Merge tag 'block-5.11-2021-01-10' of git://git.kernel.dk/linux-block
[linux/fpc-iii.git] / drivers / hwtracing / stm / core.c
blob2712e699ba08cf2d30415eef43287b36cdc5ec75
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * System Trace Module (STM) infrastructure
4 * Copyright (c) 2014, Intel Corporation.
6 * STM class implements generic infrastructure for System Trace Module devices
7 * as defined in MIPI STPv2 specification.
8 */
10 #include <linux/pm_runtime.h>
11 #include <linux/uaccess.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/device.h>
15 #include <linux/compat.h>
16 #include <linux/kdev_t.h>
17 #include <linux/srcu.h>
18 #include <linux/slab.h>
19 #include <linux/stm.h>
20 #include <linux/fs.h>
21 #include <linux/mm.h>
22 #include <linux/vmalloc.h>
23 #include "stm.h"
25 #include <uapi/linux/stm.h>
27 static unsigned int stm_core_up;
30 * The SRCU here makes sure that STM device doesn't disappear from under a
31 * stm_source_write() caller, which may want to have as little overhead as
32 * possible.
34 static struct srcu_struct stm_source_srcu;
36 static ssize_t masters_show(struct device *dev,
37 struct device_attribute *attr,
38 char *buf)
40 struct stm_device *stm = to_stm_device(dev);
41 int ret;
43 ret = sprintf(buf, "%u %u\n", stm->data->sw_start, stm->data->sw_end);
45 return ret;
48 static DEVICE_ATTR_RO(masters);
50 static ssize_t channels_show(struct device *dev,
51 struct device_attribute *attr,
52 char *buf)
54 struct stm_device *stm = to_stm_device(dev);
55 int ret;
57 ret = sprintf(buf, "%u\n", stm->data->sw_nchannels);
59 return ret;
62 static DEVICE_ATTR_RO(channels);
64 static ssize_t hw_override_show(struct device *dev,
65 struct device_attribute *attr,
66 char *buf)
68 struct stm_device *stm = to_stm_device(dev);
69 int ret;
71 ret = sprintf(buf, "%u\n", stm->data->hw_override);
73 return ret;
76 static DEVICE_ATTR_RO(hw_override);
78 static struct attribute *stm_attrs[] = {
79 &dev_attr_masters.attr,
80 &dev_attr_channels.attr,
81 &dev_attr_hw_override.attr,
82 NULL,
85 ATTRIBUTE_GROUPS(stm);
87 static struct class stm_class = {
88 .name = "stm",
89 .dev_groups = stm_groups,
92 /**
93 * stm_find_device() - find stm device by name
94 * @buf: character buffer containing the name
96 * This is called when either policy gets assigned to an stm device or an
97 * stm_source device gets linked to an stm device.
99 * This grabs device's reference (get_device()) and module reference, both
100 * of which the calling path needs to make sure to drop with stm_put_device().
102 * Return: stm device pointer or null if lookup failed.
104 struct stm_device *stm_find_device(const char *buf)
106 struct stm_device *stm;
107 struct device *dev;
109 if (!stm_core_up)
110 return NULL;
112 dev = class_find_device_by_name(&stm_class, buf);
113 if (!dev)
114 return NULL;
116 stm = to_stm_device(dev);
117 if (!try_module_get(stm->owner)) {
118 /* matches class_find_device() above */
119 put_device(dev);
120 return NULL;
123 return stm;
127 * stm_put_device() - drop references on the stm device
128 * @stm: stm device, previously acquired by stm_find_device()
130 * This drops the module reference and device reference taken by
131 * stm_find_device() or stm_char_open().
133 void stm_put_device(struct stm_device *stm)
135 module_put(stm->owner);
136 put_device(&stm->dev);
140 * Internally we only care about software-writable masters here, that is the
141 * ones in the range [stm_data->sw_start..stm_data..sw_end], however we need
142 * original master numbers to be visible externally, since they are the ones
143 * that will appear in the STP stream. Thus, the internal bookkeeping uses
144 * $master - stm_data->sw_start to reference master descriptors and such.
