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Device data is exposed through standard character device read operations. Device data is gathered when a Counter event is pushed by the respective Counter device driver. Configuration is handled via ioctl operations on the respective Counter character device node. Cc: David Lechner Cc: Gwendal Grignou Cc: Dan Carpenter Cc: Oleksij Rempel Signed-off-by: William Breathitt Gray --- drivers/counter/Makefile | 2 +- drivers/counter/counter-chrdev.c | 482 +++++++++++++++++++++++++++++++ drivers/counter/counter-chrdev.h | 14 + drivers/counter/counter-core.c | 44 ++- include/linux/counter.h | 45 +++ include/uapi/linux/counter.h | 77 +++++ 6 files changed, 658 insertions(+), 6 deletions(-) create mode 100644 drivers/counter/counter-chrdev.c create mode 100644 drivers/counter/counter-chrdev.h diff --git a/drivers/counter/Makefile b/drivers/counter/Makefile index 9a31394cb926..5e274e04a415 100644 --- a/drivers/counter/Makefile +++ b/drivers/counter/Makefile @@ -4,7 +4,7 @@ # obj-$(CONFIG_COUNTER) += counter.o -counter-y := counter-core.o counter-sysfs.o +counter-y := counter-core.o counter-sysfs.o counter-chrdev.o obj-$(CONFIG_104_QUAD_8) += 104-quad-8.o obj-$(CONFIG_INTERRUPT_CNT) += interrupt-cnt.o diff --git a/drivers/counter/counter-chrdev.c b/drivers/counter/counter-chrdev.c new file mode 100644 index 000000000000..d5f92b2d3bb4 --- /dev/null +++ b/drivers/counter/counter-chrdev.c @@ -0,0 +1,482 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Generic Counter character device interface + * Copyright (C) 2020 William Breathitt Gray + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "counter-chrdev.h" + +struct counter_comp_node { + struct list_head l; + struct counter_component component; + struct counter_comp comp; + void *parent; +}; + +static ssize_t counter_chrdev_read(struct file *filp, char __user *buf, + size_t len, loff_t *f_ps) +{ + struct counter_device *const counter = filp->private_data; + int err; + unsigned int copied; + + if (len < sizeof(struct counter_event)) + return -EINVAL; + + do { + if (kfifo_is_empty(&counter->events)) { + if (filp->f_flags & O_NONBLOCK) + return -EAGAIN; + + err = wait_event_interruptible(counter->events_wait, + !kfifo_is_empty(&counter->events)); + if (err < 0) + return err; + } + + if (mutex_lock_interruptible(&counter->events_lock)) + return -ERESTARTSYS; + err = kfifo_to_user(&counter->events, buf, len, &copied); + mutex_unlock(&counter->events_lock); + if (err < 0) + return err; + } while (!copied); + + return copied; +} + +static __poll_t counter_chrdev_poll(struct file *filp, + struct poll_table_struct *pollt) +{ + struct counter_device *const counter = filp->private_data; + __poll_t events = 0; + + poll_wait(filp, &counter->events_wait, pollt); + + if (!kfifo_is_empty(&counter->events)) + events = EPOLLIN | EPOLLRDNORM; + + return events; +} + +static void counter_events_list_free(struct list_head *const events_list) +{ + struct counter_event_node *p, *n; + struct counter_comp_node *q, *o; + + list_for_each_entry_safe(p, n, events_list, l) { + /* Free associated component nodes */ + list_for_each_entry_safe(q, o, &p->comp_list, l) { + list_del(&q->l); + kfree(q); + } + + /* Free event node */ + list_del(&p->l); + kfree(p); + } +} + +static int counter_set_event_node(struct counter_device *const counter, + struct counter_watch *const watch, + const struct counter_comp_node *const cfg) +{ + struct counter_event_node *event_node; + struct counter_comp_node *comp_node; + + /* Search for event in the list */ + list_for_each_entry(event_node, &counter->next_events_list, l) + if (event_node->event == watch->event && + event_node->channel == watch->channel) + break; + + /* If event is not already in the list */ + if (&event_node->l == &counter->next_events_list) { + /* Allocate new event