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- /*
- * 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.
- */
- #include <linux/uaccess.h>
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/device.h>
- #include <linux/compat.h>
- #include <linux/kdev_t.h>
- #include <linux/srcu.h>
- #include <linux/slab.h>
- #include <linux/stm.h>
- #include <linux/fs.h>
- #include <linux/mm.h>
- #include <linux/vmalloc.h>
- #include "stm.h"
- #include <uapi/linux/stm.h>
- static unsigned int stm_core_up;
- /*
- * The SRCU here makes sure that STM device doesn't disappear from under a
- * stm_source_write() caller, which may want to have as little overhead as
- * possible.
- */
- static struct srcu_struct stm_source_srcu;
- static ssize_t masters_show(struct device *dev,
- struct device_attribute *attr,
- char *buf)
- {
- struct stm_device *stm = to_stm_device(dev);
- int ret;
- ret = sprintf(buf, "%u %u\n", stm->data->sw_start, stm->data->sw_end);
- return ret;
- }
- static DEVICE_ATTR_RO(masters);
- static ssize_t channels_show(struct device *dev,
- struct device_attribute *attr,
- char *buf)
- {
- struct stm_device *stm = to_stm_device(dev);
- int ret;
- ret = sprintf(buf, "%u\n", stm->data->sw_nchannels);
- return ret;
- }
- static DEVICE_ATTR_RO(channels);
- static struct attribute *stm_attrs[] = {
- &dev_attr_masters.attr,
- &dev_attr_channels.attr,
- NULL,
- };
- ATTRIBUTE_GROUPS(stm);
- static struct class stm_class = {
- .name = "stm",
- .dev_groups = stm_groups,
- };
- static int stm_dev_match(struct device *dev, const void *data)
- {
- const char *name = data;
- return sysfs_streq(name, dev_name(dev));
- }
- /**
- * stm_find_device() - find stm device by name
- * @buf: character buffer containing the name
- *
- * This is called when either policy gets assigned to an stm device or an
- * stm_source device gets linked to an stm device.
- *
- * This grabs device's reference (get_device()) and module reference, both
- * of which the calling path needs to make sure to drop with stm_put_device().
- *
- * Return: stm device pointer or null if lookup failed.
- */
- struct stm_device *stm_find_device(const char *buf)
- {
- struct stm_device *stm;
- struct device *dev;
- if (!stm_core_up)
- return NULL;
- dev = class_find_device(&stm_class, NULL, buf, stm_dev_match);
- if (!dev)
- return NULL;
- stm = to_stm_device(dev);
- if (!try_module_get(stm->owner)) {
- /* matches class_find_device() above */
- put_device(dev);
- return NULL;
- }
- return stm;
- }
- /**
- * stm_put_device() - drop references on the stm device
- * @stm: stm device, previously acquired by stm_find_device()
- *
- * This drops the module reference and device reference taken by
- * stm_find_device() or stm_char_open().
- */
- void stm_put_device(struct stm_device *stm)
- {
- module_put(stm->owner);
- put_device(&stm->dev);
- }
- /*
- * Internally we only care about software-writable masters here, that is the
- * ones in the range [stm_data->sw_start..stm_data..sw_end], however we need
- * original master numbers to be visible externally, since they are the ones
- * that will appear in the STP stream. Thus, the internal bookkeeping uses
- * $master - stm_data->sw_start to reference master descriptors and such.
