// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 /****************************************************************************** * * Module Name: exfldio - Aml Field I/O * * Copyright (C) 2000 - 2022, Intel Corp. * *****************************************************************************/ #include <acpi/acpi.h> #include "accommon.h" #include "acinterp.h" #include "amlcode.h" #include "acevents.h" #include "acdispat.h" #define _COMPONENT ACPI_EXECUTER ACPI_MODULE_NAME("exfldio") /* Local prototypes */ static acpi_status acpi_ex_field_datum_io(union acpi_operand_object *obj_desc, u32 field_datum_byte_offset, u64 *value, u32 read_write); static u8 acpi_ex_register_overflow(union acpi_operand_object *obj_desc, u64 value); static acpi_status acpi_ex_setup_region(union acpi_operand_object *obj_desc, u32 field_datum_byte_offset); /******************************************************************************* * * FUNCTION: acpi_ex_setup_region * * PARAMETERS: obj_desc - Field to be read or written * field_datum_byte_offset - Byte offset of this datum within the * parent field * * RETURN: Status * * DESCRIPTION: Common processing for acpi_ex_extract_from_field and * acpi_ex_insert_into_field. Initialize the Region if necessary and * validate the request. * ******************************************************************************/ static acpi_status acpi_ex_setup_region(union acpi_operand_object *obj_desc, u32 field_datum_byte_offset) { acpi_status status = AE_OK; union acpi_operand_object *rgn_desc; u8 space_id; ACPI_FUNCTION_TRACE_U32(ex_setup_region, field_datum_byte_offset); rgn_desc = obj_desc->common_field.region_obj; /* We must have a valid region */ if (rgn_desc->common.type != ACPI_TYPE_REGION) { ACPI_ERROR((AE_INFO, "Needed Region, found type 0x%X (%s)", rgn_desc->common.type, acpi_ut_get_object_type_name(rgn_desc))); return_ACPI_STATUS(AE_AML_OPERAND_TYPE); } space_id = rgn_desc->region.space_id; /* Validate the Space ID */ if (!acpi_is_valid_space_id(space_id)) { ACPI_ERROR((AE_INFO, "Invalid/unknown Address Space ID: 0x%2.2X", space_id)); return_ACPI_STATUS(AE_AML_INVALID_SPACE_ID); } /* * If the Region Address and Length have not been previously evaluated, * evaluate them now and save the results. */ if (!(rgn_desc->common.flags & AOPOBJ_DATA_VALID)) { status = acpi_ds_get_region_arguments(rgn_desc); if (ACPI_FAILURE(status)) { return_ACPI_STATUS(status); } } /* * Exit now for SMBus, GSBus or IPMI address space, it has a non-linear * address space and the request cannot be directly validated */ if (space_id == ACPI_ADR_SPACE_SMBUS || space_id == ACPI_ADR_SPACE_GSBUS || space_id == ACPI_ADR_SPACE_IPMI) { /* SMBus or IPMI has a non-linear address space */ return_ACPI_STATUS(AE_OK); } #ifdef ACPI_UNDER_DEVELOPMENT /* * If the Field access is any_acc, we can now compute the optimal * access (because we know the length of the parent region) */ if (!(obj_desc->common.flags & AOPOBJ_DATA_VALID)) { if (ACPI_FAILURE(status)) { return_ACPI_STATUS(status); } } #endif /* * Validate the request. The entire request from the byte offset for a * length of one field datum (access width) must fit within the region. * (Region length is specified in bytes) */ if (rgn_desc->region.length < (obj_desc->common_field.base_byte_offset + field_datum_byte_offset + obj_desc->common_field.access_byte_width)) { if (acpi_gbl_enable_interpreter_slack) { /* * Slack mode only: We will go ahead and allow access to this * field if it is within the region length rounded up to the next * access width boundary. acpi_size cast for 64-bit compile. */ if (ACPI_ROUND_UP(rgn_desc->region.length, obj_desc->common_field. access_byte_width) >= ((acpi_size)obj_desc->common_field. base_byte_offset + obj_desc->common_field.access_byte_width + field_datum_byte_offset)) { return_ACPI_STATUS(AE_OK); } } if (rgn_desc->region.length < obj_desc->common_field.access_byte_width) { /* * This is the case where the access_type (acc_word, etc.) is wider * than the region itself. For example, a region of length one * byte, and a