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path: root/drivers/acpi/hardware/hwregs.c
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Diffstat (limited to 'drivers/acpi/hardware/hwregs.c')
-rw-r--r--drivers/acpi/hardware/hwregs.c77
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, &reg->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, &reg->address);
if (!address) {