- */
- #define __stm_master(_s, _m) \
- ((_s)->masters[(_m) - (_s)->data->sw_start])
- static inline struct stp_master *
- stm_master(struct stm_device *stm, unsigned int idx)
- {
- if (idx < stm->data->sw_start || idx > stm->data->sw_end)
- return NULL;
- return __stm_master(stm, idx);
- }
- static int stp_master_alloc(struct stm_device *stm, unsigned int idx)
- {
- struct stp_master *master;
- size_t size;
- size = ALIGN(stm->data->sw_nchannels, 8) / 8;
- size += sizeof(struct stp_master);
- master = kzalloc(size, GFP_ATOMIC);
- if (!master)
- return -ENOMEM;
- master->nr_free = stm->data->sw_nchannels;
- __stm_master(stm, idx) = master;
- return 0;
- }
- static void stp_master_free(struct stm_device *stm, unsigned int idx)
- {
- struct stp_master *master = stm_master(stm, idx);
- if (!master)
- return;
- __stm_master(stm, idx) = NULL;
- kfree(master);
- }
- static void stm_output_claim(struct stm_device *stm, struct stm_output *output)
- {
- struct stp_master *master = stm_master(stm, output->master);
- lockdep_assert_held(&stm->mc_lock);
- lockdep_assert_held(&output->lock);
- if (WARN_ON_ONCE(master->nr_free < output->nr_chans))
- return;
- bitmap_allocate_region(&master->chan_map[0], output->channel,
- ilog2(output->nr_chans));
- master->nr_free -= output->nr_chans;
- }
- static void
- stm_output_disclaim(struct stm_device *stm, struct stm_output *output)
- {
- struct stp_master *master = stm_master(stm, output->master);
- lockdep_assert_held(&stm->mc_lock);
- lockdep_assert_held(&output->lock);
- bitmap_release_region(&master->chan_map[0], output->channel,
- ilog2(output->nr_chans));
- output->nr_chans = 0;
- master->nr_free += output->nr_chans;
- }
- /*
- * This is like bitmap_find_free_region(), except it can ignore @start bits
- * at the beginning.
- */
- static int find_free_channels(unsigned long *bitmap, unsigned int start,
- unsigned int end, unsigned int width)
- {
- unsigned int pos;
- int i;
- for (pos = start; pos < end + 1; pos = ALIGN(pos, width)) {
- pos = find_next_zero_bit(bitmap, end + 1, pos);
- if (pos + width > end + 1)
- break;
- if (pos & (width - 1))
- continue;
- for (i = 1; i < width && !test_bit(pos + i, bitmap); i++)
- ;
- if (i == width)
- return pos;
- /* step over [pos..pos+i) to continue search */
- pos += i;
- }
- return -1;
- }
- static unsigned int
- stm_find_master_chan(struct stm_device *stm, unsigned int width,
- unsigned int *mstart, unsigned int mend,
- unsigned int *cstart, unsigned int cend)
- {
- struct stp_master *master;
- unsigned int midx;
- int pos, err;
- for (midx = *mstart; midx <= mend; midx++) {
- if (!stm_master(stm, midx)) {
- err = stp_master_alloc(stm, midx);
- if (err)
- return err;
- }
- master = stm_master(stm, midx);
- if (!master->nr_free)
- continue;
- pos = find_free_channels(master->chan_map, *cstart, cend,
- width);
- if (pos < 0)
- continue;
- *mstart = midx;
- *cstart = pos;
- return 0;
- }
- return -ENOSPC;
- }
- static int stm_output_assign(struct stm_device *stm, unsigned int width,
- struct stp_policy_node *policy_node,
- struct stm_output *output)
- {
- unsigned int midx, cidx, mend, cend;
- int ret = -EINVAL;
- if (width > stm->data->sw_nchannels)
- return -EINVAL;
- if (policy_node) {
- stp_policy_node_get_ranges(policy_node,
- &midx, &mend, &cidx, &cend);
- } else {
- midx = stm->data->sw_start;
- cidx = 0;
- mend = stm->data->sw_end;
- cend = stm->data->sw_nchannels - 1;
- }
- spin_lock(&stm->mc_lock);
- spin_lock(&output->lock);
