/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Set of common sysfs utilities.
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*
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* Copyright (C) 2018 Google, Inc.
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*/
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/* The functions described here are a set of utilities to allow each file in the
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* Gasket driver framework to manage their own set of sysfs entries, instead of
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* centralizing all that work in one file.
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*
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* The goal of these utilities is to allow for sysfs entries to be easily
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* created without causing a proliferation of sysfs "show" functions. This
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* requires O(N) string lookups during show function execution, but as reading
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* sysfs entries is rarely performance-critical, this is likely acceptible.
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*/
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#ifndef __GASKET_SYSFS_H__
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#define __GASKET_SYSFS_H__
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#include "gasket_constants.h"
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#include "gasket_core.h"
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#include <linux/device.h>
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#include <linux/stringify.h>
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#include <linux/sysfs.h>
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/* The maximum number of mappings/devices a driver needs to support. */
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#define GASKET_SYSFS_NUM_MAPPINGS (GASKET_FRAMEWORK_DESC_MAX * GASKET_DEV_MAX)
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/* The maximum number of sysfs nodes in a directory.
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*/
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#define GASKET_SYSFS_MAX_NODES 196
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/*
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* Terminator struct for a gasket_sysfs_attr array. Must be at the end of
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* all gasket_sysfs_attribute arrays.
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*/
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#define GASKET_END_OF_ATTR_ARRAY \
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{ \
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.attr = __ATTR_NULL, \
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.data.attr_type = 0, \
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}
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/*
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* Pairing of sysfs attribute and user data.
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* Used in lookups in sysfs "show" functions to return attribute metadata.
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*/
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struct gasket_sysfs_attribute {
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/* The underlying sysfs device attribute associated with this data. */
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struct device_attribute attr;
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/* User-specified data to associate with the attribute. */
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union {
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struct bar_address_ {
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ulong bar;
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ulong offset;
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} bar_address;
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uint attr_type;
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} data;
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/*
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* Function pointer to a callback to be invoked when this attribute is
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* written (if so configured). The arguments are to the Gasket device
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* pointer, the enclosing gasket_attr structure, and the value written.
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* The callback should perform any logging necessary, as errors cannot
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* be returned from the callback.
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*/
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void (*write_callback)(struct gasket_dev *dev,
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struct gasket_sysfs_attribute *attr,
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ulong value);
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};
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#define GASKET_SYSFS_RO(_name, _show_function, _attr_type) \
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{ \
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.attr = __ATTR(_name, 0444, _show_function, NULL), \
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.data.attr_type = _attr_type \
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}
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/* Initializes the Gasket sysfs subsystem.
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*
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* Description: Performs one-time initialization. Must be called before usage
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* at [Gasket] module load time.
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*/
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void gasket_sysfs_init(void);
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/*
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* Create an entry in mapping_data between a device and a Gasket device.
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* @device: Device struct to map to.
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* @gasket_dev: The dev struct associated with the driver controlling @device.
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*
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* Description: This function maps a gasket_dev* to a device*. This mapping can
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* be used in sysfs_show functions to get a handle to the gasket_dev struct
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* controlling the device node.
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*
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* If this function is not called before gasket_sysfs_create_entries, a warning
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* will be logged.
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*/
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int gasket_sysfs_create_mapping(struct device *device,
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struct gasket_dev *gasket_dev);
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/*
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* Creates bulk entries in sysfs.
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* @device: Kernel device structure.
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* @attrs: List of attributes/sysfs entries to create.
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*
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* Description: Creates each sysfs entry described in "attrs". Can be called
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* multiple times for a given @device. If the gasket_dev specified in
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* gasket_sysfs_create_mapping had a legacy device, the entries will be created
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* for it, as well.
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*/
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int gasket_sysfs_create_entries(struct device *device,
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const struct gasket_sysfs_attribute *attrs);
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/*
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* Removes a device mapping from the global table.
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* @device: Device to unmap.
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*
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* Description: Removes the device->Gasket device mapping from the internal
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* table.
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*/
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void gasket_sysfs_remove_mapping(struct device *device);
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/*
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* User data lookup based on kernel device structure.
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* @device: Kernel device structure.
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*
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* Description: Returns the user data associated with "device" in a prior call
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* to gasket_sysfs_create_entries. Returns NULL if no mapping can be found.
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* Upon success, this call take a reference to internal sysfs data that must be
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* released with gasket_sysfs_put_device_data. While this reference is held, the
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* underlying device sysfs information/structure will remain valid/will not be
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* deleted.
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*/
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struct gasket_dev *gasket_sysfs_get_device_data(struct device *device);
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/*
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* Releases a references to internal data.
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* @device: Kernel device structure.
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* @dev: Gasket device descriptor (returned by gasket_sysfs_get_device_data).
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*/
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void gasket_sysfs_put_device_data(struct device *device,
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struct gasket_dev *gasket_dev);
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/*
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* Gasket-specific attribute lookup.
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* @device: Kernel device structure.
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* @attr: Device attribute to look up.
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*
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* Returns the Gasket sysfs attribute associated with the kernel device
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* attribute and device structure itself. Upon success, this call will take a
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* reference to internal sysfs data that must be released with a call to
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* gasket_sysfs_put_attr. While this reference is held, the underlying device
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* sysfs information/structure will remain valid/will not be deleted.
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*/
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struct gasket_sysfs_attribute *
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gasket_sysfs_get_attr(struct device *device, struct device_attribute *attr);
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/*
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* Releases a references to internal data.
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* @device: Kernel device structure.
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* @attr: Gasket sysfs attribute descriptor (returned by
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* gasket_sysfs_get_attr).
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*/
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void gasket_sysfs_put_attr(struct device *device,
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struct gasket_sysfs_attribute *attr);
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/*
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* Write to a register sysfs node.
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* @buf: NULL-terminated data being written.
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* @count: number of bytes in the "buf" argument.
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*/
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ssize_t gasket_sysfs_register_store(struct device *device,
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struct device_attribute *attr,
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const char *buf, size_t count);
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#endif /* __GASKET_SYSFS_H__ */
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