147 #define __stm_master(_s, _m) \
148 ((_s)->masters[(_m) - (_s)->data->sw_start])
150 static inline struct stp_master *
151 stm_master(struct stm_device *stm, unsigned int idx)
153 if (idx < stm->data->sw_start || idx > stm->data->sw_end)
154 return NULL;
156 return __stm_master(stm, idx);
159 static int stp_master_alloc(struct stm_device *stm, unsigned int idx)
161 struct stp_master *master;
163 master = kzalloc(struct_size(master, chan_map,
164 BITS_TO_LONGS(stm->data->sw_nchannels)),
165 GFP_ATOMIC);
166 if (!master)
167 return -ENOMEM;
169 master->nr_free = stm->data->sw_nchannels;
170 __stm_master(stm, idx) = master;
172 return 0;
175 static void stp_master_free(struct stm_device *stm, unsigned int idx)
177 struct stp_master *master = stm_master(stm, idx);
179 if (!master)
180 return;
182 __stm_master(stm, idx) = NULL;
183 kfree(master);
186 static void stm_output_claim(struct stm_device *stm, struct stm_output *output)
188 struct stp_master *master = stm_master(stm, output->master);
190 lockdep_assert_held(&stm->mc_lock);
191 lockdep_assert_held(&output->lock);
193 if (WARN_ON_ONCE(master->nr_free < output->nr_chans))
194 return;
196 bitmap_allocate_region(&master->chan_map[0], output->channel,
197 ilog2(output->nr_chans));
199 master->nr_free -= output->nr_chans;
202 static void
203 stm_output_disclaim(struct stm_device *stm, struct stm_output *output)
205 struct stp_master *master = stm_master(stm, output->master);
207 lockdep_assert_held(&stm->mc_lock);
208 lockdep_assert_held(&output->lock);
210 bitmap_release_region(&master->chan_map[0], output->channel,
211 ilog2(output->nr_chans));
213 master->nr_free += output->nr_chans;
214 output->nr_chans = 0;
218 * This is like bitmap_find_free_region(), except it can ignore @start bits
219 * at the beginning.
221 static int find_free_channels(unsigned long *bitmap, unsigned int start,
222 unsigned int end, unsigned int width)
224 unsigned int pos;
225 int i;
227 for (pos = start; pos < end + 1; pos = ALIGN(pos, width)) {
228 pos = find_next_zero_bit(bitmap, end + 1, pos);
229 if (pos + width > end + 1)
230 break;
232 if (pos & (width - 1))
233 continue;
235 for (i = 1; i < width && !test_bit(pos + i, bitmap); i++)
237 if (i == width)
238 return pos;
240 /* step over [pos..pos+i) to continue search */
241 pos += i;
244 return -1;
247 static int
248 stm_find_master_chan(struct stm_device *stm, unsigned int width,
249 unsigned int *mstart, unsigned int mend,
250 unsigned int *cstart, unsigned int cend)
252 struct stp_master *master;
253 unsigned int midx;
254 int pos, err;
256 for (midx = *mstart; midx <= mend; midx++) {
257 if (!stm_master(stm, midx)) {
258 err = stp_master_alloc(stm, midx);
259 if (err)
260 return err;
263 master = stm_master(stm, midx);
265 if (!master->nr_free)
266 continue;
268 pos = find_free_channels(master->chan_map, *cstart, cend,
269 width);
270 if (pos < 0)
271 continue;
273 *mstart = midx;
274 *cstart = pos;
275 return 0;
278 return -ENOSPC;
281 static int stm_output_assign(struct stm_device *stm, unsigned int width,
282 struct stp_policy_node *policy_node,
283 struct stm_output *output)
285 unsigned int midx, cidx, mend, cend;
286 int ret = -EINVAL;
288 if (width > stm->data->sw_nchannels)
289 return -EINVAL;
291 /* We no longer accept policy_node==NULL here */
292 if (WARN_ON_ONCE(!policy_node))
293 return -EINVAL;
296 * Also, the caller holds reference to policy_node, so it won't
297 * disappear on us.
299 stp_policy_node_get_ranges(policy_node, &midx, &mend, &cidx, &cend);
301 spin_lock(&stm->mc_lock);
302 spin_lock(&output->lock);
303 /* output is already assigned -- shouldn't happen */
304 if (WARN_ON_ONCE(output->nr_chans))
305 goto unlock;
307 ret = stm_find_master_chan(stm, width, &midx, mend, &cidx, cend);
308 if (ret < 0)
309 goto unlock;
311 output->master = midx;
312 output->channel = cidx;
313 output->nr_chans = width;
314 if (stm->pdrv->output_open) {
315 void *priv = stp_policy_node_priv(policy_node);
317 if (WARN_ON_ONCE(!priv))
318 goto unlock;
320 /* configfs subsys mutex is held by the caller */
321 ret = stm->pdrv->output_open(priv, output);
322 if (ret)
323 goto unlock;
326 stm_output_claim(stm, output);
327 dev_dbg(&stm->dev, "assigned %u:%u (+%u)\n", midx, cidx, width);
329 ret = 0;
330 unlock:
331 if (ret)
332 output->nr_chans = 0;
334 spin_unlock(&output->lock);
335 spin_unlock(&stm->mc_lock);
337 return ret;
340 static void stm_output_free(struct stm_device *stm, struct stm_output *output)
342 spin_lock(&stm->mc_lock);
343 spin_lock(&output->lock);
344 if (output->nr_chans)
345 stm_output_disclaim(stm, output);
346 if (stm->pdrv && stm->pdrv->output_close)
347 stm->pdrv->output_close(output);
348 spin_unlock(&output->lock);
349 spin_unlock(&stm->mc_lock);
352 static void stm_output_init(struct stm_output *output)
354 spin_lock_init(&output->lock);
357 static int major_match(struct device *dev, const void *data)
359 unsigned int major = *(unsigned int *)data;
361 return MAJOR(dev->devt) == major;
365 * Framing protocol management
366 * Modules can implement STM protocol drivers and (un-)register them
367 * with the STM class framework.
