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Message-ID: <CANLsYkzirrkP_=joY8k8a-Ly+-yT18OOxeySkiDU-aAqGtTE6A@mail.gmail.com>
Date: Fri, 24 Apr 2015 16:07:13 -0600
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Paul Bolle <pebolle@...cali.nl>, peter.lachner@...el.com,
norbert.schulz@...el.com, keven.boell@...el.com,
yann.fouassier@...el.com, laurent.fert@...el.com,
linux-api@...r.kernel.org, Pratik Patel <pratikp@...eaurora.org>
Subject: Re: [PATCH v2 01/11] stm class: Introduce an abstraction for System
Trace Module devices
[...]
> +
> +static int __init stm_core_init(void)
> +{
> + int err;
> +
> + err = class_register(&stm_class);
> + if (err)
> + return err;
> +
> + err = class_register(&stm_source_class);
> + if (err)
> + goto err_stm;
> +
> + err = stp_configfs_init();
You can't move "stp_configfs_init()" here and leave "stm_core_init()"
as a "postcore_initcall()". Function "stp_configfs_init()" calls
"configfs_register_subsystem()" which, after some time, will end up
calling "configfs_new_dirent()". In there an access to the cache
allocator is done on "configfs_dir_cachep", but it is only initialised
in "configfs_init()" at "module_init()" time, resulting in a -ENOMEM
error.
I don't see how it can be different on x86 but on ARM it is definitely
a problem.
Mathieu
> + if (err)
> + goto err_src;
> +
> + init_srcu_struct(&stm_source_srcu);
> +
> + stm_core_up++;
> +
> + return 0;
> +
> +err_src:
> + class_unregister(&stm_source_class);
> +err_stm:
> + class_unregister(&stm_class);
> +
> + return err;
> +}
> +
> +postcore_initcall(stm_core_init);
> +
> +static void __exit stm_core_exit(void)
> +{
> + class_unregister(&stm_source_class);
> + class_unregister(&stm_class);
> + stp_configfs_exit();
> +}
> +
> +module_exit(stm_core_exit);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("System Trace Module device class");
> +MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@...ux.intel.com>");
> diff --git a/drivers/hwtracing/stm/policy.c b/drivers/hwtracing/stm/policy.c
> new file mode 100644
> index 0000000000..b5c59a0e0c
> --- /dev/null
> +++ b/drivers/hwtracing/stm/policy.c
> @@ -0,0 +1,467 @@
> +/*
> + * System Trace Module (STM) master/channel allocation policy management
> + * Copyright (c) 2014, Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * A master/channel allocation policy allows mapping string identifiers to
> + * master and channel ranges, where allocation can be done.
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/types.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/configfs.h>
> +#include <linux/slab.h>
> +#include <linux/stm.h>
> +#include "stm.h"
> +
> +/*
> + * STP Master/Channel allocation policy configfs layout.
> + */
> +
> +struct stp_policy {
> + struct config_group group;
> + struct stm_device *stm;
> +};
> +
> +struct stp_policy_node {
> + struct config_group group;
> + struct stm_device *stm;
> + struct stp_policy *policy;
> + unsigned int first_master;
> + unsigned int last_master;
> + unsigned int first_channel;
> + unsigned int last_channel;
> +};
> +
> +void stp_policy_node_get_ranges(struct stp_policy_node *policy_node,
> + unsigned int *mstart, unsigned int *mend,
> + unsigned int *cstart, unsigned int *cend)
> +{
> + *mstart = policy_node->first_master;
> + *mend = policy_node->last_master;
> + *cstart = policy_node->first_channel;
> + *cend = policy_node->last_channel;
> +}
> +
> +static inline char *stp_policy_node_name(struct stp_policy_node *policy_node)
> +{
> + return policy_node->group.cg_item.ci_name ? : "<none>";
> +}
> +
> +static inline struct stp_policy *to_stp_policy(struct config_item *item)
> +{
> + return item ?
> + container_of(to_config_group(item), struct stp_policy, group) :
> + NULL;
> +}
> +
> +static inline struct stp_policy_node *
> +to_stp_policy_node(struct config_item *item)
> +{
> + return item ?
