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1// SPDX-License-Identifier: GPL-2.02/*3 * System Trace Module (STM) infrastructure4 * Copyright (c) 2014, Intel Corporation.5 *6 * STM class implements generic infrastructure for System Trace Module devices7 * as defined in MIPI STPv2 specification.8 */9 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"24 25#include <uapi/linux/stm.h>26 27static unsigned int stm_core_up;28 29/*30 * The SRCU here makes sure that STM device doesn't disappear from under a31 * stm_source_write() caller, which may want to have as little overhead as32 * possible.33 */34static struct srcu_struct stm_source_srcu;35 36static ssize_t masters_show(struct device *dev,37 struct device_attribute *attr,38 char *buf)39{40 struct stm_device *stm = to_stm_device(dev);41 int ret;42 43 ret = sprintf(buf, "%u %u\n", stm->data->sw_start, stm->data->sw_end);44 45 return ret;46}47 48static DEVICE_ATTR_RO(masters);49 50static ssize_t channels_show(struct device *dev,51 struct device_attribute *attr,52 char *buf)53{54 struct stm_device *stm = to_stm_device(dev);55 int ret;56 57 ret = sprintf(buf, "%u\n", stm->data->sw_nchannels);58 59 return ret;60}61 62static DEVICE_ATTR_RO(channels);63 64static ssize_t hw_override_show(struct device *dev,65 struct device_attribute *attr,66 char *buf)67{68 struct stm_device *stm = to_stm_device(dev);69 int ret;70 71 ret = sprintf(buf, "%u\n", stm->data->hw_override);72 73 return ret;74}75 76static DEVICE_ATTR_RO(hw_override);77 78static struct attribute *stm_attrs[] = {79 &dev_attr_masters.attr,80 &dev_attr_channels.attr,81 &dev_attr_hw_override.attr,82 NULL,83};84 85ATTRIBUTE_GROUPS(stm);86 87static struct class stm_class = {88 .name = "stm",89 .dev_groups = stm_groups,90};91 92/**93 * stm_find_device() - find stm device by name94 * @buf: character buffer containing the name95 *96 * This is called when either policy gets assigned to an stm device or an97 * stm_source device gets linked to an stm device.98 *99 * This grabs device's reference (get_device()) and module reference, both100 * of which the calling path needs to make sure to drop with stm_put_device().101 *102 * Return: stm device pointer or null if lookup failed.103 */104struct stm_device *stm_find_device(const char *buf)105{106 struct stm_device *stm;107 struct device *dev;108 109 if (!stm_core_up)110 return NULL;111 112 dev = class_find_device_by_name(&stm_class, buf);113 if (!dev)114 return NULL;115 116 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;121 }122 123 return stm;124}125 126/**127 * stm_put_device() - drop references on the stm device128 * @stm: stm device, previously acquired by stm_find_device()129 *130 * This drops the module reference and device reference taken by131 * stm_find_device() or stm_char_open().132 */133void stm_put_device(struct stm_device *stm)134{135 module_put(stm->owner);136 put_device(&stm->dev);137}138 139/*140 * Internally we only care about software-writable masters here, that is the141 * ones in the range [stm_data->sw_start..stm_data..sw_end], however we need142 * original master numbers to be visible externally, since they are the ones143 * that will appear in the STP stream. Thus, the internal bookkeeping uses144 * $master - stm_data->sw_start to reference master descriptors and such.145 */146 147#define __stm_master(_s, _m) \148 ((_s)->masters[(_m) - (_s)->data->sw_start])149 150static inline struct stp_master *151stm_master(struct stm_device *stm, unsigned int idx)152{153 if (idx < stm->data->sw_start || idx > stm->data->sw_end)154 return NULL;155 156 return __stm_master(stm, idx);157}158 159static int stp_master_alloc(struct stm_device *stm, unsigned int idx)160{161 struct stp_master *master;162 163 master = kzalloc(struct_size(master, chan_map,164 BITS_TO_LONGS(stm->data->sw_nchannels)),165 