Messages in this thread Patch in this message | | | Date | Mon, 27 Jan 2020 18:11:48 +0000 | From | Jonathan Cameron <> | Subject | Re: [RFC PATCH 04/11] firmware: arm_scmi: Add core notifications support |
| |
On Mon, 20 Jan 2020 12:23:26 +0000 Cristian Marussi <cristian.marussi@arm.com> wrote:
> Add basic support for SCMI Notifications, using Kernel notification chains > mechanism. > > Each SCMI Protocol has a dedicated events' queue and deferred worker which > is in charge of delivering the notifications to the interested users > invoking the users' registered callbacks. > > Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
I'm not keen on the huge asymmetry on the setup and tear down paths. For instance the lack of a scmi_unregister_protocol events.
The idr usage is not standard. They aren't the right structure if you known the value you want.
Not a particularly thorough review otherwise. Out of time for today and may not get back to this for a while.
Thanks,
Jonathan
> --- > drivers/firmware/arm_scmi/Makefile | 2 +- > drivers/firmware/arm_scmi/common.h | 4 + > drivers/firmware/arm_scmi/driver.c | 2 + > drivers/firmware/arm_scmi/notify.c | 904 +++++++++++++++++++++++++++++ > drivers/firmware/arm_scmi/notify.h | 79 +++ > 5 files changed, 990 insertions(+), 1 deletion(-) > create mode 100644 drivers/firmware/arm_scmi/notify.c > create mode 100644 drivers/firmware/arm_scmi/notify.h > > diff --git a/drivers/firmware/arm_scmi/Makefile b/drivers/firmware/arm_scmi/Makefile > index 5f298f00a82e..26587ea4661f 100644 > --- a/drivers/firmware/arm_scmi/Makefile > +++ b/drivers/firmware/arm_scmi/Makefile > @@ -1,6 +1,6 @@ > # SPDX-License-Identifier: GPL-2.0-only > obj-y = scmi-bus.o scmi-driver.o scmi-protocols.o > scmi-bus-y = bus.o > -scmi-driver-y = driver.o > +scmi-driver-y = driver.o notify.o > scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o > obj-$(CONFIG_ARM_SCMI_POWER_DOMAIN) += scmi_pm_domain.o > diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h > index df35358ff324..2621c05e9149 100644 > --- a/drivers/firmware/arm_scmi/common.h > +++ b/drivers/firmware/arm_scmi/common.h > @@ -6,6 +6,8 @@ > * > * Copyright (C) 2018 ARM Ltd. > */ > +#ifndef _SCMI_COMMON_H > +#define _SCMI_COMMON_H > > #include <linux/bitfield.h> > #include <linux/completion.h> > @@ -113,3 +115,5 @@ void scmi_setup_protocol_implemented(const struct scmi_handle *handle, > u8 *prot_imp); > > int scmi_base_protocol_init(struct scmi_handle *h); > + > +#endif /* _SCMI_COMMON_H */ > diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c > index 28ed1f0cb417..a43fad29de11 100644 > --- a/drivers/firmware/arm_scmi/driver.c > +++ b/drivers/firmware/arm_scmi/driver.c > @@ -350,12 +350,14 @@ __scmi_xfer_put(struct scmi_xfers_info *minfo, struct scmi_xfer *xfer) > > static void scmi_handle_notification(struct scmi_chan_info *cinfo, u32 msg_hdr) > { > + ktime_t ts; > struct scmi_xfer *xfer; > struct device *dev = cinfo->dev; > struct scmi_info *info = handle_to_scmi_info(cinfo->handle); > struct scmi_xfers_info *minfo = &info->rx_minfo; > struct scmi_shared_mem __iomem *mem = cinfo->payload; > > + ts = ktime_get_boottime(); > xfer = scmi_xfer_get(cinfo->handle, minfo); > if (IS_ERR(xfer)) { > dev_err(dev, "failed to get free message slot (%ld)\n", > diff --git a/drivers/firmware/arm_scmi/notify.c b/drivers/firmware/arm_scmi/notify.c > new file mode 100644 > index 000000000000..da342f43021e > --- /dev/null > +++ b/drivers/firmware/arm_scmi/notify.c > @@ -0,0 +1,904 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * System Control and Management Interface (SCMI) Notification support > + * > + * Copyright (C) 2019 ARM Ltd. > + * > + * SCMI Protocol specification allows the platform to signal events to > + * interested agents via notification messages: this in an implementation > + * of the dispatch and delivery of such notifications to the interested users > + * inside the Linux kernel. > + * > + * Each SCMI Protocol implementation, during its initialization, registers with > + * this core notification framework its set of supported events via > + * @scmi_register_protocol_events(), while Kernel users interested in some > + * specific event can register their associated callbacks providing the usual > + * notifier_block descriptor, since the notification system internally supports > + * events delivery using customized notification chains. > + * > + * Given the number of possible events defined by SCMI and the extensibility > + * of the SCMI Protocol itself, such underlying notification chains are created > + * and destroyed dynamically on demand depending on the number of users > + * effectively registered for an event, so that no structures or chains are > + * allocated until at least one user has registered a notifier_block for such > + * event. Similarly, events' generation itself is enabled at the platform level > + * only after at least one user has registered, and it is shutdown after the > + * last user for that event has gone. > + * > + * An event is identified univocally by the tuple (proto_id, evt_id, src_id) > + * and is served by its own dedicated notification chain: given that such chain > + * is dynamically created, the registration API simply let the users associate > + * their callbacks with the above tuple. > + * > + * Here proto_id and evt_id are simply the protocol_id and