USB: handle bcd incrementation in usb modalias generation

This patch fixes a bug when incrementing/decrementing on a BCD formatted
integer (i.e. 0x09++ should be 0x10 not 0x0A).  It just adds a function
for incrementing/decrementing BCD integers by converting to decimal,
doing the increment/decrement and then converting back to BCD.

Signed-off-by: Nathaniel McCallum <nathaniel@natemccallum.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 47 insertions, 2 deletions

diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index e31f03aaf294..6f426afbc522 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -160,6 +160,45 @@ static void do_usb_entry(struct usb_device_id *id,
                    "MODULE_ALIAS(\"%s\");\n", alias);
 }
 
+/* Handles increment/decrement of BCD formatted integers */
+/* Returns the previous value, so it works like i++ or i-- */
+static unsigned int incbcd(unsigned int *bcd,
+                           int inc,
+                           unsigned char max,
+                           size_t chars)
+{
+        unsigned int init = *bcd, i, j;
+        unsigned long long c, dec = 0;
+
+        /* If bcd is not in BCD format, just increment */
+        if (max > 0x9) {
+                *bcd += inc;
+                return init;
+        }
+
+        /* Convert BCD to Decimal */
+        for (i=0 ; i < chars ; i++) {
+                c = (*bcd >> (i << 2)) & 0xf;
+                c = c > 9 ? 9 : c; /* force to bcd just in case */
+                for (j=0 ; j < i ; j++)
+                        c = c * 10;
+                dec += c;
+        }
+
+        /* Do our increment/decrement */
+        dec += inc;
+        *bcd  = 0;
+
+        /* Convert back to BCD */
+        for (i=0 ; i < chars ; i++) {
+                for (c=1,j=0 ; j < i ; j++)
+                        c = c * 10;
+                c = (dec / c) % 10;
+                *bcd += c << (i << 2);
+        }
+        return init;
+}
+
 static void do_usb_entry_multi(struct usb_device_id *id, struct module *mod)
 {
         unsigned int devlo, devhi;
@@ -208,10 +247,16 @@ static void do_usb_entry_multi(struct usb_device_id *id, struct module *mod)
                 }
 
                 if (clo > 0x0)
-                        do_usb_entry(id, devlo++, ndigits, clo, max, max, mod);
+                        do_usb_entry(id,
+                                     incbcd(&devlo, 1, max,
+                                            sizeof(id->bcdDevice_lo) * 2),
+                                     ndigits, clo, max, max, mod);
 
                 if (chi < max)
-                        do_usb_entry(id, devhi--, ndigits, 0x0, chi, max, mod);
+                        do_usb_entry(id,
+                                     incbcd(&devhi, -1, max,
+                                            sizeof(id->bcdDevice_lo) * 2),
+                                     ndigits, 0x0, chi, max, mod);
         }
 }