GFP_ATOMIC);166 if (!master)167 return -ENOMEM;168 169 master->nr_free = stm->data->sw_nchannels;170 __stm_master(stm, idx) = master;171 172 return 0;173}174 175static void stp_master_free(struct stm_device *stm, unsigned int idx)176{177 struct stp_master *master = stm_master(stm, idx);178 179 if (!master)180 return;181 182 __stm_master(stm, idx) = NULL;183 kfree(master);184}185 186static void stm_output_claim(struct stm_device *stm, struct stm_output *output)187{188 struct stp_master *master = stm_master(stm, output->master);189 190 lockdep_assert_held(&stm->mc_lock);191 lockdep_assert_held(&output->lock);192 193 if (WARN_ON_ONCE(master->nr_free < output->nr_chans))194 return;195 196 bitmap_allocate_region(&master->chan_map[0], output->channel,197 ilog2(output->nr_chans));198 199 master->nr_free -= output->nr_chans;200}201 202static void203stm_output_disclaim(struct stm_device *stm, struct stm_output *output)204{205 struct stp_master *master = stm_master(stm, output->master);206 207 lockdep_assert_held(&stm->mc_lock);208 lockdep_assert_held(&output->lock);209 210 bitmap_release_region(&master->chan_map[0], output->channel,211 ilog2(output->nr_chans));212 213 master->nr_free += output->nr_chans;214 output->nr_chans = 0;215}216 217/*218 * This is like bitmap_find_free_region(), except it can ignore @start bits219 * at the beginning.220 */221static int find_free_channels(unsigned long *bitmap, unsigned int start,222 unsigned int end, unsigned int width)223{224 unsigned int pos;225 int i;226 227 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;231 232 if (pos & (width - 1))233 continue;234 235 for (i = 1; i < width && !test_bit(pos + i, bitmap); i++)236 ;237 if (i == width)238 return pos;239 240 /* step over [pos..pos+i) to continue search */241 pos += i;242 }243 244 return -1;245}246 247static int248stm_find_master_chan(struct stm_device *stm, unsigned int width,249 unsigned int *mstart, unsigned int mend,250 unsigned int *cstart, unsigned int cend)251{252 struct stp_master *master;253 unsigned int midx;254 int pos, err;255 256 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;261 }262 263 master = stm_master(stm, midx);264 265 if (!master->nr_free)266 continue;267 268 pos = find_free_channels(master->chan_map, *cstart, cend,269 width);270 if (pos < 0)271 continue;272 273 *mstart = midx;274 *cstart = pos;275 return 0;276 }277 278 return -ENOSPC;279}280 281static int stm_output_assign(struct stm_device *stm, unsigned int width,282 struct stp_policy_node *policy_node,283 struct stm_output *output)284{285 unsigned int midx, cidx, mend, cend;286 int ret = -EINVAL;287 288 if (width > stm->data->sw_nchannels)289 return -EINVAL;290 291 /* We no longer accept policy_node==NULL here */292 if (WARN_ON_ONCE(!policy_node))293 return -EINVAL;294 295 /*296 * Also, the caller holds reference to policy_node, so it won't297 * disappear on us.298 */299 stp_policy_node_get_ranges(policy_node, &midx, &mend, &cidx, &cend);300 301 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;306 307 ret = stm_find_master_chan(stm, width, &midx, mend, &cidx, cend);308 if (ret < 0)309 goto unlock;310 311 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);316 317 if (WARN_ON_ONCE(!priv))318 goto unlock;319 320 /* configfs subsys mutex is held by the caller */321 ret = stm->pdrv->output_open(priv, output);322 if (ret)323 goto unlock;324 }325 326 stm_output_claim(stm, output);327 dev_dbg(&stm->dev, "assigned %u:%u (+%u)\n", midx, cidx, width);328 329 ret = 0;330unlock:331 if (ret)332 output->nr_chans = 0;333 334 spin_unlock(&output->lock);335 spin_unlock(&stm->mc_lock);336 337 return ret;338}339 340static void stm_output_free(struct stm_device *stm, struct stm_output *output)341{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);350}351 