xref: /openbmc/linux/drivers/i2c/i2c-core-acpi.c (revision 32ced09d)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Linux I2C core ACPI support code
4  *
5  * Copyright (C) 2014 Intel Corp, Author: Lan Tianyu <tianyu.lan@intel.com>
6  */
7 
8 #include <linux/acpi.h>
9 #include <linux/device.h>
10 #include <linux/err.h>
11 #include <linux/i2c.h>
12 #include <linux/list.h>
13 #include <linux/module.h>
14 #include <linux/slab.h>
15 
16 #include "i2c-core.h"
17 
18 struct i2c_acpi_handler_data {
19 	struct acpi_connection_info info;
20 	struct i2c_adapter *adapter;
21 };
22 
23 struct gsb_buffer {
24 	u8	status;
25 	u8	len;
26 	union {
27 		u16	wdata;
28 		u8	bdata;
29 		u8	data[0];
30 	};
31 } __packed;
32 
33 struct i2c_acpi_lookup {
34 	struct i2c_board_info *info;
35 	acpi_handle adapter_handle;
36 	acpi_handle device_handle;
37 	acpi_handle search_handle;
38 	int n;
39 	int index;
40 	u32 speed;
41 	u32 min_speed;
42 	u32 force_speed;
43 };
44 
45 /**
46  * i2c_acpi_get_i2c_resource - Gets I2cSerialBus resource if type matches
47  * @ares:	ACPI resource
48  * @i2c:	Pointer to I2cSerialBus resource will be returned here
49  *
50  * Checks if the given ACPI resource is of type I2cSerialBus.
51  * In this case, returns a pointer to it to the caller.
52  *
53  * Returns true if resource type is of I2cSerialBus, otherwise false.
54  */
55 bool i2c_acpi_get_i2c_resource(struct acpi_resource *ares,
56 			       struct acpi_resource_i2c_serialbus **i2c)
57 {
58 	struct acpi_resource_i2c_serialbus *sb;
59 
60 	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
61 		return false;
62 
63 	sb = &ares->data.i2c_serial_bus;
64 	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C)
65 		return false;
66 
67 	*i2c = sb;
68 	return true;
69 }
70 EXPORT_SYMBOL_GPL(i2c_acpi_get_i2c_resource);
71 
72 static int i2c_acpi_fill_info(struct acpi_resource *ares, void *data)
73 {
74 	struct i2c_acpi_lookup *lookup = data;
75 	struct i2c_board_info *info = lookup->info;
76 	struct acpi_resource_i2c_serialbus *sb;
77 	acpi_status status;
78 
79 	if (info->addr || !i2c_acpi_get_i2c_resource(ares, &sb))
80 		return 1;
81 
82 	if (lookup->index != -1 && lookup->n++ != lookup->index)
83 		return 1;
84 
85 	status = acpi_get_handle(lookup->device_handle,
86 				 sb->resource_source.string_ptr,
87 				 &lookup->adapter_handle);
88 	if (ACPI_FAILURE(status))
89 		return 1;
90 
91 	info->addr = sb->slave_address;
92 	lookup->speed = sb->connection_speed;
93 	if (sb->access_mode == ACPI_I2C_10BIT_MODE)
94 		info->flags |= I2C_CLIENT_TEN;
95 
96 	return 1;
97 }
98 
99 static const struct acpi_device_id i2c_acpi_ignored_device_ids[] = {
100 	/*
101 	 * ACPI video acpi_devices, which are handled by the acpi-video driver
102 	 * sometimes contain a SERIAL_TYPE_I2C ACPI resource, ignore these.
