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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * ACPI helpers for DMA request / controller
4 *
5 * Based on of-dma.c
6 *
7 * Copyright (C) 2013, Intel Corporation
8 * Authors: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
9 * Mika Westerberg <mika.westerberg@linux.intel.com>
10 */
11
12#include <linux/device.h>
13#include <linux/dma-mapping.h>
14#include <linux/err.h>
15#include <linux/module.h>
16#include <linux/kernel.h>
17#include <linux/list.h>
18#include <linux/mutex.h>
19#include <linux/slab.h>
20#include <linux/ioport.h>
21#include <linux/acpi.h>
22#include <linux/acpi_dma.h>
23#include <linux/property.h>
24
25static LIST_HEAD(acpi_dma_list);
26static DEFINE_MUTEX(acpi_dma_lock);
27
28/**
29 * acpi_dma_parse_resource_group - match device and parse resource group
30 * @grp: CSRT resource group
31 * @adev: ACPI device to match with
32 * @adma: struct acpi_dma of the given DMA controller
33 *
34 * In order to match a device from DSDT table to the corresponding CSRT device
35 * we use MMIO address and IRQ.
36 *
37 * Return:
38 * 1 on success, 0 when no information is available, or appropriate errno value
39 * on error.
40 */
41static int acpi_dma_parse_resource_group(const struct acpi_csrt_group *grp,
42 struct acpi_device *adev, struct acpi_dma *adma)
43{
44 const struct acpi_csrt_shared_info *si;
45 struct list_head resource_list;
46 struct resource_entry *rentry;
47 resource_size_t mem = 0, irq = 0;
48 int ret;
49
50 if (grp->shared_info_length != sizeof(struct acpi_csrt_shared_info))
51 return -ENODEV;
52
53 INIT_LIST_HEAD(&resource_list);
54 ret = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
55 if (ret <= 0)
56 return 0;
57
58 list_for_each_entry(rentry, &resource_list, node) {
59 if (resource_type(rentry->res) == IORESOURCE_MEM)
60 mem = rentry->res->start;
61 else if (resource_type(rentry->res) == IORESOURCE_IRQ)
62 irq = rentry->res->start;
63 }
64
65 acpi_dev_free_resource_list(&resource_list);
66
67 /* Consider initial zero values as resource not found */
68 if (mem == 0 && irq == 0)
69 return 0;
70
71 si = (const struct acpi_csrt_shared_info *)&grp[1];
72
73 /* Match device by MMIO and IRQ */
74 if (si->mmio_base_low != lower_32_bits(mem) ||
75 si->mmio_base_high != upper_32_bits(mem) ||
76 si->gsi_interrupt != irq)
77 return 0;
78
79 dev_dbg(&adev->dev, "matches with %.4s%04X (rev %u)\n",
80 (char *)&grp->vendor_id, grp->device_id, grp->revision);
81
82 /* Check if the request line range is available */
83 if (si->base_request_line == 0 && si->num_handshake_signals == 0)
84 return 0;
85
86 /* Set up DMA mask based on value from CSRT */
87 ret = dma_coerce_mask_and_coherent(&adev->dev,
88 DMA_BIT_MASK(si->dma_address_width));
89 if (ret)
90 return 0;
91
92 adma->base_request_line = si->base_request_line;
93 adma->end_request_line = si->base_request_line +
94 si->num_handshake_signals - 1;
95
96 dev_dbg(&adev->dev, "request line base: 0x%04x end: 0x%04x\n",
97 adma->base_request_line, adma->end_request_line);
98
99 return 1;
100}
101
102/**
103 * acpi_dma_parse_csrt - parse CSRT to exctract additional DMA resources
104 * @adev: ACPI device to match with
105 * @adma: struct acpi_dma of the given DMA controller
106 *
107 * CSRT or Core System Resources Table is a proprietary ACPI table
108 * introduced by Microsoft. This table can contain devices that are not in
109 * the system DSDT table. In particular DMA controllers might be described
110 * here.
111 *
112 * We are using this table to get the request line range of the specific DMA
113 * controller to be used later.
