// SPDX-License-Identifier: GPL-2.0
|
/* Copyright (C) 2018 Google, Inc. */
|
#include "gasket_sysfs.h"
|
|
#include "gasket_core.h"
|
|
#include <linux/device.h>
|
#include <linux/printk.h>
|
|
/*
|
* Pair of kernel device and user-specified pointer. Used in lookups in sysfs
|
* "show" functions to return user data.
|
*/
|
|
struct gasket_sysfs_mapping {
|
/*
|
* The device bound to this mapping. If this is NULL, then this mapping
|
* is free.
|
*/
|
struct device *device;
|
|
/* The Gasket descriptor for this device. */
|
struct gasket_dev *gasket_dev;
|
|
/* This device's set of sysfs attributes/nodes. */
|
struct gasket_sysfs_attribute *attributes;
|
|
/* The number of live elements in "attributes". */
|
int attribute_count;
|
|
/* Protects structure from simultaneous access. */
|
struct mutex mutex;
|
|
/* Tracks active users of this mapping. */
|
struct kref refcount;
|
};
|
|
/*
|
* Data needed to manage users of this sysfs utility.
|
* Currently has a fixed size; if space is a concern, this can be dynamically
|
* allocated.
|
*/
|
/*
|
* 'Global' (file-scoped) list of mappings between devices and gasket_data
|
* pointers. This removes the requirement to have a gasket_sysfs_data
|
* handle in all files.
|
*/
|
static struct gasket_sysfs_mapping dev_mappings[GASKET_SYSFS_NUM_MAPPINGS];
|
|
/* Callback when a mapping's refcount goes to zero. */
|
static void release_entry(struct kref *ref)
|
{
|
/* All work is done after the return from kref_put. */
|
}
|
|
/* Look up mapping information for the given device. */
|
static struct gasket_sysfs_mapping *get_mapping(struct device *device)
|
{
|
int i;
|
|
for (i = 0; i < GASKET_SYSFS_NUM_MAPPINGS; i++) {
|
mutex_lock(&dev_mappings[i].mutex);
|
if (dev_mappings[i].device == device) {
|
kref_get(&dev_mappings[i].refcount);
|
mutex_unlock(&dev_mappings[i].mutex);
|
return &dev_mappings[i];
|
}
|
mutex_unlock(&dev_mappings[i].mutex);
|
}
|
|
dev_dbg(device, "%s: Mapping to device %s not found\n",
|
__func__, device->kobj.name);
|
return NULL;
|
}
|
|
/* Put a reference to a mapping. */
|
static void put_mapping(struct gasket_sysfs_mapping *mapping)
|
{
|
int i;
|
int num_files_to_remove = 0;
|
struct device_attribute *files_to_remove;
|
struct device *device;
|
|
if (!mapping) {
|
pr_debug("%s: Mapping should not be NULL\n", __func__);
|
return;
|
}
|
|
mutex_lock(&mapping->mutex);
|
if (kref_put(&mapping->refcount, release_entry)) {
|
dev_dbg(mapping->device, "Removing Gasket sysfs mapping\n");
|
/*
|
* We can't remove the sysfs nodes in the kref callback, since
|
* device_remove_file() blocks until the node is free.
|
* Readers/writers of sysfs nodes, though, will be blocked on
|
* the mapping mutex, resulting in deadlock. To fix this, the
|
* sysfs nodes are removed outside the lock.
|
*/
|
device = mapping->device;
|
num_files_to_remove = mapping->attribute_count;
|
files_to_remove = kcalloc(num_files_to_remove,
|
sizeof(*files_to_remove),
|
GFP_KERNEL);
|
if (files_to_remove)
|
for (i = 0; i < num_files_to_remove; i++)
|
files_to_remove[i] =
|
mapping->attributes[i].attr;
|
else
|
num_files_to_remove = 0;
|
|
kfree(mapping->attributes);
|
mapping->attributes = NULL;
|
mapping->attribute_count = 0;
|
put_device(mapping->device);
|
mapping->device = NULL;
|
mapping->gasket_dev = NULL;
|
}
|
mutex_unlock(&mapping->mutex);
|
|
if (num_files_to_remove != 0) {
|
for (i = 0; i < num_files_to_remove; ++i)
|
device_remove_file(device, &files_to_remove[i]);
|
kfree(files_to_remove);
|
}
|
}
|
|
/*
|
* Put a reference to a mapping N times.
|
*
|
* In higher-level resource acquire/release function pairs, the release function
|
* will need to release a mapping 2x - once for the refcount taken in the
|
* release function itself, and once for the count taken in the acquire call.