369 static struct list_head stm_pdrv_head;
370 static struct mutex stm_pdrv_mutex;
372 struct stm_pdrv_entry {
373 struct list_head entry;
374 const struct stm_protocol_driver *pdrv;
375 const struct config_item_type *node_type;
378 static const struct stm_pdrv_entry *
379 __stm_lookup_protocol(const char *name)
381 struct stm_pdrv_entry *pe;
384 * If no name is given (NULL or ""), fall back to "p_basic".
386 if (!name || !*name)
387 name = "p_basic";
389 list_for_each_entry(pe, &stm_pdrv_head, entry) {
390 if (!strcmp(name, pe->pdrv->name))
391 return pe;
394 return NULL;
397 int stm_register_protocol(const struct stm_protocol_driver *pdrv)
399 struct stm_pdrv_entry *pe = NULL;
400 int ret = -ENOMEM;
402 mutex_lock(&stm_pdrv_mutex);
404 if (__stm_lookup_protocol(pdrv->name)) {
405 ret = -EEXIST;
406 goto unlock;
409 pe = kzalloc(sizeof(*pe), GFP_KERNEL);
410 if (!pe)
411 goto unlock;
413 if (pdrv->policy_attr) {
414 pe->node_type = get_policy_node_type(pdrv->policy_attr);
415 if (!pe->node_type)
416 goto unlock;
419 list_add_tail(&pe->entry, &stm_pdrv_head);
420 pe->pdrv = pdrv;
422 ret = 0;
423 unlock:
424 mutex_unlock(&stm_pdrv_mutex);
426 if (ret)
427 kfree(pe);
429 return ret;
431 EXPORT_SYMBOL_GPL(stm_register_protocol);
433 void stm_unregister_protocol(const struct stm_protocol_driver *pdrv)
435 struct stm_pdrv_entry *pe, *iter;
437 mutex_lock(&stm_pdrv_mutex);
439 list_for_each_entry_safe(pe, iter, &stm_pdrv_head, entry) {
440 if (pe->pdrv == pdrv) {
441 list_del(&pe->entry);
443 if (pe->node_type) {
444 kfree(pe->node_type->ct_attrs);
445 kfree(pe->node_type);
447 kfree(pe);
448 break;
452 mutex_unlock(&stm_pdrv_mutex);
454 EXPORT_SYMBOL_GPL(stm_unregister_protocol);
456 static bool stm_get_protocol(const struct stm_protocol_driver *pdrv)
458 return try_module_get(pdrv->owner);
461 void stm_put_protocol(const struct stm_protocol_driver *pdrv)
463 module_put(pdrv->owner);
466 int stm_lookup_protocol(const char *name,
467 const struct stm_protocol_driver **pdrv,
468 const struct config_item_type **node_type)
470 const struct stm_pdrv_entry *pe;
472 mutex_lock(&stm_pdrv_mutex);
474 pe = __stm_lookup_protocol(name);
475 if (pe && pe->pdrv && stm_get_protocol(pe->pdrv)) {
476 *pdrv = pe->pdrv;
477 *node_type = pe->node_type;
480 mutex_unlock(&stm_pdrv_mutex);
482 return pe ? 0 : -ENOENT;
485 static int stm_char_open(struct inode *inode, struct file *file)
487 struct stm_file *stmf;
488 struct device *dev;
489 unsigned int major = imajor(inode);
490 int err = -ENOMEM;
492 dev = class_find_device(&stm_class, NULL, &major, major_match);
493 if (!dev)
494 return -ENODEV;
496 stmf = kzalloc(sizeof(*stmf), GFP_KERNEL);
497 if (!stmf)
498 goto err_put_device;
500 err = -ENODEV;
501 stm_output_init(&stmf->output);
502 stmf->stm = to_stm_device(dev);
504 if (!try_module_get(stmf->stm->owner))
505 goto err_free;
507 file->private_data = stmf;
509 return nonseekable_open(inode, file);
511 err_free:
512 kfree(stmf);
513 err_put_device:
514 /* matches class_find_device() above */
515 put_device(dev);
517 return err;
520 static int stm_char_release(struct inode *inode, struct file *file)
522 struct stm_file *stmf = file->private_data;
523 struct stm_device *stm = stmf->stm;
525 if (stm->data->unlink)
526 stm->data->unlink(stm->data, stmf->output.master,
527 stmf->output.channel);
529 stm_output_free(stm, &stmf->output);
532 * matches the stm_char_open()'s
533 * class_find_device() + try_module_get()
535 stm_put_device(stm);
536 kfree(stmf);
538 return 0;
541 static int
542 stm_assign_first_policy(struct stm_device *stm, struct stm_output *output,
543 char **ids, unsigned int width)
545 struct stp_policy_node *pn;
546 int err, n;
549 * On success, stp_policy_node_lookup() will return holding the
550 * configfs subsystem mutex, which is then released in
551 * stp_policy_node_put(). This allows the pdrv->output_open() in
552 * stm_output_assign() to serialize against the attribute accessors.