114 */
115static void acpi_dma_parse_csrt(struct acpi_device *adev, struct acpi_dma *adma)
116{
117 struct acpi_csrt_group *grp, *end;
118 struct acpi_table_csrt *csrt;
119 acpi_status status;
120 int ret;
121
122 status = acpi_get_table(ACPI_SIG_CSRT, 0,
123 (struct acpi_table_header **)&csrt);
124 if (ACPI_FAILURE(status)) {
125 if (status != AE_NOT_FOUND)
126 dev_warn(&adev->dev, "failed to get the CSRT table\n");
127 return;
128 }
129
130 grp = (struct acpi_csrt_group *)(csrt + 1);
131 end = (struct acpi_csrt_group *)((void *)csrt + csrt->header.length);
132
133 while (grp < end) {
134 ret = acpi_dma_parse_resource_group(grp, adev, adma);
135 if (ret < 0) {
136 dev_warn(&adev->dev,
137 "error in parsing resource group\n");
138 return;
139 }
140
141 grp = (struct acpi_csrt_group *)((void *)grp + grp->length);
142 }
143}
144
145/**
146 * acpi_dma_controller_register - Register a DMA controller to ACPI DMA helpers
147 * @dev: struct device of DMA controller
148 * @acpi_dma_xlate: translation function which converts a dma specifier
149 * into a dma_chan structure
150 * @data: pointer to controller specific data to be used by
151 * translation function
152 *
153 * Allocated memory should be freed with appropriate acpi_dma_controller_free()
154 * call.
155 *
156 * Return:
157 * 0 on success or appropriate errno value on error.
158 */
159int acpi_dma_controller_register(struct device *dev,
160 struct dma_chan *(*acpi_dma_xlate)
161 (struct acpi_dma_spec *, struct acpi_dma *),
162 void *data)
163{
164 struct acpi_device *adev;
165 struct acpi_dma *adma;
166
167 if (!dev || !acpi_dma_xlate)
168 return -EINVAL;
169
170 /* Check if the device was enumerated by ACPI */
171 adev = ACPI_COMPANION(dev);
172 if (!adev)
173 return -EINVAL;
174
175 adma = kzalloc(sizeof(*adma), GFP_KERNEL);
176 if (!adma)
177 return -ENOMEM;
178
179 adma->dev = dev;
180 adma->acpi_dma_xlate = acpi_dma_xlate;
181 adma->data = data;
182
183 acpi_dma_parse_csrt(adev, adma);
184
185 /* Now queue acpi_dma controller structure in list */
186 mutex_lock(&acpi_dma_lock);
187 list_add_tail(&adma->dma_controllers, &acpi_dma_list);
188 mutex_unlock(&acpi_dma_lock);
189
190 return 0;
191}
192EXPORT_SYMBOL_GPL(acpi_dma_controller_register);
193
194/**
195 * acpi_dma_controller_free - Remove a DMA controller from ACPI DMA helpers list
196 * @dev: struct device of DMA controller
197 *
198 * Memory allocated by acpi_dma_controller_register() is freed here.
199 *
200 * Return:
201 * 0 on success or appropriate errno value on error.
202 */
203int acpi_dma_controller_free(struct device *dev)
204{
205 struct acpi_dma *adma;
206
207 if (!dev)
208 return -EINVAL;
209
210 mutex_lock(&acpi_dma_lock);
211
212 list_for_each_entry(adma, &acpi_dma_list, dma_controllers)
213 if (adma->dev == dev) {
214 list_del(&adma->dma_controllers);
215 mutex_unlock(&acpi_dma_lock);
216 kfree(adma);
217 return 0;
218 }
219
220 mutex_unlock(&acpi_dma_lock);
221 return -ENODEV;
222}
223EXPORT_SYMBOL_GPL(acpi_dma_controller_free);
224
225static void devm_acpi_dma_release(struct device *dev, void *res)
226{
227 acpi_dma_controller_free(dev);
228}
229
230/**
231 * devm_acpi_dma_controller_register - resource managed acpi_dma_controller_register()
232 * @dev: device that is registering this DMA controller
233 * @acpi_dma_xlate: translation function
234 * @data: pointer to controller specific data
235 *
236 * Managed acpi_dma_controller_register(). DMA controller registered by this
237 * function are automatically freed on driver detach. See
238 * acpi_dma_controller_register() for more information.
239 *
240 * Return:
241 * 0 on success or appropriate errno value on error.