103 	 */
104 	{ ACPI_VIDEO_HID, 0 },
105 	{}
106 };
107 
108 static int i2c_acpi_do_lookup(struct acpi_device *adev,
109 			      struct i2c_acpi_lookup *lookup)
110 {
111 	struct i2c_board_info *info = lookup->info;
112 	struct list_head resource_list;
113 	int ret;
114 
115 	if (acpi_bus_get_status(adev) || !adev->status.present)
116 		return -EINVAL;
117 
118 	if (acpi_match_device_ids(adev, i2c_acpi_ignored_device_ids) == 0)
119 		return -ENODEV;
120 
121 	memset(info, 0, sizeof(*info));
122 	lookup->device_handle = acpi_device_handle(adev);
123 
124 	/* Look up for I2cSerialBus resource */
125 	INIT_LIST_HEAD(&resource_list);
126 	ret = acpi_dev_get_resources(adev, &resource_list,
127 				     i2c_acpi_fill_info, lookup);
128 	acpi_dev_free_resource_list(&resource_list);
129 
130 	if (ret < 0 || !info->addr)
131 		return -EINVAL;
132 
133 	return 0;
134 }
135 
136 static int i2c_acpi_add_resource(struct acpi_resource *ares, void *data)
137 {
138 	int *irq = data;
139 	struct resource r;
140 
141 	if (*irq <= 0 && acpi_dev_resource_interrupt(ares, 0, &r))
142 		*irq = i2c_dev_irq_from_resources(&r, 1);
143 
144 	return 1; /* No need to add resource to the list */
145 }
146 
147 /**
148  * i2c_acpi_get_irq - get device IRQ number from ACPI
149  * @client: Pointer to the I2C client device
150  *
151  * Find the IRQ number used by a specific client device.
152  *
153  * Return: The IRQ number or an error code.
154  */
155 int i2c_acpi_get_irq(struct i2c_client *client)
156 {
157 	struct acpi_device *adev = ACPI_COMPANION(&client->dev);
158 	struct list_head resource_list;
159 	int irq = -ENOENT;
160 	int ret;
161 
162 	INIT_LIST_HEAD(&resource_list);
163 
164 	ret = acpi_dev_get_resources(adev, &resource_list,
165 				     i2c_acpi_add_resource, &irq);
166 	if (ret < 0)
167 		return ret;
168 
169 	acpi_dev_free_resource_list(&resource_list);
170 
171 	if (irq == -ENOENT)
172 		irq = acpi_dev_gpio_irq_get(adev, 0);
173 
174 	return irq;
175 }
176 
177 static int i2c_acpi_get_info(struct acpi_device *adev,
178 			     struct i2c_board_info *info,
179 			     struct i2c_adapter *adapter,
180 			     acpi_handle *adapter_handle)
181 {
182 	struct i2c_acpi_lookup lookup;
183 	int ret;
184 
185 	memset(&lookup, 0, sizeof(lookup));
186 	lookup.info = info;
187 	lookup.index = -1;
188 
189 	if (acpi_device_enumerated(adev))
190 		return -EINVAL;
191 
192 	ret = i2c_acpi_do_lookup(adev, &lookup);
193 	if (ret)
194 		return ret;
195 
196 	if (adapter) {
197 		/* The adapter must match the one in I2cSerialBus() connector */
198 		if (ACPI_HANDLE(&adapter->dev) != lookup.adapter_handle)
199 			return -ENODEV;
200 	} else {
201 		struct acpi_device *adapter_adev;
202 
203 		/* The adapter must be present */
204 		if (acpi_bus_get_device(lookup.adapter_handle, &adapter_adev))
205 			return -ENODEV;
206 		if (acpi_bus_get_status(adapter_adev) ||
207 		    !adapter_adev->status.present)
208 			return -ENODEV;
209 	}
210 
211 	info->fwnode = acpi_fwnode_handle(adev);
212 	if (adapter_handle)
213 		*adapter_handle = lookup.adapter_handle;
214 
215 	acpi_set_modalias(adev, dev_name(&adev->dev), info->type,
216 			  sizeof(info->type));
217 
218 	return 0;
219 }
220 
221 static void i2c_acpi_register_device(struct i2c_adapter *adapter,
222 				     struct acpi_device *adev,
223 				     struct i2c_board_info *info)
224 {