554 for (n = 0, pn = NULL; ids[n] && !pn; n++)
555 pn = stp_policy_node_lookup(stm, ids[n]);
557 if (!pn)
558 return -EINVAL;
560 err = stm_output_assign(stm, width, pn, output);
562 stp_policy_node_put(pn);
564 return err;
568 * stm_data_write() - send the given payload as data packets
569 * @data: stm driver's data
570 * @m: STP master
571 * @c: STP channel
572 * @ts_first: timestamp the first packet
573 * @buf: data payload buffer
574 * @count: data payload size
576 ssize_t notrace stm_data_write(struct stm_data *data, unsigned int m,
577 unsigned int c, bool ts_first, const void *buf,
578 size_t count)
580 unsigned int flags = ts_first ? STP_PACKET_TIMESTAMPED : 0;
581 ssize_t sz;
582 size_t pos;
584 for (pos = 0, sz = 0; pos < count; pos += sz) {
585 sz = min_t(unsigned int, count - pos, 8);
586 sz = data->packet(data, m, c, STP_PACKET_DATA, flags, sz,
587 &((u8 *)buf)[pos]);
588 if (sz <= 0)
589 break;
591 if (ts_first) {
592 flags = 0;
593 ts_first = false;
597 return sz < 0 ? sz : pos;
599 EXPORT_SYMBOL_GPL(stm_data_write);
601 static ssize_t notrace
602 stm_write(struct stm_device *stm, struct stm_output *output,
603 unsigned int chan, const char *buf, size_t count)
605 int err;
607 /* stm->pdrv is serialized against policy_mutex */
608 if (!stm->pdrv)
609 return -ENODEV;
611 err = stm->pdrv->write(stm->data, output, chan, buf, count);
612 if (err < 0)
613 return err;
615 return err;
618 static ssize_t stm_char_write(struct file *file, const char __user *buf,
619 size_t count, loff_t *ppos)
621 struct stm_file *stmf = file->private_data;
622 struct stm_device *stm = stmf->stm;
623 char *kbuf;
624 int err;
626 if (count + 1 > PAGE_SIZE)
627 count = PAGE_SIZE - 1;
630 * If no m/c have been assigned to this writer up to this
631 * point, try to use the task name and "default" policy entries.
633 if (!stmf->output.nr_chans) {
634 char comm[sizeof(current->comm)];
635 char *ids[] = { comm, "default", NULL };
637 get_task_comm(comm, current);
639 err = stm_assign_first_policy(stmf->stm, &stmf->output, ids, 1);
641 * EBUSY means that somebody else just assigned this
642 * output, which is just fine for write()
644 if (err)
645 return err;
648 kbuf = kmalloc(count + 1, GFP_KERNEL);
649 if (!kbuf)
650 return -ENOMEM;
652 err = copy_from_user(kbuf, buf, count);
653 if (err) {
654 kfree(kbuf);
655 return -EFAULT;
658 pm_runtime_get_sync(&stm->dev);
660 count = stm_write(stm, &stmf->output, 0, kbuf, count);
662 pm_runtime_mark_last_busy(&stm->dev);
663 pm_runtime_put_autosuspend(&stm->dev);
664 kfree(kbuf);
666 return count;
669 static void stm_mmap_open(struct vm_area_struct *vma)
671 struct stm_file *stmf = vma->vm_file->private_data;
672 struct stm_device *stm = stmf->stm;
674 pm_runtime_get(&stm->dev);
677 static void stm_mmap_close(struct vm_area_struct *vma)
679 struct stm_file *stmf = vma->vm_file->private_data;
680 struct stm_device *stm = stmf->stm;
682 pm_runtime_mark_last_busy(&stm->dev);
683 pm_runtime_put_autosuspend(&stm->dev);
686 static const struct vm_operations_struct stm_mmap_vmops = {
687 .open = stm_mmap_open,
688 .close = stm_mmap_close,
691 static int stm_char_mmap(struct file *file, struct vm_area_struct *vma)
693 struct stm_file *stmf = file->private_data;
694 struct stm_device *stm = stmf->stm;
695 unsigned long size, phys;
697 if (!stm->data->mmio_addr)
698 return -EOPNOTSUPP;
700 if (vma->vm_pgoff)
701 return -EINVAL;
703 size = vma->vm_end - vma->vm_start;
705 if (stmf->output.nr_chans * stm->data->sw_mmiosz != size)
706 return -EINVAL;
708 phys = stm->data->mmio_addr(stm->data, stmf->output.master,
709 stmf->output.channel,
710 stmf->output.nr_chans);
712 if (!phys)
713 return -EINVAL;
715 pm_runtime_get_sync(&stm->dev);
717 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
718 vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
719 vma->vm_ops = &stm_mmap_vmops;
720 vm_iomap_memory(vma, phys, size);
722 return 0;
725 static int stm_char_policy_set_ioctl(struct stm_file *stmf, void __user *arg)
727 struct stm_device *stm = stmf->stm;
728 struct stp_policy_id *id;
729 char *ids[] = { NULL, NULL };