242 */
243int devm_acpi_dma_controller_register(struct device *dev,
244 struct dma_chan *(*acpi_dma_xlate)
245 (struct acpi_dma_spec *, struct acpi_dma *),
246 void *data)
247{
248 void *res;
249 int ret;
250
251 res = devres_alloc(devm_acpi_dma_release, 0, GFP_KERNEL);
252 if (!res)
253 return -ENOMEM;
254
255 ret = acpi_dma_controller_register(dev, acpi_dma_xlate, data);
256 if (ret) {
257 devres_free(res);
258 return ret;
259 }
260 devres_add(dev, res);
261 return 0;
262}
263EXPORT_SYMBOL_GPL(devm_acpi_dma_controller_register);
264
265/**
266 * devm_acpi_dma_controller_free - resource managed acpi_dma_controller_free()
267 * @dev: device that is unregistering as DMA controller
268 *
269 * Unregister a DMA controller registered with
270 * devm_acpi_dma_controller_register(). Normally this function will not need to
271 * be called and the resource management code will ensure that the resource is
272 * freed.
273 */
274void devm_acpi_dma_controller_free(struct device *dev)
275{
276 WARN_ON(devres_release(dev, devm_acpi_dma_release, NULL, NULL));
277}
278EXPORT_SYMBOL_GPL(devm_acpi_dma_controller_free);
279
280/**
281 * acpi_dma_update_dma_spec - prepare dma specifier to pass to translation function
282 * @adma: struct acpi_dma of DMA controller
283 * @dma_spec: dma specifier to update
284 *
285 * Accordingly to ACPI 5.0 Specification Table 6-170 "Fixed DMA Resource
286 * Descriptor":
287 * DMA Request Line bits is a platform-relative number uniquely
288 * identifying the request line assigned. Request line-to-Controller
289 * mapping is done in a controller-specific OS driver.
290 * That's why we can safely adjust slave_id when the appropriate controller is
291 * found.
292 *
293 * Return:
294 * 0, if no information is avaiable, -1 on mismatch, and 1 otherwise.
295 */
296static int acpi_dma_update_dma_spec(struct acpi_dma *adma,
297 struct acpi_dma_spec *dma_spec)
298{
299 /* Set link to the DMA controller device */
300 dma_spec->dev = adma->dev;
301
302 /* Check if the request line range is available */
303 if (adma->base_request_line == 0 && adma->end_request_line == 0)
304 return 0;
305
306 /* Check if slave_id falls to the range */
307 if (dma_spec->slave_id < adma->base_request_line ||
308 dma_spec->slave_id > adma->end_request_line)
309 return -1;
310
311 /*
312 * Here we adjust slave_id. It should be a relative number to the base
313 * request line.
314 */
315 dma_spec->slave_id -= adma->base_request_line;
316
317 return 1;
318}
319
320struct acpi_dma_parser_data {
321 struct acpi_dma_spec dma_spec;
322 size_t index;
323 size_t n;
324};
325
326/**
327 * acpi_dma_parse_fixed_dma - Parse FixedDMA ACPI resources to a DMA specifier
328 * @res: struct acpi_resource to get FixedDMA resources from
329 * @data: pointer to a helper struct acpi_dma_parser_data
330 */
331static int acpi_dma_parse_fixed_dma(struct acpi_resource *res, void *data)
332{
333 struct acpi_dma_parser_data *pdata = data;
334
335 if (res->type == ACPI_RESOURCE_TYPE_FIXED_DMA) {
336 struct acpi_resource_fixed_dma *dma = &res->data.fixed_dma;
337
338 if (pdata->n++ == pdata->index) {
339 pdata->dma_spec.chan_id = dma->channels;
340 pdata->dma_spec.slave_id = dma->request_lines;
341 }
342 }
343
344 /* Tell the ACPI core to skip this resource */
345 return 1;
346}
347
348/**
349 * acpi_dma_request_slave_chan_by_index - Get the DMA slave channel
350 * @dev: struct device to get DMA request from
351 * @index: index of FixedDMA descriptor for @dev
352 *
353 * Return:
354 * Pointer to appropriate dma channel on success or an error pointer.
