx/stlc45xx based modules.
          This module does nothing by itself - the USB/PCI/SPI front-ends
index d687cb7..32d3f99 100644 (file)
@@ -23,6 +23,7 @@
 #include <linux/slab.h>
 
 #include <net/mac80211.h>
+#include <linux/crc-ccitt.h>
 
 #include "p54.h"
 #include "eeprom.h"
@@ -540,6 +541,7 @@ int p54_parse_eeprom(struct ieee80211_hw *dev, void *eeprom, int len)
        int err;
        u8 *end = (u8 *)eeprom + len;
        u16 synth = 0;
+       u16 crc16 = ~0;
 
        wrap = (struct eeprom_pda_wrap *) eeprom;
        entry = (void *)wrap->data + le16_to_cpu(wrap->len);
@@ -655,16 +657,29 @@ int p54_parse_eeprom(struct ieee80211_hw *dev, void *eeprom, int len)
                        }
                        break;
                case PDR_END:
-                       /* make it overrun */
-                       entry_len = len;
+                       crc16 = ~crc_ccitt(crc16, (u8 *) entry, sizeof(*entry));
+                       if (crc16 != le16_to_cpup((__le16 *)entry->data)) {
+                               wiphy_err(dev->wiphy, "eeprom failed checksum "
+                                        "test!\n");
+                               err = -ENOMSG;
+                               goto err;
+                       } else {
+                               goto good_eeprom;
+                       }
                        break;
                default:
                        break;
                }
 
-               entry = (void *)entry + (entry_len + 1)*2;
+               crc16 = crc_ccitt(crc16, (u8 *)entry, (entry_len + 1) * 2);
+               entry = (void *)entry + (entry_len + 1) * 2;
        }
 
+       wiphy_err(dev->wiphy, "unexpected end of eeprom data.\n");
+       err = -ENODATA;
+       goto err;
+
+good_eeprom:
        if (!synth || !priv->iq_autocal || !priv->output_limit ||
            !priv->curve_data) {
                wiphy_err(dev->wiphy,