- /* output is already assigned -- shouldn't happen */
- if (WARN_ON_ONCE(output->nr_chans))
- goto unlock;
- ret = stm_find_master_chan(stm, width, &midx, mend, &cidx, cend);
- if (ret)
- goto unlock;
- output->master = midx;
- output->channel = cidx;
- output->nr_chans = width;
- stm_output_claim(stm, output);
- dev_dbg(&stm->dev, "assigned %u:%u (+%u)\n", midx, cidx, width);
- ret = 0;
- unlock:
- spin_unlock(&output->lock);
- spin_unlock(&stm->mc_lock);
- return ret;
- }
- static void stm_output_free(struct stm_device *stm, struct stm_output *output)
- {
- spin_lock(&stm->mc_lock);
- spin_lock(&output->lock);
- if (output->nr_chans)
- stm_output_disclaim(stm, output);
- spin_unlock(&output->lock);
- spin_unlock(&stm->mc_lock);
- }
- static void stm_output_init(struct stm_output *output)
- {
- spin_lock_init(&output->lock);
- }
- static int major_match(struct device *dev, const void *data)
- {
- unsigned int major = *(unsigned int *)data;
- return MAJOR(dev->devt) == major;
- }
- static int stm_char_open(struct inode *inode, struct file *file)
- {
- struct stm_file *stmf;
- struct device *dev;
- unsigned int major = imajor(inode);
- int err = -ENODEV;
- dev = class_find_device(&stm_class, NULL, &major, major_match);
- if (!dev)
- return -ENODEV;
- stmf = kzalloc(sizeof(*stmf), GFP_KERNEL);
- if (!stmf)
- return -ENOMEM;
- stm_output_init(&stmf->output);
- stmf->stm = to_stm_device(dev);
- if (!try_module_get(stmf->stm->owner))
- goto err_free;
- file->private_data = stmf;
- return nonseekable_open(inode, file);
- err_free:
- /* matches class_find_device() above */
- put_device(dev);
- kfree(stmf);
- return err;
- }
- static int stm_char_release(struct inode *inode, struct file *file)
- {
- struct stm_file *stmf = file->private_data;
- stm_output_free(stmf->stm, &stmf->output);
- /*
- * matches the stm_char_open()'s
- * class_find_device() + try_module_get()
- */
- stm_put_device(stmf->stm);
- kfree(stmf);
- return 0;
- }
- static int stm_file_assign(struct stm_file *stmf, char *id, unsigned int width)
- {
- struct stm_device *stm = stmf->stm;
- int ret;
- stmf->policy_node = stp_policy_node_lookup(stm, id);
- ret = stm_output_assign(stm, width, stmf->policy_node, &stmf->output);
- if (stmf->policy_node)
- stp_policy_node_put(stmf->policy_node);
- return ret;
- }
- static void stm_write(struct stm_data *data, unsigned int master,
- unsigned int channel, const char *buf, size_t count)
- {
- unsigned int flags = STP_PACKET_TIMESTAMPED;
- const unsigned char *p = buf, nil = 0;
- size_t pos;
- ssize_t sz;
- for (pos = 0, p = buf; count > pos; pos += sz, p += sz) {
- sz = min_t(unsigned int, count - pos, 8);
- sz = data->packet(data, master, channel, STP_PACKET_DATA, flags,
- sz, p);
- flags = 0;
- }
- data->packet(data, master, channel, STP_PACKET_FLAG, 0, 0, &nil);
- }
- static ssize_t stm_char_write(struct file *file, const char __user *buf,
- size_t count, loff_t *ppos)
- {
- struct stm_file *stmf = file->private_data;
- struct stm_device *stm = stmf->stm;
- char *kbuf;
- int err;
- if (count + 1 > PAGE_SIZE)
- count = PAGE_SIZE - 1;
- /*
- * if no m/c have been assigned to this writer up to this
- * point, use "default" policy entry
- */
- if (!stmf->output.nr_chans) {
- err = stm_file_assign(stmf, "default", 1);
- /*
- * EBUSY means that somebody else just assigned this
- * output, which is just fine for write()
- */
- if (err && err != -EBUSY)
- return err;
- }
- kbuf = kmalloc(count + 1, GFP_KERNEL);
- if (!kbuf)