355 */
356struct dma_chan *acpi_dma_request_slave_chan_by_index(struct device *dev,
357 size_t index)
358{
359 struct acpi_dma_parser_data pdata;
360 struct acpi_dma_spec *dma_spec = &pdata.dma_spec;
361 struct list_head resource_list;
362 struct acpi_device *adev;
363 struct acpi_dma *adma;
364 struct dma_chan *chan = NULL;
365 int found;
366
367 /* Check if the device was enumerated by ACPI */
368 if (!dev)
369 return ERR_PTR(-ENODEV);
370
371 adev = ACPI_COMPANION(dev);
372 if (!adev)
373 return ERR_PTR(-ENODEV);
374
375 memset(&pdata, 0, sizeof(pdata));
376 pdata.index = index;
377
378 /* Initial values for the request line and channel */
379 dma_spec->chan_id = -1;
380 dma_spec->slave_id = -1;
381
382 INIT_LIST_HEAD(&resource_list);
383 acpi_dev_get_resources(adev, &resource_list,
384 acpi_dma_parse_fixed_dma, &pdata);
385 acpi_dev_free_resource_list(&resource_list);
386
387 if (dma_spec->slave_id < 0 || dma_spec->chan_id < 0)
388 return ERR_PTR(-ENODEV);
389
390 mutex_lock(&acpi_dma_lock);
391
392 list_for_each_entry(adma, &acpi_dma_list, dma_controllers) {
393 /*
394 * We are not going to call translation function if slave_id
395 * doesn't fall to the request range.
396 */
397 found = acpi_dma_update_dma_spec(adma, dma_spec);
398 if (found < 0)
399 continue;
400 chan = adma->acpi_dma_xlate(dma_spec, adma);
401 /*
402 * Try to get a channel only from the DMA controller that
403 * matches the slave_id. See acpi_dma_update_dma_spec()
404 * description for the details.
405 */
406 if (found > 0 || chan)
407 break;
408 }
409
410 mutex_unlock(&acpi_dma_lock);
411 return chan ? chan : ERR_PTR(-EPROBE_DEFER);
412}
413EXPORT_SYMBOL_GPL(acpi_dma_request_slave_chan_by_index);
414
415/**
416 * acpi_dma_request_slave_chan_by_name - Get the DMA slave channel
417 * @dev: struct device to get DMA request from
418 * @name: represents corresponding FixedDMA descriptor for @dev
419 *
420 * In order to support both Device Tree and ACPI in a single driver we
421 * translate the names "tx" and "rx" here based on the most common case where
422 * the first FixedDMA descriptor is TX and second is RX.
423 *
424 * If the device has "dma-names" property the FixedDMA descriptor indices
425 * are retrieved based on those. Otherwise the function falls back using
426 * hardcoded indices.
427 *
428 * Return:
429 * Pointer to appropriate dma channel on success or an error pointer.
430 */
431struct dma_chan *acpi_dma_request_slave_chan_by_name(struct device *dev,
432 const char *name)
433{
434 int index;
435
436 index = device_property_match_string(dev, "dma-names", name);
437 if (index < 0) {
438 if (!strcmp(name, "tx"))
439 index = 0;
440 else if (!strcmp(name, "rx"))
441 index = 1;
442 else
443 return ERR_PTR(-ENODEV);
444 }
445
446 dev_dbg(dev, "Looking for DMA channel \"%s\" at index %d...\n", name, index);
447 return acpi_dma_request_slave_chan_by_index(dev, index);
448}
449EXPORT_SYMBOL_GPL(acpi_dma_request_slave_chan_by_name);
450
451/**
452 * acpi_dma_simple_xlate - Simple ACPI DMA engine translation helper
453 * @dma_spec: pointer to ACPI DMA specifier
454 * @adma: pointer to ACPI DMA controller data
455 *
456 * A simple translation function for ACPI based devices. Passes &struct
457 * dma_spec to the DMA controller driver provided filter function.
458 *
459 * Return:
460 * Pointer to the channel if found or %NULL otherwise.
