linux/drivers/platform/x86/hp/hp-bioscfg/string-attributes.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Functions corresponding to string type attributes under
 * HP_WMI_BIOS_STRING_GUID for use with hp-bioscfg driver.
 *
 * Copyright (c) 2022 HP Development Company, L.P.
 */

#include "bioscfg.h"

#define WMI_STRING_TYPE "HPBIOS_BIOSString"

GET_INSTANCE_ID(string);

static ssize_t current_value_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
	int instance_id = get_string_instance_id(kobj);

	if (instance_id < 0)
		return -EIO;

	return  sysfs_emit(buf, "%s\n",
			 bioscfg_drv.string_data[instance_id].current_value);
}

/**
 * validate_string_input() -
 * Validate input of current_value against min and max lengths
 *
 * @instance_id: The instance on which input is validated
 * @buf: Input value
 */
static int validate_string_input(int instance_id, const char *buf)
{
	int in_len = strlen(buf);
	struct string_data *string_data = &bioscfg_drv.string_data[instance_id];

	/* BIOS treats it as a read only attribute */
	if (string_data->common.is_readonly)
		return -EIO;

	if (in_len < string_data->min_length || in_len > string_data->max_length)
		return -ERANGE;

	return 0;
}

static void update_string_value(int instance_id, char *attr_value)
{
	struct string_data *string_data = &bioscfg_drv.string_data[instance_id];

	/* Write settings to BIOS */
	strscpy(string_data->current_value, attr_value, sizeof(string_data->current_value));
}

/*
 * ATTRIBUTE_S_COMMON_PROPERTY_SHOW(display_name_language_code, string);
 * static struct kobj_attribute string_display_langcode =
 *	__ATTR_RO(display_name_language_code);
 */

ATTRIBUTE_S_COMMON_PROPERTY_SHOW(display_name, string);
static struct kobj_attribute string_display_name =
	__ATTR_RO(display_name);

ATTRIBUTE_PROPERTY_STORE(current_value, string);
static struct kobj_attribute string_current_val =
	__ATTR_RW_MODE(current_value, 0644);

ATTRIBUTE_N_PROPERTY_SHOW(min_length, string);
static struct kobj_attribute string_min_length =
	__ATTR_RO(min_length);

ATTRIBUTE_N_PROPERTY_SHOW(max_length, string);
static struct kobj_attribute string_max_length =
	__ATTR_RO(max_length);

static ssize_t type_show(struct kobject *kobj, struct kobj_attribute *attr,
			 char *buf)
{
	return sysfs_emit(buf, "string\n");
}

static struct kobj_attribute string_type =
	__ATTR_RO(type);

static struct attribute *string_attrs[] = {
	&common_display_langcode.attr,
	&string_display_name.attr,
	&string_current_val.attr,
	&string_min_length.attr,
	&string_max_length.attr,
	&string_type.attr,
	NULL
};

static const struct attribute_group string_attr_group = {
	.attrs = string_attrs,
};

int hp_alloc_string_data(void)
{
	bioscfg_drv.string_instances_count = hp_get_instance_count(HP_WMI_BIOS_STRING_GUID);
	bioscfg_drv.string_data = kcalloc(bioscfg_drv.string_instances_count,
					  sizeof(*bioscfg_drv.string_data), GFP_KERNEL);
	if (!bioscfg_drv.string_data) {
		bioscfg_drv.string_instances_count = 0;
		return -ENOMEM;
	}
	return 0;
}

/* Expected Values types associated with each element */
static const acpi_object_type expected_string_types[] = {
	[NAME] = ACPI_TYPE_STRING,
	[VALUE] = ACPI_TYPE_STRING,
	[PATH] = ACPI_TYPE_STRING,
	[IS_READONLY] = ACPI_TYPE_INTEGER,
	[DISPLAY_IN_UI] = ACPI_TYPE_INTEGER,
	[REQUIRES_PHYSICAL_PRESENCE] = ACPI_TYPE_INTEGER,
	[SEQUENCE] = ACPI_TYPE_INTEGER,
	[PREREQUISITES_SIZE] = ACPI_TYPE_INTEGER,
	[PREREQUISITES] = ACPI_TYPE_STRING,
	[SECURITY_LEVEL] = ACPI_TYPE_INTEGER,
	[STR_MIN_LENGTH] = ACPI_TYPE_INTEGER,
	[STR_MAX_LENGTH] = ACPI_TYPE_INTEGER,
};