node */ + event_node = kmalloc(sizeof(*event_node), GFP_ATOMIC); + if (!event_node) + return -ENOMEM; + + /* Configure event node and add to the list */ + event_node->event = watch->event; + event_node->channel = watch->channel; + INIT_LIST_HEAD(&event_node->comp_list); + list_add(&event_node->l, &counter->next_events_list); + } + + /* Check if component watch has already been set before */ + list_for_each_entry(comp_node, &event_node->comp_list, l) + if (comp_node->parent == cfg->parent && + comp_node->comp.count_u8_read == cfg->comp.count_u8_read) + return -EINVAL; + + /* Allocate component node */ + comp_node = kmalloc(sizeof(*comp_node), GFP_ATOMIC); + if (!comp_node) { + /* Free event node if no one else is watching */ + if (list_empty(&event_node->comp_list)) { + list_del(&event_node->l); + kfree(event_node); + } + return -ENOMEM; + } + *comp_node = *cfg; + + /* Add component node to event node */ + list_add_tail(&comp_node->l, &event_node->comp_list); + + return 0; +} + +static int counter_disable_events(struct counter_device *const counter) +{ + unsigned long flags; + int err = 0; + + spin_lock_irqsave(&counter->events_list_lock, flags); + + counter_events_list_free(&counter->events_list); + + if (counter->ops->events_configure) + err = counter->ops->events_configure(counter); + + spin_unlock_irqrestore(&counter->events_list_lock, flags); + + counter_events_list_free(&counter->next_events_list); + + return err; +} + +static int counter_add_watch(struct counter_device *const counter, + const unsigned long arg) +{ + void __user *const uwatch = (void __user *)arg; + struct counter_watch watch; + struct counter_comp_node comp_node = {0}; + size_t parent, id; + struct counter_comp *ext; + size_t num_ext; + int err; + + if (copy_from_user(&watch, uwatch, sizeof(watch))) + return -EFAULT; + + if (watch.component.type == COUNTER_COMPONENT_NONE) + goto no_component; + + parent = watch.component.parent; + + /* Configure parent component info for comp node */ + switch (watch.component.scope) { + case COUNTER_SCOPE_DEVICE: + ext = counter->ext; + num_ext = counter->num_ext; + break; + case COUNTER_SCOPE_SIGNAL: + if (parent >= counter->num_signals) + return -EINVAL; + parent = array_index_nospec(parent, counter->num_signals); + + comp_node.parent = counter->signals + parent; + + ext = counter->signals[parent].ext; + num_ext = counter->signals[parent].num_ext; + break; + case COUNTER_SCOPE_COUNT: + if (parent >= counter->num_counts) + return -EINVAL; + parent = array_index_nospec(parent, counter->num_counts); + + comp_node.parent = counter->counts + parent; + + ext = counter->counts[parent].ext; + num_ext = counter->counts[parent].num_ext; + break; + default: + return -EINVAL; + } + + id = watch.component.id; + + /* Configure component info for comp node */ + switch (watch.component.type) { + case COUNTER_COMPONENT_SIGNAL: + if (watch.component.scope != COUNTER_SCOPE_SIGNAL) + return -EINVAL; + + comp_node.comp.type = COUNTER_COMP_SIGNAL_LEVEL; + comp_node.comp.signal_u32_read = counter->ops->signal_read; + break; + case COUNTER_COMPONENT_COUNT: + if (watch.component.scope != COUNTER_SCOPE_COUNT) + return -EINVAL; + + comp_node.comp.type = COUNTER_COMP_U64; + comp_node.comp.count_u64_read = counter->ops->count_read; + break; + case COUNTER_COMPONENT_FUNCTION: + if (watch.component.scope != COUNTER_SCOPE_COUNT) + return -EINVAL; + + comp_node.comp.type = COUNTER_COMP_FUNCTION; + comp_node.comp.count_u32_read = counter->ops->function_read; + break; + case COUNTER_COMPONENT_SYNAPSE_ACTION: + if (watch.component.scope != COUNTER_SCOPE_COUNT) + return -EINVAL; + if (id >= counter->counts[parent].num_synapses) + return -EINVAL; + id = array_index_nospec(id, counter->counts[parent].num_synapses); + + comp_node.comp.type = COUNTER_COMP_SYNAPSE_ACTION; + comp_node.comp.action_read = counter->ops->action_read; + comp_node.comp.priv = counter->counts[parent].synapses + id; + break; + case COUNTER_COMPONENT_EXTENSION: + if (id >= num_ext) + return -EINVAL; + id = array_index_nospec(id, num_ext); + + comp_node.comp = ext[id]; + break; + default: + return -EINVAL; + } + /* Check if any read callback is set; this is part of a union */ + if (!comp_node.comp.count_u8_read) + return -EOPNOTSUPP; + +no_component: + if (counter->ops->watch_validate) { + err = counter->ops->watch_validate(counter, &watch); + if (err < 0) + return err; + } + + comp_node.component = watch.component; + + return counter_set_event_node(counter, &watch, &comp_node); +} + +static long counter_chrdev_ioctl(struct file *filp, unsigned int cmd, + unsigned long arg) +{ + struct counter_device *const counter = filp->private_data; + unsigned long flags; + int err = 0; + + switch (cmd) { + case COUNTER_ADD_WATCH_IOCTL: + return counter_add_watch(counter, arg); + case COUNTER_ENABLE_EVENTS_IOCTL: + spin_lock_irqsave(&counter->events_list_lock, flags); + + counter_events_list_free(&counter->events_list); + list_replace_init(&counter->next_events_list, + &counter->events_list); + + if (counter->ops->events_configure) + err = counter->ops->events_configure(counter); + + spin_unlock_irqrestore(&counter->events_list_lock, flags); + return err; + case COUNTER_DISABLE_EVENTS_IOCTL: + return counter_disable_events(counter); + default: + return -ENOIOCTLCMD; + } +} + +static int counter_chrdev_open(struct inode *inode, struct file *filp) +{ + struct counter_device *const counter = container_of(inode->i_cdev, + typeof(*counter), + chrdev); + + get_device(&counter->dev); + filp->private_data = counter; + + return nonseekable_open(inode, filp); +} + +static int counter_chrdev_release(struct inode *inode, struct file *filp) +{ + struct counter_device *const counter = filp->private_data; + int err; + + err = counter_disable_events(counter); + if (err < 0) + return err; + + put_device(&counter->dev); + + return 0; +} + +static const struct file_operations counter_fops = { + .llseek = no_llseek, + .read = counter_chrdev_read, + .poll = counter_chrdev_poll, + .unlocked_ioctl = counter_chrdev_ioctl, + .open = counter_chrdev_open, + .release = counter_chrdev_release, +}; + +int counter_chrdev_add(struct counter_device *const counter) +{ + /* Initialize Counter events lists */ + INIT_LIST_HEAD(&counter->events_list); + INIT_LIST_HEAD(&counter->next_events_list); + spin_lock_init(&counter->events_list_lock); + init_waitqueue_head(&counter->events_wait); + mutex_init(&counter->events_lock); + + /* Initialize character device */ + cdev_init(&counter->chrdev, &counter_fops); + + /* Allocate Counter events queue */ + return kfifo_alloc(&counter->events, 64, GFP_ATOMIC); +} + +void counter_chrdev_remove(struct counter_device *const counter) +{ + kfifo_free(&counter->events); +} + +static int counter_get_data(struct counter_device *const counter, + const struct counter_comp_node *const comp_node, + u64 *const value) +{ + const struct counter_comp *const comp = &comp_node->comp; + void *const parent = comp_node->parent; + u8 value_u8 = 0; + u32 value_u32 = 0; + int ret; + + if (comp_node->component.type == COUNTER_COMPONENT_NONE) + return 0; + + switch (comp->type) { + case COUNTER_COMP_U8: + case COUNTER_COMP_BOOL: + switch (comp_node->component.scope) { + case COUNTER_SCOPE_DEVICE: + ret = comp->device_u8_read(counter, &value_u8); + break; + case COUNTER_SCOPE_SIGNAL: + ret = comp->signal_u8_read(counter, parent, &value_u8); + break; + case COUNTER_SCOPE_COUNT: + ret = comp->count_u8_read(counter, parent, &value_u8); + break; + } + *value = value_u8; + return ret; + case COUNTER_COMP_SIGNAL_LEVEL: + case COUNTER_COMP_FUNCTION: + case COUNTER_COMP_ENUM: + case COUNTER_COMP_COUNT_DIRECTION: + case COUNTER_COMP_COUNT_MODE: + switch (comp_node->component.scope) { + case COUNTER_SCOPE_DEVICE: + ret = comp->device_u32_read(counter, &value_u32); + break; + case COUNTER_SCOPE_SIGNAL: + ret = comp->signal_u32_read(counter, parent, + &value_u32); + break; + case COUNTER_SCOPE_COUNT: + ret = comp->count_u32_read(counter, parent, &value_u32); + break; + } + *value = value_u32; + return ret; + case COUNTER_COMP_U64: + switch (comp_node->component.scope) { + case COUNTER_SCOPE_DEVICE: + return comp->device_u64_read(counter, value); + case COUNTER_SCOPE_SIGNAL: + return comp->signal_u64_read(counter, parent, value); + case COUNTER_SCOPE_COUNT: + return comp->count_u64_read(counter, parent, value); + default: + return -EINVAL; + } + case COUNTER_COMP_SYNAPSE_ACTION: + ret = comp->action_read(counter, parent, comp->priv, + &value_u32); + *value = value_u32; + return ret; + default: + return -EINVAL; + } +} + +/** + * counter_push_event - queue event for userspace reading + * @counter: pointer to Counter structure + * @event: triggered event + * @channel: event channel + * + * Note: If no one is watching for the respective event, it is silently + * discarded. + */ +void counter_push_event(struct counter_device *const counter, const u8 event, + const u8 channel) +{ + struct counter_event ev = {0}; + unsigned int copied = 0; + unsigned long flags; + struct counter_event_node *event_node; + struct counter_comp_node *comp_node; + + ev.timestamp = ktime_get_ns(); + ev.watch.event = event; + ev.watch.channel = channel; + + /* Could be in an interrupt context, so use a raw spin lock */ + spin_lock_irqsave(&counter->events_list_lock, flags); + + /* Search for event in the list */ + list_for_each_entry(event_node, &counter->events_list, l) + if (event_node->event == event && + event_node->channel == channel) + break; + + /* If event is not in the list */ + if (&event_node->l == &counter->events_list) + goto exit_early; + + /* Read and queue relevant comp for userspace */ + list_for_each_entry(comp_node, &event_node->comp_list, l) { + ev.watch.component = comp_node->component; + ev.status = -counter_get_data(counter, comp_node, &ev.value); + + copied += kfifo_in(&counter->events, &ev, 1); + } + + if (copied) + wake_up_poll(&counter->events_wait, EPOLLIN); + +exit_early: + spin_unlock_irqrestore(&counter->events_list_lock, flags); +} +EXPORT_SYMBOL_GPL(counter_push_event); diff --git a/drivers/counter/counter-chrdev.h b/drivers/counter/counter-chrdev.h new file mode 100644 index 000000000000..5529d16703c4 --- /dev/null +++ b/drivers/counter/counter-chrdev.h @@ -0,0 +1,14 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Counter character device interface + * Copyright (C) 2020 William Breathitt Gray + */ +#ifndef _COUNTER_CHRDEV_H_ +#define _COUNTER_CHRDEV_H_ + +#include + +int counter_chrdev_add(struct counter_device *const counter); +void counter_chrdev_remove(struct counter_device *const counter); + +#endif /* _COUNTER_CHRDEV_H_ */ diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c index 407661c6feb0..91af3f8a5df8 100644 --- a/drivers/counter/counter-core.c +++ b/drivers/counter/counter-core.c @@ -3,14 +3,20 @@ * Generic Counter interface * Copyright (C) 2020 William Breathitt Gray */ +#include #include #include +#include #include +#include #include #include #include +#include #include +#include +#include "counter-chrdev.h" #include "counter-sysfs.h" /* Provides a unique ID for each counter device */ @@ -34,6 +40,8 @@ static struct bus_type counter_bus_type = { .dev_name = "counter", }; +static dev_t counter_devt; + /** * counter_register - register Counter to the system * @counter: pointer to Counter to register @@ -60,6 +68,7 @@ int counter_register(struct counter_device *const counter) dev->id = id; dev->type = &counter_device_type; dev->bus = &counter_bus_type; + dev->devt = MKDEV(MAJOR(counter_devt), id); if (counter->parent) { dev->parent = counter->parent; dev->of_node = counter->parent->of_node; @@ -67,18 +76,25 @@ int counter_register(struct counter_device *const counter) device_initialize(dev); dev_set_drvdata(dev, counter); + /* Add Counter character device */ + err = counter_chrdev_add(counter); + if (err < 0) + goto err_free_id; + /* Add Counter sysfs attributes */ err = counter_sysfs_add(counter); if (err < 0) - goto err_free_id; + goto err_remove_chrdev; /* Add device to system */ - err = device_add(dev); + err = cdev_device_add(&counter->chrdev, dev); if (err < 0) - goto err_free_id; + goto err_remove_chrdev; return 0; +err_remove_chrdev: + counter_chrdev_remove(counter); err_free_id: put_device(dev); return err; @@ -96,7 +112,8 @@ void counter_unregister(struct counter_device *const counter) if (!counter) return; - device_unregister(&counter->dev); + cdev_device_del(&counter->chrdev, &counter->dev); + put_device(&counter->dev); } EXPORT_SYMBOL_GPL(counter_unregister); @@ -140,13 +157,30 @@ int devm_counter_register(struct device *dev, } EXPORT_SYMBOL_GPL(devm_counter_register); +#define COUNTER_DEV_MAX 256 + static int __init counter_init(void) { - return bus_register(&counter_bus_type); + int err; + + err = bus_register(&counter_bus_type); + if (err < 0) + return err; + + err = alloc_chrdev_region(&counter_devt, 0, COUNTER_DEV_MAX, "counter"); + if (err < 0) + goto err_unregister_bus; + + return 0; + +err_unregister_bus: + bus_unregister(&counter_bus_type); + return err; } static void __exit counter_exit(void) { + unregister_chrdev_region(counter_devt, COUNTER_DEV_MAX); bus_unregister(&counter_bus_type); } diff --git a/include/linux/counter.h b/include/linux/counter.h index eee85db8e332..3f0bbe4ff702 100644 --- a/include/linux/counter.h +++ b/include/linux/counter.h @@ -6,9 +6,14 @@ #ifndef _COUNTER_H_ #define _COUNTER_H_ +#include #include #include +#include +#include +#include #include +#include #include struct counter_device; @@ -199,6 +204,20 @@ struct counter_count { size_t num_ext; }; +/** + * struct counter_event_node - Counter Event node + * @l: list of current watching Counter events + * @event: event that triggers + * @channel: event channel + * @comp_list: list of components to watch when event triggers + */ +struct counter_event_node { + struct list_head l; + u8 event; + u8 channel; + struct list_head comp_list; +}; + /** * struct counter_ops - Callbacks from driver * @signal_read: read callback for Signals. The read level of the @@ -221,6 +240,13 @@ struct counter_count { * @action_write: write callback for Synapse action modes. The action mode * to write for the respective Synapse is passed in via the * action parameter. + * @events_configure: write callback to configure events. The list of struct + * counter_event_node may be accessed via the events_list + * member of the counter parameter. + * @watch_validate: callback to validate a watch. The Counter component + * watch configuration is passed in via the watch + * parameter. A return value of 0 indicates a valid Counter + * component watch configuration. */ struct counter_ops { int (*signal_read)(struct counter_device *counter, @@ -244,6 +270,9 @@ struct counter_ops { struct counter_count *count, struct counter_synapse *synapse, enum counter_synapse_action action); + int (*events_configure)(struct counter_device *counter); + int (*watch_validate)(struct counter_device *counter, + const struct counter_watch *watch); }; /** @@ -259,6 +288,13 @@ struct counter_ops { * @num_ext: number of Counter device extensions specified in @ext * @priv: optional private data supplied by driver * @dev: internal device structure + * @chrdev: internal character device structure + * @events_list: list of current watching Counter events + * @events_list_lock: lock to protect Counter events list operations + * @next_events_list: list of next