> + container_of(to_config_group(item), struct stp_policy_node,
> + group) :
> + NULL;
> +}
> +
> +static ssize_t stp_policy_node_masters_show(struct stp_policy_node *policy_node,
> + char *page)
> +{
> + ssize_t count;
> +
> + count = sprintf(page, "%u %u\n", policy_node->first_master,
> + policy_node->last_master);
> +
> + return count;
> +}
> +
> +static ssize_t
> +stp_policy_node_masters_store(struct stp_policy_node *policy_node,
> + const char *page, size_t count)
> +{
> + struct stm_device *stm = policy_node->stm;
> + unsigned int first, last;
> + char *p = (char *) page;
> +
> + if (sscanf(p, "%u %u", &first, &last) != 2)
> + return -EINVAL;
> +
> + /* must be within [sw_start..sw_end], which is an inclusive range */
> + if (first > INT_MAX || last > INT_MAX || first > last ||
> + first < stm->data->sw_start ||
> + last > stm->data->sw_end)
> + return -ERANGE;
> +
> + policy_node->first_master = first;
> + policy_node->last_master = last;
> +
> + return count;
> +}
> +
> +static ssize_t
> +stp_policy_node_channels_show(struct stp_policy_node *policy_node, char *page)
> +{
> + ssize_t count;
> +
> + count = sprintf(page, "%u %u\n", policy_node->first_channel,
> + policy_node->last_channel);
> +
> + return count;
> +}
> +
> +static ssize_t
> +stp_policy_node_channels_store(struct stp_policy_node *policy_node,
> + const char *page, size_t count)
> +{
> + unsigned int first, last;
> + char *p = (char *) page;
> +
> + if (sscanf(p, "%u %u", &first, &last) != 2)
> + return -EINVAL;
> +
> + if (first > INT_MAX || last > INT_MAX || first > last ||
> + last >= policy_node->stm->data->sw_nchannels)
> + return -ERANGE;
> +
> + policy_node->first_channel = first;
> + policy_node->last_channel = last;
> +
> + return count;
> +}
> +
> +static void stp_policy_node_release(struct config_item *item)
> +{
> + kfree(to_stp_policy_node(item));
> +}
> +
> +struct stp_policy_node_attribute {
> + struct configfs_attribute attr;
> + ssize_t (*show)(struct stp_policy_node *, char *);
> + ssize_t (*store)(struct stp_policy_node *, const char *, size_t);
> +};
> +
> +static ssize_t stp_policy_node_attr_show(struct config_item *item,
> + struct configfs_attribute *attr,
> + char *page)
> +{
> + struct stp_policy_node *policy_node = to_stp_policy_node(item);
> + struct stp_policy_node_attribute *pn_attr =
> + container_of(attr, struct stp_policy_node_attribute, attr);
> + ssize_t count = 0;
> +
> + if (pn_attr->show)
> + count = pn_attr->show(policy_node, page);
> +
> + return count;
> +}
> +
> +static ssize_t stp_policy_node_attr_store(struct config_item *item,
> + struct configfs_attribute *attr,
> + const char *page, size_t len)
> +{
> + struct stp_policy_node *policy_node = to_stp_policy_node(item);
> + struct stp_policy_node_attribute *pn_attr =
> + container_of(attr, struct stp_policy_node_attribute, attr);
> + ssize_t count = -EINVAL;
> +
> + if (pn_attr->store)
> + count = pn_attr->store(policy_node, page, len);
> +
> + return count;
> +}
> +
> +static struct configfs_item_operations stp_policy_node_item_ops = {
> + .release = stp_policy_node_release,
