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);
468