461 */
462struct dma_chan *acpi_dma_simple_xlate(struct acpi_dma_spec *dma_spec,
463 struct acpi_dma *adma)
464{
465 struct acpi_dma_filter_info *info = adma->data;
466
467 if (!info || !info->filter_fn)
468 return NULL;
469
470 return dma_request_channel(info->dma_cap, info->filter_fn, dma_spec);
471}
472EXPORT_SYMBOL_GPL(acpi_dma_simple_xlate);
1/*
2 * ACPI helpers for DMA request / controller
3 *
4 * Based on of-dma.c
5 *
6 * Copyright (C) 2013, Intel Corporation
7 * Authors: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
8 * Mika Westerberg <mika.westerberg@linux.intel.com>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14
15#include <linux/device.h>
16#include <linux/err.h>
17#include <linux/module.h>
18#include <linux/kernel.h>
19#include <linux/list.h>
20#include <linux/mutex.h>
21#include <linux/slab.h>
22#include <linux/ioport.h>
23#include <linux/acpi.h>
24#include <linux/acpi_dma.h>
25#include <linux/property.h>
26
27static LIST_HEAD(acpi_dma_list);
28static DEFINE_MUTEX(acpi_dma_lock);
29
30/**
31 * acpi_dma_parse_resource_group - match device and parse resource group
32 * @grp: CSRT resource group
33 * @adev: ACPI device to match with
34 * @adma: struct acpi_dma of the given DMA controller
35 *
36 * In order to match a device from DSDT table to the corresponding CSRT device
37 * we use MMIO address and IRQ.
38 *
39 * Return:
40 * 1 on success, 0 when no information is available, or appropriate errno value
41 * on error.
42 */
43static int acpi_dma_parse_resource_group(const struct acpi_csrt_group *grp,
44 struct acpi_device *adev, struct acpi_dma *adma)
45{
46 const struct acpi_csrt_shared_info *si;
47 struct list_head resource_list;
48 struct resource_entry *rentry;
49 resource_size_t mem = 0, irq = 0;
50 int ret;
51
52 if (grp->shared_info_length != sizeof(struct acpi_csrt_shared_info))
53 return -ENODEV;
54
55 INIT_LIST_HEAD(&resource_list);
56 ret = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
57 if (ret <= 0)
58 return 0;
59
60 list_for_each_entry(rentry, &resource_list, node) {
61 if (resource_type(rentry->res) == IORESOURCE_MEM)
62 mem = rentry->res->start;
63 else if (resource_type(rentry->res) == IORESOURCE_IRQ)
64 irq = rentry->res->start;
65 }
66
67 acpi_dev_free_resource_list(&resource_list);
68
69 /* Consider initial zero values as resource not found */
70 if (mem == 0 && irq == 0)
71 return 0;
72
73 si = (const struct acpi_csrt_shared_info *)&grp[1];
74
75 /* Match device by MMIO and IRQ */
76 if (si->mmio_base_low != lower_32_bits(mem) ||
77 si->mmio_base_high != upper_32_bits(mem) ||
78 si->gsi_interrupt != irq)
79 return 0;
80
81 dev_dbg(&adev->dev, "matches with %.4s%04X (rev %u)\n",
82 (char *)&grp->vendor_id, grp->device_id, grp->revision);
83
84 /* Check if the request line range is available */
85 if (si->base_request_line == 0 && si->num_handshake_signals == 0)
86 return 0;
87
88 adma->base_request_line = si->base_request_line;
89 adma->end_request_line = si->base_request_line +
90 si->num_handshake_signals - 1;
91
92 dev_dbg(&adev->dev, "request line base: 0x%04x end: 0x%04x\n",
93 adma->base_request_line, adma->end_request_line);
94
95 return 1;
96}
97
98/**
99 * acpi_dma_parse_csrt - parse CSRT to exctract additional DMA resources
100 * @adev: ACPI device to match with
101 * @adma: struct acpi_dma of the given DMA controller
102 *
103 * CSRT or Core System Resources Table is a proprietary ACPI table
104 * introduced by Microsoft. This table can contain devices that are not in
105 * the system DSDT table. In particular DMA controllers might be described
106 * here.
107 *
108 * We are using this table to get the request line range of the specific DMA
109 * controller to be used later.
