return (&acpi_gbl_bit_register_info[register_id]);
 }
 
+/******************************************************************************
+ *
+ * FUNCTION:    acpi_hw_write_pm1_control
+ *
+ * PARAMETERS:  pm1a_control        - Value to be written to PM1A control
+ *              pm1b_control        - Value to be written to PM1B control
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Write the PM1 A/B control registers. These registers are
+ *              different than than the PM1 A/B status and enable registers
+ *              in that different values can be written to the A/B registers.
+ *              Most notably, the SLP_TYP bits can be different, as per the
+ *              values returned from the _Sx predefined methods.
+ *
+ ******************************************************************************/
+
+acpi_status acpi_hw_write_pm1_control(u32 pm1a_control, u32 pm1b_control)
+{
+       acpi_status status;
+
+       ACPI_FUNCTION_TRACE(hw_write_pm1_control);
+
+       status = acpi_write(pm1a_control, &acpi_gbl_FADT.xpm1a_control_block);
+       if (ACPI_FAILURE(status)) {
+               return_ACPI_STATUS(status);
+       }
+
+       if (acpi_gbl_FADT.xpm1b_control_block.address) {
+               status =
+                   acpi_write(pm1b_control,
+                              &acpi_gbl_FADT.xpm1b_control_block);
+       }
+       return_ACPI_STATUS(status);
+}
+
 /******************************************************************************
  *
  * FUNCTION:    acpi_hw_register_read
                                                xpm1b_control_block);
                break;
 
-       case ACPI_REGISTER_PM1A_CONTROL:        /* 16-bit access */
-
-               status = acpi_write(value, &acpi_gbl_FADT.xpm1a_control_block);
-               break;
-
-       case ACPI_REGISTER_PM1B_CONTROL:        /* 16-bit access */
-
-               status = acpi_write(value, &acpi_gbl_FADT.xpm1b_control_block);
-               break;
-
        case ACPI_REGISTER_PM2_CONTROL: /* 8-bit access */
 
                status = acpi_write(value, &acpi_gbl_FADT.xpm2_control_block);
 
 
        ACPI_FUNCTION_TRACE(acpi_enter_sleep_state_prep);
 
-       /*
-        * _PSW methods could be run here to enable wake-on keyboard, LAN, etc.
-        */
+       /* _PSW methods could be run here to enable wake-on keyboard, LAN, etc. */
+
        status = acpi_get_sleep_type_data(sleep_state,
                                          &acpi_gbl_sleep_type_a,
                                          &acpi_gbl_sleep_type_b);
  ******************************************************************************/
 acpi_status asmlinkage acpi_enter_sleep_state(u8 sleep_state)
 {
-       u32 PM1Acontrol;
-       u32 PM1Bcontrol;
+       u32 pm1a_control;
+       u32 pm1b_control;
        struct acpi_bit_register_info *sleep_type_reg_info;
        struct acpi_bit_register_info *sleep_enable_reg_info;
        u32 in_value;
 
        /* Get current value of PM1A control */
 
-       status = acpi_hw_register_read(ACPI_REGISTER_PM1_CONTROL, &PM1Acontrol);
+       status = acpi_hw_register_read(ACPI_REGISTER_PM1_CONTROL,
+                                      &pm1a_control);
        if (ACPI_FAILURE(status)) {
                return_ACPI_STATUS(status);
        }
        ACPI_DEBUG_PRINT((ACPI_DB_INIT,
                          "Entering sleep state [S%d]\n", sleep_state));
 
-       /* Clear SLP_EN and SLP_TYP fields */
+       /* Clear the SLP_EN and SLP_TYP fields */
 
-       PM1Acontrol &= ~(sleep_type_reg_info->access_bit_mask |
-                        sleep_enable_reg_info->access_bit_mask);
-       PM1Bcontrol = PM1Acontrol;
+       pm1a_control &= ~(sleep_type_reg_info->access_bit_mask |
+                         sleep_enable_reg_info->access_bit_mask);
+       pm1b_control = pm1a_control;
 
-       /* Insert SLP_TYP bits */
+       /* Insert the SLP_TYP bits */
 
-       PM1Acontrol |=
+       pm1a_control |=
            (acpi_gbl_sleep_type_a << sleep_type_reg_info->bit_position);
-       PM1Bcontrol |=
+       pm1b_control |=
            (acpi_gbl_sleep_type_b << sleep_type_reg_info->bit_position);
 