field with Dword access specified. */ ACPI_ERROR((AE_INFO, "Field [%4.4s] access width (%u bytes) " "too large for region [%4.4s] (length %u)", acpi_ut_get_node_name(obj_desc-> common_field.node), obj_desc->common_field.access_byte_width, acpi_ut_get_node_name(rgn_desc->region. node), rgn_desc->region.length)); } /* * Offset rounded up to next multiple of field width * exceeds region length, indicate an error */ ACPI_ERROR((AE_INFO, "Field [%4.4s] Base+Offset+Width %u+%u+%u " "is beyond end of region [%4.4s] (length %u)", acpi_ut_get_node_name(obj_desc->common_field.node), obj_desc->common_field.base_byte_offset, field_datum_byte_offset, obj_desc->common_field.access_byte_width, acpi_ut_get_node_name(rgn_desc->region.node), rgn_desc->region.length)); return_ACPI_STATUS(AE_AML_REGION_LIMIT); } return_ACPI_STATUS(AE_OK); } /******************************************************************************* * * FUNCTION: acpi_ex_access_region * * PARAMETERS: obj_desc - Field to be read * field_datum_byte_offset - Byte offset of this datum within the * parent field * value - Where to store value (must at least * 64 bits) * function - Read or Write flag plus other region- * dependent flags * * RETURN: Status * * DESCRIPTION: Read or Write a single field datum to an Operation Region. * ******************************************************************************/ acpi_status acpi_ex_access_region(union acpi_operand_object *obj_desc, u32 field_datum_byte_offset, u64 *value, u32 function) { acpi_status status; union acpi_operand_object *rgn_desc; u32 region_offset; ACPI_FUNCTION_TRACE(ex_access_region); /* * Ensure that the region operands are fully evaluated and verify * the validity of the request */ status = acpi_ex_setup_region(obj_desc, field_datum_byte_offset); if (ACPI_FAILURE(status)) { return_ACPI_STATUS(status); } /* * The physical address of this field datum is: * * 1) The base of the region, plus * 2) The base offset of the field, plus * 3) The current offset into the field */ rgn_desc = obj_desc->common_field.region_obj; region_offset = obj_desc->common_field.base_byte_offset + field_datum_byte_offset; if ((function & ACPI_IO_MASK) == ACPI_READ) { ACPI_DEBUG_PRINT((ACPI_DB_BFIELD, "[READ]")); } else { ACPI_DEBUG_PRINT((ACPI_DB_BFIELD, "[WRITE]")); } ACPI_DEBUG_PRINT_RAW((ACPI_DB_BFIELD, " Region [%s:%X], Width %X, ByteBase %X, Offset %X at %8.8X%8.8X\n", acpi_ut_get_region_name(rgn_desc->region. space_id), rgn_desc->region.space_id, obj_desc->common_field.access_byte_width, obj_desc->common_field.base_byte_offset, field_datum_byte_offset, ACPI_FORMAT_UINT64(rgn_desc->region.address + region_offset))); /* Invoke the appropriate address_space/op_region handler */ status = acpi_ev_address_space_dispatch(rgn_desc, obj_desc, function, region_offset, ACPI_MUL_8(obj_desc-> common_field. access_byte_width), value); if (ACPI_FAILURE(status)) { if (status == AE_NOT_IMPLEMENTED) { ACPI_ERROR((AE_INFO, "Region %s (ID=%u) not implemented", acpi_ut_get_region_name(rgn_desc->region. space_id), rgn_desc->region.space_id)); } else if (status == AE_NOT_EXIST) { ACPI_ERROR((AE_INFO, "Region %s (ID=%u) has no handler", acpi_ut_get_region_name(rgn_desc->region. space_id), rgn_desc->region.space_id)); } } return_ACPI_STATUS(status); } /******************************************************************************* * * FUNCTION: acpi_ex_register_overflow * * PARAMETERS: obj_desc - Register(Field) to be written * value - Value to be stored * * RETURN: TRUE if value overflows the field, FALSE otherwise * * DESCRIPTION: Check if a value is out of range of the field being written. * Used to check if the values written to Index and Bank registers * are out of range. Normally, the value is simply truncated * to fit the field, but this case is most likely a serious * coding error in the ASL. * ******************************************************************************/ static u8 acpi_ex_register_overflow(union acpi_operand_object *obj_desc, u64 value) { if (obj_desc->common_field.bit_length >= ACPI_INTEGER_BIT_SIZE) { /* * The