From 5085cb26503a662a5cfdf53ce96fd606c1fbe9ba Mon Sep 17 00:00:00 2001 From: Dominik Brodowski Date: Mon, 27 Jun 2005 16:28:45 -0700 Subject: [PATCH] pcmcia: add some Documentation 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/pcmcia/devicetable.txt | 64 ++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 Documentation/pcmcia/devicetable.txt (limited to 'Documentation/pcmcia/devicetable.txt') diff --git a/Documentation/pcmcia/devicetable.txt b/Documentation/pcmcia/devicetable.txt new file mode 100644 index 0000000..7225f9e --- /dev/null +++ b/Documentation/pcmcia/devicetable.txt @@ -0,0 +1,64 @@ +Matching of PCMCIA devices to drivers is done using one or more of the +following criteria: + +- manufactor ID +- card ID +- product ID strings _and_ hashes of these strings +- function ID +- device function (actual and pseudo) + +You should use the helpers in include/pcmcia/device_id.h for generating the +struct pcmcia_device_id[] entries which match devices to drivers. + +If you want to match product ID strings, you also need to pass the crc32 +hashes of the string to the macro, e.g. if you want to match the product ID +string 1, you need to use + +PCMCIA_DEVICE_PROD_ID1("some_string", 0x(hash_of_some_string)), + +If the hash is incorrect, the kernel will inform you about this in "dmesg" +upon module initialization, and tell you of the correct hash. + +You can determine the hash of the product ID strings by running +"pcmcia-modalias %n.%m" [%n being replaced with the socket number and %m being +replaced with the device function] from pcmciautils. It generates a string +in the following form: +pcmcia:m0149cC1ABf06pfn00fn00pa725B842DpbF1EFEE84pc0877B627pd00000000 + +The hex value after "pa" is the hash of product ID string 1, after "pb" for +string 2 and so on. + +Alternatively, you can use this small tool to determine the crc32 hash. +simply pass the string you want to evaluate as argument to this program, +e.g. +$ ./crc32hash "Dual Speed" + +------------------------------------------------------------------------- +/* crc32hash.c - derived from linux/lib/crc32.c, GNU GPL v2 */ +#include +#include +#include +#include + +unsigned int crc32(unsigned char const *p, unsigned int len) +{ + int i; + unsigned int crc = 0; + while (len--) + crc ^= *p++; + for (i = 0; i < 8; i++) + crc = (crc >> 1) ^ ((crc & 1) ? 0xedb88320 : 0); + } + return crc; +} + +int main(int argc, char **argv) { + unsigned int result; + if (argc != 2) { + printf("no string passed as argument\n"); + return -1; + } + result = crc32(argv[1], strlen(argv[1])); + printf("0x%x\n", result); + return 0; +} -- cgit v1.1