352static void stm_output_init(struct stm_output *output)353{354 spin_lock_init(&output->lock);355}356 357static int major_match(struct device *dev, const void *data)358{359 unsigned int major = *(unsigned int *)data;360 361 return MAJOR(dev->devt) == major;362}363 364/*365 * Framing protocol management366 * Modules can implement STM protocol drivers and (un-)register them367 * with the STM class framework.368 */369static struct list_head stm_pdrv_head;370static struct mutex stm_pdrv_mutex;371 372struct stm_pdrv_entry {373 struct list_head entry;374 const struct stm_protocol_driver *pdrv;375 const struct config_item_type *node_type;376};377 378static const struct stm_pdrv_entry *379__stm_lookup_protocol(const char *name)380{381 struct stm_pdrv_entry *pe;382 383 /*384 * If no name is given (NULL or ""), fall back to "p_basic".385 */386 if (!name || !*name)387 name = "p_basic";388 389 list_for_each_entry(pe, &stm_pdrv_head, entry) {390 if (!strcmp(name, pe->pdrv->name))391 return pe;392 }393 394 return NULL;395}396 397int stm_register_protocol(const struct stm_protocol_driver *pdrv)398{399 struct stm_pdrv_entry *pe = NULL;400 int ret = -ENOMEM;401 402 mutex_lock(&stm_pdrv_mutex);403 404 if (__stm_lookup_protocol(pdrv->name)) {405 ret = -EEXIST;406 goto unlock;407 }408 409 pe = kzalloc(sizeof(*pe), GFP_KERNEL);410 if (!pe)411 goto unlock;412 413 if (pdrv->policy_attr) {414 pe->node_type = get_policy_node_type(pdrv->policy_attr);415 if (!pe->node_type)416 goto unlock;417 }418 419 list_add_tail(&pe->entry, &stm_pdrv_head);420 pe->pdrv = pdrv;421 422 ret = 0;423unlock:424 mutex_unlock(&stm_pdrv_mutex);425 426 if (ret)427 kfree(pe);428 429 return ret;430}431EXPORT_SYMBOL_GPL(stm_register_protocol);432 433void stm_unregister_protocol(const struct stm_protocol_driver *pdrv)434{435 struct stm_pdrv_entry *pe, *iter;436 437 mutex_lock(&stm_pdrv_mutex);438 439 list_for_each_entry_safe(pe, iter, &stm_pdrv_head, entry) {440 if (pe->pdrv == pdrv) {441 list_del(&pe->entry);442 443 if (pe->node_type) {444 kfree(pe->node_type->ct_attrs);445 kfree(pe->node_type);446 }447 kfree(pe);448 break;449 }450 }451 452 mutex_unlock(&stm_pdrv_mutex);453}454EXPORT_SYMBOL_GPL(stm_unregister_protocol);455 456static bool stm_get_protocol(const struct stm_protocol_driver *pdrv)457{458 return try_module_get(pdrv->owner);459}460 461void stm_put_protocol(const struct stm_protocol_driver *pdrv)462{463 module_put(pdrv->owner);464}465 466int stm_lookup_protocol(const char *name,467 const struct stm_protocol_driver **pdrv,468 const struct config_item_type **node_type)469{470 const struct stm_pdrv_entry *pe;471 472 mutex_lock(&stm_pdrv_mutex);473 474 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;478 }479 480 mutex_unlock(&stm_pdrv_mutex);481 482 return pe ? 0 : -ENOENT;483}484 485static int stm_char_open(struct inode *inode, struct file *file)486{487 struct stm_file *stmf;488 struct device *dev;489 unsigned int major = imajor(inode);490 int err = -ENOMEM;491 492 dev = class_find_device(&stm_class, NULL, &major, major_match);493 if (!dev)494 return -ENODEV;495 496 stmf = kzalloc(sizeof(*stmf), GFP_KERNEL);497 if (!stmf)498 goto err_put_device;499 500 err = -ENODEV;501 stm_output_init(&stmf->output);502 stmf->stm = to_stm_device(dev);503 504 if (!try_module_get(stmf->stm->owner))505 goto err_free;506 507 file->private_data = stmf;508 509 return nonseekable_open(inode, file);510 511err_free:512 kfree(stmf);513err_put_device:514 /* matches class_find_device() above */515 put_device(dev);516 517 return err;518}519 520static int stm_char_release(struct inode *inode, struct file *file)521{522 struct stm_file *stmf = file->private_data;523 struct stm_device *stm = stmf->stm;524 525 if (stm->data->unlink)526 stm->data->unlink(stm->data, stmf->output.master,527 