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author | Bjorn Helgaas <bjorn.helgaas@hp.com> | 2008-04-28 16:33:53 -0600 |
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committer | Len Brown <len.brown@intel.com> | 2008-04-29 03:22:16 -0400 |
commit | 25eb846189d20db4114cebf14fee96d69bef4667 (patch) | |
tree | bca11a6cc777f4ee121b1c04aa9e86075ae04a3e /drivers/pnp/support.c | |
parent | 772defc6292bae8b6db298476d1dabd22a99492b (diff) | |
download | lwn-25eb846189d20db4114cebf14fee96d69bef4667.tar.gz lwn-25eb846189d20db4114cebf14fee96d69bef4667.zip |
PNP: add pnp_eisa_id_to_string()
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>
Diffstat (limited to 'drivers/pnp/support.c')
-rw-r--r-- | drivers/pnp/support.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/drivers/pnp/support.c b/drivers/pnp/support.c index 13c608f5fb30..e848b794e312 100644 --- a/drivers/pnp/support.c +++ b/drivers/pnp/support.c @@ -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'; +} |