> + .show_attribute = stp_policy_node_attr_show,
> + .store_attribute = stp_policy_node_attr_store,
> +};
> +
> +static struct stp_policy_node_attribute stp_policy_node_attr_range = {
> + .attr = {
> + .ca_owner = THIS_MODULE,
> + .ca_name = "masters",
> + .ca_mode = S_IRUGO | S_IWUSR,
> + },
> + .show = stp_policy_node_masters_show,
> + .store = stp_policy_node_masters_store,
> +};
> +
> +static struct stp_policy_node_attribute stp_policy_node_attr_channels = {
> + .attr = {
> + .ca_owner = THIS_MODULE,
> + .ca_name = "channels",
> + .ca_mode = S_IRUGO | S_IWUSR,
> + },
> + .show = stp_policy_node_channels_show,
> + .store = stp_policy_node_channels_store,
> +};
> +
> +static struct configfs_attribute *stp_policy_node_attrs[] = {
> + &stp_policy_node_attr_range.attr,
> + &stp_policy_node_attr_channels.attr,
> + NULL,
> +};
> +
> +static struct config_item_type stp_policy_type;
> +static struct config_item_type stp_policy_node_type;
> +
> +static struct config_group *
> +stp_policy_node_make(struct config_group *group, const char *name)
> +{
> + struct stp_policy_node *policy_node, *parent_node;
> + struct stp_policy *policy;
> +
> + if (group->cg_item.ci_type == &stp_policy_type) {
> + policy = container_of(group, struct stp_policy, group);
> + } else {
> + parent_node = container_of(group, struct stp_policy_node,
> + group);
> + policy = parent_node->policy;
> + }
> +
> + if (!policy->stm)
> + return ERR_PTR(-ENODEV);
> +
> + policy_node = kzalloc(sizeof(struct stp_policy_node), GFP_KERNEL);
> + if (!policy_node)
> + return ERR_PTR(-ENOMEM);
> +
> + config_group_init_type_name(&policy_node->group, name,
> + &stp_policy_node_type);
> +
> + policy_node->policy = policy;
> + policy_node->stm = policy->stm;
> +
> + /* default values for the attributes */
> + policy_node->first_master = policy->stm->data->sw_start;
> + policy_node->last_master = policy->stm->data->sw_end;
> + policy_node->first_channel = 0;
> + policy_node->last_channel = policy->stm->data->sw_nchannels - 1;
> +
> + return &policy_node->group;
> +}
> +
> +static void
> +stp_policy_node_drop(struct config_group *group, struct config_item *item)
> +{
> + config_item_put(item);
> +}
> +
> +static struct configfs_group_operations stp_policy_node_group_ops = {
> + .make_group = stp_policy_node_make,
> + .drop_item = stp_policy_node_drop,
> +};
> +
> +static struct config_item_type stp_policy_node_type = {
> + .ct_item_ops = &stp_policy_node_item_ops,
> + .ct_group_ops = &stp_policy_node_group_ops,
> + .ct_attrs = stp_policy_node_attrs,
> + .ct_owner = THIS_MODULE,
> +};
> +
> +/*
> + * Root group: policies.
> + */
> +static struct configfs_attribute stp_policy_attr_device = {
> + .ca_owner = THIS_MODULE,
> + .ca_name = "device",
> + .ca_mode = S_IRUGO | S_IWUSR,
> +};
> +
> +static struct configfs_attribute *stp_policy_attrs[] = {
> + &stp_policy_attr_device,
> + NULL,
> +};
> +
> +static ssize_t stp_policy_attr_show(struct config_item *item,
> + struct configfs_attribute *attr,
> + char *page)
> +{
> + struct stp_policy *policy = to_stp_policy(item);
> +
> + return sprintf(page, "%s\n",
> + (policy && policy->stm) ?
