blob: c15928b8c5cc9976b9f12ca5a7e4154dcbb0e888 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* System Control and Management Interface (SCMI) Message Protocol bus layer
*
* Copyright (C) 2018-2021 ARM Ltd.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/atomic.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/device.h>
#include "common.h"
BLOCKING_NOTIFIER_HEAD(scmi_requested_devices_nh);
EXPORT_SYMBOL_GPL(scmi_requested_devices_nh);
static DEFINE_IDA(scmi_bus_id);
static DEFINE_IDR(scmi_requested_devices);
/* Protect access to scmi_requested_devices */
static DEFINE_MUTEX(scmi_requested_devices_mtx);
struct scmi_requested_dev {
const struct scmi_device_id *id_table;
struct list_head node;
};
/* Track globally the creation of SCMI SystemPower related devices */
static atomic_t scmi_syspower_registered = ATOMIC_INIT(0);
/**
* scmi_protocol_device_request - Helper to request a device
*
* @id_table: A protocol/name pair descriptor for the device to be created.
*
* This helper let an SCMI driver request specific devices identified by the
* @id_table to be created for each active SCMI instance.
*
* The requested device name MUST NOT be already existent for any protocol;
* at first the freshly requested @id_table is annotated in the IDR table
* @scmi_requested_devices and then the requested device is advertised to any
* registered party via the @scmi_requested_devices_nh notification chain.
*
* Return: 0 on Success
*/
static int scmi_protocol_device_request(const struct scmi_device_id *id_table)
{
int ret = 0;
unsigned int id = 0;
struct list_head *head, *phead = NULL;
struct scmi_requested_dev *rdev;
pr_debug("Requesting SCMI device (%s) for protocol %x\n",
id_table->name, id_table->protocol_id);
if (IS_ENABLED(CONFIG_ARM_SCMI_RAW_MODE_SUPPORT) &&
!IS_ENABLED(CONFIG_ARM_SCMI_RAW_MODE_SUPPORT_COEX)) {
pr_warn("SCMI Raw mode active. Rejecting '%s'/0x%02X\n",
id_table->name, id_table->protocol_id);
return -EINVAL;
}
/*
* Search for the matching protocol rdev list and then search
* of any existent equally named device...fails if any duplicate found.
*/
mutex_lock(&scmi_requested_devices_mtx);
idr_for_each_entry(&scmi_requested_devices, head, id) {
if (!phead) {
/* A list found registered in the IDR is never empty */
rdev = list_first_entry(head, struct scmi_requested_dev,
node);
if (rdev->id_table->protocol_id ==
id_table->protocol_id)
phead = head;
}
list_for_each_entry(rdev, head, node) {
if (!strcmp(rdev->id_table->name, id_table->name)) {
pr_err("Ignoring duplicate request [%d] %s\n",
rdev->id_table->protocol_id,
rdev->id_table->name);
ret = -EINVAL;
goto out;
}
}
}
/*
* No duplicate found for requested id_table, so let's create a new
* requested device entry for this new valid request.
*/
rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
if (!rdev) {
ret = -ENOMEM;
goto out;
}
rdev->id_table = id_table;
/*
* Append the new requested device table descriptor to the head of the
* related protocol list, eventually creating such head if not already
* there.
*/
if (!phead) {
phead = kzalloc(sizeof(*phead), GFP_KERNEL);
if (!phead) {
kfree(rdev);
ret = -ENOMEM;
goto out;
}
INIT_LIST_HEAD(phead);
ret = idr_alloc(&scmi_requested_devices, (void *)phead,
id_table->protocol_id,
id_table->protocol_id + 1, GFP_KERNEL);
if (ret != id_table->protocol_id) {
pr_err("Failed to save SCMI device - ret:%d\n", ret);
kfree(rdev);
kfree(phead);
ret = -EINVAL;
goto out;
}
ret = 0;
}
list_add(&rdev->node, phead);
out:
mutex_unlock(&scmi_requested_devices_mtx);
if (!ret)
blocking_notifier_call_chain(&scmi_requested_devices_nh,
SCMI_BUS_NOTIFY_DEVICE_REQUEST,
(void *)rdev->id_table);
return ret;
}
/**
* scmi_protocol_device_unrequest - Helper to unrequest a device
*
* @id_table: A protocol/name pair descriptor for the device to be unrequested.
