ACPICA: Restructure bit register access functions

Update code for acpi_read_bit_register and acpi_write_bit_register.
Simplified code path, condensed duplicate code.
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/acpica/hwxface.c

@@ -133,8 +133,8 @@ acpi_status acpi_read(u32 *value, struct acpi_generic_address *reg)
 	*value = 0;
 
 	/*
-	 * Two address spaces supported: Memory or IO.
-	 * PCI_Config is not supported here because the GAS struct is insufficient
+	 * Two address spaces supported: Memory or IO. PCI_Config is
+	 * not supported here because the GAS structure is insufficient
 	 */
 	switch (reg->space_id) {
 	case ACPI_ADR_SPACE_SYSTEM_MEMORY:
@@ -266,11 +266,12 @@ ACPI_EXPORT_SYMBOL(acpi_write)
  ******************************************************************************/
 acpi_status acpi_read_bit_register(u32 register_id, u32 *return_value)
 {
-	u32 register_value = 0;
 	struct acpi_bit_register_info *bit_reg_info;
+	u32 register_value;
+	u32 value;
 	acpi_status status;
 
-	ACPI_FUNCTION_TRACE(acpi_read_bit_register);
+	ACPI_FUNCTION_TRACE_U32(acpi_read_bit_register, register_id);
 
 	/* Get the info structure corresponding to the requested ACPI Register */
 
@@ -283,23 +284,22 @@ acpi_status acpi_read_bit_register(u32 register_id, u32 *return_value)
 
 	status = acpi_hw_register_read(bit_reg_info->parent_register,
 				       &register_value);
+	if (ACPI_FAILURE(status)) {
+		return_ACPI_STATUS(status);
+	}
 
-	if (ACPI_SUCCESS(status)) {
-
-		/* Normalize the value that was read */
+	/* Normalize the value that was read, mask off other bits */
 
-		register_value =
-		    ((register_value & bit_reg_info->access_bit_mask)
+	value = ((register_value & bit_reg_info->access_bit_mask)
 		 >> bit_reg_info->bit_position);
 
-		*return_value = register_value;
-
-		ACPI_DEBUG_PRINT((ACPI_DB_IO, "Read value %8.8X register %X\n",
-				  register_value,
-				  bit_reg_info->parent_register));
-	}
+	ACPI_DEBUG_PRINT((ACPI_DB_IO,
+			  "BitReg %X, ParentReg %X, Actual %8.8X, ReturnValue %8.8X\n",
+			  register_id, bit_reg_info->parent_register,
+			  register_value, value));
 
-	return_ACPI_STATUS(status);
+	*return_value = value;
+	return_ACPI_STATUS(AE_OK);
 }
 
 ACPI_EXPORT_SYMBOL(acpi_read_bit_register)
@@ -321,13 +321,16 @@ ACPI_EXPORT_SYMBOL(acpi_read_bit_register)
  * SUPPORTS:    Bit fields in PM1 Status, PM1 Enable, PM1 Control, and
  *              PM2 Control.
  *
+ * Note that at this level, the fact that there may be actually two
+ * hardware registers (A and B - and B may not exist) is abstracted.
+ *
  ******************************************************************************/
 acpi_status acpi_write_bit_register(u32 register_id, u32 value)
 {
-	u32 register_value = 0;
 	struct acpi_bit_register_info *bit_reg_info;
-	acpi_status status;
 	acpi_cpu_flags lock_flags;
+	u32 register_value;
+	acpi_status status = AE_OK;
 
 	ACPI_FUNCTION_TRACE_U32(acpi_write_bit_register, register_id);
 
@@ -335,15 +338,22 @@ acpi_status acpi_write_bit_register(u32 register_id, u32 value)
 
 	bit_reg_info = acpi_hw_get_bit_register_info(register_id);
 	if (!bit_reg_info) {
-		ACPI_ERROR((AE_INFO, "Bad ACPI HW RegisterId: %X",
-			    register_id));
 		return_ACPI_STATUS(AE_BAD_PARAMETER);
 	}
 
 	lock_flags = acpi_os_acquire_lock(acpi_gbl_hardware_lock);
 
-	/* Always do a register read first so we can insert the new bits  */
-
+	/*
+	 * At this point, we know that the parent register is one of the
+	 * following: PM1 Status, PM1 Enable, PM1 Control, or PM2 Control
+	 */
+	if (bit_reg_info->parent_register != ACPI_REGISTER_PM1_STATUS) {
+		/*
+		 * 1) Case for PM1 Enable, PM1 Control, and PM2 Control
+		 *
+		 * Perform a register read to preserve the bits that we are not
+		 * interested in
+		 */
 		status = acpi_hw_register_read(bit_reg_info->parent_register,
 					       &register_value);
 		if (ACPI_FAILURE(status)) {
@@ -351,111 +361,48 @@ acpi_status acpi_write_bit_register(u32 register_id, u32 value)
 		}
 