730 int ret = -EINVAL, wlimit = 1;
731 u32 size;
733 if (stmf->output.nr_chans)
734 return -EBUSY;
736 if (copy_from_user(&size, arg, sizeof(size)))
737 return -EFAULT;
739 if (size < sizeof(*id) || size >= PATH_MAX + sizeof(*id))
740 return -EINVAL;
743 * size + 1 to make sure the .id string at the bottom is terminated,
744 * which is also why memdup_user() is not useful here
746 id = kzalloc(size + 1, GFP_KERNEL);
747 if (!id)
748 return -ENOMEM;
750 if (copy_from_user(id, arg, size)) {
751 ret = -EFAULT;
752 goto err_free;
755 if (id->__reserved_0 || id->__reserved_1)
756 goto err_free;
758 if (stm->data->sw_mmiosz)
759 wlimit = PAGE_SIZE / stm->data->sw_mmiosz;
761 if (id->width < 1 || id->width > wlimit)
762 goto err_free;
764 ids[0] = id->id;
765 ret = stm_assign_first_policy(stmf->stm, &stmf->output, ids,
766 id->width);
767 if (ret)
768 goto err_free;
770 if (stm->data->link)
771 ret = stm->data->link(stm->data, stmf->output.master,
772 stmf->output.channel);
774 if (ret)
775 stm_output_free(stmf->stm, &stmf->output);
777 err_free:
778 kfree(id);
780 return ret;
783 static int stm_char_policy_get_ioctl(struct stm_file *stmf, void __user *arg)
785 struct stp_policy_id id = {
786 .size = sizeof(id),
787 .master = stmf->output.master,
788 .channel = stmf->output.channel,
789 .width = stmf->output.nr_chans,
790 .__reserved_0 = 0,
791 .__reserved_1 = 0,
794 return copy_to_user(arg, &id, id.size) ? -EFAULT : 0;
797 static long
798 stm_char_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
800 struct stm_file *stmf = file->private_data;
801 struct stm_data *stm_data = stmf->stm->data;
802 int err = -ENOTTY;
803 u64 options;
805 switch (cmd) {
806 case STP_POLICY_ID_SET:
807 err = stm_char_policy_set_ioctl(stmf, (void __user *)arg);
808 if (err)
809 return err;
811 return stm_char_policy_get_ioctl(stmf, (void __user *)arg);
813 case STP_POLICY_ID_GET:
814 return stm_char_policy_get_ioctl(stmf, (void __user *)arg);
816 case STP_SET_OPTIONS:
817 if (copy_from_user(&options, (u64 __user *)arg, sizeof(u64)))
818 return -EFAULT;
820 if (stm_data->set_options)
821 err = stm_data->set_options(stm_data,
822 stmf->output.master,
823 stmf->output.channel,
824 stmf->output.nr_chans,
825 options);
827 break;
828 default:
829 break;
832 return err;
835 static const struct file_operations stm_fops = {
836 .open = stm_char_open,
837 .release = stm_char_release,
838 .write = stm_char_write,
839 .mmap = stm_char_mmap,
840 .unlocked_ioctl = stm_char_ioctl,
841 .compat_ioctl = compat_ptr_ioctl,
842 .llseek = no_llseek,
845 static void stm_device_release(struct device *dev)
847 struct stm_device *stm = to_stm_device(dev);
849 vfree(stm);
852 int stm_register_device(struct device *parent, struct stm_data *stm_data,
853 struct module *owner)
855 struct stm_device *stm;
856 unsigned int nmasters;
857 int err = -ENOMEM;
859 if (!stm_core_up)
860 return -EPROBE_DEFER;
862 if (!stm_data->packet || !stm_data->sw_nchannels)
863 return -EINVAL;
865 nmasters = stm_data->sw_end - stm_data->sw_start + 1;
866 stm = vzalloc(sizeof(*stm) + nmasters * sizeof(void *));
867 if (!stm)
868 return -ENOMEM;
870 stm->major = register_chrdev(0, stm_data->name, &stm_fops);
871 if (stm->major < 0)
872 goto err_free;
874 device_initialize(&stm->dev);
875 stm->dev.devt = MKDEV(stm->major, 0);
876 stm->dev.class = &stm_class;
877 stm->dev.parent = parent;
878 stm->dev.release = stm_device_release;
880 mutex_init(&stm->link_mutex);
881 spin_lock_init(&stm->link_lock);
882 INIT_LIST_HEAD(&stm->link_list);
884 /* initialize the object before it is accessible via sysfs */
885 spin_lock_init(&stm->mc_lock);
886 mutex_init(&stm->policy_mutex);
887 stm->sw_nmasters = nmasters;
888 stm->owner = owner;
889 stm->data = stm_data;
890 stm_data->stm = stm;
892 err = kobject_set_name(&stm->dev.kobj, "%s", stm_data->name);
893 if (err)
894 goto err_device;
896 err = device_add(&stm->dev);
897 if (err)
898 goto err_device;
901 * Use delayed autosuspend to avoid bouncing back and forth
902 * on recurring character device writes, with the initial
903 * delay time of 2 seconds.