*
* The unrequested device, described by the provided id_table, is at first
* removed from the IDR @scmi_requested_devices and then the removal is
* advertised to any registered party via the @scmi_requested_devices_nh
* notification chain.
*/
static void scmi_protocol_device_unrequest(const struct scmi_device_id *id_table)
{
struct list_head *phead;
pr_debug("Unrequesting SCMI device (%s) for protocol %x\n",
id_table->name, id_table->protocol_id);
mutex_lock(&scmi_requested_devices_mtx);
phead = idr_find(&scmi_requested_devices, id_table->protocol_id);
if (phead) {
struct scmi_requested_dev *victim, *tmp;
list_for_each_entry_safe(victim, tmp, phead, node) {
if (!strcmp(victim->id_table->name, id_table->name)) {
list_del(&victim->node);
mutex_unlock(&scmi_requested_devices_mtx);
blocking_notifier_call_chain(&scmi_requested_devices_nh,
SCMI_BUS_NOTIFY_DEVICE_UNREQUEST,
(void *)victim->id_table);
kfree(victim);
mutex_lock(&scmi_requested_devices_mtx);
break;
}
}
if (list_empty(phead)) {
idr_remove(&scmi_requested_devices,
id_table->protocol_id);
kfree(phead);
}
}
mutex_unlock(&scmi_requested_devices_mtx);
}
static const struct scmi_device_id *
scmi_dev_match_id(struct scmi_device *scmi_dev, struct scmi_driver *scmi_drv)
{
const struct scmi_device_id *id = scmi_drv->id_table;
if (!id)
return NULL;
for (; id->protocol_id; id++)
if (id->protocol_id == scmi_dev->protocol_id) {
if (!id->name)
return id;
else if (!strcmp(id->name, scmi_dev->name))
return id;
}
return NULL;
}
static int scmi_dev_match(struct device *dev, struct device_driver *drv)
{
struct scmi_driver *scmi_drv = to_scmi_driver(drv);
struct scmi_device *scmi_dev = to_scmi_dev(dev);
const struct scmi_device_id *id;
id = scmi_dev_match_id(scmi_dev, scmi_drv);
if (id)
return 1;
return 0;
}
static int scmi_match_by_id_table(struct device *dev, void *data)
{
struct scmi_device *sdev = to_scmi_dev(dev);
struct scmi_device_id *id_table = data;
return sdev->protocol_id == id_table->protocol_id &&
(id_table->name && !strcmp(sdev->name, id_table->name));
}
static struct scmi_device *scmi_child_dev_find(struct device *parent,
int prot_id, const char *name)
{
struct scmi_device_id id_table;
struct device *dev;
id_table.protocol_id = prot_id;
id_table.name = name;
dev = device_find_child(parent, &id_table, scmi_match_by_id_table);
if (!dev)
return NULL;
return to_scmi_dev(dev);
}
static int scmi_dev_probe(struct device *dev)
{
struct scmi_driver *scmi_drv = to_scmi_driver(dev->driver);
struct scmi_device *scmi_dev = to_scmi_dev(dev);
if (!scmi_dev->handle)
return -EPROBE_DEFER;
return scmi_drv->probe(scmi_dev);
}
static void scmi_dev_remove(struct device *dev)
{
struct scmi_driver *scmi_drv = to_scmi_driver(dev->driver);
struct scmi_device *scmi_dev = to_scmi_dev(dev);
if (scmi_drv->remove)
scmi_drv->remove(scmi_dev);
}
struct bus_type scmi_bus_type = {
.name = "scmi_protocol",
.match = scmi_dev_match,
.probe = scmi_dev_probe,
.remove = scmi_dev_remove,
};
EXPORT_SYMBOL_GPL(scmi_bus_type);
int scmi_driver_register(struct scmi_driver *driver, struct module *owner,
const char *mod_name)
{
int retval;
if (!driver->probe)
return -EINVAL;
retval = scmi_protocol_device_request(driver->id_table);
if (retval)
return retval;
driver->driver.bus = &scmi_bus_type;
driver->driver.name = driver->name;
driver->driver.owner = owner;
driver->driver.mod_name = mod_name;