- return -ENOMEM;
- err = copy_from_user(kbuf, buf, count);
- if (err) {
- kfree(kbuf);
- return -EFAULT;
- }
- stm_write(stm->data, stmf->output.master, stmf->output.channel, kbuf,
- count);
- kfree(kbuf);
- return count;
- }
- static int stm_char_mmap(struct file *file, struct vm_area_struct *vma)
- {
- struct stm_file *stmf = file->private_data;
- struct stm_device *stm = stmf->stm;
- unsigned long size, phys;
- if (!stm->data->mmio_addr)
- return -EOPNOTSUPP;
- if (vma->vm_pgoff)
- return -EINVAL;
- size = vma->vm_end - vma->vm_start;
- if (stmf->output.nr_chans * stm->data->sw_mmiosz != size)
- return -EINVAL;
- phys = stm->data->mmio_addr(stm->data, stmf->output.master,
- stmf->output.channel,
- stmf->output.nr_chans);
- if (!phys)
- return -EINVAL;
- vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
- vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
- vm_iomap_memory(vma, phys, size);
- return 0;
- }
- static int stm_char_policy_set_ioctl(struct stm_file *stmf, void __user *arg)
- {
- struct stm_device *stm = stmf->stm;
- struct stp_policy_id *id;
- int ret = -EINVAL, wlimit = 1;
- u32 size;
- if (stmf->output.nr_chans)
- return -EBUSY;
- if (copy_from_user(&size, arg, sizeof(size)))
- return -EFAULT;
- if (size >= PATH_MAX + sizeof(*id))
- return -EINVAL;
- /*
- * size + 1 to make sure the .id string at the bottom is terminated,
- * which is also why memdup_user() is not useful here
- */
- id = kzalloc(size + 1, GFP_KERNEL);
- if (!id)
- return -ENOMEM;
- if (copy_from_user(id, arg, size)) {
- ret = -EFAULT;
- goto err_free;
- }
- if (id->__reserved_0 || id->__reserved_1)
- goto err_free;
- if (stm->data->sw_mmiosz)
- wlimit = PAGE_SIZE / stm->data->sw_mmiosz;
- if (id->width < 1 || id->width > wlimit)
- goto err_free;
- ret = stm_file_assign(stmf, id->id, id->width);
- if (ret)
- goto err_free;
- ret = 0;
- if (stm->data->link)
- ret = stm->data->link(stm->data, stmf->output.master,
- stmf->output.channel);
- if (ret)
- stm_output_free(stmf->stm, &stmf->output);
- err_free:
- kfree(id);
- return ret;
- }
- static int stm_char_policy_get_ioctl(struct stm_file *stmf, void __user *arg)
- {
- struct stp_policy_id id = {
- .size = sizeof(id),
- .master = stmf->output.master,
- .channel = stmf->output.channel,
- .width = stmf->output.nr_chans,
- .__reserved_0 = 0,
- .__reserved_1 = 0,
- };
- return copy_to_user(arg, &id, id.size) ? -EFAULT : 0;
- }
- static long
- stm_char_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
- {
- struct stm_file *stmf = file->private_data;
- struct stm_data *stm_data = stmf->stm->data;
- int err = -ENOTTY;
- u64 options;
- switch (cmd) {
- case STP_POLICY_ID_SET:
- err = stm_char_policy_set_ioctl(stmf, (void __user *)arg);
- if (err)
- return err;
- return stm_char_policy_get_ioctl(stmf, (void __user *)arg);
- case STP_POLICY_ID_GET:
- return stm_char_policy_get_ioctl(stmf, (void __user *)arg);
- case STP_SET_OPTIONS:
- if (copy_from_user(&options, (u64 __user *)arg, sizeof(u64)))
- return -EFAULT;
- if (stm_data->set_options)
- err = stm_data->set_options(stm_data,
- stmf->output.master,
- stmf->output.channel,
- stmf->output.nr_chans,
- options);
- break;
- default:
- break;
- }
- return err;
- }
- #ifdef CONFIG_COMPAT
- static long
- stm_char_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
- {
- return stm_char_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
- }
- #else
- #define stm_char_compat_ioctl NULL
- #endif
- static const struct file_operations stm_fops = {