905 pm_runtime_no_callbacks(&stm->dev);
906 pm_runtime_use_autosuspend(&stm->dev);
907 pm_runtime_set_autosuspend_delay(&stm->dev, 2000);
908 pm_runtime_set_suspended(&stm->dev);
909 pm_runtime_enable(&stm->dev);
911 return 0;
913 err_device:
914 unregister_chrdev(stm->major, stm_data->name);
916 /* matches device_initialize() above */
917 put_device(&stm->dev);
918 err_free:
919 vfree(stm);
921 return err;
923 EXPORT_SYMBOL_GPL(stm_register_device);
925 static int __stm_source_link_drop(struct stm_source_device *src,
926 struct stm_device *stm);
928 void stm_unregister_device(struct stm_data *stm_data)
930 struct stm_device *stm = stm_data->stm;
931 struct stm_source_device *src, *iter;
932 int i, ret;
934 pm_runtime_dont_use_autosuspend(&stm->dev);
935 pm_runtime_disable(&stm->dev);
937 mutex_lock(&stm->link_mutex);
938 list_for_each_entry_safe(src, iter, &stm->link_list, link_entry) {
939 ret = __stm_source_link_drop(src, stm);
941 * src <-> stm link must not change under the same
942 * stm::link_mutex, so complain loudly if it has;
943 * also in this situation ret!=0 means this src is
944 * not connected to this stm and it should be otherwise
945 * safe to proceed with the tear-down of stm.
947 WARN_ON_ONCE(ret);
949 mutex_unlock(&stm->link_mutex);
951 synchronize_srcu(&stm_source_srcu);
953 unregister_chrdev(stm->major, stm_data->name);
955 mutex_lock(&stm->policy_mutex);
956 if (stm->policy)
957 stp_policy_unbind(stm->policy);
958 mutex_unlock(&stm->policy_mutex);
960 for (i = stm->data->sw_start; i <= stm->data->sw_end; i++)
961 stp_master_free(stm, i);
963 device_unregister(&stm->dev);
964 stm_data->stm = NULL;
966 EXPORT_SYMBOL_GPL(stm_unregister_device);
969 * stm::link_list access serialization uses a spinlock and a mutex; holding
970 * either of them guarantees that the list is stable; modification requires
971 * holding both of them.
973 * Lock ordering is as follows:
974 * stm::link_mutex
975 * stm::link_lock
976 * src::link_lock
980 * stm_source_link_add() - connect an stm_source device to an stm device
981 * @src: stm_source device
982 * @stm: stm device
984 * This function establishes a link from stm_source to an stm device so that
985 * the former can send out trace data to the latter.
987 * Return: 0 on success, -errno otherwise.
989 static int stm_source_link_add(struct stm_source_device *src,
990 struct stm_device *stm)
992 char *ids[] = { NULL, "default", NULL };
993 int err = -ENOMEM;
995 mutex_lock(&stm->link_mutex);
996 spin_lock(&stm->link_lock);
997 spin_lock(&src->link_lock);
999 /* src->link is dereferenced under stm_source_srcu but not the list */
1000 rcu_assign_pointer(src->link, stm);
1001 list_add_tail(&src->link_entry, &stm->link_list);
1003 spin_unlock(&src->link_lock);
1004 spin_unlock(&stm->link_lock);
1005 mutex_unlock(&stm->link_mutex);
1007 ids[0] = kstrdup(src->data->name, GFP_KERNEL);
1008 if (!ids[0])
1009 goto fail_detach;
1011 err = stm_assign_first_policy(stm, &src->output, ids,
1012 src->data->nr_chans);
1013 kfree(ids[0]);
1015 if (err)
1016 goto fail_detach;
1018 /* this is to notify the STM device that a new link has been made */
1019 if (stm->data->link)
1020 err = stm->data->link(stm->data, src->output.master,
1021 src->output.channel);
1023 if (err)
1024 goto fail_free_output;
1026 /* this is to let the source carry out all necessary preparations */
1027 if (src->data->link)
1028 src->data->link(src->data);
1030 return 0;
1032 fail_free_output:
1033 stm_output_free(stm, &src->output);
1035 fail_detach:
1036 mutex_lock(&stm->link_mutex);
1037 spin_lock(&stm->link_lock);
1038 spin_lock(&src->link_lock);
1040 rcu_assign_pointer(src->link, NULL);
1041 list_del_init(&src->link_entry);
1043 spin_unlock(&src->link_lock);
1044 spin_unlock(&stm->link_lock);
1045 mutex_unlock(&stm->link_mutex);
1047 return err;
1051 * __stm_source_link_drop() - detach stm_source from an stm device
1052 * @src: stm_source device
1053 * @stm: stm device
1055 * If @stm is @src::link, disconnect them from one another and put the
1056 * reference on the @stm device.