retval = driver_register(&driver->driver);
if (!retval)
pr_debug("Registered new scmi driver %s\n", driver->name);
return retval;
}
EXPORT_SYMBOL_GPL(scmi_driver_register);
void scmi_driver_unregister(struct scmi_driver *driver)
{
driver_unregister(&driver->driver);
scmi_protocol_device_unrequest(driver->id_table);
}
EXPORT_SYMBOL_GPL(scmi_driver_unregister);
static void scmi_device_release(struct device *dev)
{
kfree(to_scmi_dev(dev));
}
static void __scmi_device_destroy(struct scmi_device *scmi_dev)
{
pr_debug("(%s) Destroying SCMI device '%s' for protocol 0x%x (%s)\n",
of_node_full_name(scmi_dev->dev.parent->of_node),
dev_name(&scmi_dev->dev), scmi_dev->protocol_id,
scmi_dev->name);
if (scmi_dev->protocol_id == SCMI_PROTOCOL_SYSTEM)
atomic_set(&scmi_syspower_registered, 0);
kfree_const(scmi_dev->name);
ida_free(&scmi_bus_id, scmi_dev->id);
device_unregister(&scmi_dev->dev);
}
static struct scmi_device *
__scmi_device_create(struct device_node *np, struct device *parent,
int protocol, const char *name)
{
int id, retval;
struct scmi_device *scmi_dev;
/*
* If the same protocol/name device already exist under the same parent
* (i.e. SCMI instance) just return the existent device.
* This avoids any race between the SCMI driver, creating devices for
* each DT defined protocol at probe time, and the concurrent
* registration of SCMI drivers.
*/
scmi_dev = scmi_child_dev_find(parent, protocol, name);
if (scmi_dev)
return scmi_dev;
/*
* Ignore any possible subsequent failures while creating the device
* since we are doomed anyway at that point; not using a mutex which
* spans across this whole function to keep things simple and to avoid
* to serialize all the __scmi_device_create calls across possibly
* different SCMI server instances (parent)
*/
if (protocol == SCMI_PROTOCOL_SYSTEM &&
atomic_cmpxchg(&scmi_syspower_registered, 0, 1)) {
dev_warn(parent,
"SCMI SystemPower protocol device must be unique !\n");
return NULL;
}
scmi_dev = kzalloc(sizeof(*scmi_dev), GFP_KERNEL);
if (!scmi_dev)
return NULL;
scmi_dev->name = kstrdup_const(name ?: "unknown", GFP_KERNEL);
if (!scmi_dev->name) {
kfree(scmi_dev);
return NULL;
}
id = ida_alloc_min(&scmi_bus_id, 1, GFP_KERNEL);
if (id < 0) {
kfree_const(scmi_dev->name);
kfree(scmi_dev);
return NULL;
}
scmi_dev->id = id;
scmi_dev->protocol_id = protocol;
scmi_dev->dev.parent = parent;
device_set_node(&scmi_dev->dev, of_fwnode_handle(np));
scmi_dev->dev.bus = &scmi_bus_type;
scmi_dev->dev.release = scmi_device_release;
dev_set_name(&scmi_dev->dev, "scmi_dev.%d", id);
retval = device_register(&scmi_dev->dev);
if (retval)
goto put_dev;
pr_debug("(%s) Created SCMI device '%s' for protocol 0x%x (%s)\n",
of_node_full_name(parent->of_node),
dev_name(&scmi_dev->dev), protocol, name);
return scmi_dev;
put_dev:
kfree_const(scmi_dev->name);
put_device(&scmi_dev->dev);
ida_free(&scmi_bus_id, id);
return NULL;
}
/**
* scmi_device_create - A method to create one or more SCMI devices
*
* @np: A reference to the device node to use for the new device(s)
* @parent: The parent device to use identifying a specific SCMI instance
* @protocol: The SCMI protocol to be associated with this device
* @name: The requested-name of the device to be created; this is optional
* and if no @name is provided, all the devices currently known to
* be requested on the SCMI bus for @protocol will be created.
