diff options
Diffstat (limited to 'drivers/acpi')
| -rw-r--r-- | drivers/acpi/acpica/hwregs.c | 49 |
1 files changed, 47 insertions, 2 deletions
diff --git a/drivers/acpi/acpica/hwregs.c b/drivers/acpi/acpica/hwregs.c index 035fb52c3bcd..892e677f524f 100644 --- a/drivers/acpi/acpica/hwregs.c +++ b/drivers/acpi/acpica/hwregs.c @@ -51,6 +51,10 @@ ACPI_MODULE_NAME("hwregs") #if (!ACPI_REDUCED_HARDWARE) /* Local Prototypes */ +static u8 +acpi_hw_get_access_bit_width(struct acpi_generic_address *reg, + u8 max_bit_width); + static acpi_status acpi_hw_read_multiple(u32 *value, struct acpi_generic_address *register_a, @@ -65,6 +69,48 @@ acpi_hw_write_multiple(u32 value, /****************************************************************************** * + * FUNCTION: acpi_hw_get_access_bit_width + * + * PARAMETERS: reg - GAS register structure + * max_bit_width - Max bit_width supported (32 or 64) + * + * RETURN: Status + * + * DESCRIPTION: Obtain optimal access bit width + * + ******************************************************************************/ + +static u8 +acpi_hw_get_access_bit_width(struct acpi_generic_address *reg, u8 max_bit_width) +{ + u64 address; + + if (!reg->access_width) { + /* + * Detect old register descriptors where only the bit_width field + * makes senses. The target address is copied to handle possible + * alignment issues. + */ + ACPI_MOVE_64_TO_64(&address, ®->address); + if (!reg->bit_offset && reg->bit_width && + ACPI_IS_POWER_OF_TWO(reg->bit_width) && + ACPI_IS_ALIGNED(reg->bit_width, 8) && + ACPI_IS_ALIGNED(address, reg->bit_width)) { + return (reg->bit_width); + } else { + if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) { + return (32); + } else { + return (max_bit_width); + } + } + } else { + return (1 << (reg->access_width + 2)); + } +} + +/****************************************************************************** + * * FUNCTION: acpi_hw_validate_register * * PARAMETERS: reg - GAS register structure @@ -122,8 +168,7 @@ acpi_hw_validate_register(struct acpi_generic_address *reg, /* Validate the bit_width, convert access_width into number of bits */ - access_width = reg->access_width ? reg->access_width : 1; - access_width = 1 << (access_width + 2); + access_width = acpi_hw_get_access_bit_width(reg, max_bit_width); bit_width = ACPI_ROUND_UP(reg->bit_offset + reg->bit_width, access_width); if (max_bit_width < bit_width) { |