message_id numbers as > + * reported in the SCMI Protocol specification, while src_id represents an > + * optional, protocol dependent, source identifier (like domain_id, perf_id > + * or sensor_id and so forth), so that a user can register its callbacks for a > + * particular event coming only from a defined source (like CPU vs GPU). > + * When the source is not specified the user callback will be registered for > + * all existing sources for that event (if any). > + * > + * Upon reception of a notification message from the platform the SCMI RX ISR > + * passes the received message payload and some ancillary information (including > + * an arrival timestamp in nanoseconds) to the core via @scmi_notify(), which, > + * in turn, after having looked up the event in the registered events mapping, > + * pushes the event-data itself on a protocol dedicated kfifo queue for deferred > + * processing. > + * > + * Such dedicated protocols' queues are allocated once for all at initialization > + * time, together with a dedicated work_item running the common delivery logic > + * of @scmi_events_dispatcher(), so that each protocol has it own dedicated > + * worker which, once kicked by the ISR, takes care to empty is own dedicated > + * queue deliverying the queued items into the proper notification chain. > + * Note that since the underlying cmwq workers run one distinct work_item per > + * protocol and there are a number of max-active workers equal to the number of > + * protocols, notifications processing can proceed concurrently only between > + * events belonging to different protocols, while delivery of events within the > + * same protocol is still strictly sequentially ordered by time of arrival; this > + * separation effectively avoids the possibility that one particularly verbose > + * protocol, flooding the queues with events, can cause other protocols' events > + * to be lost or their processing starved. > + * > + * Event's information is converted to a custom per-event report struct before > + * being fed as void *data param to the user callback embedded in the registered > + * notifier_block so that it looks like as follow from the user perspective: > + * > + * int user_cb(struct notifier_block *nb, unsigned long event_id, void *report) > + * No point in having blank lines at the end of a comment block. > + * > + */ > + > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > + > +#include <linux/bug.h> > +#include <linux/bitfield.h> > +#include <linux/err.h> > +#include <linux/idr.h> > +#include <linux/kernel.h> > +#include <linux/kfifo.h> > +#include <linux/notifier.h> > +#include <linux/refcount.h> > +#include <linux/slab.h> > +#include <linux/scmi_protocol.h> > +#include <linux/types.h> > +#include <linux/workqueue.h> > + > +#include "notify.h" > + > +#define SCMI_NOTIF_MAX_ACTIVE_QUEUES 7 > + > +/* > + * Builds an unsigned 32bit key from the given input tuple to be used as a key > + * in IDR mappings; note that if __src_p is passed in as NULL, the returned key > + * is built using SCMI_ALL_SRC_IDS as src_id. > + */ > +#define MAKE_EVT_KEY(__proto, __evt, __src_p) \ > + ({ \ > + u32 __evt_key, __src_id; \ > + \ > + __src_id = ((__src_p)) ? \ > + (*((u32 *)(__src_p)) & SCMI_ALL_SRC_IDS) : \ > + SCMI_ALL_SRC_IDS; \ > + __evt_key = ((__proto) << 24) | \ > + ((__evt) << 16) | __src_id; \ > + __evt_key; \ > + }) > + > +#define PROTO_ID_MASK GENMASK(31, 24) > +#define EVT_ID_MASK GENMASK(23, 16) > +#define SRC_ID_MASK GENMASK(15, 0) > +#define KEY_XTRACT_PROTO_ID(key) FIELD_GET(PROTO_ID_MASK, (key)) > +#define KEY_XTRACT_EVT_ID(key) FIELD_GET(EVT_ID_MASK, (key)) > +#define KEY_XTRACT_SRC_ID(key) FIELD_GET(SRC_ID_MASK, (key)) > + > +/** > + * events_queue - Describes a queue and its associated worker Not valid kernel-doc. I'll assume all other instances will get fixed and not bother talking about them.
> + * > + * Each protocol has its own dedicated events_queue descriptor. > + * > + * @sz: Size in bytes of the related kfifo > + * @kfifo: A dedicated Kernel kfifo > + * @notify_work: A custom work item bound to this queue > + * @wq: A reference to the related workqueue > + */ > +struct events_queue { > + size_t sz; > + struct kfifo kfifo; > + struct work_struct notify_work; > + struct workqueue_struct *wq; > +}; > + > +/** > + * scmi_registered_protocol_events_desc - Protocol Specific information > + * > + * All protocols that registers at least an event have their protocol-specific > + * information stored here, together with a pointer to the allocated > + * events_queue. > + * > + * @id: Protocol ID > + * @ops: Protocol specific and event-related operations > + * @equeue: A reference to the associated per-protocol events_queue > + */ > +struct scmi_registered_protocol_events_desc { > + u8 id; > + const struct scmi_protocol_event_ops *ops; > + struct events_queue *equeue; > +}; > + > +/** > + * scmi_registered_event - Event Specific Information > + * > + * All registered events are represented by one of these structures. > + * > + * @proto: A reference to the associated protocol descriptor > + * @evt: A reference to the associated event descriptor (as provided at > + * registration time) > + * @scratch_isr: A pre-allocated buffer to be used as a scratch area by ISR > + * @scratch_isr: A pre-allocated buffer to be used as a scratch area by the > + * deferred worker scratch_bh.