field is large enough to hold the maximum integer, so we can * never overflow it. */ return (FALSE); } if (value >= ((u64) 1 << obj_desc->common_field.bit_length)) { /* * The Value is larger than the maximum value that can fit into * the register. */ ACPI_ERROR((AE_INFO, "Index value 0x%8.8X%8.8X overflows field width 0x%X", ACPI_FORMAT_UINT64(value), obj_desc->common_field.bit_length)); return (TRUE); } /* The Value will fit into the field with no truncation */ return (FALSE); } /******************************************************************************* * * FUNCTION: acpi_ex_field_datum_io * * PARAMETERS: obj_desc - Field to be read * field_datum_byte_offset - Byte offset of this datum within the * parent field * value - Where to store value (must be 64 bits) * read_write - Read or Write flag * * RETURN: Status * * DESCRIPTION: Read or Write a single datum of a field. The field_type is * demultiplexed here to handle the different types of fields * (buffer_field, region_field, index_field, bank_field) * ******************************************************************************/ static acpi_status acpi_ex_field_datum_io(union acpi_operand_object *obj_desc, u32 field_datum_byte_offset, u64 *value, u32 read_write) { acpi_status status; u64 local_value; ACPI_FUNCTION_TRACE_U32(ex_field_datum_io, field_datum_byte_offset); if (read_write == ACPI_READ) { if (!value) { local_value = 0; /* To support reads without saving return value */ value = &local_value; } /* Clear the entire return buffer first, [Very Important!] */ *value = 0; } /* * The four types of fields are: * * buffer_field - Read/write from/to a Buffer * region_field - Read/write from/to a Operation Region. * bank_field - Write to a Bank Register, then read/write from/to an * operation_region * index_field - Write to an Index Register, then read/write from/to a * Data Register */ switch (obj_desc->common.type) { case ACPI_TYPE_BUFFER_FIELD: /* * If the buffer_field arguments have not been previously evaluated, * evaluate them now and save the results. */ if (!(obj_desc->common.flags & AOPOBJ_DATA_VALID)) { status = acpi_ds_get_buffer_field_arguments(obj_desc); if (ACPI_FAILURE(status)) { return_ACPI_STATUS(status); } } if (read_write == ACPI_READ) { /* * Copy the data from the source buffer. * Length is the field width in bytes. */ memcpy(value, (obj_desc->buffer_field.buffer_obj)->buffer. pointer + obj_desc->buffer_field.base_byte_offset + field_datum_byte_offset, obj_desc->common_field.access_byte_width); } else { /* * Copy the data to the target buffer. * Length is the field width in bytes. */ memcpy((obj_desc->buffer_field.buffer_obj)->buffer. pointer + obj_desc->buffer_field.base_byte_offset + field_datum_byte_offset, value, obj_desc->common_field.access_byte_width); } status = AE_OK; break; case ACPI_TYPE_LOCAL_BANK_FIELD: /* * Ensure that the bank_value is not beyond the capacity of * the register */ if (acpi_ex_register_overflow(obj_desc->bank_field.bank_obj, (u64) obj_desc->bank_field. value)) { return_ACPI_STATUS(AE_AML_REGISTER_LIMIT); } /* * For bank_fields, we must write the bank_value to the bank_register * (itself a region_field) before we can access the data. */ status = acpi_ex_insert_into_field(obj_desc->bank_field.bank_obj, &obj_desc->bank_field.value, sizeof(obj_desc->bank_field. value)); if (ACPI_FAILURE(status)) { return_ACPI_STATUS(status); } /* * Now that the Bank has been selected, fall through to the * region_field case and write the datum to the Operation Region */ ACPI_FALLTHROUGH; case ACPI_TYPE_LOCAL_REGION_FIELD: /* * For simple region_fields, we just directly access the owning * Operation Region. */ status = acpi_ex_access_region(obj_desc, field_datum_byte_offset, value, read_write); break; case ACPI_TYPE_LOCAL_INDEX_FIELD: /* * Ensure that the index_value is not beyond the capacity of * the register */ if (acpi_ex_register_overflow(obj_desc->index_field.index_obj, (u64) obj_desc->index_field. value)) { return_ACPI_STATUS(AE_AML_REGISTER_LIMIT); } /* Write the index value to the