static u8
acpi_hw_get_access_bit_width(u64 address,
struct acpi_generic_address *reg, u8 max_bit_width)
{
u8 access_bit_width;
/*
* GAS format "register", used by FADT:
* 1. Detected if bit_offset is 0 and bit_width is 8/16/32/64;
* 2. access_size field is ignored and bit_width field is used for
* determining the boundary of the IO accesses.
* GAS format "region", used by APEI registers:
* 1. Detected if bit_offset is not 0 or bit_width is not 8/16/32/64;
* 2. access_size field is used for determining the boundary of the
* IO accesses;
* 3. bit_offset/bit_width fields are used to describe the "region".
*
* Note: This algorithm assumes that the "Address" fields should always
* contain aligned values.
*/
if (!reg->bit_offset && reg->bit_width &&
ACPI_IS_POWER_OF_TWO(reg->bit_width) &&
ACPI_IS_ALIGNED(reg->bit_width, 8)) {
access_bit_width = reg->bit_width;
} else if (reg->access_width) {
access_bit_width = ACPI_ACCESS_BIT_WIDTH(reg->access_width);
} else {
access_bit_width =
ACPI_ROUND_UP_POWER_OF_TWO_8(reg->bit_offset +
reg->bit_width);
if (access_bit_width <= 8) {
access_bit_width = 8;
} else {
while (!ACPI_IS_ALIGNED(address, access_bit_width >> 3)) {
access_bit_width >>= 1;
}
}
}
/* Maximum IO port access bit width is 32 */
if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
max_bit_width = 32;
}
/*
* Return access width according to the requested maximum access bit width,
* as the caller should know the format of the register and may enforce
* a 32-bit accesses.
*/
if (access_bit_width < max_bit_width) {
return (access_bit_width);
}
return (max_bit_width);
}
static UINT8
AcpiHwGetAccessBitWidth (
UINT64 Address,
ACPI_GENERIC_ADDRESS *Reg,
UINT8 MaxBitWidth)
{
UINT8 AccessBitWidth;
/*
* GAS format "register", used by FADT:
* 1. Detected if BitOffset is 0 and BitWidth is 8/16/32/64;
* 2. AccessSize field is ignored and BitWidth field is used for
* determining the boundary of the IO accesses.
* GAS format "region", used by APEI registers:
* 1. Detected if BitOffset is not 0 or BitWidth is not 8/16/32/64;
* 2. AccessSize field is used for determining the boundary of the
* IO accesses;
* 3. BitOffset/BitWidth fields are used to describe the "region".
*
* Note: This algorithm assumes that the "Address" fields should always
* contain aligned values.
*/
if (!Reg->BitOffset && Reg->BitWidth &&
ACPI_IS_POWER_OF_TWO (Reg->BitWidth) &&
ACPI_IS_ALIGNED (Reg->BitWidth, 8))
{
AccessBitWidth = Reg->BitWidth;
}
else if (Reg->AccessWidth)
{
AccessBitWidth = ACPI_ACCESS_BIT_WIDTH (Reg->AccessWidth);
}
else
{
AccessBitWidth = ACPI_ROUND_UP_POWER_OF_TWO_8 (
Reg->BitOffset + Reg->BitWidth);
if (AccessBitWidth <= 8)
{
AccessBitWidth = 8;
}
else
{
while (!ACPI_IS_ALIGNED (Address, AccessBitWidth >> 3))
{
AccessBitWidth >>= 1;
}
}
}
/* Maximum IO port access bit width is 32 */
if (Reg->SpaceId == ACPI_ADR_SPACE_SYSTEM_IO)
{
MaxBitWidth = 32;
}
/*
* Return access width according to the requested maximum access bit width,
* as the caller should know the format of the register and may enforce
* a 32-bit accesses.
*/
if (AccessBitWidth < MaxBitWidth)
{
return (AccessBitWidth);
}
return (MaxBitWidth);
}