> + policy->stm->data->name :
> + "<none>");
> +}
> +
> +static ssize_t stp_policy_attr_store(struct config_item *item,
> + struct configfs_attribute *attr,
> + const char *page, size_t len)
> +{
> + struct stp_policy *policy = to_stp_policy(item);
> + ssize_t count = -EINVAL;
> + struct device *dev;
> +
> + dev = stm_find_device(page, len);
> + if (dev) {
> + count = len;
> + if (policy->stm)
> + put_device(policy->stm->dev);
> +
> + policy->stm = dev_get_drvdata(dev);
> +
> + mutex_lock(&policy->stm->policy_mutex);
> + policy->stm->policy = policy;
> + mutex_unlock(&policy->stm->policy_mutex);
> + }
> +
> + return count;
> +}
> +
> +void stp_policy_unbind(struct stp_policy *policy)
> +{
> + put_device(policy->stm->dev);
> +
> + mutex_lock(&policy->stm->policy_mutex);
> + policy->stm->policy = NULL;
> + mutex_unlock(&policy->stm->policy_mutex);
> +
> + policy->stm = NULL;
> +}
> +
> +static void stp_policy_release(struct config_item *item)
> +{
> + struct stp_policy *policy = to_stp_policy(item);
> +
> + stp_policy_unbind(policy);
> + kfree(policy);
> +}
> +
> +static struct configfs_item_operations stp_policy_item_ops = {
> + .release = stp_policy_release,
> + .show_attribute = stp_policy_attr_show,
> + .store_attribute = stp_policy_attr_store,
> +};
> +
> +static struct configfs_group_operations stp_policy_group_ops = {
> + .make_group = stp_policy_node_make,
> +};
> +
> +static struct config_item_type stp_policy_type = {
> + .ct_item_ops = &stp_policy_item_ops,
> + .ct_group_ops = &stp_policy_group_ops,
> + .ct_attrs = stp_policy_attrs,
> + .ct_owner = THIS_MODULE,
> +};
> +
> +static struct config_group *
> +stp_policies_make(struct config_group *group, const char *name)
> +{
> + struct stp_policy *policy;
> +
> + policy = kzalloc(sizeof(*policy), GFP_KERNEL);
> + if (!policy)
> + return ERR_PTR(-ENOMEM);
> +
> + config_group_init_type_name(&policy->group, name,
> + &stp_policy_type);
> + policy->stm = NULL;
> +
> + return &policy->group;
> +}
> +
> +static struct configfs_group_operations stp_policies_group_ops = {
> + .make_group = stp_policies_make,
> +};
> +
> +static struct config_item_type stp_policies_type = {
> + .ct_group_ops = &stp_policies_group_ops,
> + .ct_owner = THIS_MODULE,
> +};
> +
> +static struct configfs_subsystem stp_policy_subsys = {
> + .su_group = {
> + .cg_item = {
> + .ci_namebuf = "stp-policy",
> + .ci_type = &stp_policies_type,
> + },
> + },
> +};
> +
> +/*
> + * Lock the policy mutex from the outside
> + */
> +static struct stp_policy_node *
> +__stp_policy_node_lookup(struct stp_policy *policy, char *s)
> +{
> + struct stp_policy_node *policy_node, *ret;
> + struct list_head *head = &policy->group.cg_children;
> + struct config_item *item;
> + char *start, *end = s;
> +
> + if (list_empty(head))
> + return NULL;
> +
> + /* return the first entry if everything else fails */
> + item = list_entry(head->next, struct config_item, ci_entry);
> + ret = to_stp_policy_node(item);
> +
> +next:
> + for (;;) {
> + start = strsep(&end, "/");
> + if (!start)
> + break;
> +
> + if (!*start)
> + continue;
> +
> + list_for_each_entry(item, head, ci_entry) {
> + policy_node = to_stp_policy_node(item);
> +
> + if (!strcmp(start,
> + policy_node->group.cg_item.ci_name)) {
> + ret = policy_node;
> +
> + if (!end)
> + goto out;
> +
> + head = &policy_node->group.cg_children;
> + goto next;
> + }
> + }
> + break;
> + }
> +
> +out:
> + return ret;
> +}
> +
> +struct stp_policy_node *
> +stp_policy_node_lookup(struct stp_policy *policy, char *s)
> +{
> + struct stp_policy_node *policy_node;
> +
> + mutex_lock(&stp_policy_subsys.su_mutex);
> + policy_node = __stp_policy_node_lookup(policy, s);
> + mutex_unlock(&stp_policy_subsys.su_mutex);
> +
> + return policy_node;
> +}
> +
> +int __init stp_configfs_init(void)
> +{
> + int err;
> +
> + config_group_init(&stp_policy_subsys.su_group);
> + mutex_init(&stp_policy_subsys.su_mutex);
> + err = configfs_register_subsystem(&stp_policy_subsys);
> +
> + return err;
> +}
> +
> +void __exit stp_configfs_exit(void)
> +{
> + configfs_unregister_subsystem(&stp_policy_subsys);
> +}
> diff --git a/drivers/hwtracing/stm/stm.h b/drivers/hwtracing/stm/stm.h
> new file mode 100644
> index 0000000000..4d088a1400
> --- /dev/null
> +++ b/drivers/hwtracing/stm/stm.h
> @@ -0,0 +1,79 @@
> +/*
> + * System Trace Module (STM) infrastructure
> + * Copyright (c) 2014, Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * STM class implements generic infrastructure for System Trace Module devices
> + * as defined in MIPI STPv2 specification.