225 	adev->power.flags.ignore_parent = true;
226 	acpi_device_set_enumerated(adev);
227 
228 	if (IS_ERR(i2c_new_client_device(adapter, info))) {
229 		adev->power.flags.ignore_parent = false;
230 		dev_err(&adapter->dev,
231 			"failed to add I2C device %s from ACPI\n",
232 			dev_name(&adev->dev));
233 	}
234 }
235 
236 static acpi_status i2c_acpi_add_device(acpi_handle handle, u32 level,
237 				       void *data, void **return_value)
238 {
239 	struct i2c_adapter *adapter = data;
240 	struct acpi_device *adev;
241 	struct i2c_board_info info;
242 
243 	if (acpi_bus_get_device(handle, &adev))
244 		return AE_OK;
245 
246 	if (i2c_acpi_get_info(adev, &info, adapter, NULL))
247 		return AE_OK;
248 
249 	i2c_acpi_register_device(adapter, adev, &info);
250 
251 	return AE_OK;
252 }
253 
254 #define I2C_ACPI_MAX_SCAN_DEPTH 32
255 
256 /**
257  * i2c_acpi_register_devices - enumerate I2C slave devices behind adapter
258  * @adap: pointer to adapter
259  *
260  * Enumerate all I2C slave devices behind this adapter by walking the ACPI
261  * namespace. When a device is found it will be added to the Linux device
262  * model and bound to the corresponding ACPI handle.
263  */
264 void i2c_acpi_register_devices(struct i2c_adapter *adap)
265 {
266 	acpi_status status;
267 
268 	if (!has_acpi_companion(&adap->dev))
269 		return;
270 
271 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
272 				     I2C_ACPI_MAX_SCAN_DEPTH,
273 				     i2c_acpi_add_device, NULL,
274 				     adap, NULL);
275 	if (ACPI_FAILURE(status))
276 		dev_warn(&adap->dev, "failed to enumerate I2C slaves\n");
277 }
278 
279 const struct acpi_device_id *
280 i2c_acpi_match_device(const struct acpi_device_id *matches,
281 		      struct i2c_client *client)
282 {
283 	if (!(client && matches))
284 		return NULL;
285 
286 	return acpi_match_device(matches, &client->dev);
287 }
288 
289 static const struct acpi_device_id i2c_acpi_force_400khz_device_ids[] = {
290 	/*
291 	 * These Silead touchscreen controllers only work at 400KHz, for
292 	 * some reason they do not work at 100KHz. On some devices the ACPI
293 	 * tables list another device at their bus as only being capable
294 	 * of 100KHz, testing has shown that these other devices work fine
295 	 * at 400KHz (as can be expected of any recent i2c hw) so we force
296 	 * the speed of the bus to 400 KHz if a Silead device is present.
297 	 */
298 	{ "MSSL1680", 0 },
299 	{}
300 };
301 
302 static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level,
303 					   void *data, void **return_value)
304 {
305 	struct i2c_acpi_lookup *lookup = data;
306 	struct acpi_device *adev;
307 
308 	if (acpi_bus_get_device(handle, &adev))
309 		return AE_OK;
310 
311 	if (i2c_acpi_do_lookup(adev, lookup))
312 		return AE_OK;
313 
314 	if (lookup->search_handle != lookup->adapter_handle)
315 		return AE_OK;
316 
317 	if (lookup->speed <= lookup->min_speed)
318 		lookup->min_speed = lookup->speed;
319 
320 	if (acpi_match_device_ids(adev, i2c_acpi_force_400khz_device_ids) == 0)
321 		lookup->force_speed = 400000;
322 
323 	return AE_OK;
324 }
325 
326 /**
327  * i2c_acpi_find_bus_speed - find I2C bus speed from ACPI
328  * @dev: The device owning the bus
329  *
330  * Find the I2C bus speed by walking the ACPI namespace for all I2C slaves
331  * devices connected to this bus and use the speed of slowest device.