|
*/
|
static void put_mapping_n(struct gasket_sysfs_mapping *mapping, int times)
|
{
|
int i;
|
|
for (i = 0; i < times; i++)
|
put_mapping(mapping);
|
}
|
|
void gasket_sysfs_init(void)
|
{
|
int i;
|
|
for (i = 0; i < GASKET_SYSFS_NUM_MAPPINGS; i++) {
|
dev_mappings[i].device = NULL;
|
mutex_init(&dev_mappings[i].mutex);
|
}
|
}
|
|
int gasket_sysfs_create_mapping(struct device *device,
|
struct gasket_dev *gasket_dev)
|
{
|
struct gasket_sysfs_mapping *mapping;
|
int map_idx = -1;
|
|
/*
|
* We need a function-level mutex to protect against the same device
|
* being added [multiple times] simultaneously.
|
*/
|
static DEFINE_MUTEX(function_mutex);
|
|
mutex_lock(&function_mutex);
|
dev_dbg(device, "Creating sysfs entries for device\n");
|
|
/* Check that the device we're adding hasn't already been added. */
|
mapping = get_mapping(device);
|
if (mapping) {
|
dev_err(device,
|
"Attempting to re-initialize sysfs mapping for device\n");
|
put_mapping(mapping);
|
mutex_unlock(&function_mutex);
|
return -EBUSY;
|
}
|
|
/* Find the first empty entry in the array. */
|
for (map_idx = 0; map_idx < GASKET_SYSFS_NUM_MAPPINGS; ++map_idx) {
|
mutex_lock(&dev_mappings[map_idx].mutex);
|
if (!dev_mappings[map_idx].device)
|
/* Break with the mutex held! */
|
break;
|
mutex_unlock(&dev_mappings[map_idx].mutex);
|
}
|
|
if (map_idx == GASKET_SYSFS_NUM_MAPPINGS) {
|
dev_err(device, "All mappings have been exhausted\n");
|
mutex_unlock(&function_mutex);
|
return -ENOMEM;
|
}
|
|
dev_dbg(device, "Creating sysfs mapping for device %s\n",
|
device->kobj.name);
|
|
mapping = &dev_mappings[map_idx];
|
mapping->attributes = kcalloc(GASKET_SYSFS_MAX_NODES,
|
sizeof(*mapping->attributes),
|
GFP_KERNEL);
|
if (!mapping->attributes) {
|
dev_dbg(device, "Unable to allocate sysfs attribute array\n");
|
mutex_unlock(&mapping->mutex);
|
mutex_unlock(&function_mutex);
|
return -ENOMEM;
|
}
|
|
kref_init(&mapping->refcount);
|
mapping->device = get_device(device);
|
mapping->gasket_dev = gasket_dev;
|
mapping->attribute_count = 0;
|
mutex_unlock(&mapping->mutex);
|
mutex_unlock(&function_mutex);
|
|
/* Don't decrement the refcount here! One open count keeps it alive! */
|
return 0;
|
}
|
|
int gasket_sysfs_create_entries(struct device *device,
|
const struct gasket_sysfs_attribute *attrs)
|
{
|
int i;
|
int ret;
|
struct gasket_sysfs_mapping *mapping = get_mapping(device);
|
|
if (!mapping) {
|
dev_dbg(device,
|
"Creating entries for device without first initializing mapping\n");
|
return -EINVAL;
|
}
|
|
mutex_lock(&mapping->mutex);
|
for (i = 0; attrs[i].attr.attr.name != NULL; i++) {
|
if (mapping->attribute_count == GASKET_SYSFS_MAX_NODES) {
|
dev_err(device,
|
"Maximum number of sysfs nodes reached for device\n");
|
mutex_unlock(&mapping->mutex);
|
put_mapping(mapping);
|
return -ENOMEM;
|
}
|
|
ret = device_create_file(device, &attrs[i].attr);
|
if (ret) {
|
dev_dbg(device, "Unable to create device entries\n");
|
mutex_unlock(&mapping->mutex);
|
put_mapping(mapping);
|
return ret;
|
}
|
|
mapping->attributes[mapping->attribute_count] = attrs[i];
|
++mapping->attribute_count;
|
}
|
|
mutex_unlock(&mapping->mutex);
|
put_mapping(mapping);
|
return 0;
|
}
|
EXPORT_SYMBOL(gasket_sysfs_create_entries);
|
|
void gasket_sysfs_remove_mapping(struct device *device)
|
{
|
struct gasket_sysfs_mapping *mapping = get_mapping(device);
|
|
