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
20 static LIST_HEAD(of_dma_list);
21 static 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 */
of_dma_find_controller(struct of_phandle_args * dma_spec)32 static struct of_dma *of_dma_find_controller(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 */
of_dma_router_xlate(struct of_phandle_args * dma_spec,struct of_dma * ofdma)55 static 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 chan->router = ofdma->dma_router;
83 chan->route_data = route_data;
84 }
85
86 err:
87 /*
88 * Need to put the node back since the ofdma->of_dma_route_allocate
89 * has taken it for generating the new, translated dma_spec
90 */
91 of_node_put(dma_spec_target.np);
92 return chan;
93 }
94
95 /**
96 * of_dma_controller_register - Register a DMA controller to DT DMA helpers
97 * @np: device node of DMA controller
98 * @of_dma_xlate: translation function which converts a phandle
99 * arguments list into a dma_chan structure
100 * @data: pointer to controller specific data to be used by
101 * translation function
102 *
103 * Returns 0 on success or appropriate errno value on error.
104 *
105 * Allocated memory should be freed with appropriate of_dma_controller_free()
106 * call.
107 */
of_dma_controller_register(struct device_node * np,struct dma_chan * (* of_dma_xlate)(struct of_phandle_args *,struct of_dma *),void * data)108 int of_dma_controller_register(struct device_node *np,
109 struct dma_chan *(*of_dma_xlate)
110 (struct of_phandle_args *, struct of_dma *),
111 void *data)
112 {
113 struct of_dma *ofdma;
114
115 if (!np || !of_dma_xlate) {
116 pr_err("%s: not enough information provided\n", __func__);
117 return -EINVAL;
118 }
119
120 ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
121 if (!ofdma)
122 return -ENOMEM;
123
124 ofdma->of_node = np;
125 ofdma->of_dma_xlate = of_dma_xlate;
126 ofdma->of_dma_data = data;
127
128 /* Now queue of_dma controller structure in list */
129 mutex_lock(&of_dma_lock);
130 list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
131 mutex_unlock(&of_dma_lock);
132
133 return 0;
134 }
135 EXPORT_SYMBOL_GPL(of_dma_controller_register);
136
137 /**
138 * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list
139 * @np: device node of DMA controller
140 *
141 * Memory allocated by of_dma_controller_register() is freed here.
142 */
of_dma_controller_free(struct device_node * np)143 void of_dma_controller_free(struct device_node *np)
144 {
145 struct of_dma *ofdma;
146
147 mutex_lock(&of_dma_lock);
148
149 list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
150 if (ofdma->of_node == np) {
151 list_del(&ofdma->of_dma_controllers);
152 kfree(ofdma);
153 break;
154 }
155
156 mutex_unlock(&of_dma_lock);
157 }
158 EXPORT_SYMBOL_GPL(of_dma_controller_free);
159
160 /**
161 * of_dma_router_register - Register a DMA router to DT DMA helpers as a
162 * controller
163 * @np: device node of DMA router
164 * @of_dma_route_allocate: setup function for the router which need to
165 * modify the dma_spec for the DMA controller to
166 * use and to set up the requested route.
167 * @dma_router: pointer to dma_router structure to be used when
168 * the route need to be free up.
169 *
170 * Returns 0 on success or appropriate errno value on error.
171 *
172 * Allocated memory should be freed with appropriate of_dma_controller_free()
173 * call.
174 */
of_dma_router_register(struct device_node * np,void * (* of_dma_route_allocate)(struct of_phandle_args *,struct of_dma *),struct dma_router * dma_router)175 int of_dma_router_register(struct device_node *np,
176 void *(*of_dma_route_allocate)
177 (struct of_phandle_args *, struct of_dma *),
178 struct dma_router *dma_router)
179 {
180 struct of_dma *ofdma;
181
182 if (!np || !of_dma_route_allocate || !dma_router) {
183 pr_err("%s: not enough information provided\n", __func__);
184 return -EINVAL;
185 }
186
187 ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
188 if (!ofdma)
189 return -ENOMEM;
190
191 ofdma->of_node = np;
192 ofdma->of_dma_xlate = of_dma_router_xlate;
193 ofdma->of_dma_route_allocate = of_dma_route_allocate;
194 ofdma->dma_router = dma_router;
195
196 /* Now queue of_dma controller structure in list */
197 mutex_lock(&of_dma_lock);
198 list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
199 mutex_unlock(&of_dma_lock);
200
201 return 0;
202 }
203 EXPORT_SYMBOL_GPL(of_dma_router_register);
204
205 /**
206 * of_dma_match_channel - Check if a DMA specifier matches name
207 * @np: device node to look for DMA channels
208 * @name: channel name to be matched
209 * @index: index of DMA specifier in list of DMA specifiers
210 * @dma_spec: pointer to DMA specifier as found in the device tree
211 *
212 * Check if the DMA specifier pointed to by the index in a list of DMA
213 * specifiers, matches the name provided. Returns 0 if the name matches and
214 * a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV.