332  *
333  * Returns the speed in Hz or zero
334  */
335 u32 i2c_acpi_find_bus_speed(struct device *dev)
336 {
337 	struct i2c_acpi_lookup lookup;
338 	struct i2c_board_info dummy;
339 	acpi_status status;
340 
341 	if (!has_acpi_companion(dev))
342 		return 0;
343 
344 	memset(&lookup, 0, sizeof(lookup));
345 	lookup.search_handle = ACPI_HANDLE(dev);
346 	lookup.min_speed = UINT_MAX;
347 	lookup.info = &dummy;
348 	lookup.index = -1;
349 
350 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
351 				     I2C_ACPI_MAX_SCAN_DEPTH,
352 				     i2c_acpi_lookup_speed, NULL,
353 				     &lookup, NULL);
354 
355 	if (ACPI_FAILURE(status)) {
356 		dev_warn(dev, "unable to find I2C bus speed from ACPI\n");
357 		return 0;
358 	}
359 
360 	if (lookup.force_speed) {
361 		if (lookup.force_speed != lookup.min_speed)
362 			dev_warn(dev, FW_BUG "DSDT uses known not-working I2C bus speed %d, forcing it to %d\n",
363 				 lookup.min_speed, lookup.force_speed);
364 		return lookup.force_speed;
365 	} else if (lookup.min_speed != UINT_MAX) {
366 		return lookup.min_speed;
367 	} else {
368 		return 0;
369 	}
370 }
371 EXPORT_SYMBOL_GPL(i2c_acpi_find_bus_speed);
372 
373 static int i2c_acpi_find_match_adapter(struct device *dev, const void *data)
374 {
375 	struct i2c_adapter *adapter = i2c_verify_adapter(dev);
376 
377 	if (!adapter)
378 		return 0;
379 
380 	return ACPI_HANDLE(dev) == (acpi_handle)data;
381 }
382 
383 struct i2c_adapter *i2c_acpi_find_adapter_by_handle(acpi_handle handle)
384 {
385 	struct device *dev;
386 
387 	dev = bus_find_device(&i2c_bus_type, NULL, handle,
388 			      i2c_acpi_find_match_adapter);
389 
390 	return dev ? i2c_verify_adapter(dev) : NULL;
391 }
392 EXPORT_SYMBOL_GPL(i2c_acpi_find_adapter_by_handle);
393 
394 static struct i2c_client *i2c_acpi_find_client_by_adev(struct acpi_device *adev)
395 {
396 	struct device *dev;
397 
398 	dev = bus_find_device_by_acpi_dev(&i2c_bus_type, adev);
399 	return dev ? i2c_verify_client(dev) : NULL;
400 }
401 
402 static int i2c_acpi_notify(struct notifier_block *nb, unsigned long value,
403 			   void *arg)
404 {
405 	struct acpi_device *adev = arg;
406 	struct i2c_board_info info;
407 	acpi_handle adapter_handle;
408 	struct i2c_adapter *adapter;
409 	struct i2c_client *client;
410 
411 	switch (value) {
412 	case ACPI_RECONFIG_DEVICE_ADD:
413 		if (i2c_acpi_get_info(adev, &info, NULL, &adapter_handle))
414 			break;
415 
416 		adapter = i2c_acpi_find_adapter_by_handle(adapter_handle);
417 		if (!adapter)
418 			break;
419 
420 		i2c_acpi_register_device(adapter, adev, &info);
421 		break;
422 	case ACPI_RECONFIG_DEVICE_REMOVE:
423 		if (!acpi_device_enumerated(adev))
424 			break;
425 
426 		client = i2c_acpi_find_client_by_adev(adev);
427 		if (!client)
428 			break;
429 
430 		i2c_unregister_device(client);
431 		put_device(&client->dev);
432 		break;
433 	}
434 
435 	return NOTIFY_OK;
436 }
437 
438 struct notifier_block i2c_acpi_notifier = {
439 	.notifier_call = i2c_acpi_notify,
440 };
441 
442 /**
443  * i2c_acpi_new_device - Create i2c-client for the Nth I2cSerialBus resource
444  * @dev:     Device owning the ACPI resources to get the client from
445  * @index:   Index of ACPI resource to get
446  * @info:    describes the I2C device; note this is modified (addr gets set)
447  * Context: can sleep
448  *
449  * By default the i2c subsys creates an i2c-client for the first I2cSerialBus
450  * resource of an acpi_device, but some acpi_devices have multiple I2cSerialBus
451  * resources, in that case this function can be used to create an i2c-client
452  * for other I2cSerialBus resources in the Current Resource Settings table.
