1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Device tree helpers for DMA request / controller
4 *
5 * Based on of_gpio.c
6 *
7 * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
8 */
9
10#include <linux/device.h>
11#include <linux/err.h>
12#include <linux/module.h>
13#include <linux/mutex.h>
14#include <linux/slab.h>
15#include <linux/of.h>
16#include <linux/of_dma.h>
17
18#include "dmaengine.h"
19
20static LIST_HEAD(of_dma_list);
21static DEFINE_MUTEX(of_dma_lock);
22
23/**
24 * of_dma_find_controller - Get a DMA controller in DT DMA helpers list
25 * @dma_spec:	pointer to DMA specifier as found in the device tree
26 *
27 * Finds a DMA controller with matching device node and number for dma cells
28 * in a list of registered DMA controllers. If a match is found a valid pointer
29 * to the DMA data stored is retuned. A NULL pointer is returned if no match is
30 * found.
31 */
32static struct of_dma *of_dma_find_controller(const struct of_phandle_args *dma_spec)
33{
34	struct of_dma *ofdma;
35
36	list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
37		if (ofdma->of_node == dma_spec->np)
38			return ofdma;
39
40	pr_debug("%s: can't find DMA controller %pOF\n", __func__,
41		 dma_spec->np);
42
43	return NULL;
44}
45
46/**
47 * of_dma_router_xlate - translation function for router devices
48 * @dma_spec:	pointer to DMA specifier as found in the device tree
49 * @ofdma:	pointer to DMA controller data (router information)
50 *
51 * The function creates new dma_spec to be passed to the router driver's
52 * of_dma_route_allocate() function to prepare a dma_spec which will be used
53 * to request channel from the real DMA controller.
54 */
55static struct dma_chan *of_dma_router_xlate(struct of_phandle_args *dma_spec,
56					    struct of_dma *ofdma)
57{
58	struct dma_chan		*chan;
59	struct of_dma		*ofdma_target;
60	struct of_phandle_args	dma_spec_target;
61	void			*route_data;
62
63	/* translate the request for the real DMA controller */
64	memcpy(&dma_spec_target, dma_spec, sizeof(dma_spec_target));
65	route_data = ofdma->of_dma_route_allocate(&dma_spec_target, ofdma);
66	if (IS_ERR(route_data))
67		return NULL;
68
69	ofdma_target = of_dma_find_controller(&dma_spec_target);
70	if (!ofdma_target) {
71		ofdma->dma_router->route_free(ofdma->dma_router->dev,
72					      route_data);
73		chan = ERR_PTR(-EPROBE_DEFER);
74		goto err;
75	}
76
77	chan = ofdma_target->of_dma_xlate(&dma_spec_target, ofdma_target);
78	if (IS_ERR_OR_NULL(chan)) {
79		ofdma->dma_router->route_free(ofdma->dma_router->dev,
80					      route_data);
81	} else {
82		int ret = 0;
83
84		chan->router = ofdma->dma_router;
85		chan->route_data = route_data;
86
87		if (chan->device->device_router_config)
88			ret = chan->device->device_router_config(chan);
89
90		if (ret) {
91			dma_release_channel(chan);
92			chan = ERR_PTR(ret);
93		}
94	}
95
96err:
97	/*
98	 * Need to put the node back since the ofdma->of_dma_route_allocate
99	 * has taken it for generating the new, translated dma_spec
100	 */
101	of_node_put(dma_spec_target.np);
102	return chan;
103}
104
105/**
106 * of_dma_controller_register - Register a DMA controller to DT DMA helpers
107 * @np:			device node of DMA controller
108 * @of_dma_xlate:	translation function which converts a phandle
109 *			arguments list into a dma_chan structure
110 * @data:		pointer to controller specific data to be used by
111 *			translation function
112 *
113 * Returns 0 on success or appropriate errno value on error.
114 *
115 * Allocated memory should be freed with appropriate of_dma_controller_free()
116 * call.
