forked from Minki/linux
5085cb2650
Add some information useful for PCMCIA device driver authors to Documentation/pcmcia/, and reference it in dmesg in case of hash mismatches. Also add a reference to pcmciautils to Documentation/Changes. With recent changes, you don't need to concern yourself with pcmcia-cs even if you have PCMCIA hardware, so the example above the list needed to be adapted as well. Signed-off-by: Dominik Brodowski <linux@dominikbrodowksi.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
65 lines
1.9 KiB
Plaintext
65 lines
1.9 KiB
Plaintext
Matching of PCMCIA devices to drivers is done using one or more of the
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following criteria:
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- manufactor ID
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- card ID
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- product ID strings _and_ hashes of these strings
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- function ID
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- device function (actual and pseudo)
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You should use the helpers in include/pcmcia/device_id.h for generating the
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struct pcmcia_device_id[] entries which match devices to drivers.
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If you want to match product ID strings, you also need to pass the crc32
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hashes of the string to the macro, e.g. if you want to match the product ID
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string 1, you need to use
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PCMCIA_DEVICE_PROD_ID1("some_string", 0x(hash_of_some_string)),
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If the hash is incorrect, the kernel will inform you about this in "dmesg"
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upon module initialization, and tell you of the correct hash.
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You can determine the hash of the product ID strings by running
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"pcmcia-modalias %n.%m" [%n being replaced with the socket number and %m being
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replaced with the device function] from pcmciautils. It generates a string
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in the following form:
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pcmcia:m0149cC1ABf06pfn00fn00pa725B842DpbF1EFEE84pc0877B627pd00000000
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The hex value after "pa" is the hash of product ID string 1, after "pb" for
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string 2 and so on.
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Alternatively, you can use this small tool to determine the crc32 hash.
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simply pass the string you want to evaluate as argument to this program,
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e.g.
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$ ./crc32hash "Dual Speed"
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-------------------------------------------------------------------------
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/* crc32hash.c - derived from linux/lib/crc32.c, GNU GPL v2 */
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#include <string.h>
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#include <stdio.h>
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#include <ctype.h>
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#include <stdlib.h>
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unsigned int crc32(unsigned char const *p, unsigned int len)
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{
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int i;
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unsigned int crc = 0;
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while (len--)
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crc ^= *p++;
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for (i = 0; i < 8; i++)
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crc = (crc >> 1) ^ ((crc & 1) ? 0xedb88320 : 0);
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}
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return crc;
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}
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int main(int argc, char **argv) {
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unsigned int result;
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if (argc != 2) {
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printf("no string passed as argument\n");
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return -1;
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}
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result = crc32(argv[1], strlen(argv[1]));
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printf("0x%x\n", result);
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return 0;
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}
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