453  *
454  * Also see i2c_new_client_device, which this function calls to create the
455  * i2c-client.
456  *
457  * Returns a pointer to the new i2c-client, or error pointer in case of failure.
458  * Specifically, -EPROBE_DEFER is returned if the adapter is not found.
459  */
460 struct i2c_client *i2c_acpi_new_device(struct device *dev, int index,
461 				       struct i2c_board_info *info)
462 {
463 	struct i2c_acpi_lookup lookup;
464 	struct i2c_adapter *adapter;
465 	struct acpi_device *adev;
466 	LIST_HEAD(resource_list);
467 	int ret;
468 
469 	adev = ACPI_COMPANION(dev);
470 	if (!adev)
471 		return ERR_PTR(-EINVAL);
472 
473 	memset(&lookup, 0, sizeof(lookup));
474 	lookup.info = info;
475 	lookup.device_handle = acpi_device_handle(adev);
476 	lookup.index = index;
477 
478 	ret = acpi_dev_get_resources(adev, &resource_list,
479 				     i2c_acpi_fill_info, &lookup);
480 	if (ret < 0)
481 		return ERR_PTR(ret);
482 
483 	acpi_dev_free_resource_list(&resource_list);
484 
485 	if (!info->addr)
486 		return ERR_PTR(-EADDRNOTAVAIL);
487 
488 	adapter = i2c_acpi_find_adapter_by_handle(lookup.adapter_handle);
489 	if (!adapter)
490 		return ERR_PTR(-EPROBE_DEFER);
491 
492 	return i2c_new_client_device(adapter, info);
493 }
494 EXPORT_SYMBOL_GPL(i2c_acpi_new_device);
495 
496 #ifdef CONFIG_ACPI_I2C_OPREGION
497 static int acpi_gsb_i2c_read_bytes(struct i2c_client *client,
498 		u8 cmd, u8 *data, u8 data_len)
499 {
500 
501 	struct i2c_msg msgs[2];
502 	int ret;
503 	u8 *buffer;
504 
505 	buffer = kzalloc(data_len, GFP_KERNEL);
506 	if (!buffer)
507 		return AE_NO_MEMORY;
508 
509 	msgs[0].addr = client->addr;
510 	msgs[0].flags = client->flags;
511 	msgs[0].len = 1;
512 	msgs[0].buf = &cmd;
513 
514 	msgs[1].addr = client->addr;
515 	msgs[1].flags = client->flags | I2C_M_RD;
516 	msgs[1].len = data_len;
517 	msgs[1].buf = buffer;
518 
519 	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
520 	if (ret < 0) {
521 		/* Getting a NACK is unfortunately normal with some DSTDs */
522 		if (ret == -EREMOTEIO)
523 			dev_dbg(&client->adapter->dev, "i2c read %d bytes from client@%#x starting at reg %#x failed, error: %d\n",
524 				data_len, client->addr, cmd, ret);
525 		else
526 			dev_err(&client->adapter->dev, "i2c read %d bytes from client@%#x starting at reg %#x failed, error: %d\n",
527 				data_len, client->addr, cmd, ret);
528 	/* 2 transfers must have completed successfully */
529 	} else if (ret == 2) {
530 		memcpy(data, buffer, data_len);
531 		ret = 0;
532 	} else {
533 		ret = -EIO;
534 	}
535 
536 	kfree(buffer);
537 	return ret;
538 }
539 
540 static int acpi_gsb_i2c_write_bytes(struct i2c_client *client,
541 		u8 cmd, u8 *data, u8 data_len)
542 {
543 
544 	struct i2c_msg msgs[1];
545 	u8 *buffer;