110 */
111static void acpi_dma_parse_csrt(struct acpi_device *adev, struct acpi_dma *adma)
112{
113 struct acpi_csrt_group *grp, *end;
114 struct acpi_table_csrt *csrt;
115 acpi_status status;
116 int ret;
117
118 status = acpi_get_table(ACPI_SIG_CSRT, 0,
119 (struct acpi_table_header **)&csrt);
120 if (ACPI_FAILURE(status)) {
121 if (status != AE_NOT_FOUND)
122 dev_warn(&adev->dev, "failed to get the CSRT table\n");
123 return;
124 }
125
126 grp = (struct acpi_csrt_group *)(csrt + 1);
127 end = (struct acpi_csrt_group *)((void *)csrt + csrt->header.length);
128
129 while (grp < end) {
130 ret = acpi_dma_parse_resource_group(grp, adev, adma);
131 if (ret < 0) {
132 dev_warn(&adev->dev,
133 "error in parsing resource group\n");
134 return;
135 }
136
137 grp = (struct acpi_csrt_group *)((void *)grp + grp->length);
138 }
139}
140
141/**
142 * acpi_dma_controller_register - Register a DMA controller to ACPI DMA helpers
143 * @dev: struct device of DMA controller
144 * @acpi_dma_xlate: translation function which converts a dma specifier
145 * into a dma_chan structure
146 * @data pointer to controller specific data to be used by
147 * translation function
148 *
149 * Allocated memory should be freed with appropriate acpi_dma_controller_free()
150 * call.
151 *
152 * Return:
153 * 0 on success or appropriate errno value on error.
154 */
155int acpi_dma_controller_register(struct device *dev,
156 struct dma_chan *(*acpi_dma_xlate)
157 (struct acpi_dma_spec *, struct acpi_dma *),
158 void *data)
159{
160 struct acpi_device *adev;
161 struct acpi_dma *adma;
162
163 if (!dev || !acpi_dma_xlate)
164 return -EINVAL;
165
166 /* Check if the device was enumerated by ACPI */
167 adev = ACPI_COMPANION(dev);
168 if (!adev)
169 return -EINVAL;
170
171 adma = kzalloc(sizeof(*adma), GFP_KERNEL);
172 if (!adma)
173 return -ENOMEM;
174
175 adma->dev = dev;
176 adma->acpi_dma_xlate = acpi_dma_xlate;
177 adma->data = data;
178
179 acpi_dma_parse_csrt(adev, adma);
180
181 /* Now queue acpi_dma controller structure in list */
182 mutex_lock(&acpi_dma_lock);
183 list_add_tail(&adma->dma_controllers, &acpi_dma_list);
184 mutex_unlock(&acpi_dma_lock);
185
186 return 0;
187}
188EXPORT_SYMBOL_GPL(acpi_dma_controller_register);
189
190/**
191 * acpi_dma_controller_free - Remove a DMA controller from ACPI DMA helpers list
192 * @dev: struct device of DMA controller
193 *
194 * Memory allocated by acpi_dma_controller_register() is freed here.
195 *
196 * Return:
197 * 0 on success or appropriate errno value on error.
198 */
199int acpi_dma_controller_free(struct device *dev)
200{
201 struct acpi_dma *adma;
202
203 if (!dev)
204 return -EINVAL;
205
206 mutex_lock(&acpi_dma_lock);
207
208 list_for_each_entry(adma, &acpi_dma_list, dma_controllers)
209 if (adma->dev == dev) {
210 list_del(&adma->dma_controllers);
211 mutex_unlock(&acpi_dma_lock);
212 kfree(adma);
213 return 0;
214 }
215
216 mutex_unlock(&acpi_dma_lock);
217 return -ENODEV;
218}
219EXPORT_SYMBOL_GPL(acpi_dma_controller_free);
220
221static void devm_acpi_dma_release(struct device *dev, void *res)
222{
223 acpi_dma_controller_free(dev);
224}
225
226/**
227 * devm_acpi_dma_controller_register - resource managed acpi_dma_controller_register()
228 * @dev: device that is registering this DMA controller
229 * @acpi_dma_xlate: translation function
230 * @data pointer to controller specific data
231 *
232 * Managed acpi_dma_controller_register(). DMA controller registered by this
233 * function are automatically freed on driver detach. See
234 * acpi_dma_controller_register() for more information.
235 *
236 * Return:
237 * 0 on success or appropriate errno value on error.