- .open = stm_char_open,
- .release = stm_char_release,
- .write = stm_char_write,
- .mmap = stm_char_mmap,
- .unlocked_ioctl = stm_char_ioctl,
- .compat_ioctl = stm_char_compat_ioctl,
- .llseek = no_llseek,
- };
- static void stm_device_release(struct device *dev)
- {
- struct stm_device *stm = to_stm_device(dev);
- vfree(stm);
- }
- int stm_register_device(struct device *parent, struct stm_data *stm_data,
- struct module *owner)
- {
- struct stm_device *stm;
- unsigned int nmasters;
- int err = -ENOMEM;
- if (!stm_core_up)
- return -EPROBE_DEFER;
- if (!stm_data->packet || !stm_data->sw_nchannels)
- return -EINVAL;
- nmasters = stm_data->sw_end - stm_data->sw_start;
- stm = vzalloc(sizeof(*stm) + nmasters * sizeof(void *));
- if (!stm)
- return -ENOMEM;
- stm->major = register_chrdev(0, stm_data->name, &stm_fops);
- if (stm->major < 0)
- goto err_free;
- device_initialize(&stm->dev);
- stm->dev.devt = MKDEV(stm->major, 0);
- stm->dev.class = &stm_class;
- stm->dev.parent = parent;
- stm->dev.release = stm_device_release;
- mutex_init(&stm->link_mutex);
- spin_lock_init(&stm->link_lock);
- INIT_LIST_HEAD(&stm->link_list);
- /* initialize the object before it is accessible via sysfs */
- spin_lock_init(&stm->mc_lock);
- mutex_init(&stm->policy_mutex);
- stm->sw_nmasters = nmasters;
- stm->owner = owner;
- stm->data = stm_data;
- stm_data->stm = stm;
- err = kobject_set_name(&stm->dev.kobj, "%s", stm_data->name);
- if (err)
- goto err_device;
- err = device_add(&stm->dev);
- if (err)
- goto err_device;
- return 0;
- err_device:
- unregister_chrdev(stm->major, stm_data->name);
- /* matches device_initialize() above */
- put_device(&stm->dev);
- err_free:
- vfree(stm);
- return err;
- }
- EXPORT_SYMBOL_GPL(stm_register_device);
- static int __stm_source_link_drop(struct stm_source_device *src,
- struct stm_device *stm);
- void stm_unregister_device(struct stm_data *stm_data)
- {
- struct stm_device *stm = stm_data->stm;
- struct stm_source_device *src, *iter;
- int i, ret;
- mutex_lock(&stm->link_mutex);
- list_for_each_entry_safe(src, iter, &stm->link_list, link_entry) {
- ret = __stm_source_link_drop(src, stm);
- /*
- * src <-> stm link must not change under the same
- * stm::link_mutex, so complain loudly if it has;
- * also in this situation ret!=0 means this src is
- * not connected to this stm and it should be otherwise
- * safe to proceed with the tear-down of stm.
- */
- WARN_ON_ONCE(ret);
- }
- mutex_unlock(&stm->link_mutex);
- synchronize_srcu(&stm_source_srcu);
- unregister_chrdev(stm->major, stm_data->name);
- mutex_lock(&stm->policy_mutex);
- if (stm->policy)
- stp_policy_unbind(stm->policy);
- mutex_unlock(&stm->policy_mutex);
- for (i = 0; i < stm->sw_nmasters; i++)
- stp_master_free(stm, i);
- device_unregister(&stm->dev);
- stm_data->stm = NULL;
- }
- EXPORT_SYMBOL_GPL(stm_unregister_device);
- /*
- * stm::link_list access serialization uses a spinlock and a mutex; holding
- * either of them guarantees that the list is stable; modification requires
- * holding both of them.
- *
- * Lock ordering is as follows:
- * stm::link_mutex
- * stm::link_lock
- * src::link_lock
- */
- /**
- * stm_source_link_add() - connect an stm_source device to an stm device
- * @src: stm_source device
- * @stm: stm device
- *
- * This function establishes a link from stm_source to an stm device so that
- * the former can send out trace data to the latter.
- *
- * Return: 0 on success, -errno otherwise.
