dts of-platform几个函数分析

DTS 驱动分析

1、clk框架

时钟父子节点关系

clk_prepare_enable如何使能父节点enable函数

在DTS中时钟配置功能

注册时钟：clk_provider

寻找时钟:从DTS树中分析节点,of_parse_phandle_with_args函数，再到clk­provider中找到匹配的时钟，也可以通过时钟名字匹配。

2、watch-dog框架

时钟获取

sp805-wdt-rpoble

devm-clk-get

clk-get

of_clk_get_by_name

of_clk_get

of_parse_phandle_with_args

fclk_get_from_provider

3、of-platform框架

为每个dts中根节点创建平台设备，以及符合的特定总线设备。

/**

410 *of_platform_bus_probe() - Probe the device-tree for platform buses

411 * @root: parent of thefirst level to probe or NULL for the root of the tree

412 * @matches: match tablefor bus nodes

413 * @parent: parent tohook devices from, NULL for toplevel

414 *

415 * Note that children ofthe provided root are not instantiated as devices

416 * unless the specifiedroot itself matches the bus list and is not NULL.

417 */

418 intof_platform_bus_probe(struct device_node *root,

419 conststruct of_device_id *matches,

420 structdevice *parent)

421 {

422 struct device_node*child;

423 int rc = 0;

424

425 root = root ?of_node_get(root) : of_find_node_by_path("/");

426 if (!root)

427 return -EINVAL;

428

429 pr_debug("of_platform_bus_probe()\n");

430 pr_debug("starting at: %s\n", root->full_name);

431

432 /* Do a self checkof bus type, if there's a match, create children */

433 if(of_match_node(matches, root)) {

434 rc =of_platform_bus_create(root, matches, NULL, parent, false);

435 } elsefor_each_child_of_node(root, child) {

436 if(!of_match_node(matches, child))

437 continue;

438 rc =of_platform_bus_create(child, matches, NULL, parent, false);

439 if (rc)

440 break;

441 }

442

443 of_node_put(root);

444 return rc;

445 }

446EXPORT_SYMBOL(of_platform_bus_probe);

447

//先把每个子节点创建完成，若子节点符合匹配，再为每个子节点的子节点创建平台设备。

450 * @root: parent of thefirst level to probe or NULL for the root of the tree

451 * @matches: matchtable, NULL to use the default

452 * @lookup: auxdatatable for matching id and platform_data with device nodes

453 * @parent: parent tohook devices from, NULL for toplevel

454 *

455 * Similar toof_platform_bus_probe(), this function walks the device tree

456 * and creates devicesfrom nodes. It differs in that it follows the modern

457 * convention ofrequiring all device nodes to have a 'compatible' property,

458 * and it is suitablefor creating devices which are children of the root

459 * node(of_platform_bus_probe will only createchildren of the root which

460 *are selected by the @matches argument).

461 *

462 * New board supportshould be using this function instead of

463 *of_platform_bus_probe().

464 *

465 * Returns 0 on success,< 0 on failure.

466 */

467 intof_platform_populate(struct device_node *root,

468 const structof_device_id *matches,

469 const structof_dev_auxdata *lookup,

470 structdevice *parent)

471 {

472 struct device_node*child;

473 int rc = 0;

474

475 root = root ?of_node_get(root) : of_find_node_by_path("/");

476 if (!root)

477 return -EINVAL;

478

479 for_each_child_of_node(root, child) {

480 rc =of_platform_bus_create(child, matches, lookup, parent, true);

481 if (rc)

482 break;

483 }

484

485 of_node_put(root);

486 return rc;

487 }

488EXPORT_SYMBOL_GPL(of_platform_populate);

static intof_platform_bus_create(struct device_node *bus,

361 conststruct of_device_id *matches,

362 conststruct of_dev_auxdata *lookup,

363 structdevice *parent, bool strict)

364 {

365 const structof_dev_auxdata *auxdata;

366 struct device_node*child;

367 structplatform_device *dev;

368 const char *bus_id =NULL;

369 void *platform_data= NULL;

370 int rc = 0;

371

372 /* Make sure it hasa compatible property */

373 if (strict &&(!of_get_property(bus, "compatible", NULL))) {

374 pr_debug("%s()- skipping %s, no compatible prop\n",

375 __func__,bus->full_name);

376 return 0;

377 }

378

379 auxdata =of_dev_lookup(lookup, bus);

380 if (auxdata) {

381 bus_id =auxdata->name;

382 platform_data =auxdata->platform_data;

383 }

384

385 if(of_device_is_compatible(bus, "arm,primecell")) {

386 /*

387 * Don't returnan error here to keep compatibility with older

388 * device treefiles.

389 */