> + * @report: A pre-allocated buffer used by the deferred workr to fill a
worker
> + * customized event report > + */ > +struct scmi_registered_event { > + struct scmi_registered_protocol_events_desc *proto; > + const struct scmi_event *evt; > + void *scratch_isr; > + void *scratch_bh; > + void *report; > +}; > + > +/** > + * scmi_event_handler - Event handler information > + * > + * This structure collects all the information needed to process a received > + * event, calling all the registered notifier callbacks. > + * Note this an event handler is associated to a tuple of values like: > + * (proto_id, evt_id, src_id) > + * through the means of a key and an IDR mapping. > + * > + * @evt_key: The unsigned 32bit key associated to this descriptor in the > + * related IDR mapping > + * @r_evt: A reference to the underlying registered event > + * @chain: The notification chain dedicated to this specific event tuple > + */ > +struct scmi_event_handler { > + u32 evt_key; > + bool enabled; > + refcount_t users; > + struct scmi_registered_event *r_evt; > + struct blocking_notifier_head chain; > +}; > + > +/** > + * scmi_event_header - A utility header
That's not a good description.
> + * > + * This header is prepended to each received event message payload before > + * being queued on the related events_queue, and describes the attached event > + * message. > + * > + * @timestamp: The timestamp, innanoseconds (boottime), which was associated > + * to this event as soon as it entered the SCMI RX ISR > + * @proto_id: Protocol ID > + * @evt_id: Event ID (corresponds to the Event MsgID for this Protocol) > + * @payld_sz: Effective size of the attached message payload which follows > + * @payld: A reference to the included Event payload > + */ > +struct scmi_event_header { > + u64 timestamp; > + u8 proto_id; > + u8 evt_id; > + size_t payld_sz; > + u8 payld[]; > +} __packed; > + > +/* > + * A few IDR maps to track: > + * > + * - @scmi_registered_events: All event's descriptors registered by the > + * protocols, together with their ancillary data > + * - @scmi_registered_events_handlers: All event's handlers descriptors, created > + * to collect all the users' notifier_block > + * callbacks and related notification chains > + * - @scmi_registered_protocols: All protocol-level specific information related > + * to events' handling > + */ > +static struct idr scmi_registered_events; > +static struct idr scmi_registered_events_handlers; > +static DEFINE_MUTEX(scmi_registered_events_handler_mtx); > +static struct idr scmi_registered_protocols; > + > +/* Common Kernel cmwq workqueue used by notifications core */ > +static struct workqueue_struct *scmi_notify_wq; > + > +static bool scmi_notifications_initialized; > + > +static struct scmi_event_handler *scmi_get_event_handler(u32 evt_key); > +static void scmi_put_event_handler(struct scmi_event_handler *hndl); > + > +/** > + * scmi_discard_bad_evt_payloadi() - Discard data from a kfifo
function name is wrong.
> + * > + * @kq: The kfifo to act on > + * @count: Number of bytes to flush > + */ > +static inline void scmi_discard_bad_evt_payload(struct kfifo *kq, > + const unsigned int count) > +{ > + int i = 0; > + > + pr_warn("SCMI Notification WQ :: skipping bad EVT Payload - %d bytes\n", > + count); > + /* Discard stale pending queued payload. */ > + for (i = 0; i < count; i++) > + kfifo_skip(kq); > +} > + > +/** > + * scmi_lookup_and_call_event_chain - Lookup the proper chain and call it > + * > + * @evt_key: The event key to use to lookup the related notification chain > + * @report: The customized event-specific report to pass down to the callbacks > + * as their *data parameter. > + */ > +static inline void scmi_lookup_and_call_event_chain(u32 evt_key, void *report) > +{ > + int ret; > + struct scmi_event_handler *hndl; > + > + hndl = scmi_get_event_handler(evt_key); > + if (IS_ERR_OR_NULL(hndl)) > + return; > + > + ret = blocking_notifier_call_chain(&hndl->chain, > + KEY_XTRACT_EVT_ID(evt_key), > + report); > + /* Notifiers are NOT supposed to cut the chain */ > + WARN_ON_ONCE(ret & NOTIFY_STOP_MASK); > + > + scmi_put_event_handler(hndl); > +} > + > +/** > + * scmi_events_dispatcher - Common worker logic for all work items. > + * > + * In turn: > + * 1. dequeue one pending RX notification (queued in SCMI RX ISR context) > + * 2. generate a custom event report from the received event message > + * 3. lookup for any registered ALL_SRC_IDs handler > + * - > call the related notification chain passing in the report > + * 4. lookup for any registered specific SRC_ID handler > + * - > call the related notification chain passing in the report > + * > + * Note that: > + * - a dedicated per-protocol kfifo queue is used: in this way an anomalous > + * flood of events cannot saturate other protocols' queues. > + * > + * - each per-protocol queue is associated to a distinct work_item, which > + * means, in turn, that: > + * + all