546 	int ret = AE_OK;
547 
548 	buffer = kzalloc(data_len + 1, GFP_KERNEL);
549 	if (!buffer)
550 		return AE_NO_MEMORY;
551 
552 	buffer[0] = cmd;
553 	memcpy(buffer + 1, data, data_len);
554 
555 	msgs[0].addr = client->addr;
556 	msgs[0].flags = client->flags;
557 	msgs[0].len = data_len + 1;
558 	msgs[0].buf = buffer;
559 
560 	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
561 
562 	kfree(buffer);
563 
564 	if (ret < 0) {
565 		dev_err(&client->adapter->dev, "i2c write failed: %d\n", ret);
566 		return ret;
567 	}
568 
569 	/* 1 transfer must have completed successfully */
570 	return (ret == 1) ? 0 : -EIO;
571 }
572 
573 static acpi_status
574 i2c_acpi_space_handler(u32 function, acpi_physical_address command,
575 			u32 bits, u64 *value64,
576 			void *handler_context, void *region_context)
577 {
578 	struct gsb_buffer *gsb = (struct gsb_buffer *)value64;
579 	struct i2c_acpi_handler_data *data = handler_context;
580 	struct acpi_connection_info *info = &data->info;
581 	struct acpi_resource_i2c_serialbus *sb;
582 	struct i2c_adapter *adapter = data->adapter;
583 	struct i2c_client *client;
584 	struct acpi_resource *ares;
585 	u32 accessor_type = function >> 16;
586 	u8 action = function & ACPI_IO_MASK;
587 	acpi_status ret;
588 	int status;
589 
590 	ret = acpi_buffer_to_resource(info->connection, info->length, &ares);
591 	if (ACPI_FAILURE(ret))
592 		return ret;
593 
594 	client = kzalloc(sizeof(*client), GFP_KERNEL);
595 	if (!client) {
596 		ret = AE_NO_MEMORY;
597 		goto err;
598 	}
599 
600 	if (!value64 || !i2c_acpi_get_i2c_resource(ares, &sb)) {
601 		ret = AE_BAD_PARAMETER;
602 		goto err;
603 	}
604 
605 	client->adapter = adapter;
606 	client->addr = sb->slave_address;
607 
608 	if (sb->access_mode == ACPI_I2C_10BIT_MODE)
609 		client->flags |= I2C_CLIENT_TEN;
610 
611 	switch (accessor_type) {
612 	case ACPI_GSB_ACCESS_ATTRIB_SEND_RCV:
613 		if (action == ACPI_READ) {
614 			status = i2c_smbus_read_byte(client);
615 			if (status >= 0) {
616 				gsb->bdata = status;
617 				status = 0;
618 			}
619 		} else {
620 			status = i2c_smbus_write_byte(client, gsb->bdata);
621 		}
622 		break;
623 
624 	case ACPI_GSB_ACCESS_ATTRIB_BYTE:
625 		if (action == ACPI_READ) {
626 			status = i2c_smbus_read_byte_data(client, command);
627 			if (status >= 0) {
628 				gsb->bdata = status;
629 				status = 0;
630 			}
631 		} else {
632 			status = i2c_smbus_write_byte_data(client, command,
633 					gsb->bdata);
634 		}
635 		break;
636 
637 	case ACPI_GSB_ACCESS_ATTRIB_WORD:
638 		if (action == ACPI_READ) {
639 			status = i2c_smbus_read_word_data(client, command);
640 			if (status >= 0) {
641 				gsb->wdata = status;
642 				status = 0;
643 			}
644 		} else {
645 			status = i2c_smbus_write_word_data(client, command,