stmf->output.channel);528 529 stm_output_free(stm, &stmf->output);530 531 /*532 * matches the stm_char_open()'s533 * class_find_device() + try_module_get()534 */535 stm_put_device(stm);536 kfree(stmf);537 538 return 0;539}540 541static int542stm_assign_first_policy(struct stm_device *stm, struct stm_output *output,543 char **ids, unsigned int width)544{545 struct stp_policy_node *pn;546 int err, n;547 548 /*549 * On success, stp_policy_node_lookup() will return holding the550 * configfs subsystem mutex, which is then released in551 * stp_policy_node_put(). This allows the pdrv->output_open() in552 * stm_output_assign() to serialize against the attribute accessors.553 */554 for (n = 0, pn = NULL; ids[n] && !pn; n++)555 pn = stp_policy_node_lookup(stm, ids[n]);556 557 if (!pn)558 return -EINVAL;559 560 err = stm_output_assign(stm, width, pn, output);561 562 stp_policy_node_put(pn);563 564 return err;565}566 567/**568 * stm_data_write() - send the given payload as data packets569 * @data: stm driver's data570 * @m: STP master571 * @c: STP channel572 * @ts_first: timestamp the first packet573 * @buf: data payload buffer574 * @count: data payload size575 */576ssize_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)579{580 unsigned int flags = ts_first ? STP_PACKET_TIMESTAMPED : 0;581 ssize_t sz;582 size_t pos;583 584 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;590 591 if (ts_first) {592 flags = 0;593 ts_first = false;594 }595 }596 597 return sz < 0 ? sz : pos;598}599EXPORT_SYMBOL_GPL(stm_data_write);600 601static ssize_t notrace602stm_write(struct stm_device *stm, struct stm_output *output,603 unsigned int chan, const char *buf, size_t count, struct stm_source_data *source)604{605 int err;606 607 /* stm->pdrv is serialized against policy_mutex */608 if (!stm->pdrv)609 return -ENODEV;610 611 err = stm->pdrv->write(stm->data, output, chan, buf, count, source);612 if (err < 0)613 return err;614 615 return err;616}617 618static ssize_t stm_char_write(struct file *file, const char __user *buf,619 size_t count, loff_t *ppos)620{621 struct stm_file *stmf = file->private_data;622 struct stm_device *stm = stmf->stm;623 char *kbuf;624 int err;625 626 if (count + 1 > PAGE_SIZE)627 count = PAGE_SIZE - 1;628 629 /*630 * If no m/c have been assigned to this writer up to this631 * point, try to use the task name and "default" policy entries.632 */633 if (!stmf->output.nr_chans) {634 char comm[sizeof(current->comm)];635 char *ids[] = { comm, "default", NULL };636 637 get_task_comm(comm, current);638 639 err = stm_assign_first_policy(stmf->stm, &stmf->output, ids, 1);640 /*641 * EBUSY means that somebody else just assigned this642 * output, which is just fine for write()643 */644 if (err)645 return err;646 }647 648 kbuf = kmalloc(count + 1, GFP_KERNEL);649 if (!kbuf)650 return -ENOMEM;651 652 err = copy_from_user(kbuf, buf, count);653 if (err) {654 kfree(kbuf);655 return -EFAULT;656 }657 658 pm_runtime_get_sync(&stm->dev);659 660 count = stm_write(stm, &stmf->output, 0, kbuf, count, NULL);661 662 pm_runtime_mark_last_busy(&stm->dev);663 pm_runtime_put_autosuspend(&stm->dev);664 kfree(kbuf);665 666 return count;667}668 669static void stm_mmap_open(struct vm_area_struct *vma)670{671 struct stm_file *stmf = vma->vm_file->private_data;672 struct stm_device *stm = stmf->stm;673 674 pm_runtime_get(&stm->dev);675}676 677static void stm_mmap_close(struct vm_area_struct *vma)678{679 struct stm_file *stmf = vma->vm_file->private_data;680 struct stm_device *stm = stmf->stm;681 682 pm_runtime_mark_last_busy(&stm->dev);683 pm_runtime_put_autosuspend(&stm->dev);684}685 686static const struct vm_operations_struct stm_mmap_vmops = {687 .open = stm_mmap_open,688 .close = stm_mmap_close,689};690 691static int stm_char_mmap(struct file *file, struct vm_area_struct *vma)692{693 struct stm_file *stmf = file->private_data;694 struct stm_device *stm = stmf->stm;695 unsigned long size, phys;696 697 if (!stm->data->mmio_addr)698 return -EOPNOTSUPP;699 700 if (vma->vm_pgoff)701 return -EINVAL;702 703 size = vma->vm_end - vma->vm_start;704 705 if (stmf->output.nr_chans * stm->data->sw_mmiosz != size)706 return -EINVAL;707 708 phys = stm->data->mmio_addr(stm->data, stmf->output.master,709 stmf->output.channel,710 stmf->output.nr_chans);711 712 if (!phys)713 return -EINVAL;714 715 pm_runtime_get_sync(&stm->dev);716 717 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);718 vm_flags_set(vma, VM_IO | VM_DONTEXPAND | VM_DONTDUMP);719 vma->vm_ops = &stm_mmap_vmops;720 vm_iomap_memory(vma, phys, size);721 722 return 0;723}724 725static int stm_char_policy_set_ioctl(struct stm_file *stmf, void __user *arg)726{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;732 733 if (stmf->output.nr_chans)734 return -EBUSY;735 736 if (copy_from_user(&size, arg, sizeof(size)))737 return -EFAULT;738 739 if (size < sizeof(*id) || size >= PATH_MAX + sizeof(*id))740 return -EINVAL;741 742 /*743 * size + 1 to make sure the .id string at the bottom is terminated,744 * which is also why memdup_user() is not useful here745 */746 id = kzalloc(size + 1, GFP_KERNEL);747 if (!id)748 return -ENOMEM;749 750 if (copy_from_user(id, arg, size)) {751 ret = -EFAULT;752 goto err_free;753 }754 755 if (id->__reserved_0 || id->__reserved_1)756 goto err_free;757 758 if (stm->data->sw_mmiosz)759 wlimit = PAGE_SIZE / stm->data->sw_mmiosz;760 761 if (id->width < 1 || id->width > wlimit)762 goto err_free;763 764 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;769 770 if (stm->data->link)771 ret = stm->data->link(stm->data, stmf->output.master,772 stmf->output.channel);773 774 if (ret)775 stm_output_free(stmf->stm, &stmf->output);776 777err_free:778 kfree(id);779 780 return ret;781}782 783static int stm_char_policy_get_ioctl(struct stm_file *stmf, void __user *arg)784{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 = 0,792 };793 794 return copy_to_user(arg, &id, id.size) ? -EFAULT : 0;795}796 797static long798stm_char_ioctl(struct file *file, unsigned int cmd, unsigned long arg)799{800 struct stm_file *stmf = file->private_data;801 struct stm_data *stm_data = stmf->stm->data;802 int err = -ENOTTY;803 u64 options;804 805 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;810 811 return stm_char_policy_get_ioctl(stmf, (void __user *)arg);812 813 case STP_POLICY_ID_GET:814 return stm_char_policy_get_ioctl(stmf, (void __user *)arg);815 816 case STP_SET_OPTIONS:817 if (copy_from_user(&options, (u64 __user *)arg, sizeof(u64)))818 return -EFAULT;819 820 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);826 827 break;828 default:829 break;830 }831 832 return err;833}834 835static 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};843 844static void stm_device_release(struct device *dev)845{846 struct stm_device *stm = to_stm_device(dev);847 848 vfree(stm);849}850 851int stm_register_device(struct device *parent, struct stm_data *stm_data,852 struct module *owner)853{854 struct stm_device *stm;855 unsigned int nmasters;856 int err = -ENOMEM;857 858 if (!stm_core_up)859 return -EPROBE_DEFER;860 861 if (!stm_data->packet || !stm_data->sw_nchannels)862 return -EINVAL;863 864 nmasters = stm_data->sw_end - stm_data->sw_start + 1;865 stm = vzalloc(sizeof(*stm) + nmasters * sizeof(void *));866 if (!stm)867 return -ENOMEM;868 869 stm->major = register_chrdev(0, stm_data->name, &stm_fops);870 if (stm->major < 0) {871 err = stm->major;872 vfree(stm);873 return err;874 }875 876 device_initialize(&stm->dev);877 stm->dev.devt = MKDEV(stm->major, 0);878 stm->dev.class = &stm_class;879 stm->dev.parent = parent;880 stm->dev.release = stm_device_release;881 