238 */
239int devm_acpi_dma_controller_register(struct device *dev,
240 struct dma_chan *(*acpi_dma_xlate)
241 (struct acpi_dma_spec *, struct acpi_dma *),
242 void *data)
243{
244 void *res;
245 int ret;
246
247 res = devres_alloc(devm_acpi_dma_release, 0, GFP_KERNEL);
248 if (!res)
249 return -ENOMEM;
250
251 ret = acpi_dma_controller_register(dev, acpi_dma_xlate, data);
252 if (ret) {
253 devres_free(res);
254 return ret;
255 }
256 devres_add(dev, res);
257 return 0;
258}
259EXPORT_SYMBOL_GPL(devm_acpi_dma_controller_register);
260
261/**
262 * devm_acpi_dma_controller_free - resource managed acpi_dma_controller_free()
263 *
264 * Unregister a DMA controller registered with
265 * devm_acpi_dma_controller_register(). Normally this function will not need to
266 * be called and the resource management code will ensure that the resource is
267 * freed.
268 */
269void devm_acpi_dma_controller_free(struct device *dev)
270{
271 WARN_ON(devres_release(dev, devm_acpi_dma_release, NULL, NULL));
272}
273EXPORT_SYMBOL_GPL(devm_acpi_dma_controller_free);
274
275/**
276 * acpi_dma_update_dma_spec - prepare dma specifier to pass to translation function
277 * @adma: struct acpi_dma of DMA controller
278 * @dma_spec: dma specifier to update
279 *
280 * Accordingly to ACPI 5.0 Specification Table 6-170 "Fixed DMA Resource
281 * Descriptor":
282 * DMA Request Line bits is a platform-relative number uniquely
283 * identifying the request line assigned. Request line-to-Controller
284 * mapping is done in a controller-specific OS driver.
285 * That's why we can safely adjust slave_id when the appropriate controller is
286 * found.
287 *
288 * Return:
289 * 0, if no information is avaiable, -1 on mismatch, and 1 otherwise.
290 */
291static int acpi_dma_update_dma_spec(struct acpi_dma *adma,
292 struct acpi_dma_spec *dma_spec)
293{
294 /* Set link to the DMA controller device */
295 dma_spec->dev = adma->dev;
296
297 /* Check if the request line range is available */
298 if (adma->base_request_line == 0 && adma->end_request_line == 0)
299 return 0;
300
301 /* Check if slave_id falls to the range */
302 if (dma_spec->slave_id < adma->base_request_line ||
303 dma_spec->slave_id > adma->end_request_line)
304 return -1;
305
306 /*
307 * Here we adjust slave_id. It should be a relative number to the base
308 * request line.
309 */
310 dma_spec->slave_id -= adma->base_request_line;
311
312 return 1;
313}
314
315struct acpi_dma_parser_data {
316 struct acpi_dma_spec dma_spec;
317 size_t index;
318 size_t n;
319};
320
321/**
322 * acpi_dma_parse_fixed_dma - Parse FixedDMA ACPI resources to a DMA specifier
323 * @res: struct acpi_resource to get FixedDMA resources from
324 * @data: pointer to a helper struct acpi_dma_parser_data
325 */
326static int acpi_dma_parse_fixed_dma(struct acpi_resource *res, void *data)
327{
328 struct acpi_dma_parser_data *pdata = data;
329
330 if (res->type == ACPI_RESOURCE_TYPE_FIXED_DMA) {
331 struct acpi_resource_fixed_dma *dma = &res->data.fixed_dma;
332
333 if (pdata->n++ == pdata->index) {
334 pdata->dma_spec.chan_id = dma->channels;
335 pdata->dma_spec.slave_id = dma->request_lines;
336 }
337 }
338
339 /* Tell the ACPI core to skip this resource */
340 return 1;
341}
342
343/**
344 * acpi_dma_request_slave_chan_by_index - Get the DMA slave channel
345 * @dev: struct device to get DMA request from
346 * @index: index of FixedDMA descriptor for @dev
347 *
348 * Return:
349 * Pointer to appropriate dma channel on success or an error pointer.