*
* This method can be invoked to create a single well-defined device (like
* a transport device or a device requested by an SCMI driver loaded after
* the core SCMI stack has been probed), or to create all the devices currently
* known to have been requested by the loaded SCMI drivers for a specific
* protocol (typically during SCMI core protocol enumeration at probe time).
*
* Return: The created device (or one of them if @name was NOT provided and
* multiple devices were created) or NULL if no device was created;
* note that NULL indicates an error ONLY in case a specific @name
* was provided: when @name param was not provided, a number of devices
* could have been potentially created for a whole protocol, unless no
* device was found to have been requested for that specific protocol.
*/
struct scmi_device *scmi_device_create(struct device_node *np,
struct device *parent, int protocol,
const char *name)
{
struct list_head *phead;
struct scmi_requested_dev *rdev;
struct scmi_device *scmi_dev = NULL;
if (name)
return __scmi_device_create(np, parent, protocol, name);
mutex_lock(&scmi_requested_devices_mtx);
phead = idr_find(&scmi_requested_devices, protocol);
/* Nothing to do. */
if (!phead) {
mutex_unlock(&scmi_requested_devices_mtx);
return NULL;
}
/* Walk the list of requested devices for protocol and create them */
list_for_each_entry(rdev, phead, node) {
struct scmi_device *sdev;
sdev = __scmi_device_create(np, parent,
rdev->id_table->protocol_id,
rdev->id_table->name);
/* Report errors and carry on... */
if (sdev)
scmi_dev = sdev;
else
pr_err("(%s) Failed to create device for protocol 0x%x (%s)\n",
of_node_full_name(parent->of_node),
rdev->id_table->protocol_id,
rdev->id_table->name);
}
mutex_unlock(&scmi_requested_devices_mtx);
return scmi_dev;
}
EXPORT_SYMBOL_GPL(scmi_device_create);
void scmi_device_destroy(struct device *parent, int protocol, const char *name)
{
struct scmi_device *scmi_dev;
scmi_dev = scmi_child_dev_find(parent, protocol, name);
if (scmi_dev)
__scmi_device_destroy(scmi_dev);
}
EXPORT_SYMBOL_GPL(scmi_device_destroy);
static int __scmi_devices_unregister(struct device *dev, void *data)
{
struct scmi_device *scmi_dev = to_scmi_dev(dev);
__scmi_device_destroy(scmi_dev);
return 0;
}
static void scmi_devices_unregister(void)
{
bus_for_each_dev(&scmi_bus_type, NULL, NULL, __scmi_devices_unregister);
}
static int __init scmi_bus_init(void)
{
int retval;
retval = bus_register(&scmi_bus_type);
if (retval)
pr_err("SCMI protocol bus register failed (%d)\n", retval);
pr_info("SCMI protocol bus registered\n");
return retval;
}
subsys_initcall(scmi_bus_init);
static void __exit scmi_bus_exit(void)
{
/*
* Destroy all remaining devices: just in case the drivers were
* manually unbound and at first and then the modules unloaded.
*/
scmi_devices_unregister();
bus_unregister(&scmi_bus_type);
ida_destroy(&scmi_bus_id);
}
module_exit(scmi_bus_exit);
MODULE_ALIAS("scmi-core");
MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
MODULE_DESCRIPTION("ARM SCMI protocol bus");
MODULE_LICENSE("GPL");