117 */
118int of_dma_controller_register(struct device_node *np,
119				struct dma_chan *(*of_dma_xlate)
120				(struct of_phandle_args *, struct of_dma *),
121				void *data)
122{
123	struct of_dma	*ofdma;
124
125	if (!np || !of_dma_xlate) {
126		pr_err("%s: not enough information provided\n", __func__);
127		return -EINVAL;
128	}
129
130	ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
131	if (!ofdma)
132		return -ENOMEM;
133
134	ofdma->of_node = np;
135	ofdma->of_dma_xlate = of_dma_xlate;
136	ofdma->of_dma_data = data;
137
138	/* Now queue of_dma controller structure in list */
139	mutex_lock(&of_dma_lock);
140	list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
141	mutex_unlock(&of_dma_lock);
142
143	return 0;
144}
145EXPORT_SYMBOL_GPL(of_dma_controller_register);
146
147/**
148 * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list
149 * @np:		device node of DMA controller
150 *
151 * Memory allocated by of_dma_controller_register() is freed here.
152 */
153void of_dma_controller_free(struct device_node *np)
154{
155	struct of_dma *ofdma;
156
157	mutex_lock(&of_dma_lock);
158
159	list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
160		if (ofdma->of_node == np) {
161			list_del(&ofdma->of_dma_controllers);
162			kfree(ofdma);
163			break;
164		}
165
166	mutex_unlock(&of_dma_lock);
167}
168EXPORT_SYMBOL_GPL(of_dma_controller_free);
169
170/**
171 * of_dma_router_register - Register a DMA router to DT DMA helpers as a
172 *			    controller
173 * @np:				device node of DMA router
174 * @of_dma_route_allocate:	setup function for the router which need to
175 *				modify the dma_spec for the DMA controller to
176 *				use and to set up the requested route.
177 * @dma_router:			pointer to dma_router structure to be used when
178 *				the route need to be free up.
179 *
180 * Returns 0 on success or appropriate errno value on error.
181 *
182 * Allocated memory should be freed with appropriate of_dma_controller_free()
183 * call.
184 */
185int of_dma_router_register(struct device_node *np,
186			   void *(*of_dma_route_allocate)
187			   (struct of_phandle_args *, struct of_dma *),
188			   struct dma_router *dma_router)
189{
190	struct of_dma	*ofdma;
191
192	if (!np || !of_dma_route_allocate || !dma_router) {
193		pr_err("%s: not enough information provided\n", __func__);
194		return -EINVAL;
195	}
196
197	ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
198	if (!ofdma)
199		return -ENOMEM;
200
201	ofdma->of_node = np;
202	ofdma->of_dma_xlate = of_dma_router_xlate;
203	ofdma->of_dma_route_allocate = of_dma_route_allocate;
204	ofdma->dma_router = dma_router;
205
206	/* Now queue of_dma controller structure in list */
207	mutex_lock(&of_dma_lock);
208	list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
209	mutex_unlock(&of_dma_lock);
210
211	return 0;
212}
213EXPORT_SYMBOL_GPL(of_dma_router_register);
214
215/**
216 * of_dma_match_channel - Check if a DMA specifier matches name
217 * @np:		device node to look for DMA channels
218 * @name:	channel name to be matched
219 * @index:	index of DMA specifier in list of DMA specifiers
220 * @dma_spec:	pointer to DMA specifier as found in the device tree
221 *
222 * Check if the DMA specifier pointed to by the index in a list of DMA
223 * specifiers, matches the name provided. Returns 0 if the name matches and
224 * a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV.
225 */
226static int of_dma_match_channel(struct device_node *np, const char *name,
227				int index, struct of_phandle_args *dma_spec)
228{
229	const char *s;
230
231	if (of_property_read_string_index(np, "dma-names", index, &s))
232		return -ENODEV;
233
234	if (strcmp(name, s))
235		return -ENODEV;
236
237	if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index,
238				       dma_spec))
239		return -ENODEV;
240
241	return 0;
242}
243
244/**
245 * of_dma_request_slave_channel - Get the DMA slave channel
246 * @np:		device node to get DMA request from
247 * @name:	name of desired channel
248 *
249 * Returns pointer to appropriate DMA channel on success or an error pointer.