static int hp_populate_string_elements_from_package(union acpi_object *string_obj,
						    int string_obj_count,
						    int instance_id)
{
	char *str_value = NULL;
	int value_len;
	int ret = 0;
	u32 int_value = 0;
	int elem;
	int reqs;
	int eloc;
	int size;
	struct string_data *string_data = &bioscfg_drv.string_data[instance_id];

	if (!string_obj)
		return -EINVAL;

	for (elem = 1, eloc = 1; elem < string_obj_count; elem++, eloc++) {
		/* ONLY look at the first STRING_ELEM_CNT elements */
		if (eloc == STR_ELEM_CNT)
			goto exit_string_package;

		switch (string_obj[elem].type) {
		case ACPI_TYPE_STRING:
			if (elem != PREREQUISITES) {
				ret = hp_convert_hexstr_to_str(string_obj[elem].string.pointer,
							       string_obj[elem].string.length,
							       &str_value, &value_len);

				if (ret)
					continue;
			}
			break;
		case ACPI_TYPE_INTEGER:
			int_value = (u32)string_obj[elem].integer.value;
			break;
		default:
			pr_warn("Unsupported object type [%d]\n", string_obj[elem].type);
			continue;
		}

		/* Check that both expected and read object type match */
		if (expected_string_types[eloc] != string_obj[elem].type) {
			pr_err("Error expected type %d for elem %d, but got type %d instead\n",
			       expected_string_types[eloc], elem, string_obj[elem].type);
			kfree(str_value);
			return -EIO;
		}

		/* Assign appropriate element value to corresponding field*/
		switch (eloc) {
		case VALUE:
			strscpy(string_data->current_value,
				str_value, sizeof(string_data->current_value));
			break;
		case PATH:
			strscpy(string_data->common.path, str_value,
				sizeof(string_data->common.path));
			break;
		case IS_READONLY:
			string_data->common.is_readonly = int_value;
			break;
		case DISPLAY_IN_UI:
			string_data->common.display_in_ui = int_value;
			break;
		case REQUIRES_PHYSICAL_PRESENCE:
			string_data->common.requires_physical_presence = int_value;
			break;
		case SEQUENCE:
			string_data->common.sequence = int_value;
			break;
		case PREREQUISITES_SIZE:
			if (int_value > MAX_PREREQUISITES_SIZE) {
				pr_warn("Prerequisites size value exceeded the maximum number of elements supported or data may be malformed\n");
				int_value = MAX_PREREQUISITES_SIZE;
			}
			string_data->common.prerequisites_size = int_value;

			/*
			 * This step is needed to keep the expected
			 * element list pointing to the right obj[elem].type
			 * when the size is zero. PREREQUISITES
			 * object is omitted by BIOS when the size is
			 * zero.
			 */
			if (string_data->common.prerequisites_size == 0)
				eloc++;
			break;
		case PREREQUISITES:
			size = min_t(u32, string_data->common.prerequisites_size,
				     MAX_PREREQUISITES_SIZE);

			for (reqs = 0; reqs < size; reqs++) {
				if (elem >= string_obj_count) {
					pr_err("Error elem-objects package is too small\n");
					return -EINVAL;
				}

				ret = hp_convert_hexstr_to_str(string_obj[elem + reqs].string.pointer,
							       string_obj[elem + reqs].string.length,
							       &str_value, &value_len);

				if (ret)
					continue;

				strscpy(string_data->common.prerequisites[reqs],
					str_value,
					sizeof(string_data->common.prerequisites[reqs]));
				kfree(str_value);
				str_value = NULL;
			}
			break;

		case SECURITY_LEVEL:
			string_data->common.security_level = int_value;
			break;
		case STR_MIN_LENGTH:
			string_data->min_length = int_value;
			break;
		case STR_MAX_LENGTH:
			string_data->max_length = int_value;
			break;
		default:
			pr_warn("Invalid element: %d found in String attribute or data may be malformed\n", elem);
			break;
		}

