diff options
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'; +} |