protocol can process their dedicated queues concurrently > + * (since scmi_notify_wq:max_active > 1) > + * + anyway at most one worker instance is allowed to run on the same queue > + * concurrently: this ensures that we can have only one concurrent > + * reader/writer on the associated kfifo (needed for lock-less access) > + * > + * @work: The work item to use, which is associated to the proper events_queue > + */ > +static void scmi_events_dispatcher(struct work_struct *work) > +{ > + struct events_queue *equeue; > + struct scmi_event_header eh; > + > + equeue = container_of(work, struct events_queue, notify_work); > + while (kfifo_out(&equeue->kfifo, &eh, sizeof(eh))) { > + u32 src_id, evt_key; > + unsigned int outs; > + struct scmi_registered_event *r_evt; > + void *report = NULL; > + > + evt_key = MAKE_EVT_KEY(eh.proto_id, eh.evt_id, NULL); > + r_evt = idr_find(&scmi_registered_events, evt_key); > + if (!r_evt) { > + scmi_discard_bad_evt_payload(&equeue->kfifo, > + eh.payld_sz); > + continue; > + } > + > + outs = kfifo_out(&equeue->kfifo, r_evt->scratch_bh, > + eh.payld_sz); > + if (outs != eh.payld_sz) { > + pr_warn("SCMI Notification WQ :: SKIP corrupted EVT Payload.\n"); > + continue; > + } > + > + /* Reset and fill custom report */ > + memset(r_evt->report, 0x00, r_evt->evt->max_report_sz); > + report = r_evt->proto->ops->fill_custom_report(eh.evt_id, > + eh.timestamp, > + r_evt->scratch_bh, > + eh.payld_sz, > + r_evt->report, > + &src_id); > + if (!report) > + continue; > + > + /* At first search for a generic ALL src_ids handler... */ > + scmi_lookup_and_call_event_chain(evt_key, report); > + if (src_id != SCMI_ALL_SRC_IDS) { > + u32 *__sub_p = &src_id; > + > + evt_key = MAKE_EVT_KEY(eh.proto_id, eh.evt_id, __sub_p); > + scmi_lookup_and_call_event_chain(evt_key, report); > + } > + } > +} > + > +/** > + * scmi_notify - Queues a notification for further deferred processing > + * > + * This is called in interrupt context to queue a received event for > + * deferred processing. > + * > + * @proto_id: Protocol ID > + * @evt_id: Event ID (msgID) > + * @buf: Event Message Payload (without the header) > + * @len: Event Message Payload size > + * @ts: RX Timestamp in nanoseconds (boottime) > + * > + * Return: 0 on Success > + */ > +int scmi_notify(u8 proto_id, u8 evt_id, const void *buf, size_t len, u64 ts) > +{ > + struct scmi_registered_event *r_evt; > + struct scmi_event_header *eh; > + > + if (unlikely(!scmi_notifications_initialized)) > + return 0; > + > + r_evt = idr_find(&scmi_registered_events, > + MAKE_EVT_KEY(proto_id, evt_id, NULL)); > + if (unlikely(!r_evt || !r_evt->proto->equeue)) > + return -EINVAL; > + > + if (unlikely(len > r_evt->evt->max_payld_sz)) { > + pr_err("SCMI Notification discard badly sized message\n"); > + return -EINVAL; > + } > + if (unlikely(kfifo_avail(&r_evt->proto->equeue->kfifo) < > + sizeof(*eh) + len)) { > + pr_warn("SCMI Notification queue full: dropping proto_id:%d evt_id:%d ts:%lld\n", > + proto_id, evt_id, ts); > + return -ENOMEM; > + } > + > + /* > + * Note that we can use the per protocol kfifo in a lock-less manner > + * since we have only one concurrent reader and writer but, in order > + * to avoid any trouble on the reader side, here we perform one single > + * write, so we have to collate event header and payload in a scratch > + * area at first. > + */ > + eh = r_evt->scratch_isr; > + eh->timestamp = ts; > + eh->proto_id = proto_id; > + eh->evt_id = evt_id; > + eh->payld_sz = len; > + memcpy(eh->payld, buf, eh->payld_sz); > + kfifo_in(&r_evt->proto->equeue->kfifo, eh, sizeof(*eh) + eh->payld_sz); > + queue_work(r_evt->proto->equeue->wq, > + &r_evt->proto->equeue->notify_work); > + > + return 0; > +} > + > +/** > + * scmi_allocate_events_queue - Allocate an events_queue descriptor > + * > + * @sz: Size of the kfifo to initialize > + * > + * Return: A valid pointer to the allocated events_queue on Success > + */ > +static struct events_queue *scmi_allocate_events_queue(size_t sz) > +{ > + int ret; > + struct events_queue *equeue; > + > + equeue = kzalloc(sizeof(*equeue), GFP_KERNEL); > + if (!equeue) > + return ERR_PTR(-ENOMEM); > + ret = kfifo_alloc(&equeue->kfifo, sz, GFP_KERNEL); > + if (ret) { > + kfree(equeue); > + return ERR_PTR(ret); > + } > + equeue->sz = sz; > + INIT_WORK(&equeue->notify_work, scmi_events_dispatcher); > + equeue->wq = scmi_notify_wq; > + > + return equeue; > +} > + > +/** > + * scmi_deallocate_events_queue - Deallocate am events_queue descriptor > + * > + * @equeue: The events_queue to free > + */ > +static void scmi_deallocate_events_queue(struct events_queue *equeue) > +{ > + kfifo_free(&equeue->kfifo); > + kfree(equeue); > +} > + > +/** > + * scmi_allocate_registered_protocol_desc - Allocate a registered protocol > + * events' descriptor > + * > + * Used to keep protocol specific information related to events handling for any > + * protocl which has registered at least one event.
