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