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