protocol
> + * > + * @proto_id: Protocol ID > + * @queue_sz: Size of the associated queue to allocate > + * @ops: Pointer to a struct holding references to protocol specific helpers > + * needed during events handling > + */ > +static struct scmi_registered_protocol_events_desc * > +scmi_allocate_registered_protocol_desc(u8 proto_id, size_t queue_sz, > + const struct scmi_protocol_event_ops *ops) > +{ > + int ret; > + struct scmi_registered_protocol_events_desc *pdesc; > + > + pdesc = idr_find(&scmi_registered_protocols, proto_id);
Perhaps add a comment here on why this might get called multiple times but is still safe from point of view of release path.
> + if (pdesc) > + return pdesc;
> + > + pdesc = kzalloc(sizeof(*pdesc), GFP_KERNEL); > + if (!pdesc) > + return ERR_PTR(-ENOMEM); > + pdesc->id = proto_id; > + pdesc->ops = ops; > + > + pdesc->equeue = scmi_allocate_events_queue(queue_sz); > + if (IS_ERR(pdesc->equeue)) { > + kfree(pdesc); > + return ERR_CAST(pdesc->equeue); > + } > + > + ret = idr_alloc(&scmi_registered_protocols, pdesc, > + pdesc->id, pdesc->id + 1, GFP_KERNEL); > + if (ret < 0) { > + pr_err("SCMI Failed to allocate PDESC IDR - key:%d - err:%d\n", > + pdesc->id, ret); > + scmi_deallocate_events_queue(pdesc->equeue); > + kfree(pdesc); > + return ERR_PTR(ret); > + } > + > + return pdesc; > +} > + > +/** > + * scmi_register_protocol_events - Register Protocol Events with the core > + * > + * Used by SCMI Protocols initialization code to register with the notification > + * core the list of supported events and their description: this takes care to > + * pre-allocate all needed scratch buffers and link the proper event queue to > + * this event. > + * > + * @proto_id: Protocol ID > + * @queue_sz: Size in bytes of the associated queue to be allocated > + * @ops: Protocol specific event-related operations > + * @evt: Event descriptor array > + * @num_events: Number of events in @evt array > + * > + * Return: 0 on Success > + */ > +int scmi_register_protocol_events(u8 proto_id, size_t queue_sz, > + const struct scmi_protocol_event_ops *ops, > + const struct scmi_event *evt, int num_events) > +{ > + int i; > + struct scmi_registered_protocol_events_desc *pdesc; > + > + if (!scmi_notifications_initialized) > + return -EAGAIN; > + > + if (!ops || !evt) > + return -EINVAL; > + > + pdesc = scmi_allocate_registered_protocol_desc(proto_id, queue_sz, ops); > + if (IS_ERR(pdesc)) > + return -ENOMEM; > + > + for (i = 0; i < num_events; i++, evt++) { > + int ret; > + u32 key; > + struct scmi_registered_event *r_evt; > + > + r_evt = kzalloc(sizeof(*r_evt), GFP_KERNEL); > + if (!r_evt) > + continue; > + r_evt->proto = pdesc; > + r_evt->evt = evt; > + > + r_evt->scratch_isr = kzalloc(sizeof(struct scmi_event_header) + > + evt->max_payld_sz, GFP_KERNEL); > + if (!r_evt->scratch_isr) > + goto continue_isr_fail; > + > + r_evt->scratch_bh = kzalloc(evt->max_payld_sz, GFP_KERNEL); > + if (!r_evt->scratch_bh) > + goto continue_bh_fail; > + > + r_evt->report = kzalloc(evt->max_report_sz, GFP_KERNEL); > + if (!r_evt->report) > + goto continue_report_fail; > + > + key = MAKE_EVT_KEY(r_evt->proto->id, evt->evt_id, NULL); > + ret = idr_alloc(&scmi_registered_events, r_evt, > + key, key + 1, GFP_KERNEL); > + if (ret < 0) { > + pr_err("SCMI Failed to allocate EVENT IDR - key:%X - err:%d\n", > + key, ret); > + goto continue_idr_fail; > + } > + > + pr_info("SCMI Notification registered event - key:%X\n", key); > + continue; > + > + /* yes, this is not nice ... */ > +continue_idr_fail: > + kfree(r_evt->report); > +continue_report_fail: > + kfree(r_evt->scratch_bh); > +continue_bh_fail: > + kfree(r_evt->scratch_isr); > +continue_isr_fail: > + kfree(r_evt); > + } > + > + return 0; > +} > + > +/** > + * scmi_register_event_handler - Allocate an Event handler > + * > + * Allocate an event handler and related notification chain associated with > + * the event identified by the provided event key. Fails if the associated > + * event is unknown to the core (i.e. it had not been successfully registered > + * upfront by some protocol) > + * > + * @evt_key: 32bit key uniquely bind to the event identified by the tuple > + * (proto_id, evt_id, src_id) > + * > + * Return: the freshly allocated structure on Success > + */ > +static struct scmi_event_handler *scmi_register_event_handler(u32 evt_key) > +{ > + int id; > + u8 proto_id, evt_id; > + struct scmi_registered_event *r_evt; > + struct scmi_event_handler *hndl; > + > + proto_id = KEY_XTRACT_PROTO_ID(evt_key); > + evt_id = KEY_XTRACT_EVT_ID(evt_key); > + r_evt = idr_find(&scmi_registered_events, > + MAKE_EVT_KEY(proto_id, evt_id, NULL)); > + if (!r_evt) > + return ERR_PTR(-EINVAL); > + > + hndl = kzalloc(sizeof(*hndl), GFP_KERNEL); > + if (!hndl) > + return ERR_PTR(-ENOMEM); > + hndl->r_evt = r_evt; > + hndl->evt_key = evt_key; > + BLOCKING_INIT_NOTIFIER_HEAD(&hndl->chain); > + refcount_set(&hndl->users, 1); > + > + /* Register freshly allocated event handler */ > + id = idr_alloc(&scmi_registered_events_handlers, hndl, > + evt_key, evt_key + 1, GFP_KERNEL);