882 mutex_init(&stm->link_mutex);883 spin_lock_init(&stm->link_lock);884 INIT_LIST_HEAD(&stm->link_list);885 886 /* initialize the object before it is accessible via sysfs */887 spin_lock_init(&stm->mc_lock);888 mutex_init(&stm->policy_mutex);889 stm->sw_nmasters = nmasters;890 stm->owner = owner;891 stm->data = stm_data;892 stm_data->stm = stm;893 894 err = kobject_set_name(&stm->dev.kobj, "%s", stm_data->name);895 if (err)896 goto err_device;897 898 err = device_add(&stm->dev);899 if (err)900 goto err_device;901 902 /*903 * Use delayed autosuspend to avoid bouncing back and forth904 * on recurring character device writes, with the initial905 * delay time of 2 seconds.906 */907 pm_runtime_no_callbacks(&stm->dev);908 pm_runtime_use_autosuspend(&stm->dev);909 pm_runtime_set_autosuspend_delay(&stm->dev, 2000);910 pm_runtime_set_suspended(&stm->dev);911 pm_runtime_enable(&stm->dev);912 913 return 0;914 915err_device:916 unregister_chrdev(stm->major, stm_data->name);917 918 /* calls stm_device_release() */919 put_device(&stm->dev);920 921 return err;922}923EXPORT_SYMBOL_GPL(stm_register_device);924 925static int __stm_source_link_drop(struct stm_source_device *src,926 struct stm_device *stm);927 928void stm_unregister_device(struct stm_data *stm_data)929{930 struct stm_device *stm = stm_data->stm;931 struct stm_source_device *src, *iter;932 int i, ret;933 934 pm_runtime_dont_use_autosuspend(&stm->dev);935 pm_runtime_disable(&stm->dev);936 937 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);940 /*941 * src <-> stm link must not change under the same942 * stm::link_mutex, so complain loudly if it has;943 * also in this situation ret!=0 means this src is944 * not connected to this stm and it should be otherwise945 * safe to proceed with the tear-down of stm.946 */947 WARN_ON_ONCE(ret);948 }949 mutex_unlock(&stm->link_mutex);950 951 synchronize_srcu(&stm_source_srcu);952 953 unregister_chrdev(stm->major, stm_data->name);954 955 mutex_lock(&stm->policy_mutex);956 if (stm->policy)957 stp_policy_unbind(stm->policy);958 mutex_unlock(&stm->policy_mutex);959 960 for (i = stm->data->sw_start; i <= stm->data->sw_end; i++)961 stp_master_free(stm, i);962 963 device_unregister(&stm->dev);964 stm_data->stm = NULL;965}966EXPORT_SYMBOL_GPL(stm_unregister_device);967 968/*969 * stm::link_list access serialization uses a spinlock and a mutex; holding970 * either of them guarantees that the list is stable; modification requires971 * holding both of them.972 *973 * Lock ordering is as follows:974 * stm::link_mutex975 * stm::link_lock976 * src::link_lock977 */978 979/**980 * stm_source_link_add() - connect an stm_source device to an stm device981 * @src: stm_source device982 * @stm: stm device983 *984 * This function establishes a link from stm_source to an stm device so that985 * the former can send out trace data to the latter.986 *987 * Return: 0 on success, -errno otherwise.988 */989static int stm_source_link_add(struct stm_source_device *src,990 struct stm_device *stm)991{992 char *ids[] = { NULL, "default", NULL };993 int err = -ENOMEM;994 995 mutex_lock(&stm->link_mutex);996 spin_lock(&stm->link_lock);997 spin_lock(&src->link_lock);998 999 /* 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);1002 1003 spin_unlock(&src->link_lock);1004 spin_unlock(&stm->link_lock);1005 mutex_unlock(&stm->link_mutex);1006 1007 ids[0] = kstrdup(src->data->name, GFP_KERNEL);1008 if (!ids[0])1009 goto fail_detach;1010 1011 err = stm_assign_first_policy(stm, &src->output, ids,1012 src->data->nr_chans);1013 kfree(ids[0]);1014 1015 if (err)1016 goto fail_detach;1017 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);1022 1023 if (err)1024 goto fail_free_output;1025 1026 /* this is to let the source carry out all necessary preparations */1027 if (src->data->link)1028 src->data->link(src->data);1029 1030 return 0;1031 1032fail_free_output:1033 stm_output_free(stm, &src->output);1034 1035fail_detach:1036 mutex_lock(&stm->link_mutex);1037 spin_lock(&stm->link_lock);1038 spin_lock(&src->link_lock);1039 1040 rcu_assign_pointer(src->link, NULL);1041 list_del_init(&src->link_entry);1042 1043 spin_unlock(&src->link_lock);1044 spin_unlock(&stm->link_lock);1045 mutex_unlock(&stm->link_mutex);1046 1047 return err;1048}1049 1050/**1051 * __stm_source_link_drop() - detach stm_source from an stm device1052 * @src: stm_source device1053 * @stm: stm device1054 *1055 * If @stm is @src::link, disconnect them from one another and put the1056 * reference on the @stm device.1057 *1058 * Caller must hold stm::link_mutex.1059 */1060static int __stm_source_link_drop(struct stm_source_device *src,1061 struct stm_device *stm)1062{1063 struct stm_device *link;1064 int ret = 0;1065 1066 lockdep_assert_held(&stm->link_mutex);1067 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);1072 1073 /*1074 * The linked device may have changed since we last looked, because1075 * we weren't holding the src::link_lock back then; if this is the1076 * case, tell the caller to retry.1077 */1078 if (link != stm) {1079 ret = -EAGAIN;1080 goto unlock;1081 }1082 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);1090 1091unlock:1092 spin_unlock(&src->link_lock);1093 spin_unlock(&stm->link_lock);1094 1095 /*1096 * Call the unlink callbacks for both source and stm, when we know1097 * that we have actually performed the unlinking.1098 */1099 if (!ret) {1100 if (src->data->unlink)1101 src->data->unlink(src->data);1102 1103 if (stm->data->unlink)1104 stm->data->unlink(stm->data, src->output.master,1105 src->output.channel);1106 }1107 1108 return ret;1109}1110 1111/**1112 * stm_source_link_drop() - detach stm_source from its stm device1113 * @src: stm_source device1114 *1115 * Unlinking means disconnecting from source's STM device; after this1116 * writes will be unsuccessful until it is linked to a new STM device.1117 *1118 * This will happen on "stm_source_link" sysfs attribute write to undo1119 * the existing link (if any), or on linked STM device's de-registration.1120 */1121static void stm_source_link_drop(struct stm_source_device *src)1122{1123 struct stm_device *stm;1124 int idx, ret;1125 1126retry:1127 idx = srcu_read_lock(&stm_source_srcu);1128 /*1129 * The stm device will be valid for the duration of this1130 * read section, but the link may change before we grab1131 * the src::link_lock in __stm_source_link_drop().1132 */1133 stm = srcu_dereference(src->link, &stm_source_srcu);1134 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);1140 }1141 1142 srcu_read_unlock(&stm_source_srcu, idx);1143 1144 /* if it did change, retry */1145 if (ret == -EAGAIN)1146 goto retry;1147}1148 1149static ssize_t stm_source_link_show(struct device *dev,1150 struct device_attribute *attr,1151 char *buf)1152{1153 struct stm_source_device *src = to_stm_source_device(dev);1154 struct stm_device *stm;1155 int idx, ret;1156 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);1162 1163 return ret;1164}1165 1166static ssize_t stm_source_link_store(struct device *dev,1167 struct device_attribute *attr,1168 const char *buf, size_t count)1169{1170 struct stm_source_device *src = to_stm_source_device(dev);1171 struct stm_device *link;1172 int err;1173 1174 stm_source_link_drop(src);1175 1176 link = stm_find_device(buf);1177 if (!link)1178 return -EINVAL;1179 1180 pm_runtime_get(&link->dev);1181 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);1187 }1188 1189 return err ? : count;1190}1191 1192static DEVICE_ATTR_RW(stm_source_link);1193 1194static struct attribute *stm_source_attrs[] = {1195 &dev_attr_stm_source_link.attr,1196 