646 					gsb->wdata);
647 		}
648 		break;
649 
650 	case ACPI_GSB_ACCESS_ATTRIB_BLOCK:
651 		if (action == ACPI_READ) {
652 			status = i2c_smbus_read_block_data(client, command,
653 					gsb->data);
654 			if (status >= 0) {
655 				gsb->len = status;
656 				status = 0;
657 			}
658 		} else {
659 			status = i2c_smbus_write_block_data(client, command,
660 					gsb->len, gsb->data);
661 		}
662 		break;
663 
664 	case ACPI_GSB_ACCESS_ATTRIB_MULTIBYTE:
665 		if (action == ACPI_READ) {
666 			status = acpi_gsb_i2c_read_bytes(client, command,
667 					gsb->data, info->access_length);
668 		} else {
669 			status = acpi_gsb_i2c_write_bytes(client, command,
670 					gsb->data, info->access_length);
671 		}
672 		break;
673 
674 	default:
675 		dev_warn(&adapter->dev, "protocol 0x%02x not supported for client 0x%02x\n",
676 			 accessor_type, client->addr);
677 		ret = AE_BAD_PARAMETER;
678 		goto err;
679 	}
680 
681 	gsb->status = status;
682 
683  err:
684 	kfree(client);
685 	ACPI_FREE(ares);
686 	return ret;
687 }
688 
689 
690 int i2c_acpi_install_space_handler(struct i2c_adapter *adapter)
691 {
692 	acpi_handle handle;
693 	struct i2c_acpi_handler_data *data;
694 	acpi_status status;
695 
696 	if (!adapter->dev.parent)
697 		return -ENODEV;
698 
699 	handle = ACPI_HANDLE(adapter->dev.parent);
700 
701 	if (!handle)
702 		return -ENODEV;
703 
704 	data = kzalloc(sizeof(struct i2c_acpi_handler_data),
705 			    GFP_KERNEL);
706 	if (!data)
707 		return -ENOMEM;
708 
709 	data->adapter = adapter;
710 	status = acpi_bus_attach_private_data(handle, (void *)data);
711 	if (ACPI_FAILURE(status)) {
712 		kfree(data);
713 		return -ENOMEM;
714 	}
715 
716 	status = acpi_install_address_space_handler(handle,
717 				ACPI_ADR_SPACE_GSBUS,
718 				&i2c_acpi_space_handler,
719 				NULL,
720 				data);
721 	if (ACPI_FAILURE(status)) {
722 		dev_err(&adapter->dev, "Error installing i2c space handler\n");
723 		acpi_bus_detach_private_data(handle);
724 		kfree(data);
725 		return -ENOMEM;
726 	}
727 
728 	acpi_walk_dep_device_list(handle);
729 	return 0;
730 }
731 
732 void i2c_acpi_remove_space_handler(struct i2c_adapter *adapter)
733 {
734 	acpi_handle handle;
735 	struct i2c_acpi_handler_data *data;
736 	acpi_status status;
737 
738 	if (!adapter->dev.parent)
739 		return;
740 
741 	handle = ACPI_HANDLE(adapter->dev.parent);
742 
743 	if (!handle)
744 		return;
745 
746 	acpi_remove_address_space_handler(handle,
747 				ACPI_ADR_SPACE_GSBUS,
748 				&i2c_acpi_space_handler);
749 
750 	status = acpi_bus_get_private_data(handle, (void **)&data);
751 	if (ACPI_SUCCESS(status))
752 		kfree(data);
753 
754 	acpi_bus_detach_private_data(handle);
755 }
756 #endif /* CONFIG_ACPI_I2C_OPREGION */
757