watching Counter events + * @events: queue of detected Counter events + * @events_wait: wait queue to allow blocking reads of Counter events + * @events_lock: lock to protect Counter events queue read operations */ struct counter_device { const char *name; @@ -277,12 +313,21 @@ struct counter_device { void *priv; struct device dev; + struct cdev chrdev; + struct list_head events_list; + spinlock_t events_list_lock; + struct list_head next_events_list; + DECLARE_KFIFO_PTR(events, struct counter_event); + wait_queue_head_t events_wait; + struct mutex events_lock; }; int counter_register(struct counter_device *const counter); void counter_unregister(struct counter_device *const counter); int devm_counter_register(struct device *dev, struct counter_device *const counter); +void counter_push_event(struct counter_device *const counter, const u8 event, + const u8 channel); #define COUNTER_COMP_DEVICE_U8(_name, _read, _write) \ { \ diff --git a/include/uapi/linux/counter.h b/include/uapi/linux/counter.h index 6113938a6044..e55dfc9de887 100644 --- a/include/uapi/linux/counter.h +++ b/include/uapi/linux/counter.h @@ -6,6 +6,19 @@ #ifndef _UAPI_COUNTER_H_ #define _UAPI_COUNTER_H_ +#include +#include + +/* Component type definitions */ +enum counter_component_type { + COUNTER_COMPONENT_NONE, + COUNTER_COMPONENT_SIGNAL, + COUNTER_COMPONENT_COUNT, + COUNTER_COMPONENT_FUNCTION, + COUNTER_COMPONENT_SYNAPSE_ACTION, + COUNTER_COMPONENT_EXTENSION, +}; + /* Component scope definitions */ enum counter_scope { COUNTER_SCOPE_DEVICE, @@ -13,6 +26,70 @@ enum counter_scope { COUNTER_SCOPE_COUNT, }; +/** + * struct counter_component - Counter component identification + * @type: component type (one of enum counter_component_type) + * @scope: component scope (one of enum counter_scope) + * @parent: parent ID (matching the ID suffix of the respective parent sysfs + * path as described by the ABI documentation file + * Documentation/ABI/testing/sysfs-bus-counter; e.g. if the component + * attribute path is /sys/bus/counter/devices/counter4/count2/count, + * the parent is count2 and thus parent ID is 2) + * @id: component ID (matching the ID provided by the respective *_component_id + * sysfs attribute of the desired component; for example, if the component + * attribute path is /sys/bus/counter/devices/counter4/count2/ceiling, the + * respective /sys/bus/counter/devices/counter4/count2/ceiling_component_id + * attribute will provide the necessary component ID) + * ) + */ +struct counter_component { + __u8 type; + __u8 scope; + __u8 parent; + __u8 id; +}; + +/* Event type definitions */ +enum counter_event_type { + COUNTER_EVENT_OVERFLOW, + COUNTER_EVENT_UNDERFLOW, + COUNTER_EVENT_OVERFLOW_UNDERFLOW, + COUNTER_EVENT_THRESHOLD, + COUNTER_EVENT_INDEX, +}; + +/** + * struct counter_watch - Counter component watch configuration + * @component: component to watch when event triggers + * @event: event that triggers (one of enum counter_event_type) + * @channel: event channel (typically 0 unless the device supports concurrent + * events of the same type) + */ +struct counter_watch { + struct counter_component component; + __u8 event; + __u8 channel; +}; + +/* ioctl commands */ +#define COUNTER_ADD_WATCH_IOCTL _IOW(0x3E, 0x00, struct counter_watch) +#define COUNTER_ENABLE_EVENTS_IOCTL _IO(0x3E, 0x01) +#define COUNTER_DISABLE_EVENTS_IOCTL _IO(0x3E, 0x02) + +/** + * struct counter_event - Counter event data + * @timestamp: best estimate of time of event occurrence, in nanoseconds + * @value: component value + * @watch: component watch configuration + * @status: return status (system error number) + */ +struct counter_event { + __aligned_u64 timestamp; + __aligned_u64 value; + struct counter_watch watch; + __u8 status; +}; + /* Count direction values */ enum counter_count_direction { COUNTER_COUNT_DIRECTION_FORWARD, -- 2.30.1