Umm. That's not using an idr for what it is meant for. You aren't allocating an id, you are using it as a poor wrapper around an xarray.
> + if (id < 0) { > + pr_err("SCMI Failed to allocate HNDL IDR - key:%X err:%d\n", > + evt_key, id); > + kfree(hndl); > + return ERR_PTR(id); > + } > + > + return hndl; > +} > + > +/** > + * scmi_unregister_event_handler - Free the provided Event handler > + * > + * @hndl: The event handler structure to free > + */ > +static void scmi_unregister_event_handler(struct scmi_event_handler *hndl) > +{ > + idr_remove(&scmi_registered_events_handlers, hndl->evt_key); > + kfree(hndl); > +} > + > +/** > + * __scmi_event_handler_get_ops - Get or create an event handler > + * > + * After having got exclusive access to the registered events map, searches for > + * the desired handler matching the key: when found adjust refcount, when not > + * create and register a new handler is asked to do so. > + * Events generation is NOT enabled within this routine since at creation time > + * we usually want to have all setup and registered before events starts > + * flowing. > + * > + * @evt_key: The event key to use > + * @create: A boolean flag to specify if a handler must be created > + * when not found > + */ > +static inline struct scmi_event_handler * > +__scmi_event_handler_get_ops(u32 evt_key, bool create) > +{ > + struct scmi_event_handler *hndl = NULL; > + > + mutex_lock(&scmi_registered_events_handler_mtx); > + hndl = idr_find(&scmi_registered_events_handlers, evt_key); > + if (hndl) > + refcount_inc(&hndl->users); > + else if (create) > + hndl = scmi_register_event_handler(evt_key); > + mutex_unlock(&scmi_registered_events_handler_mtx); > + > + return hndl; > +} > + > +static struct scmi_event_handler *scmi_get_event_handler(u32 evt_key) > +{ > + return __scmi_event_handler_get_ops(evt_key, false); > +} > + > +static struct scmi_event_handler *scmi_get_or_create_event_handler(u32 evt_key) > +{ > + return __scmi_event_handler_get_ops(evt_key, true); > +} > + > +/** > + * __scmi_enable_events_ops - Enable/disable events generation > + * > + * @hndl: The handler specifying the events enable/disable > + * @action: The action to perform: true->Enable false->Disable > + * > + * Return: True when the required @action has been successfully executed > + */ > +static inline bool __scmi_enable_events_ops(struct scmi_event_handler *hndl, > + bool action) > +{ > + bool ret = true; > + > + if (hndl->enabled != action) { > + u8 evt_id; > + u32 src_id; > + > + evt_id = KEY_XTRACT_EVT_ID(hndl->evt_key); > + src_id = KEY_XTRACT_SRC_ID(hndl->evt_key); > + ret = hndl->r_evt->proto->ops->set_notify_enabled(evt_id, > + src_id != SCMI_ALL_SRC_IDS ? &src_id : NULL, > + action); > + if (ret) > + hndl->enabled = action; > + } > + > + return ret; > +} > + > +static bool scmi_enable_events(struct scmi_event_handler *hndl) > +{ > + return __scmi_enable_events_ops(hndl, true); > +} > + > +static bool scmi_disable_events(struct scmi_event_handler *hndl) > +{ > + return __scmi_enable_events_ops(hndl, false); > +} > + > +/** > + * scmi_put_event_handler - Put an event handler > + * > + * After having got exclusive access to the registered events map, update > + * the refcount and if @hndl is no more in use by anyone: > + * - disable the events generation > + * - unregister and free the handler itself > + * > + * @hndl: The handler to act upon > + */ > +static void scmi_put_event_handler(struct scmi_event_handler *hndl) > +{ > + mutex_lock(&scmi_registered_events_handler_mtx); > + if (refcount_dec_and_test(&hndl->users)) { > + scmi_disable_events(hndl); > + scmi_unregister_event_handler(hndl); > + } > + mutex_unlock(&scmi_registered_events_handler_mtx); > +} > + > +/** > + * scmi_register_event_notifier - Register a notifier_block for an event > + * > + * Generic helper to register a notifier_block attached to a protocol event. > + * > + * A notifier_block @nb will be registered for each distinct event identified > + * by the tuple (proto_id, evt_id, src_id) on a dedicated notification chain > + * so that: > + * > + * (proto_X, evt_Y, src_Z) --> chain_X_Y_Z > + * > + * @src_id meaning is protocol specific and identifies the origin of the event > + * (like domain_id, sensor_id and os forth); @src_id can be NULL to signify that