        /*
         * poorly implemented hardware.
         */
 
-       /* Write #1: fill in SLP_TYP data */
-
-       status = acpi_hw_register_write(ACPI_REGISTER_PM1A_CONTROL,
-                                       PM1Acontrol);
-       if (ACPI_FAILURE(status)) {
-               return_ACPI_STATUS(status);
-       }
+       /* Write #1: write the SLP_TYP data to the PM1 Control registers */
 
-       status = acpi_hw_register_write(ACPI_REGISTER_PM1B_CONTROL,
-                                       PM1Bcontrol);
+       status = acpi_hw_write_pm1_control(pm1a_control, pm1b_control);
        if (ACPI_FAILURE(status)) {
                return_ACPI_STATUS(status);
        }
 
-       /* Insert SLP_ENABLE bit */
+       /* Insert the sleep enable (SLP_EN) bit */
 
-       PM1Acontrol |= sleep_enable_reg_info->access_bit_mask;
-       PM1Bcontrol |= sleep_enable_reg_info->access_bit_mask;
+       pm1a_control |= sleep_enable_reg_info->access_bit_mask;
+       pm1b_control |= sleep_enable_reg_info->access_bit_mask;
 
-       /* Write #2: SLP_TYP + SLP_EN */
+       /* Flush caches, as per ACPI specification */
 
        ACPI_FLUSH_CPU_CACHE();
 
-       status = acpi_hw_register_write(ACPI_REGISTER_PM1A_CONTROL,
-                                       PM1Acontrol);
-       if (ACPI_FAILURE(status)) {
-               return_ACPI_STATUS(status);
-       }
+       /* Write #2: Write both SLP_TYP + SLP_EN */
 
-       status = acpi_hw_register_write(ACPI_REGISTER_PM1B_CONTROL,
-                                       PM1Bcontrol);
+       status = acpi_hw_write_pm1_control(pm1a_control, pm1b_control);
        if (ACPI_FAILURE(status)) {
                return_ACPI_STATUS(status);
        }
        acpi_status status;
        struct acpi_bit_register_info *sleep_type_reg_info;
        struct acpi_bit_register_info *sleep_enable_reg_info;
-       u32 PM1Acontrol;
-       u32 PM1Bcontrol;
+       u32 pm1a_control;
+       u32 pm1b_control;
 
        ACPI_FUNCTION_TRACE(acpi_leave_sleep_state_prep);
 
                /* Get current value of PM1A control */
 
                status = acpi_hw_register_read(ACPI_REGISTER_PM1_CONTROL,
-                                              &PM1Acontrol);
+                                              &pm1a_control);
                if (ACPI_SUCCESS(status)) {
 
-                       /* Clear SLP_EN and SLP_TYP fields */
+                       /* Clear the SLP_EN and SLP_TYP fields */
 
-                       PM1Acontrol &= ~(sleep_type_reg_info->access_bit_mask |
-                                        sleep_enable_reg_info->
-                                        access_bit_mask);
-                       PM1Bcontrol = PM1Acontrol;
+                       pm1a_control &= ~(sleep_type_reg_info->access_bit_mask |
+                                         sleep_enable_reg_info->
+                                         access_bit_mask);
+                       pm1b_control = pm1a_control;
 
-                       /* Insert SLP_TYP bits */
+                       /* Insert the SLP_TYP bits */
 
-                       PM1Acontrol |=
+                       pm1a_control |=
                            (acpi_gbl_sleep_type_a << sleep_type_reg_info->
                             bit_position);
-                       PM1Bcontrol |=
+                       pm1b_control |=
                            (acpi_gbl_sleep_type_b << sleep_type_reg_info->
                             bit_position);
 
-                       /* Just ignore any errors */
+                       /* Write the control registers and ignore any errors */
 
-                       (void)acpi_hw_register_write(ACPI_REGISTER_PM1A_CONTROL,
-                                                    PM1Acontrol);
-                       (void)acpi_hw_register_write(ACPI_REGISTER_PM1B_CONTROL,
-                                                    PM1Bcontrol);
+                       (void)acpi_hw_write_pm1_control(pm1a_control,
+                                                       pm1b_control);
                }
        }