NULL,1197};1198 1199ATTRIBUTE_GROUPS(stm_source);1200 1201static struct class stm_source_class = {1202 .name = "stm_source",1203 .dev_groups = stm_source_groups,1204};1205 1206static void stm_source_device_release(struct device *dev)1207{1208 struct stm_source_device *src = to_stm_source_device(dev);1209 1210 kfree(src);1211}1212 1213/**1214 * stm_source_register_device() - register an stm_source device1215 * @parent: parent device1216 * @data: device description structure1217 *1218 * This will create a device of stm_source class that can write1219 * data to an stm device once linked.1220 *1221 * Return: 0 on success, -errno otherwise.1222 */1223int stm_source_register_device(struct device *parent,1224 struct stm_source_data *data)1225{1226 struct stm_source_device *src;1227 int err;1228 1229 if (!stm_core_up)1230 return -EPROBE_DEFER;1231 1232 src = kzalloc(sizeof(*src), GFP_KERNEL);1233 if (!src)1234 return -ENOMEM;1235 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;1240 1241 err = kobject_set_name(&src->dev.kobj, "%s", data->name);1242 if (err)1243 goto err;1244 1245 pm_runtime_no_callbacks(&src->dev);1246 pm_runtime_forbid(&src->dev);1247 1248 err = device_add(&src->dev);1249 if (err)1250 goto err;1251 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;1257 1258 return 0;1259 1260err:1261 put_device(&src->dev);1262 1263 return err;1264}1265EXPORT_SYMBOL_GPL(stm_source_register_device);1266 1267/**1268 * stm_source_unregister_device() - unregister an stm_source device1269 * @data: device description that was used to register the device1270 *1271 * This will remove a previously created stm_source device from the system.1272 */1273void stm_source_unregister_device(struct stm_source_data *data)1274{1275 struct stm_source_device *src = data->src;1276 1277 stm_source_link_drop(src);1278 1279 device_unregister(&src->dev);1280}1281EXPORT_SYMBOL_GPL(stm_source_unregister_device);1282 1283int notrace stm_source_write(struct stm_source_data *data,1284 unsigned int chan,1285 const char *buf, size_t count)1286{1287 struct stm_source_device *src = data->src;1288 struct stm_device *stm;1289 int idx;1290 1291 if (!src->output.nr_chans)1292 return -ENODEV;1293 1294 if (chan >= src->output.nr_chans)1295 return -EINVAL;1296 1297 idx = srcu_read_lock(&stm_source_srcu);1298 1299 stm = srcu_dereference(src->link, &stm_source_srcu);1300 if (stm)1301 count = stm_write(stm, &src->output, chan, buf, count, data);1302 else1303 count = -ENODEV;1304 1305 srcu_read_unlock(&stm_source_srcu, idx);1306 1307 return count;1308}1309EXPORT_SYMBOL_GPL(stm_source_write);1310 1311static int __init stm_core_init(void)1312{1313 int err;1314 1315 err = class_register(&stm_class);1316 if (err)1317 return err;1318 1319 err = class_register(&stm_source_class);1320 if (err)1321 goto err_stm;1322 1323 err = stp_configfs_init();1324 if (err)1325 goto err_src;1326 1327 init_srcu_struct(&stm_source_srcu);1328 INIT_LIST_HEAD(&stm_pdrv_head);1329 mutex_init(&stm_pdrv_mutex);1330 1331 /*1332 * So as to not confuse existing users with a requirement1333 * to load yet another module, do it here.1334 */1335 if (IS_ENABLED(CONFIG_STM_PROTO_BASIC))1336 (void)request_module_nowait("stm_p_basic");1337 stm_core_up++;1338 1339 return 0;1340 1341err_src:1342 class_unregister(&stm_source_class);1343err_stm:1344 class_unregister(&stm_class);1345 1346 return err;1347}1348 1349module_init(stm_core_init);1350 1351static void __exit stm_core_exit(void)1352{1353 cleanup_srcu_struct(&stm_source_srcu);1354 class_unregister(&stm_source_class);1355 class_unregister(&stm_class);1356 stp_configfs_exit();1357}1358 1359module_exit(stm_core_exit);1360 1361MODULE_LICENSE("GPL v2");1362MODULE_DESCRIPTION("System Trace Module device class");1363MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");1364