215 */
of_dma_match_channel(struct device_node * np,const char * name,int index,struct of_phandle_args * dma_spec)216 static int of_dma_match_channel(struct device_node *np, const char *name,
217 int index, struct of_phandle_args *dma_spec)
218 {
219 const char *s;
220
221 if (of_property_read_string_index(np, "dma-names", index, &s))
222 return -ENODEV;
223
224 if (strcmp(name, s))
225 return -ENODEV;
226
227 if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index,
228 dma_spec))
229 return -ENODEV;
230
231 return 0;
232 }
233
234 /**
235 * of_dma_request_slave_channel - Get the DMA slave channel
236 * @np: device node to get DMA request from
237 * @name: name of desired channel
238 *
239 * Returns pointer to appropriate DMA channel on success or an error pointer.
240 */
of_dma_request_slave_channel(struct device_node * np,const char * name)241 struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
242 const char *name)
243 {
244 struct of_phandle_args dma_spec;
245 struct of_dma *ofdma;
246 struct dma_chan *chan;
247 int count, i, start;
248 int ret_no_channel = -ENODEV;
249 static atomic_t last_index;
250
251 if (!np || !name) {
252 pr_err("%s: not enough information provided\n", __func__);
253 return ERR_PTR(-ENODEV);
254 }
255
256 /* Silently fail if there is not even the "dmas" property */
257 if (!of_find_property(np, "dmas", NULL))
258 return ERR_PTR(-ENODEV);
259
260 count = of_property_count_strings(np, "dma-names");
261 if (count < 0) {
262 pr_err("%s: dma-names property of node '%pOF' missing or empty\n",
263 __func__, np);
264 return ERR_PTR(-ENODEV);
265 }
266
267 /*
268 * approximate an average distribution across multiple
269 * entries with the same name
270 */
271 start = atomic_inc_return(&last_index);
272 for (i = 0; i < count; i++) {
273 if (of_dma_match_channel(np, name,
274 (i + start) % count,
275 &dma_spec))
276 continue;
277
278 mutex_lock(&of_dma_lock);
279 ofdma = of_dma_find_controller(&dma_spec);
280
281 if (ofdma) {
282 chan = ofdma->of_dma_xlate(&dma_spec, ofdma);
283 } else {
284 ret_no_channel = -EPROBE_DEFER;
285 chan = NULL;
286 }
287
288 mutex_unlock(&of_dma_lock);
289
290 of_node_put(dma_spec.np);
291
292 if (chan)
293 return chan;
294 }
295
296 return ERR_PTR(ret_no_channel);
297 }
298 EXPORT_SYMBOL_GPL(of_dma_request_slave_channel);
299
300 /**
301 * of_dma_simple_xlate - Simple DMA engine translation function
302 * @dma_spec: pointer to DMA specifier as found in the device tree
303 * @ofdma: pointer to DMA controller data
304 *
305 * A simple translation function for devices that use a 32-bit value for the
306 * filter_param when calling the DMA engine dma_request_channel() function.
307 * Note that this translation function requires that #dma-cells is equal to 1
308 * and the argument of the dma specifier is the 32-bit filter_param. Returns
309 * pointer to appropriate dma channel on success or NULL on error.
310 */
of_dma_simple_xlate(struct of_phandle_args * dma_spec,struct of_dma * ofdma)311 struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
312 struct of_dma *ofdma)
313 {
314 int count = dma_spec->args_count;
315 struct of_dma_filter_info *info = ofdma->of_dma_data;
316
317 if (!info || !info->filter_fn)
318 return NULL;
319
320 if (count != 1)
321 return NULL;
322
323 return __dma_request_channel(&info->dma_cap, info->filter_fn,
324 &dma_spec->args[0], dma_spec->np);
325 }
326 EXPORT_SYMBOL_GPL(of_dma_simple_xlate);
327
328 /**
329 * of_dma_xlate_by_chan_id - Translate dt property to DMA channel by channel id
330 * @dma_spec: pointer to DMA specifier as found in the device tree
331 * @ofdma: pointer to DMA controller data
332 *
333 * This function can be used as the of xlate callback for DMA driver which wants
334 * to match the channel based on the channel id. When using this xlate function
335 * the #dma-cells propety of the DMA controller dt node needs to be set to 1.
336 * The data parameter of of_dma_controller_register must be a pointer to the
337 * dma_device struct the function should match upon.
338 *
339 * Returns pointer to appropriate dma channel on success or NULL on error.
340 */
of_dma_xlate_by_chan_id(struct of_phandle_args * dma_spec,struct of_dma * ofdma)341 struct dma_chan *of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec,
342 struct of_dma *ofdma)
343 {
344 struct dma_device *dev = ofdma->of_dma_data;
345 struct dma_chan *chan, *candidate = NULL;
346
347 if (!dev || dma_spec->args_count != 1)
348 return NULL;
349
350 list_for_each_entry(chan, &dev->channels, device_node)
351 if (chan->chan_id == dma_spec->args[0]) {
352 candidate = chan;
353 break;
354 }
355
356 if (!candidate)
357 return NULL;
358
359 return dma_get_slave_channel(candidate);
360 }
361 EXPORT_SYMBOL_GPL(of_dma_xlate_by_chan_id);
362