so
> + * the caller is interested in receiving notifications from ALL the available > + * sources for that protocol OR simply that the protocol does not support > + * distinct sources: in these cases @nb will be attached to a generic > + * notification chain defined for ALL src_id of that proto_id/evt_id pair like: > + * > + * (proto_X, evt_Y, NULL) --> chain_X_Y_ALL > + * > + * Any received event will be then dispatched to both such chains if at least > + * one user had registered an @nb on them.
both should be all I think.
> + * > + * Note also that notification chains are created dynamically: a new chain is > + * created each time a new distinct tuple is detected and then the provided @nb > + * is bound to such chain; at creation time the related SCMI notifications are > + * also enabled: this way, only when at least one user has registered its > + * interest for a specific event tuple, the underlying notification chain is > + * created and the related notifications are enabled in the platform.
That's one of the most complex bits of punctuation I've seenin a comment for a long time. Please break that sentence up for readability.
> + * > + * @proto_id: Protocol ID > + * @evt_id: Event ID > + * @src_id: Source ID > + * @nb: A standard notifier block to register for the specified event > + * > + * Return: Return 0 on Success > + */ > +int scmi_register_event_notifier(u8 proto_id, u8 evt_id, u32 *src_id, > + struct notifier_block *nb) > +{ > + u32 evt_key; > + struct scmi_event_handler *hndl; > + > + evt_key = MAKE_EVT_KEY(proto_id, evt_id, src_id); > + hndl = scmi_get_or_create_event_handler(evt_key); > + if (IS_ERR_OR_NULL(hndl)) > + return PTR_ERR(hndl); > + > + blocking_notifier_chain_register(&hndl->chain, nb); > + > + if (!scmi_enable_events(hndl)) { > + pr_err("SCMI Failed to ENABLE events for key:%X !\n", evt_key); > + blocking_notifier_chain_unregister(&hndl->chain, nb); > + scmi_put_event_handler(hndl); > + return -EINVAL; > + } > + > + return 0; > +} > + > +/** > + * scmi_unregister_event_notifier - Unregister a notifier_block for an event > + * > + * Takes care to unregister the provided @nb from the notification chain > + * associated to the specified event and, if there are no more users for the > + * event handler, frees also the associated event handler structures. > + * > + * @proto_id: Protocol ID > + * @evt_id: Event ID > + * @src_id: Source ID > + * @nb: The notifier_block to unregister > + * > + * Return: 0 on Success > + */ > +int scmi_unregister_event_notifier(u8 proto_id, u8 evt_id, u32 *src_id, > + struct notifier_block *nb) > +{ > + u32 evt_key; > + struct scmi_event_handler *hndl; > + > + evt_key = MAKE_EVT_KEY(proto_id, evt_id, src_id); > + hndl = scmi_get_event_handler(evt_key); > + if (IS_ERR_OR_NULL(hndl)) > + return -EINVAL; > + > + blocking_notifier_chain_unregister(&hndl->chain, nb); > + > + scmi_put_event_handler(hndl); > + /* > + * If this was the last user callback for this handler, this last put > + * will force the handler to be freed. > + * Note that if a call_chain walk is ongoing it will be the call_chain > + * put request which will finally free the handler; note also that any > + * operation on the inner notifier_block chain is protected on its own. > + */ > + scmi_put_event_handler(hndl); > + > + return 0; > +} > + > +/** > + * scmi_notification_init - Initializes Notification Core Support > + * > + * Return: 0 on Success > + */ > +int __init scmi_notification_init(void) > +{ > + scmi_notify_wq = alloc_workqueue("scmi_notify", > + WQ_UNBOUND | WQ_FREEZABLE, > + SCMI_NOTIF_MAX_ACTIVE_QUEUES); > + if (!scmi_notify_wq) > + return -ENOMEM; > + idr_init(&scmi_registered_events); > + idr_init(&scmi_registered_events_handlers); > + idr_init(&scmi_registered_protocols); > + > + scmi_notifications_initialized = true; > + > + pr_info("SCMI Notifications enabled.