350 */
351struct dma_chan *acpi_dma_request_slave_chan_by_index(struct device *dev,
352 size_t index)
353{
354 struct acpi_dma_parser_data pdata;
355 struct acpi_dma_spec *dma_spec = &pdata.dma_spec;
356 struct list_head resource_list;
357 struct acpi_device *adev;
358 struct acpi_dma *adma;
359 struct dma_chan *chan = NULL;
360 int found;
361
362 /* Check if the device was enumerated by ACPI */
363 if (!dev)
364 return ERR_PTR(-ENODEV);
365
366 adev = ACPI_COMPANION(dev);
367 if (!adev)
368 return ERR_PTR(-ENODEV);
369
370 memset(&pdata, 0, sizeof(pdata));
371 pdata.index = index;
372
373 /* Initial values for the request line and channel */
374 dma_spec->chan_id = -1;
375 dma_spec->slave_id = -1;
376
377 INIT_LIST_HEAD(&resource_list);
378 acpi_dev_get_resources(adev, &resource_list,
379 acpi_dma_parse_fixed_dma, &pdata);
380 acpi_dev_free_resource_list(&resource_list);
381
382 if (dma_spec->slave_id < 0 || dma_spec->chan_id < 0)
383 return ERR_PTR(-ENODEV);
384
385 mutex_lock(&acpi_dma_lock);
386
387 list_for_each_entry(adma, &acpi_dma_list, dma_controllers) {
388 /*
389 * We are not going to call translation function if slave_id
390 * doesn't fall to the request range.
391 */
392 found = acpi_dma_update_dma_spec(adma, dma_spec);
393 if (found < 0)
394 continue;
395 chan = adma->acpi_dma_xlate(dma_spec, adma);
396 /*
397 * Try to get a channel only from the DMA controller that
398 * matches the slave_id. See acpi_dma_update_dma_spec()
399 * description for the details.
400 */
401 if (found > 0 || chan)
402 break;
403 }
404
405 mutex_unlock(&acpi_dma_lock);
406 return chan ? chan : ERR_PTR(-EPROBE_DEFER);
407}
408EXPORT_SYMBOL_GPL(acpi_dma_request_slave_chan_by_index);
409
410/**
411 * acpi_dma_request_slave_chan_by_name - Get the DMA slave channel
412 * @dev: struct device to get DMA request from
413 * @name: represents corresponding FixedDMA descriptor for @dev
414 *
415 * In order to support both Device Tree and ACPI in a single driver we
416 * translate the names "tx" and "rx" here based on the most common case where
417 * the first FixedDMA descriptor is TX and second is RX.
418 *
419 * If the device has "dma-names" property the FixedDMA descriptor indices
420 * are retrieved based on those. Otherwise the function falls back using
421 * hardcoded indices.
422 *
423 * Return:
424 * Pointer to appropriate dma channel on success or an error pointer.
425 */
426struct dma_chan *acpi_dma_request_slave_chan_by_name(struct device *dev,
427 const char *name)
428{
429 int index;
430
431 index = device_property_match_string(dev, "dma-names", name);
432 if (index < 0) {
433 if (!strcmp(name, "tx"))
434 index = 0;
435 else if (!strcmp(name, "rx"))
436 index = 1;
437 else
438 return ERR_PTR(-ENODEV);
439 }
440
441 dev_dbg(dev, "Looking for DMA channel \"%s\" at index %d...\n", name, index);
442 return acpi_dma_request_slave_chan_by_index(dev, index);
443}
444EXPORT_SYMBOL_GPL(acpi_dma_request_slave_chan_by_name);
445
446/**
447 * acpi_dma_simple_xlate - Simple ACPI DMA engine translation helper
448 * @dma_spec: pointer to ACPI DMA specifier
449 * @adma: pointer to ACPI DMA controller data
450 *
451 * A simple translation function for ACPI based devices. Passes &struct
452 * dma_spec to the DMA controller driver provided filter function.
453 *
454 * Return:
455 * Pointer to the channel if found or %NULL otherwise.
456 */
457struct dma_chan *acpi_dma_simple_xlate(struct acpi_dma_spec *dma_spec,
458 struct acpi_dma *adma)
459{
460 struct acpi_dma_filter_info *info = adma->data;
461
462 if (!info || !info->filter_fn)
463 return NULL;
464
465 return dma_request_channel(info->dma_cap, info->filter_fn, dma_spec);
466}
467EXPORT_SYMBOL_GPL(acpi_dma_simple_xlate);