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