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>

1 files changed, 62 insertions, 115 deletions

diff --git a/drivers/acpi/acpica/hwxface.c b/drivers/acpi/acpica/hwxface.c
index 529251c7f911..caad51680bd6 100644
--- a/drivers/acpi/acpica/hwxface.c
+++ b/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 */
-
-                register_value =
-                    ((register_value & bit_reg_info->access_bit_mask)
-                     >> bit_reg_info->bit_position);
+        /* Normalize the value that was read, mask off other bits */
 
-                *return_value = register_value;
+        value = ((register_value & bit_reg_info->access_bit_mask)
+                 >> bit_reg_info->bit_position);
 
-                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);
 
@@ -335,127 +338,71 @@ 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  */
-
-        status = acpi_hw_register_read(bit_reg_info->parent_register,
-                                       &register_value);
-        if (ACPI_FAILURE(status)) {
-                goto unlock_and_exit;
-        }
-
         /*
-         * 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.
+         * At this point, we know that the parent register is one of the
+         * following: PM1 Status, PM1 Enable, PM1 Control, or PM2 Control
          */
-        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.
-                 */
-                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:
-
+        if (bit_reg_info->parent_register != ACPI_REGISTER_PM1_STATUS) {
                 /*
-                 * 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.
+                 * 1) Case for PM1 Enable, PM1 Control, and PM2 Control
+                 *
+                 * Perform a register read to preserve the bits that we are not
+                 * interested in
                  */
-                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;
-
-        case ACPI_REGISTER_PM2_CONTROL:
-
-                status = acpi_hw_register_read(ACPI_REGISTER_PM2_CONTROL,
+                status = acpi_hw_register_read(bit_reg_info->parent_register,
                                                &register_value);
                 if (ACPI_FAILURE(status)) {
                         goto unlock_and_exit;
                 }
 
-                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)));
-
+                /*
+                 * Insert the input bit into the value that was just read
+                 * and write the register
+                 */
                 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(bit_reg_info->parent_register,
+                                                register_value);
+        } else {
+                /*
+                 * 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.
+                 */
+                register_value = ACPI_REGISTER_PREPARE_BITS(value,
+                                                            bit_reg_info->
+                                                            bit_position,
+                                                            bit_reg_info->
+                                                            access_bit_mask);
 
-                status = acpi_hw_register_write(ACPI_REGISTER_PM2_CONTROL,
-                                                (u8) (register_value));
-                break;
+                /* No need to write the register if value is all zeros */
 
-        default:
-                break;
+                if (register_value) {
+                        status =
+                            acpi_hw_register_write(ACPI_REGISTER_PM1_STATUS,
+                                                   register_value);
+                }
         }
 
-      unlock_and_exit:
-
-        acpi_os_release_lock(acpi_gbl_hardware_lock, lock_flags);
-
-        /* Normalize the value that was read */
+        ACPI_DEBUG_PRINT((ACPI_DB_IO,
+                          "BitReg %X, ParentReg %X, Value %8.8X, Actual %8.8X\n",
+                          register_id, bit_reg_info->parent_register, value,
+                          register_value));
 
-        ACPI_DEBUG_EXEC(register_value =
-                        ((register_value & bit_reg_info->access_bit_mask) >>
-                         bit_reg_info->bit_position));
+unlock_and_exit:
 
-        ACPI_DEBUG_PRINT((ACPI_DB_IO,
-                          "Set bits: %8.8X actual %8.8X register %X\n", value,
-                          register_value, bit_reg_info->parent_register));
+        acpi_os_release_lock(acpi_gbl_hardware_lock, lock_flags);
         return_ACPI_STATUS(status);
 }