- */
- static int stm_source_link_add(struct stm_source_device *src,
- struct stm_device *stm)
- {
- char *id;
- int err;
- mutex_lock(&stm->link_mutex);
- spin_lock(&stm->link_lock);
- spin_lock(&src->link_lock);
- /* src->link is dereferenced under stm_source_srcu but not the list */
- rcu_assign_pointer(src->link, stm);
- list_add_tail(&src->link_entry, &stm->link_list);
- spin_unlock(&src->link_lock);
- spin_unlock(&stm->link_lock);
- mutex_unlock(&stm->link_mutex);
- id = kstrdup(src->data->name, GFP_KERNEL);
- if (id) {
- src->policy_node =
- stp_policy_node_lookup(stm, id);
- kfree(id);
- }
- err = stm_output_assign(stm, src->data->nr_chans,
- src->policy_node, &src->output);
- if (src->policy_node)
- stp_policy_node_put(src->policy_node);
- if (err)
- goto fail_detach;
- /* this is to notify the STM device that a new link has been made */
- if (stm->data->link)
- err = stm->data->link(stm->data, src->output.master,
- src->output.channel);
- if (err)
- goto fail_free_output;
- /* this is to let the source carry out all necessary preparations */
- if (src->data->link)
- src->data->link(src->data);
- return 0;
- fail_free_output:
- stm_output_free(stm, &src->output);
- fail_detach:
- mutex_lock(&stm->link_mutex);
- spin_lock(&stm->link_lock);
- spin_lock(&src->link_lock);
- rcu_assign_pointer(src->link, NULL);
- list_del_init(&src->link_entry);
- spin_unlock(&src->link_lock);
- spin_unlock(&stm->link_lock);
- mutex_unlock(&stm->link_mutex);
- return err;
- }
- /**
- * __stm_source_link_drop() - detach stm_source from an stm device
- * @src: stm_source device
- * @stm: stm device
- *
- * If @stm is @src::link, disconnect them from one another and put the
- * reference on the @stm device.
- *
- * Caller must hold stm::link_mutex.
- */
- static int __stm_source_link_drop(struct stm_source_device *src,
- struct stm_device *stm)
- {
- struct stm_device *link;
- int ret = 0;
- lockdep_assert_held(&stm->link_mutex);
- /* for stm::link_list modification, we hold both mutex and spinlock */
- spin_lock(&stm->link_lock);
- spin_lock(&src->link_lock);
- link = srcu_dereference_check(src->link, &stm_source_srcu, 1);
- /*
- * The linked device may have changed since we last looked, because
- * we weren't holding the src::link_lock back then; if this is the
- * case, tell the caller to retry.
- */
- if (link != stm) {
- ret = -EAGAIN;
- goto unlock;
- }
- stm_output_free(link, &src->output);
- list_del_init(&src->link_entry);
- /* matches stm_find_device() from stm_source_link_store() */
- stm_put_device(link);
- rcu_assign_pointer(src->link, NULL);
- unlock:
- spin_unlock(&src->link_lock);
- spin_unlock(&stm->link_lock);
- if (!ret && src->data->unlink)
- src->data->unlink(src->data);
- return ret;
- }
- /**
- * stm_source_link_drop() - detach stm_source from its stm device
- * @src: stm_source device
- *
- * Unlinking means disconnecting from source's STM device; after this
- * writes will be unsuccessful until it is linked to a new STM device.
- *
- * This will happen on "stm_source_link" sysfs attribute write to undo
- * the existing link (if any), or on linked STM device's de-registration.
- */
- static void stm_source_link_drop(struct stm_source_device *src)
- {
- struct stm_device *stm;
- int idx, ret;
- retry:
- idx = srcu_read_lock(&stm_source_srcu);
- /*
- * The stm device will be valid for the duration of this
- * read section, but the link may change before we grab
- * the src::link_lock in __stm_source_link_drop().