1058 * Caller must hold stm::link_mutex.
1060 static int __stm_source_link_drop(struct stm_source_device *src,
1061 struct stm_device *stm)
1063 struct stm_device *link;
1064 int ret = 0;
1066 lockdep_assert_held(&stm->link_mutex);
1068 /* for stm::link_list modification, we hold both mutex and spinlock */
1069 spin_lock(&stm->link_lock);
1070 spin_lock(&src->link_lock);
1071 link = srcu_dereference_check(src->link, &stm_source_srcu, 1);
1074 * The linked device may have changed since we last looked, because
1075 * we weren't holding the src::link_lock back then; if this is the
1076 * case, tell the caller to retry.
1078 if (link != stm) {
1079 ret = -EAGAIN;
1080 goto unlock;
1083 stm_output_free(link, &src->output);
1084 list_del_init(&src->link_entry);
1085 pm_runtime_mark_last_busy(&link->dev);
1086 pm_runtime_put_autosuspend(&link->dev);
1087 /* matches stm_find_device() from stm_source_link_store() */
1088 stm_put_device(link);
1089 rcu_assign_pointer(src->link, NULL);
1091 unlock:
1092 spin_unlock(&src->link_lock);
1093 spin_unlock(&stm->link_lock);
1096 * Call the unlink callbacks for both source and stm, when we know
1097 * that we have actually performed the unlinking.
1099 if (!ret) {
1100 if (src->data->unlink)
1101 src->data->unlink(src->data);
1103 if (stm->data->unlink)
1104 stm->data->unlink(stm->data, src->output.master,
1105 src->output.channel);
1108 return ret;
1112 * stm_source_link_drop() - detach stm_source from its stm device
1113 * @src: stm_source device
1115 * Unlinking means disconnecting from source's STM device; after this
1116 * writes will be unsuccessful until it is linked to a new STM device.
1118 * This will happen on "stm_source_link" sysfs attribute write to undo
1119 * the existing link (if any), or on linked STM device's de-registration.
1121 static void stm_source_link_drop(struct stm_source_device *src)
1123 struct stm_device *stm;
1124 int idx, ret;
1126 retry:
1127 idx = srcu_read_lock(&stm_source_srcu);
1129 * The stm device will be valid for the duration of this
1130 * read section, but the link may change before we grab
1131 * the src::link_lock in __stm_source_link_drop().
1133 stm = srcu_dereference(src->link, &stm_source_srcu);
1135 ret = 0;
1136 if (stm) {
1137 mutex_lock(&stm->link_mutex);
1138 ret = __stm_source_link_drop(src, stm);
1139 mutex_unlock(&stm->link_mutex);
1142 srcu_read_unlock(&stm_source_srcu, idx);
1144 /* if it did change, retry */
1145 if (ret == -EAGAIN)
1146 goto retry;
1149 static ssize_t stm_source_link_show(struct device *dev,
1150 struct device_attribute *attr,
1151 char *buf)
1153 struct stm_source_device *src = to_stm_source_device(dev);
1154 struct stm_device *stm;
1155 int idx, ret;
1157 idx = srcu_read_lock(&stm_source_srcu);
1158 stm = srcu_dereference(src->link, &stm_source_srcu);
1159 ret = sprintf(buf, "%s\n",
1160 stm ? dev_name(&stm->dev) : "<none>");
1161 srcu_read_unlock(&stm_source_srcu, idx);
1163 return ret;
1166 static ssize_t stm_source_link_store(struct device *dev,
1167 struct device_attribute *attr,
1168 const char *buf, size_t count)
1170 struct stm_source_device *src = to_stm_source_device(dev);
1171 struct stm_device *link;
1172 int err;
1174 stm_source_link_drop(src);
1176 link = stm_find_device(buf);
1177 if (!link)
1178 return -EINVAL;
1180 pm_runtime_get(&link->dev);
1182 err = stm_source_link_add(src, link);
1183 if (err) {
1184 pm_runtime_put_autosuspend(&link->dev);
1185 /* matches the stm_find_device() above */
1186 stm_put_device(link);
1189 return err ? : count;
1192 static DEVICE_ATTR_RW(stm_source_link);
1194 static struct attribute *stm_source_attrs[] = {
1195 &dev_attr_stm_source_link.attr,
1196 NULL,
1199 ATTRIBUTE_GROUPS(stm_source);
1201 static struct class stm_source_class = {
1202 .name = "stm_source",
1203 .dev_groups = stm_source_groups,
1206 static void stm_source_device_release(struct device *dev)
1208 struct stm_source_device *src = to_stm_source_device(dev);
1210 kfree(src);
1214 * stm_source_register_device() - register an stm_source device
1215 * @parent: parent device
1216 * @data: device description structure
1218 * This will create a device of stm_source class that can write
1219 * data to an stm device once linked.