if (!mapping) {
|
dev_err(device,
|
"Attempted to remove non-existent sysfs mapping to device\n");
|
return;
|
}
|
|
put_mapping_n(mapping, 2);
|
}
|
|
struct gasket_dev *gasket_sysfs_get_device_data(struct device *device)
|
{
|
struct gasket_sysfs_mapping *mapping = get_mapping(device);
|
|
if (!mapping) {
|
dev_err(device, "device not registered\n");
|
return NULL;
|
}
|
|
return mapping->gasket_dev;
|
}
|
EXPORT_SYMBOL(gasket_sysfs_get_device_data);
|
|
void gasket_sysfs_put_device_data(struct device *device, struct gasket_dev *dev)
|
{
|
struct gasket_sysfs_mapping *mapping = get_mapping(device);
|
|
if (!mapping)
|
return;
|
|
/* See comment of put_mapping_n() for why the '2' is necessary. */
|
put_mapping_n(mapping, 2);
|
}
|
EXPORT_SYMBOL(gasket_sysfs_put_device_data);
|
|
struct gasket_sysfs_attribute *
|
gasket_sysfs_get_attr(struct device *device, struct device_attribute *attr)
|
{
|
int i;
|
int num_attrs;
|
struct gasket_sysfs_mapping *mapping = get_mapping(device);
|
struct gasket_sysfs_attribute *attrs = NULL;
|
|
if (!mapping)
|
return NULL;
|
|
attrs = mapping->attributes;
|
num_attrs = mapping->attribute_count;
|
for (i = 0; i < num_attrs; ++i) {
|
if (!strcmp(attrs[i].attr.attr.name, attr->attr.name))
|
return &attrs[i];
|
}
|
|
dev_err(device, "Unable to find match for device_attribute %s\n",
|
attr->attr.name);
|
return NULL;
|
}
|
EXPORT_SYMBOL(gasket_sysfs_get_attr);
|
|
void gasket_sysfs_put_attr(struct device *device,
|
struct gasket_sysfs_attribute *attr)
|
{
|
int i;
|
int num_attrs;
|
struct gasket_sysfs_mapping *mapping = get_mapping(device);
|
struct gasket_sysfs_attribute *attrs = NULL;
|
|
if (!mapping)
|
return;
|
|
attrs = mapping->attributes;
|
num_attrs = mapping->attribute_count;
|
for (i = 0; i < num_attrs; ++i) {
|
if (&attrs[i] == attr) {
|
put_mapping_n(mapping, 2);
|
return;
|
}
|
}
|
|
dev_err(device, "Unable to put unknown attribute: %s\n",
|
attr->attr.attr.name);
|
put_mapping(mapping);
|
}
|
EXPORT_SYMBOL(gasket_sysfs_put_attr);
|
|
ssize_t gasket_sysfs_register_store(struct device *device,
|
struct device_attribute *attr,
|
const char *buf, size_t count)
|
{
|
ulong parsed_value = 0;
|
struct gasket_sysfs_mapping *mapping;
|
struct gasket_dev *gasket_dev;
|
struct gasket_sysfs_attribute *gasket_attr;
|
|
if (count < 3 || buf[0] != '0' || buf[1] != 'x') {
|
dev_err(device,
|
"sysfs register write format: \"0x<hex value>\"\n");
|
return -EINVAL;
|
}
|
|
if (kstrtoul(buf, 16, &parsed_value) != 0) {
|
dev_err(device,
|
"Unable to parse input as 64-bit hex value: %s\n", buf);
|
return -EINVAL;
|
}
|
|
mapping = get_mapping(device);
|
if (!mapping) {
|
dev_err(device, "Device driver may have been removed\n");
|
return 0;
|
}
|
|
gasket_dev = mapping->gasket_dev;
|
if (!gasket_dev) {
|
dev_err(device, "Device driver may have been removed\n");
|
put_mapping(mapping);
|
return 0;
|
}
|
|
gasket_attr = gasket_sysfs_get_attr(device, attr);
|
if (!gasket_attr) {
|
put_mapping(mapping);
|
return count;
|
}
|
|
gasket_dev_write_64(gasket_dev, parsed_value,
|
gasket_attr->data.bar_address.bar,
|
gasket_attr->data.bar_address.offset);
|
|
if (gasket_attr->write_callback)
|
gasket_attr->write_callback(gasket_dev, gasket_attr,
|
parsed_value);
|
|
gasket_sysfs_put_attr(device, gasket_attr);
|
put_mapping(mapping);
|
return count;
|
}
|
EXPORT_SYMBOL(gasket_sysfs_register_store);
|