		kfree(str_value);
		str_value = NULL;
	}

exit_string_package:
	kfree(str_value);
	return 0;
}

/**
 * hp_populate_string_package_data() -
 * Populate all properties of an instance under string attribute
 *
 * @string_obj: ACPI object with string data
 * @instance_id: The instance to enumerate
 * @attr_name_kobj: The parent kernel object
 */
int hp_populate_string_package_data(union acpi_object *string_obj,
				    int instance_id,
				    struct kobject *attr_name_kobj)
{
	struct string_data *string_data = &bioscfg_drv.string_data[instance_id];

	string_data->attr_name_kobj = attr_name_kobj;

	hp_populate_string_elements_from_package(string_obj,
						 string_obj->package.count,
						 instance_id);

	hp_update_attribute_permissions(string_data->common.is_readonly,
					&string_current_val);
	hp_friendly_user_name_update(string_data->common.path,
				     attr_name_kobj->name,
				     string_data->common.display_name,
				     sizeof(string_data->common.display_name));
	return sysfs_create_group(attr_name_kobj, &string_attr_group);
}

static int hp_populate_string_elements_from_buffer(u8 *buffer_ptr, u32 *buffer_size,
						   int instance_id)
{
	int ret = 0;
	struct string_data *string_data = &bioscfg_drv.string_data[instance_id];

	/*
	 * Only data relevant to this driver and its functionality is
	 * read. BIOS defines the order in which each * element is
	 * read. Element 0 data is not relevant to this
	 * driver hence it is ignored. For clarity, all element names
	 * (DISPLAY_IN_UI) which defines the order in which is read
	 * and the name matches the variable where the data is stored.
	 *
	 * In earlier implementation, reported errors were ignored
	 * causing the data to remain uninitialized. It is not
	 * possible to determine if data read from BIOS is valid or
	 * not. It is for this reason functions may return a error
	 * without validating the data itself.
	 */

	// VALUE:
	ret = hp_get_string_from_buffer(&buffer_ptr, buffer_size, string_data->current_value,
					sizeof(string_data->current_value));
	if (ret < 0)
		goto buffer_exit;

	// COMMON:
	ret = hp_get_common_data_from_buffer(&buffer_ptr, buffer_size, &string_data->common);
	if (ret < 0)
		goto buffer_exit;

	// STR_MIN_LENGTH:
	ret = hp_get_integer_from_buffer(&buffer_ptr, buffer_size,
					 &string_data->min_length);
	if (ret < 0)
		goto buffer_exit;

	// STR_MAX_LENGTH:
	ret = hp_get_integer_from_buffer(&buffer_ptr, buffer_size,
					 &string_data->max_length);

buffer_exit:

	return ret;
}

/**
 * hp_populate_string_buffer_data() -
 * Populate all properties of an instance under string attribute
 *
 * @buffer_ptr: Buffer pointer
 * @buffer_size: Buffer size
 * @instance_id: The instance to enumerate
 * @attr_name_kobj: The parent kernel object
 */
int hp_populate_string_buffer_data(u8 *buffer_ptr, u32 *buffer_size,
				   int instance_id,
				   struct kobject *attr_name_kobj)
{
	struct string_data *string_data = &bioscfg_drv.string_data[instance_id];
	int ret = 0;

	string_data->attr_name_kobj = attr_name_kobj;

	ret = hp_populate_string_elements_from_buffer(buffer_ptr, buffer_size,
						      instance_id);
	if (ret < 0)
		return ret;

	hp_update_attribute_permissions(string_data->common.is_readonly,
					&string_current_val);
	hp_friendly_user_name_update(string_data->common.path,
				     attr_name_kobj->name,
				     string_data->common.display_name,
				     sizeof(string_data->common.display_name));

	return sysfs_create_group(attr_name_kobj, &string_attr_group);
}

/**
 * hp_exit_string_attributes() - Clear all attribute data
 *
 * Clears all data allocated for this group of attributes
 */
void hp_exit_string_attributes(void)
{
	int instance_id;

	for (instance_id = 0; instance_id < bioscfg_drv.string_instances_count;
	     instance_id++) {
		struct kobject *attr_name_kobj =
			bioscfg_drv.string_data[instance_id].attr_name_kobj;

		if (attr_name_kobj)
			sysfs_remove_group(attr_name_kobj, &string_attr_group);
	}
	bioscfg_drv.string_instances_count = 0;

	kfree(bioscfg_drv.string_data);
	bioscfg_drv.string_data = NULL;
}