250 */
251struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
252					      const char *name)
253{
254	struct of_phandle_args	dma_spec;
255	struct of_dma		*ofdma;
256	struct dma_chan		*chan;
257	int			count, i, start;
258	int			ret_no_channel = -ENODEV;
259	static atomic_t		last_index;
260
261	if (!np || !name) {
262		pr_err("%s: not enough information provided\n", __func__);
263		return ERR_PTR(-ENODEV);
264	}
265
266	/* Silently fail if there is not even the "dmas" property */
267	if (!of_property_present(np, "dmas"))
268		return ERR_PTR(-ENODEV);
269
270	count = of_property_count_strings(np, "dma-names");
271	if (count < 0) {
272		pr_err("%s: dma-names property of node '%pOF' missing or empty\n",
273			__func__, np);
274		return ERR_PTR(-ENODEV);
275	}
276
277	/*
278	 * approximate an average distribution across multiple
279	 * entries with the same name
280	 */
281	start = atomic_inc_return(&last_index);
282	for (i = 0; i < count; i++) {
283		if (of_dma_match_channel(np, name,
284					 (i + start) % count,
285					 &dma_spec))
286			continue;
287
288		mutex_lock(&of_dma_lock);
289		ofdma = of_dma_find_controller(&dma_spec);
290
291		if (ofdma) {
292			chan = ofdma->of_dma_xlate(&dma_spec, ofdma);
293		} else {
294			ret_no_channel = -EPROBE_DEFER;
295			chan = NULL;
296		}
297
298		mutex_unlock(&of_dma_lock);
299
300		of_node_put(dma_spec.np);
301
302		if (chan)
303			return chan;
304	}
305
306	return ERR_PTR(ret_no_channel);
307}
308EXPORT_SYMBOL_GPL(of_dma_request_slave_channel);
309
310/**
311 * of_dma_simple_xlate - Simple DMA engine translation function
312 * @dma_spec:	pointer to DMA specifier as found in the device tree
313 * @ofdma:	pointer to DMA controller data
314 *
315 * A simple translation function for devices that use a 32-bit value for the
316 * filter_param when calling the DMA engine dma_request_channel() function.
317 * Note that this translation function requires that #dma-cells is equal to 1
318 * and the argument of the dma specifier is the 32-bit filter_param. Returns
319 * pointer to appropriate dma channel on success or NULL on error.
320 */
321struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
322						struct of_dma *ofdma)
323{
324	int count = dma_spec->args_count;
325	struct of_dma_filter_info *info = ofdma->of_dma_data;
326
327	if (!info || !info->filter_fn)
328		return NULL;
329
330	if (count != 1)
331		return NULL;
332
333	return __dma_request_channel(&info->dma_cap, info->filter_fn,
334				     &dma_spec->args[0], dma_spec->np);
335}
336EXPORT_SYMBOL_GPL(of_dma_simple_xlate);
337
338/**
339 * of_dma_xlate_by_chan_id - Translate dt property to DMA channel by channel id
340 * @dma_spec:	pointer to DMA specifier as found in the device tree
341 * @ofdma:	pointer to DMA controller data
342 *
343 * This function can be used as the of xlate callback for DMA driver which wants
344 * to match the channel based on the channel id. When using this xlate function
345 * the #dma-cells propety of the DMA controller dt node needs to be set to 1.
346 * The data parameter of of_dma_controller_register must be a pointer to the
347 * dma_device struct the function should match upon.
348 *
349 * Returns pointer to appropriate dma channel on success or NULL on error.
350 */
351struct dma_chan *of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec,
352					 struct of_dma *ofdma)
353{
354	struct dma_device *dev = ofdma->of_dma_data;
355	struct dma_chan *chan, *candidate = NULL;
356
357	if (!dev || dma_spec->args_count != 1)
358		return NULL;
359
360	list_for_each_entry(chan, &dev->channels, device_node)
361		if (chan->chan_id == dma_spec->args[0]) {
362			candidate = chan;
363			break;
364		}
365
366	if (!candidate)
367		return NULL;
368
369	return dma_get_slave_channel(candidate);
370}
371EXPORT_SYMBOL_GPL(of_dma_xlate_by_chan_id);
372