\n"); > + > + return 0; > +} > + > +/** > + * scmi_notification_exit - Shutdown and clean Notification core > + */ > +void __exit scmi_notification_exit(void) > +{ > + int k; > + struct scmi_event_handler *hndl; > + struct scmi_registered_protocol_events_desc *pdesc; > + struct scmi_registered_event *r_evt; > + > + scmi_notifications_initialized = false; > + > + /* Disable notifications' generation */ > + idr_for_each_entry(&scmi_registered_events_handlers, hndl, k) > + scmi_disable_events(hndl); > + > + /* Let pending work complete */ > + destroy_workqueue(scmi_notify_wq); > + > + /* Remove ALL events handlers */ > + idr_for_each_entry(&scmi_registered_events_handlers, hndl, k) > + scmi_put_event_handler(hndl); > + idr_destroy(&scmi_registered_events_handlers); > + > + /* Finally remove all registered events */
Finally seems a bit premature here ;)
> + idr_for_each_entry(&scmi_registered_events, r_evt, k) { > + idr_remove(&scmi_registered_events, k); > + kfree(r_evt->report); > + kfree(r_evt->scratch_isr); > + kfree(r_evt->scratch_bh); > + kfree(r_evt); > + } > + idr_destroy(&scmi_registered_events); > + > + /* free any remaining protocol data */ > + idr_for_each_entry(&scmi_registered_protocols, pdesc, k) { > + idr_remove(&scmi_registered_protocols, k); > + scmi_deallocate_events_queue(pdesc->equeue); > + kfree(pdesc); > + } > + idr_destroy(&scmi_registered_protocols); > +} > diff --git a/drivers/firmware/arm_scmi/notify.h b/drivers/firmware/arm_scmi/notify.h > new file mode 100644 > index 000000000000..6fa07b244b14 > --- /dev/null > +++ b/drivers/firmware/arm_scmi/notify.h > @@ -0,0 +1,79 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * System Control and Management Interface (SCMI) Message Protocol > + * notification header file containing some definitions, structures > + * and function prototypes related to SCMI Notification handling. > + * > + * Copyright (C) 2019 ARM Ltd. > + */ > +#ifndef _SCMI_NOTIFY_H > +#define _SCMI_NOTIFY_H > + > +#include <linux/bug.h> > +#include <linux/notifier.h> > +#include <linux/types.h> > + > +#define SCMI_ALL_SRC_IDS 0x0000ffffL > + > +#define MAP_EVT_TO_ENABLE_CMD(id, map) \ > +({ \ > + int ret = -1; \ > + \ > + if (likely((id) < ARRAY_SIZE((map)))) \ > + ret = (map)[(id)]; \ > + else \ > + WARN(1, "UN-KNOWN evt_id:%d\n", (id)); \ > + ret; \ > +}) > + > +/** > + * scmi_event - Describes an event to be supported
I don't think this is valid kernel-doc. Make sure to point the scripts at the file and check and fix any warnings.
> + * > + * Each SCMI protocol, during its initialization phase, can describe the events > + * it wishes to support in a few struct scmi_event and pass them to the core > + * using scmi_register_protocol_events(). > + * > + * @evt_id: Event ID > + * @max_payld_sz: Max possible size for the payload of a notif msg of this kind > + * @max_report_sz: Max possible size for the report of a notif msg of this kind > + */ > +struct scmi_event { > + u8 evt_id; > + size_t max_payld_sz; > + size_t max_report_sz; > + > +}; > + > +/** > + * scmi_protocol_event_ops - Helpers called by notification core. > + * > + * These are called only in process context. > + * > + * @set_notify_enabled: Enable/disable the required evt_id/src_id notifications > + * using the proper custom protocol commands. > + * Return true if at least one the required src_id > + * has been successfully enabled/disabled > + * @fill_custom_report: fills a custom event report from the provided
Nitpick. Inconsistent capitalization after the :
> + * event message payld identifying the event > + * specific src_id. > + * Return NULL on failure otherwise @report now fully > + * populated > + */ > +struct scmi_protocol_event_ops { > + bool (*set_notify_enabled)(u8 evt_id, const u32 *src_id, bool enabled); > + void *(*fill_custom_report)(u8 evt_id, u64 timestamp, const void *payld, > + size_t payld_sz, void *report, u32 *src_id); > +}; > + > +int scmi_notification_init(void); > +void scmi_notification_exit(void); > +int scmi_register_protocol_events(u8 proto_id, size_t queue_sz, > + const struct scmi_protocol_event_ops *ops, > + const struct scmi_event *evt, int num_events); > +int scmi_register_event_notifier(u8 proto_id, u8 evt_id, u32 *sub_id, > + struct notifier_block *nb); > +int scmi_unregister_event_notifier(u8 proto_id, u8 evt_id, u32 *sub_id, > + struct notifier_block *nb); > +int scmi_notify(u8 proto_id, u8 evt_id, const void *buf, size_t len, u64 ts); > + > +#endif /* _SCMI_NOTIFY_H */
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