1221 * Return: 0 on success, -errno otherwise.
1223 int stm_source_register_device(struct device *parent,
1224 struct stm_source_data *data)
1226 struct stm_source_device *src;
1227 int err;
1229 if (!stm_core_up)
1230 return -EPROBE_DEFER;
1232 src = kzalloc(sizeof(*src), GFP_KERNEL);
1233 if (!src)
1234 return -ENOMEM;
1236 device_initialize(&src->dev);
1237 src->dev.class = &stm_source_class;
1238 src->dev.parent = parent;
1239 src->dev.release = stm_source_device_release;
1241 err = kobject_set_name(&src->dev.kobj, "%s", data->name);
1242 if (err)
1243 goto err;
1245 pm_runtime_no_callbacks(&src->dev);
1246 pm_runtime_forbid(&src->dev);
1248 err = device_add(&src->dev);
1249 if (err)
1250 goto err;
1252 stm_output_init(&src->output);
1253 spin_lock_init(&src->link_lock);
1254 INIT_LIST_HEAD(&src->link_entry);
1255 src->data = data;
1256 data->src = src;
1258 return 0;
1260 err:
1261 put_device(&src->dev);
1263 return err;
1265 EXPORT_SYMBOL_GPL(stm_source_register_device);
1268 * stm_source_unregister_device() - unregister an stm_source device
1269 * @data: device description that was used to register the device
1271 * This will remove a previously created stm_source device from the system.
1273 void stm_source_unregister_device(struct stm_source_data *data)
1275 struct stm_source_device *src = data->src;
1277 stm_source_link_drop(src);
1279 device_unregister(&src->dev);
1281 EXPORT_SYMBOL_GPL(stm_source_unregister_device);
1283 int notrace stm_source_write(struct stm_source_data *data,
1284 unsigned int chan,
1285 const char *buf, size_t count)
1287 struct stm_source_device *src = data->src;
1288 struct stm_device *stm;
1289 int idx;
1291 if (!src->output.nr_chans)
1292 return -ENODEV;
1294 if (chan >= src->output.nr_chans)
1295 return -EINVAL;
1297 idx = srcu_read_lock(&stm_source_srcu);
1299 stm = srcu_dereference(src->link, &stm_source_srcu);
1300 if (stm)
1301 count = stm_write(stm, &src->output, chan, buf, count);
1302 else
1303 count = -ENODEV;
1305 srcu_read_unlock(&stm_source_srcu, idx);
1307 return count;
1309 EXPORT_SYMBOL_GPL(stm_source_write);
1311 static int __init stm_core_init(void)
1313 int err;
1315 err = class_register(&stm_class);
1316 if (err)
1317 return err;
1319 err = class_register(&stm_source_class);
1320 if (err)
1321 goto err_stm;
1323 err = stp_configfs_init();
1324 if (err)
1325 goto err_src;
1327 init_srcu_struct(&stm_source_srcu);
1328 INIT_LIST_HEAD(&stm_pdrv_head);
1329 mutex_init(&stm_pdrv_mutex);
1332 * So as to not confuse existing users with a requirement
1333 * to load yet another module, do it here.
1335 if (IS_ENABLED(CONFIG_STM_PROTO_BASIC))
1336 (void)request_module_nowait("stm_p_basic");
1337 stm_core_up++;
1339 return 0;
1341 err_src:
1342 class_unregister(&stm_source_class);
1343 err_stm:
1344 class_unregister(&stm_class);
1346 return err;
1349 module_init(stm_core_init);
1351 static void __exit stm_core_exit(void)
1353 cleanup_srcu_struct(&stm_source_srcu);
1354 class_unregister(&stm_source_class);
1355 class_unregister(&stm_class);
1356 stp_configfs_exit();
1359 module_exit(stm_core_exit);
1361 MODULE_LICENSE("GPL v2");
1362 MODULE_DESCRIPTION("System Trace Module device class");
1363 MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");