> + */
> +
> +#ifndef _CLASS_STM_H_
> +#define _CLASS_STM_H_
> +
> +struct stp_policy;
> +struct stp_policy_node;
> +
> +struct stp_policy_node *
> +stp_policy_node_lookup(struct stp_policy *policy, char *s);
> +void stp_policy_unbind(struct stp_policy *policy);
> +
> +void stp_policy_node_get_ranges(struct stp_policy_node *policy_node,
> + unsigned int *mstart, unsigned int *mend,
> + unsigned int *cstart, unsigned int *cend);
> +int stp_configfs_init(void);
> +void stp_configfs_exit(void);
> +
> +struct stp_master {
> + unsigned int nr_free;
> + unsigned long chan_map[0];
> +};
> +
> +struct stm_device {
> + struct device *dev;
> + struct module *owner;
> + struct stp_policy *policy;
> + struct mutex policy_mutex;
> + int major;
> + unsigned int sw_nmasters;
> + struct stm_data *data;
> + spinlock_t link_lock;
> + struct list_head link_list;
> + /* master allocation */
> + spinlock_t mc_lock;
> + struct stp_master *masters[0];
> +};
> +
> +struct stm_output {
> + unsigned int master;
> + unsigned int channel;
> + unsigned int nr_chans;
> +};
> +
> +struct stm_file {
> + struct stm_device *stm;
> + struct stp_policy_node *policy_node;
> + struct stm_output output;
> +};
> +
> +struct device *stm_find_device(const char *name, size_t len);
> +
> +struct stm_source_device {
> + struct device *dev;
> + struct stm_source_data *data;
> + spinlock_t link_lock;
> + struct stm_device *link;
> + struct list_head link_entry;
> + /* one output per stm_source device */
> + struct stp_policy_node *policy_node;
> + struct stm_output output;
> +};
> +
> +#endif /* _CLASS_STM_H_ */
> diff --git a/include/linux/stm.h b/include/linux/stm.h
> new file mode 100644
> index 0000000000..976c94d8f1
> --- /dev/null
> +++ b/include/linux/stm.h
> @@ -0,0 +1,102 @@
> +/*
> + * System Trace Module (STM) infrastructure apis
> + * Copyright (C) 2014 Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + */
> +
> +#ifndef _STM_H_
> +#define _STM_H_
> +
> +#include <linux/device.h>
> +
> +struct stp_policy;
> +
> +struct stm_device;
> +
> +/**
> + * struct stm_data - STM device description and callbacks
> + * @name: device name
> + * @stm: internal structure, only used by stm class code
> + * @sw_start: first STP master available to software
> + * @sw_end: last STP master available to software
> + * @sw_nchannels: number of STP channels per master
> + * @sw_mmiosz: size of one channel's IO space, for mmap, optional
> + * @write: write callback
> + * @mmio_addr: mmap callback, optional
> + * @link: called when a new stm_source gets linked to us, optional
> + * @unlink: likewise for unlinking, again optional
> + * @ioctl: ioctl callback for device-specific commands
> + *
> + * Fill out this structure before calling stm_register_device() to create
> + * an STM device and stm_unregister_device() to destroy it. It will also be
> + * passed back to @write(), @mmio_addr(), @link(), @unlink() and @ioctl()
> + * callbacks.
