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Staging: ipack: check the device ID space CRC.

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We check the CRC and store the result of the check in struct ipac_device.
A warning is emitted if the check fails.  However we leave it to the
IPack module device to refuse to initialize due to a bad CRC.  I have seen
otherwise good modules with bad CRCs.

Signed-off-by: Jens Taprogge <jens.taprogge@taprogge.org>
Signed-off-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jens Taprogge 2012-09-11 13:35:03 +02:00 committed by Greg Kroah-Hartman
parent 8a3ae16e60
commit a92caeb8e1
2 changed files with 59 additions and 1 deletions
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59
drivers/staging/ipack/ipack.c
View File

@ -253,20 +253,71 @@ void ipack_driver_unregister(struct ipack_driver *edrv)
}
EXPORT_SYMBOL_GPL(ipack_driver_unregister);
static u16 ipack_crc_byte(u16 crc, u8 c)
{
int i;
crc ^= c << 8;
for (i = 0; i < 8; i++)
crc = (crc << 1) ^ ((crc & 0x8000) ? 0x1021 : 0);
return crc;
}
/*
* The algorithm in lib/crc-ccitt.c does not seem to apply since it uses the
* opposite bit ordering.
*/
static u8 ipack_calc_crc1(struct ipack_device *dev)
{
u8 c;
u16 crc;
unsigned int i;
crc = 0xffff;
for (i = 0; i < dev->id_avail; i++) {
c = (i != 11) ? dev->id[i] : 0;
crc = ipack_crc_byte(crc, c);
}
crc = ~crc;
return crc & 0xff;
}
static u16 ipack_calc_crc2(struct ipack_device *dev)
{
u8 c;
u16 crc;
unsigned int i;
crc = 0xffff;
for (i = 0; i < dev->id_avail; i++) {
c = ((i != 0x18) && (i != 0x19)) ? dev->id[i] : 0;
crc = ipack_crc_byte(crc, c);
}
crc = ~crc;
return crc;
}
static void ipack_parse_id1(struct ipack_device *dev)
{
u8 *id = dev->id;
u8 crc;
dev->id_vendor = id[4];
dev->id_device = id[5];
dev->speed_8mhz = 1;
dev->speed_32mhz = (id[7] == 'H');
crc = ipack_calc_crc1(dev);
dev->id_crc_correct = (crc == id[11]);
if (!dev->id_crc_correct) {
dev_warn(&dev->dev, "ID CRC invalid found 0x%x, expected 0x%x.\n",
id[11], crc);
}
}
static void ipack_parse_id2(struct ipack_device *dev)
{
__be16 *id = (__be16 *) dev->id;
u16 flags;
u16 flags, crc;
dev->id_vendor = ((be16_to_cpu(id[3]) & 0xff) << 16)
+ be16_to_cpu(id[4]);
@ -274,6 +325,12 @@ static void ipack_parse_id2(struct ipack_device *dev)
flags = be16_to_cpu(id[10]);
dev->speed_8mhz = !!(flags & 2);
dev->speed_32mhz = !!(flags & 4);
crc = ipack_calc_crc2(dev);
dev->id_crc_correct = (crc == be16_to_cpu(id[12]));
if (!dev->id_crc_correct) {
dev_warn(&dev->dev, "ID CRC invalid found 0x%x, expected 0x%x.\n",
id[11], crc);
}
}
static int ipack_device_read_id(struct ipack_device *dev)

1
drivers/staging/ipack/ipack.h
View File

@ -77,6 +77,7 @@ struct ipack_device {
u32 id_vendor;
u32 id_device;
u8 id_format;
unsigned int id_crc_correct:1;
unsigned int speed_8mhz:1;
unsigned int speed_32mhz:1;
};