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-rw-r--r--kernel/drivers/hwtracing/stm/core.c1032
1 files changed, 1032 insertions, 0 deletions
diff --git a/kernel/drivers/hwtracing/stm/core.c b/kernel/drivers/hwtracing/stm/core.c
new file mode 100644
index 000000000..b6445d9e5
--- /dev/null
+++ b/kernel/drivers/hwtracing/stm/core.c
@@ -0,0 +1,1032 @@
+/*
+ * 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 "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)) {
+ 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().
+ */
+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);
+
+ 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);
+
+ 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;
+ }
+
+ 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);
+ /* 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(&stm->mc_lock);
+
+ return ret;
+}
+
+static void stm_output_free(struct stm_device *stm, struct stm_output *output)
+{
+ spin_lock(&stm->mc_lock);
+ if (output->nr_chans)
+ stm_output_disclaim(stm, output);
+ spin_unlock(&stm->mc_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;
+
+ 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:
+ 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);
+ 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 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;
+ 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 (id->width < 1 ||
+ id->width > PAGE_SIZE / stm->data->sw_mmiosz)
+ 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);
+ stm_put_device(stmf->stm);
+ }
+
+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);
+
+ kfree(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 = kzalloc(sizeof(*stm) + nmasters * sizeof(void *), GFP_KERNEL);
+ 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;
+
+ 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;
+
+ spin_lock_init(&stm->link_lock);
+ INIT_LIST_HEAD(&stm->link_list);
+
+ 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;
+
+ return 0;
+
+err_device:
+ put_device(&stm->dev);
+err_free:
+ kfree(stm);
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(stm_register_device);
+
+static void __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;
+
+ spin_lock(&stm->link_lock);
+ list_for_each_entry_safe(src, iter, &stm->link_list, link_entry) {
+ __stm_source_link_drop(src, stm);
+ }
+ spin_unlock(&stm->link_lock);
+
+ 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_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;
+
+ 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);
+
+ 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);
+ stm_put_device(stm);
+
+fail_detach:
+ 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);
+
+ 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_lock.
+ */
+static void __stm_source_link_drop(struct stm_source_device *src,
+ struct stm_device *stm)
+{
+ struct stm_device *link;
+
+ spin_lock(&src->link_lock);
+ link = srcu_dereference_check(src->link, &stm_source_srcu, 1);
+ if (WARN_ON_ONCE(link != stm)) {
+ spin_unlock(&src->link_lock);
+ return;
+ }
+
+ stm_output_free(link, &src->output);
+ /* caller must hold stm::link_lock */
+ 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);
+
+ spin_unlock(&src->link_lock);
+}
+
+/**
+ * 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;
+
+ idx = srcu_read_lock(&stm_source_srcu);
+ stm = srcu_dereference(src->link, &stm_source_srcu);
+
+ if (stm) {
+ if (src->data->unlink)
+ src->data->unlink(src->data);
+
+ spin_lock(&stm->link_lock);
+ __stm_source_link_drop(src, stm);
+ spin_unlock(&stm->link_lock);
+ }
+
+ srcu_read_unlock(&stm_source_srcu, idx);
+}
+
+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)
+ 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;
+
+ 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_destroy(&stm_source_class, src->dev.devt);
+}
+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>");