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