> + *
> + * Normally, an STM device will have a range of masters available to software
> + * and the rest being statically assigned to various hardware trace sources.
> + * The former is defined by the the range [@sw_start..@...end] of the device
> + * description. That is, the lowest master that can be allocated to software
> + * writers is @sw_start and data from this writer will appear is @sw_start
> + * master in the STP stream.
> + */
> +struct stm_data {
> + const char *name;
> + struct stm_device *stm;
> + unsigned int sw_start;
> + unsigned int sw_end;
> + unsigned int sw_nchannels;
> + unsigned int sw_mmiosz;
> + ssize_t (*write)(struct stm_data *, unsigned int,
> + unsigned int, const char *, size_t);
> + phys_addr_t (*mmio_addr)(struct stm_data *, unsigned int,
> + unsigned int, unsigned int);
> + void (*link)(struct stm_data *, unsigned int,
> + unsigned int);
> + void (*unlink)(struct stm_data *, unsigned int,
> + unsigned int);
> + long (*ioctl)(struct stm_data *, unsigned int,
> + unsigned long);
> +};
> +
> +int stm_register_device(struct device *parent, struct stm_data *stm_data,
> + struct module *owner);
> +void stm_unregister_device(struct stm_data *stm_data);
> +
> +struct stm_source_device;
> +
> +/**
> + * struct stm_source_data - STM source device description and callbacks
> + * @name: device name, will be used for policy lookup
> + * @src: internal structure, only used by stm class code
> + * @nr_chans: number of channels to allocate
> + * @link: called when this source gets linked to an STM device
> + * @unlink: called when this source is about to get unlinked from its STM
> + *
> + * Fill in this structure before calling stm_source_register_device() to
> + * register a source device. Also pass it to unregister and write calls.
> + */
> +struct stm_source_data {
> + const char *name;
> + struct stm_source_device *src;
> + unsigned int percpu;
> + unsigned int nr_chans;
> + int (*link)(struct stm_source_data *data);
> + void (*unlink)(struct stm_source_data *data);
> +};
> +
> +int stm_source_register_device(struct device *parent,
> + struct stm_source_data *data);
> +void stm_source_unregister_device(struct stm_source_data *data);
> +
> +int stm_source_write(struct stm_source_data *data, unsigned int chan,
> + const char *buf, size_t count);
> +
> +#endif /* _STM_H_ */
> diff --git a/include/uapi/linux/stm.h b/include/uapi/linux/stm.h
> new file mode 100644
> index 0000000000..042b58b53b
> --- /dev/null
> +++ b/include/uapi/linux/stm.h
> @@ -0,0 +1,47 @@
> +/*
> + * System Trace Module (STM) userspace interfaces
> + * Copyright (c) 2014, Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * STM class implements generic infrastructure for System Trace Module devices
> + * as defined in MIPI STPv2 specification.
> + */
> +
> +#ifndef _UAPI_LINUX_STM_H
> +#define _UAPI_LINUX_STM_H
> +
> +/**
> + * struct stp_policy_id - identification for the STP policy
> + * @size: size of the structure including real id[] length
> + * @master: assigned master
> + * @channel: first assigned channel
> + * @width: number of requested channels
> + * @id: identification string
> + *
> + * User must calculate the total size of the structure and put it into
> + * @size field, fill out the @id and desired @width. In return, kernel
> + * fills out @master, @channel and @width.
> + */
> +struct stp_policy_id {
> + __u32 size;
> + __u16 master;
> + __u16 channel;
> + __u16 width;
> + /* padding */
> + __u16 __reserved_0;
> + __u32 __reserved_1;
> + char id[0];
> +};
> +
> +#define STP_POLICY_ID_SET _IOWR('%', 0, struct stp_policy_id)
> +#define STP_POLICY_ID_GET _IOR('%', 1, struct stp_policy_id)
> +
> +#endif /* _UAPI_LINUX_STM_H */
> --
> 2.1.4
>
--
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