- */
- stm = srcu_dereference(src->link, &stm_source_srcu);
- ret = 0;
- if (stm) {
- mutex_lock(&stm->link_mutex);
- ret = __stm_source_link_drop(src, stm);
- mutex_unlock(&stm->link_mutex);
- }
- srcu_read_unlock(&stm_source_srcu, idx);
- /* if it did change, retry */
- if (ret == -EAGAIN)
- goto retry;
- }
- static ssize_t stm_source_link_show(struct device *dev,
- struct device_attribute *attr,
- char *buf)
- {
- struct stm_source_device *src = to_stm_source_device(dev);
- struct stm_device *stm;
- int idx, ret;
- idx = srcu_read_lock(&stm_source_srcu);
- stm = srcu_dereference(src->link, &stm_source_srcu);
- ret = sprintf(buf, "%s\n",
- stm ? dev_name(&stm->dev) : "<none>");
- srcu_read_unlock(&stm_source_srcu, idx);
- return ret;
- }
- static ssize_t stm_source_link_store(struct device *dev,
- struct device_attribute *attr,
- const char *buf, size_t count)
- {
- struct stm_source_device *src = to_stm_source_device(dev);
- struct stm_device *link;
- int err;
- stm_source_link_drop(src);
- link = stm_find_device(buf);
- if (!link)
- return -EINVAL;
- err = stm_source_link_add(src, link);
- if (err) {
- /* matches the stm_find_device() above */
- stm_put_device(link);
- }
- return err ? : count;
- }
- static DEVICE_ATTR_RW(stm_source_link);
- static struct attribute *stm_source_attrs[] = {
- &dev_attr_stm_source_link.attr,
- NULL,
- };
- ATTRIBUTE_GROUPS(stm_source);
- static struct class stm_source_class = {
- .name = "stm_source",
- .dev_groups = stm_source_groups,
- };
- static void stm_source_device_release(struct device *dev)
- {
- struct stm_source_device *src = to_stm_source_device(dev);
- kfree(src);
- }
- /**
- * stm_source_register_device() - register an stm_source device
- * @parent: parent device
- * @data: device description structure
- *
- * This will create a device of stm_source class that can write
- * data to an stm device once linked.
- *
- * Return: 0 on success, -errno otherwise.
- */
- int stm_source_register_device(struct device *parent,
- struct stm_source_data *data)
- {
- struct stm_source_device *src;
- int err;
- if (!stm_core_up)
- return -EPROBE_DEFER;
- src = kzalloc(sizeof(*src), GFP_KERNEL);
- if (!src)
- return -ENOMEM;
- device_initialize(&src->dev);
- src->dev.class = &stm_source_class;
- src->dev.parent = parent;
- src->dev.release = stm_source_device_release;
- err = kobject_set_name(&src->dev.kobj, "%s", data->name);
- if (err)
- goto err;
- err = device_add(&src->dev);
- if (err)
- goto err;
- stm_output_init(&src->output);
- spin_lock_init(&src->link_lock);
- INIT_LIST_HEAD(&src->link_entry);
- src->data = data;
- data->src = src;
- return 0;
- err:
- put_device(&src->dev);
- kfree(src);
- return err;
- }
- EXPORT_SYMBOL_GPL(stm_source_register_device);
- /**
- * stm_source_unregister_device() - unregister an stm_source device
- * @data: device description that was used to register the device
- *
- * This will remove a previously created stm_source device from the system.
- */
- void stm_source_unregister_device(struct stm_source_data *data)
- {
- struct stm_source_device *src = data->src;
- stm_source_link_drop(src);
- device_unregister(&src->dev);
- }
- EXPORT_SYMBOL_GPL(stm_source_unregister_device);
- int stm_source_write(struct stm_source_data *data, unsigned int chan,
- const char *buf, size_t count)
- {
- struct stm_source_device *src = data->src;
- struct stm_device *stm;
- int idx;
- if (!src->output.nr_chans)
- return -ENODEV;
- if (chan >= src->output.nr_chans)
- return -EINVAL;
- idx = srcu_read_lock(&stm_source_srcu);
- stm = srcu_dereference(src->link, &stm_source_srcu);
- if (stm)
- stm_write(stm->data, src->output.master,
- src->output.channel + chan,
- buf, count);
- else
- count = -ENODEV;
- srcu_read_unlock(&stm_source_srcu, idx);
- return count;
- }
- EXPORT_SYMBOL_GPL(stm_source_write);
- 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();
- 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;
- }
- module_init(stm_core_init);
- static void __exit stm_core_exit(void)
- {
- cleanup_srcu_struct(&stm_source_srcu);
- 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@linux.intel.com>");
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