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PNP: add pnp_eisa_id_to_string()

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Converting the EISA ID to a string is messy and error-prone, and
we might as well use the same code for ISAPNP and PNPBIOS.

PNPACPI uses the conversion done by the ACPI core with
acpi_ex_eisa_id_to_string().

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Acked-By: Rene Herman <rene.herman@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Bjorn Helgaas 2008-04-28 16:33:53 -06:00 • committed by Len Brown
parent 772defc629
commit 25eb846189
5 changed files with 43 additions and 45 deletions
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26
drivers/pnp/support.c
View file

@ -25,3 +25,29 @@ int pnp_is_active(struct pnp_dev *dev)
}
EXPORT_SYMBOL(pnp_is_active);
/*
* Functionally similar to acpi_ex_eisa_id_to_string(), but that's
* buried in the ACPI CA, and we can't depend on it being present.
*/
void pnp_eisa_id_to_string(u32 id, char *str)
{
id = be32_to_cpu(id);
/*
* According to the specs, the first three characters are five-bit
* compressed ASCII, and the left-over high order bit should be zero.
* However, the Linux ISAPNP code historically used six bits for the
* first character, and there seem to be IDs that depend on that,
* e.g., "nEC8241" in the Linux 8250_pnp serial driver and the
* FreeBSD sys/pc98/cbus/sio_cbus.c driver.
*/
str[0] = 'A' + ((id >> 26) & 0x3f) - 1;
str[1] = 'A' + ((id >> 21) & 0x1f) - 1;
str[2] = 'A' + ((id >> 16) & 0x1f) - 1;
str[3] = hex_asc((id >> 12) & 0xf);
str[4] = hex_asc((id >> 8) & 0xf);
str[5] = hex_asc((id >> 4) & 0xf);
str[6] = hex_asc((id >> 0) & 0xf);
str[7] = '\0';
}