diff options
Diffstat (limited to 'drivers/firmware/arm_scmi/bus.c')
| -rw-r--r-- | drivers/firmware/arm_scmi/bus.c | 515 |
1 files changed, 515 insertions, 0 deletions
diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c new file mode 100644 index 0000000000..c15928b8c5 --- /dev/null +++ b/drivers/firmware/arm_scmi/bus.c @@ -0,0 +1,515 @@ +// 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"); |