diff options
Diffstat (limited to 'drivers/acpi/hardware/hwregs.c')
| -rw-r--r-- | drivers/acpi/hardware/hwregs.c | 77 |
1 files changed, 62 insertions, 15 deletions
diff --git a/drivers/acpi/hardware/hwregs.c b/drivers/acpi/hardware/hwregs.c index ae142de19507..3143f36fcec9 100644 --- a/drivers/acpi/hardware/hwregs.c +++ b/drivers/acpi/hardware/hwregs.c @@ -172,9 +172,9 @@ acpi_get_sleep_type_data(u8 sleep_state, u8 * sleep_type_a, u8 * sleep_type_b) } /* - * The package must have at least two elements. NOTE (March 2005): This + * The package must have at least two elements. NOTE (March 2005): This * goes against the current ACPI spec which defines this object as a - * package with one encoded DWORD element. However, existing practice + * package with one encoded DWORD element. However, existing practice * by BIOS vendors seems to be to have 2 or more elements, at least * one per sleep type (A/B). */ @@ -255,7 +255,7 @@ struct acpi_bit_register_info *acpi_hw_get_bit_register_info(u32 register_id) * return_value - Value that was read from the register * Flags - Lock the hardware or not * - * RETURN: Status and the value read from specified Register. Value + * RETURN: Status and the value read from specified Register. Value * returned is normalized to bit0 (is shifted all the way right) * * DESCRIPTION: ACPI bit_register read function. @@ -361,8 +361,8 @@ acpi_status acpi_set_register(u32 register_id, u32 value, u32 flags) case ACPI_REGISTER_PM1_STATUS: /* - * Status Registers are different from the rest. Clear by - * writing 1, and writing 0 has no effect. So, the only relevant + * Status Registers are different from the rest. Clear by + * writing 1, and writing 0 has no effect. So, the only relevant * information is the single bit we're interested in, all others should * be written as 0 so they will be left unchanged. */ @@ -467,14 +467,13 @@ ACPI_EXPORT_SYMBOL(acpi_set_register) * * FUNCTION: acpi_hw_register_read * - * PARAMETERS: use_lock - Mutex hw access - * register_id - register_iD + Offset + * PARAMETERS: use_lock - Lock hardware? True/False + * register_id - ACPI Register ID * return_value - Where the register value is returned * * RETURN: Status and the value read. * - * DESCRIPTION: Acpi register read function. Registers are read at the - * given offset. + * DESCRIPTION: Read from the specified ACPI register * ******************************************************************************/ acpi_status @@ -580,14 +579,26 @@ acpi_hw_register_read(u8 use_lock, u32 register_id, u32 * return_value) * * FUNCTION: acpi_hw_register_write * - * PARAMETERS: use_lock - Mutex hw access - * register_id - register_iD + Offset + * PARAMETERS: use_lock - Lock hardware? True/False + * register_id - ACPI Register ID * Value - The value to write * * RETURN: Status * - * DESCRIPTION: Acpi register Write function. Registers are written at the - * given offset. + * DESCRIPTION: Write to the specified ACPI register + * + * NOTE: In accordance with the ACPI specification, this function automatically + * preserves the value of the following bits, meaning that these bits cannot be + * changed via this interface: + * + * PM1_CONTROL[0] = SCI_EN + * PM1_CONTROL[9] + * PM1_STATUS[11] + * + * ACPI References: + * 1) Hardware Ignored Bits: When software writes to a register with ignored + * bit fields, it preserves the ignored bit fields + * 2) SCI_EN: OSPM always preserves this bit position * ******************************************************************************/ @@ -595,6 +606,7 @@ acpi_status acpi_hw_register_write(u8 use_lock, u32 register_id, u32 value) { acpi_status status; acpi_cpu_flags lock_flags = 0; + u32 read_value; ACPI_FUNCTION_TRACE(hw_register_write); @@ -605,6 +617,22 @@ acpi_status acpi_hw_register_write(u8 use_lock, u32 register_id, u32 value) switch (register_id) { case ACPI_REGISTER_PM1_STATUS: /* 16-bit access */ + /* Perform a read first to preserve certain bits (per ACPI spec) */ + + status = acpi_hw_register_read(ACPI_MTX_DO_NOT_LOCK, + ACPI_REGISTER_PM1_STATUS, + &read_value); + if (ACPI_FAILURE(status)) { + goto unlock_and_exit; + } + + /* Insert the bits to be preserved */ + + ACPI_INSERT_BITS(value, ACPI_PM1_STATUS_PRESERVED_BITS, + read_value); + + /* Now we can write the data */ + status = acpi_hw_low_level_write(16, value, &acpi_gbl_FADT->xpm1a_evt_blk); @@ -635,6 +663,25 @@ acpi_status acpi_hw_register_write(u8 use_lock, u32 register_id, u32 value) case ACPI_REGISTER_PM1_CONTROL: /* 16-bit access */ + /* + * Perform a read first to preserve certain bits (per ACPI spec) + * + * Note: This includes SCI_EN, we never want to change this bit + */ + status = acpi_hw_register_read(ACPI_MTX_DO_NOT_LOCK, + ACPI_REGISTER_PM1_CONTROL, + &read_value); + if (ACPI_FAILURE(status)) { + goto unlock_and_exit; + } + + /* Insert the bits to be preserved */ + + ACPI_INSERT_BITS(value, ACPI_PM1_CONTROL_PRESERVED_BITS, + read_value); + + /* Now we can write the data */ + status = acpi_hw_low_level_write(16, value, &acpi_gbl_FADT->xpm1a_cnt_blk); @@ -726,7 +773,7 @@ acpi_hw_low_level_read(u32 width, u32 * value, struct acpi_generic_address *reg) return (AE_OK); } - /* Get a local copy of the address. Handles possible alignment issues */ + /* Get a local copy of the address. Handles possible alignment issues */ ACPI_MOVE_64_TO_64(&address, ®->address); if (!address) { @@ -798,7 +845,7 @@ acpi_hw_low_level_write(u32 width, u32 value, struct acpi_generic_address * reg) return (AE_OK); } - /* Get a local copy of the address. Handles possible alignment issues */ + /* Get a local copy of the address. Handles possible alignment issues */ ACPI_MOVE_64_TO_64(&address, ®->address); if (!address) { |