index_register (itself a region_field) */ field_datum_byte_offset += obj_desc->index_field.value; ACPI_DEBUG_PRINT((ACPI_DB_BFIELD, "Write to Index Register: Value %8.8X\n", field_datum_byte_offset)); status = acpi_ex_insert_into_field(obj_desc->index_field.index_obj, &field_datum_byte_offset, sizeof(field_datum_byte_offset)); if (ACPI_FAILURE(status)) { return_ACPI_STATUS(status); } if (read_write == ACPI_READ) { /* Read the datum from the data_register */ ACPI_DEBUG_PRINT((ACPI_DB_BFIELD, "Read from Data Register\n")); status = acpi_ex_extract_from_field(obj_desc->index_field. data_obj, value, sizeof(u64)); } else { /* Write the datum to the data_register */ ACPI_DEBUG_PRINT((ACPI_DB_BFIELD, "Write to Data Register: Value %8.8X%8.8X\n", ACPI_FORMAT_UINT64(*value))); status = acpi_ex_insert_into_field(obj_desc->index_field. data_obj, value, sizeof(u64)); } break; default: ACPI_ERROR((AE_INFO, "Wrong object type in field I/O %u", obj_desc->common.type)); status = AE_AML_INTERNAL; break; } if (ACPI_SUCCESS(status)) { if (read_write == ACPI_READ) { ACPI_DEBUG_PRINT((ACPI_DB_BFIELD, "Value Read %8.8X%8.8X, Width %u\n", ACPI_FORMAT_UINT64(*value), obj_desc->common_field. access_byte_width)); } else { ACPI_DEBUG_PRINT((ACPI_DB_BFIELD, "Value Written %8.8X%8.8X, Width %u\n", ACPI_FORMAT_UINT64(*value), obj_desc->common_field. access_byte_width)); } } return_ACPI_STATUS(status); } /******************************************************************************* * * FUNCTION: acpi_ex_write_with_update_rule * * PARAMETERS: obj_desc - Field to be written * mask - bitmask within field datum * field_value - Value to write * field_datum_byte_offset - Offset of datum within field * * RETURN: Status * * DESCRIPTION: Apply the field update rule to a field write * ******************************************************************************/ acpi_status acpi_ex_write_with_update_rule(union acpi_operand_object *obj_desc, u64 mask, u64 field_value, u32 field_datum_byte_offset) { acpi_status status = AE_OK; u64 merged_value; u64 current_value; ACPI_FUNCTION_TRACE_U32(ex_write_with_update_rule, mask); /* Start with the new bits */ merged_value = field_value; /* If the mask is all ones, we don't need to worry about the update rule */ if (mask != ACPI_UINT64_MAX) { /* Decode the update rule */ switch (obj_desc->common_field. field_flags & AML_FIELD_UPDATE_RULE_MASK) { case AML_FIELD_UPDATE_PRESERVE: /* * Check if update rule needs to be applied (not if mask is all * ones) The left shift drops the bits we want to ignore. */ if ((~mask << (ACPI_MUL_8(sizeof(mask)) - ACPI_MUL_8(obj_desc->common_field. access_byte_width))) != 0) { /* * Read the current contents of the byte/word/dword containing * the field, and merge with the new field value. */ status = acpi_ex_field_datum_io(obj_desc, field_datum_byte_offset, ¤t_value, ACPI_READ); if (ACPI_FAILURE(status)) { return_ACPI_STATUS(status); } merged_value |= (current_value & ~mask); } break; case AML_FIELD_UPDATE_WRITE_AS_ONES: /* Set positions outside the field to all ones */ merged_value |= ~mask; break; case AML_FIELD_UPDATE_WRITE_AS_ZEROS: /* Set positions outside the field to all zeros */ merged_value &= mask; break; default: ACPI_ERROR((AE_INFO, "Unknown UpdateRule value: 0x%X", (obj_desc->common_field.field_flags & AML_FIELD_UPDATE_RULE_MASK))); return_ACPI_STATUS(AE_AML_OPERAND_VALUE); } } ACPI_DEBUG_PRINT((ACPI_DB_BFIELD, "Mask %8.8X%8.8X, DatumOffset %X, Width %X, " "Value %8.8X%8.8X, MergedValue %8.8X%8.8X\n", ACPI_FORMAT_UINT64(mask), field_datum_byte_offset, obj_desc->common_field.access_byte_width, ACPI_FORMAT_UINT64(field_value), ACPI_FORMAT_UINT64(merged_value))); /* Write the merged value */ status = acpi_ex_field_datum_io(obj_desc, field_datum_byte_offset, &merged_value, ACPI_WRITE); return_ACPI_STATUS(status); } /******************************************************************************* * * FUNCTION: acpi_ex_extract_from_field * * PARAMETERS: obj_desc - Field to be read * buffer - Where to store the field data * buffer_length - Length of Buffer * * RETURN: Status * * DESCRIPTION: Retrieve the current value of the given field * ******************************************************************************/ acpi_status acpi_ex_extract_from_field(union acpi_operand_object *obj_desc, void *buffer, u32 buffer_length) { acpi_status status; u64 raw_datum; u64 merged_datum; u32 field_offset = 0; u32 buffer_offset = 0; u32 buffer_tail_bits; u32 datum_count; u32 field_datum_count; u32 access_bit_width; u32 i; ACPI_FUNCTION_TRACE(ex_extract_from_field); /* Validate target buffer and clear it */ if (buffer_length < ACPI_ROUND_BITS_UP_TO_BYTES(obj_desc->common_field.bit_length)) { ACPI_ERROR((AE_INFO, "Field size %u (bits) is too large for buffer (%u)", obj_desc->common_field.bit_length, buffer_length)); return_ACPI_STATUS(AE_BUFFER_OVERFLOW); } memset(buffer, 0, buffer_length); access_bit_width = ACPI_MUL_8(obj_desc->common_field.access_byte_width); /* Handle the simple case here */ if ((obj_desc->common_field.start_field_bit_offset == 0) && (obj_desc->common_field.bit_length == access_bit_width)) { if (buffer_length >= sizeof(u64)) { status = acpi_ex_field_datum_io(obj_desc, 0, buffer, ACPI_READ); } else { /* Use raw_datum (u64) to handle buffers < 64 bits */ status = acpi_ex_field_datum_io(obj_desc, 0, &raw_datum, ACPI_READ); memcpy(buffer, &raw_datum, buffer_length); } return_ACPI_STATUS(status); } /* TBD: Move to common setup code */ /* Field algorithm is limited to sizeof(u64), truncate if needed */ if (obj_desc->common_field.access_byte_width > sizeof(u64)) { obj_desc->common_field.access_byte_width = sizeof(u64); access_bit_width = sizeof(u64) * 8; } /* Compute the number of datums (access width data items) */ datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length, access_bit_width); field_datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length + obj_desc->common_field. start_field_bit_offset, access_bit_width); /* Priming read from the field */ status = acpi_ex_field_datum_io(obj_desc, field_offset, &raw_datum, ACPI_READ); if (ACPI_FAILURE(status)) { return_ACPI_STATUS(status); } merged_datum = raw_datum >> obj_desc->common_field.start_field_bit_offset; /* Read the rest of the field */ for (i = 1; i < field_datum_count; i++) { /* Get next input datum from the field */ field_offset += obj_desc->common_field.access_byte_width; status = acpi_ex_field_datum_io(obj_desc, field_offset, &raw_datum, ACPI_READ); if (ACPI_FAILURE(status)) { return_ACPI_STATUS(status); } /* * Merge with previous datum if necessary. * * Note: Before the shift, check if the shift value will be larger than * the integer size. If so, there is no need to perform the operation. * This avoids the differences in behavior between different compilers * concerning shift values larger than the target data width. */ if (access_bit_width - obj_desc->common_field.start_field_bit_offset < ACPI_INTEGER_BIT_SIZE) { merged_datum |= raw_datum << (access_bit_width - obj_desc->common_field. start_field_bit_offset); } if (i == datum_count) { break; } /* Write merged datum to target buffer */ memcpy(((char *)buffer) + buffer_offset, &merged_datum, ACPI_MIN(obj_desc->common_field.access_byte_width, buffer_length - buffer_offset)); buffer_offset += obj_desc->common_field.access_byte_width; merged_datum = raw_datum >> obj_desc->common_field.start_field_bit_offset; } /* Mask off any extra bits in the last datum */ buffer_tail_bits = obj_desc->common_field.bit_length % access_bit_width; if (buffer_tail_bits) { merged_datum &= ACPI_MASK_BITS_ABOVE(buffer_tail_bits); } /* Write the last datum to the buffer */ memcpy(((char *)buffer) + buffer_offset, &merged_datum, ACPI_MIN(obj_desc->common_field.access_byte_width, buffer_length - buffer_offset)); return_ACPI_STATUS(AE_OK); } /******************************************************************************* * * FUNCTION: acpi_ex_insert_into_field * * PARAMETERS: obj_desc - Field to be written * buffer - Data to be written * buffer_length - Length of Buffer * * RETURN: Status * * DESCRIPTION: Store the Buffer contents into the given