 		/*
-	 * Decode the Register ID
-	 * Register ID = [Register block ID] | [bit ID]
-	 *
-	 * Check bit ID to fine locate Register offset.
-	 * Check Mask to determine Register offset, and then read-write.
-	 */
-	switch (bit_reg_info->parent_register) {
-	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
-		 * information is the single bit we're interested in, all others should
-		 * be written as 0 so they will be left unchanged.
+		 * Insert the input bit into the value that was just read
+		 * and write the register
 		 */
-		value = ACPI_REGISTER_PREPARE_BITS(value,
-						   bit_reg_info->bit_position,
-						   bit_reg_info->
-						   access_bit_mask);
-		if (value) {
-			status =
-			    acpi_hw_register_write(ACPI_REGISTER_PM1_STATUS,
-						   (u16) value);
-			register_value = 0;
-		}
-		break;
-
-	case ACPI_REGISTER_PM1_ENABLE:
-
 		ACPI_REGISTER_INSERT_VALUE(register_value,
 					   bit_reg_info->bit_position,
 					   bit_reg_info->access_bit_mask,
 					   value);
 
-		status = acpi_hw_register_write(ACPI_REGISTER_PM1_ENABLE,
-						(u16) register_value);
-		break;
-
-	case ACPI_REGISTER_PM1_CONTROL:
-
+		status = acpi_hw_register_write(bit_reg_info->parent_register,
+						register_value);
+	} else {
 		/*
-		 * Write the PM1 Control register.
-		 * Note that at this level, the fact that there are actually TWO
-		 * registers (A and B - and B may not exist) is abstracted.
+		 * 2) Case for PM1 Status
+		 *
+		 * The Status register is different from the rest. Clear an event
+		 * by writing 1, 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.
 		 */
-		ACPI_DEBUG_PRINT((ACPI_DB_IO, "PM1 control: Read %X\n",
-				  register_value));
-
-		ACPI_REGISTER_INSERT_VALUE(register_value,
-					   bit_reg_info->bit_position,
-					   bit_reg_info->access_bit_mask,
-					   value);
-
-		status = acpi_hw_register_write(ACPI_REGISTER_PM1_CONTROL,
-						(u16) register_value);
-		break;
+		register_value = ACPI_REGISTER_PREPARE_BITS(value,
+							    bit_reg_info->
+							    bit_position,
+							    bit_reg_info->
+							    access_bit_mask);
 
-	case ACPI_REGISTER_PM2_CONTROL:
+		/* No need to write the register if value is all zeros */
 
-		status = acpi_hw_register_read(ACPI_REGISTER_PM2_CONTROL,
-					       &register_value);
-		if (ACPI_FAILURE(status)) {
-			goto unlock_and_exit;
+		if (register_value) {
+			status =
+			    acpi_hw_register_write(ACPI_REGISTER_PM1_STATUS,
+						   register_value);
+		}
 	}
 
 	ACPI_DEBUG_PRINT((ACPI_DB_IO,
-				  "PM2 control: Read %X from %8.8X%8.8X\n",
-				  register_value,
-				  ACPI_FORMAT_UINT64(acpi_gbl_FADT.
-						     xpm2_control_block.
-						     address)));
-
-		ACPI_REGISTER_INSERT_VALUE(register_value,
-					   bit_reg_info->bit_position,
-					   bit_reg_info->access_bit_mask,
-					   value);
-
-		ACPI_DEBUG_PRINT((ACPI_DB_IO,
-				  "About to write %4.4X to %8.8X%8.8X\n",
-				  register_value,
-				  ACPI_FORMAT_UINT64(acpi_gbl_FADT.
-						     xpm2_control_block.
-						     address)));
-
-		status = acpi_hw_register_write(ACPI_REGISTER_PM2_CONTROL,
-						(u8) (register_value));
-		break;
-
-	default:
-		break;
-	}
+			  "BitReg %X, ParentReg %X, Value %8.8X, Actual %8.8X\n",
+			  register_id, bit_reg_info->parent_register, value,
+			  register_value));
 
-      unlock_and_exit:
+unlock_and_exit:
 
 	acpi_os_release_lock(acpi_gbl_hardware_lock, lock_flags);
-
-	/* Normalize the value that was read */
-
-	ACPI_DEBUG_EXEC(register_value =
-			((register_value & bit_reg_info->access_bit_mask) >>
-			 bit_reg_info->bit_position));
-
-	ACPI_DEBUG_PRINT((ACPI_DB_IO,
-			  "Set bits: %8.8X actual %8.8X register %X\n", value,
-			  register_value, bit_reg_info->parent_register));
 	return_ACPI_STATUS(status);
 }