field * ******************************************************************************/ acpi_status acpi_ex_insert_into_field(union acpi_operand_object *obj_desc, void *buffer, u32 buffer_length) { void *new_buffer; acpi_status status; u64 mask; u64 width_mask; u64 merged_datum; u64 raw_datum = 0; u32 field_offset = 0; u32 buffer_offset = 0; u32 buffer_tail_bits; u32 datum_count; u32 field_datum_count; u32 access_bit_width; u32 required_length; u32 i; ACPI_FUNCTION_TRACE(ex_insert_into_field); /* Validate input buffer */ new_buffer = NULL; required_length = ACPI_ROUND_BITS_UP_TO_BYTES(obj_desc->common_field.bit_length); /* * We must have a buffer that is at least as long as the field * we are writing to. This is because individual fields are * indivisible and partial writes are not supported -- as per * the ACPI specification. */ if (buffer_length < required_length) { /* We need to create a new buffer */ new_buffer = ACPI_ALLOCATE_ZEROED(required_length); if (!new_buffer) { return_ACPI_STATUS(AE_NO_MEMORY); } /* * Copy the original data to the new buffer, starting * at Byte zero. All unused (upper) bytes of the * buffer will be 0. */ memcpy((char *)new_buffer, (char *)buffer, buffer_length); buffer = new_buffer; buffer_length = required_length; } /* TBD: Move to common setup code */ /* Algo is limited to sizeof(u64), so cut the access_byte_width */ if (obj_desc->common_field.access_byte_width > sizeof(u64)) { obj_desc->common_field.access_byte_width = sizeof(u64); } access_bit_width = ACPI_MUL_8(obj_desc->common_field.access_byte_width); /* Create the bitmasks used for bit insertion */ width_mask = ACPI_MASK_BITS_ABOVE_64(access_bit_width); mask = width_mask & ACPI_MASK_BITS_BELOW(obj_desc->common_field.start_field_bit_offset); /* Compute the number of datums (access width data items) */ datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length, access_bit_width); field_datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length + obj_desc->common_field. start_field_bit_offset, access_bit_width); /* Get initial Datum from the input buffer */ memcpy(&raw_datum, buffer, ACPI_MIN(obj_desc->common_field.access_byte_width, buffer_length - buffer_offset)); merged_datum = raw_datum << obj_desc->common_field.start_field_bit_offset; /* Write the entire field */ for (i = 1; i < field_datum_count; i++) { /* Write merged datum to the target field */ merged_datum &= mask; status = acpi_ex_write_with_update_rule(obj_desc, mask, merged_datum, field_offset); if (ACPI_FAILURE(status)) { goto exit; } field_offset += obj_desc->common_field.access_byte_width; /* * Start new output datum by merging with previous input datum * if necessary. * * Note: Before the shift, check if the shift value will be larger than * the integer size. If so, there is no need to perform the operation. * This avoids the differences in behavior between different compilers * concerning shift values larger than the target data width. */ if ((access_bit_width - obj_desc->common_field.start_field_bit_offset) < ACPI_INTEGER_BIT_SIZE) { merged_datum = raw_datum >> (access_bit_width - obj_desc->common_field. start_field_bit_offset); } else { merged_datum = 0; } mask = width_mask; if (i == datum_count) { break; } /* Get the next input datum from the buffer */ buffer_offset += obj_desc->common_field.access_byte_width; memcpy(&raw_datum, ((char *)buffer) + buffer_offset, ACPI_MIN(obj_desc->common_field.access_byte_width, buffer_length - buffer_offset)); merged_datum |= raw_datum << obj_desc->common_field.start_field_bit_offset; } /* Mask off any extra bits in the last datum */ buffer_tail_bits = (obj_desc->common_field.bit_length + obj_desc->common_field.start_field_bit_offset) % access_bit_width; if (buffer_tail_bits) { mask &= ACPI_MASK_BITS_ABOVE(buffer_tail_bits); } /* Write the last datum to the field */ merged_datum &= mask; status = acpi_ex_write_with_update_rule(obj_desc, mask, merged_datum, field_offset); exit: /* Free temporary buffer if we used one */ if (new_buffer) { ACPI_FREE(new_buffer); } return_ACPI_STATUS(status); }