2 * Device tree helpers for DMA request / controller
6 * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
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.
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>
19 #include <linux/of_dma.h>
21 static LIST_HEAD(of_dma_list);
22 static DEFINE_MUTEX(of_dma_lock);
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
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
33 static struct of_dma *of_dma_find_controller(struct of_phandle_args *dma_spec)
37 list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
38 if (ofdma->of_node == dma_spec->np)
41 pr_debug("%s: can't find DMA controller %pOF\n", __func__,
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)
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.
56 static struct dma_chan *of_dma_router_xlate(struct of_phandle_args *dma_spec,
59 struct dma_chan *chan;
60 struct of_dma *ofdma_target;
61 struct of_phandle_args dma_spec_target;
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))
70 ofdma_target = of_dma_find_controller(&dma_spec_target);
74 chan = ofdma_target->of_dma_xlate(&dma_spec_target, ofdma_target);
76 chan->router = ofdma->dma_router;
77 chan->route_data = route_data;
79 ofdma->dma_router->route_free(ofdma->dma_router->dev,
84 * Need to put the node back since the ofdma->of_dma_route_allocate
85 * has taken it for generating the new, translated dma_spec
87 of_node_put(dma_spec_target.np);
92 * of_dma_controller_register - Register a DMA controller to DT DMA helpers
93 * @np: device node of DMA controller
94 * @of_dma_xlate: translation function which converts a phandle
95 * arguments list into a dma_chan structure
96 * @data pointer to controller specific data to be used by
97 * translation function
99 * Returns 0 on success or appropriate errno value on error.
101 * Allocated memory should be freed with appropriate of_dma_controller_free()
104 int of_dma_controller_register(struct device_node *np,
105 struct dma_chan *(*of_dma_xlate)
106 (struct of_phandle_args *, struct of_dma *),
109 struct of_dma *ofdma;
111 if (!np || !of_dma_xlate) {
112 pr_err("%s: not enough information provided\n", __func__);
116 ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
121 ofdma->of_dma_xlate = of_dma_xlate;
122 ofdma->of_dma_data = data;
124 /* Now queue of_dma controller structure in list */
125 mutex_lock(&of_dma_lock);
126 list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
127 mutex_unlock(&of_dma_lock);
131 EXPORT_SYMBOL_GPL(of_dma_controller_register);
134 * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list
135 * @np: device node of DMA controller
137 * Memory allocated by of_dma_controller_register() is freed here.
139 void of_dma_controller_free(struct device_node *np)
141 struct of_dma *ofdma;
143 mutex_lock(&of_dma_lock);
145 list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
146 if (ofdma->of_node == np) {
147 list_del(&ofdma->of_dma_controllers);
152 mutex_unlock(&of_dma_lock);
154 EXPORT_SYMBOL_GPL(of_dma_controller_free);
157 * of_dma_router_register - Register a DMA router to DT DMA helpers as a
159 * @np: device node of DMA router
160 * @of_dma_route_allocate: setup function for the router which need to
161 * modify the dma_spec for the DMA controller to
162 * use and to set up the requested route.
163 * @dma_router: pointer to dma_router structure to be used when
164 * the route need to be free up.
166 * Returns 0 on success or appropriate errno value on error.
168 * Allocated memory should be freed with appropriate of_dma_controller_free()
171 int of_dma_router_register(struct device_node *np,
172 void *(*of_dma_route_allocate)
173 (struct of_phandle_args *, struct of_dma *),
174 struct dma_router *dma_router)
176 struct of_dma *ofdma;
178 if (!np || !of_dma_route_allocate || !dma_router) {
179 pr_err("%s: not enough information provided\n", __func__);
183 ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
188 ofdma->of_dma_xlate = of_dma_router_xlate;
189 ofdma->of_dma_route_allocate = of_dma_route_allocate;
190 ofdma->dma_router = dma_router;
192 /* Now queue of_dma controller structure in list */
193 mutex_lock(&of_dma_lock);
194 list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
195 mutex_unlock(&of_dma_lock);
199 EXPORT_SYMBOL_GPL(of_dma_router_register);
202 * of_dma_match_channel - Check if a DMA specifier matches name
203 * @np: device node to look for DMA channels
204 * @name: channel name to be matched
205 * @index: index of DMA specifier in list of DMA specifiers
206 * @dma_spec: pointer to DMA specifier as found in the device tree
208 * Check if the DMA specifier pointed to by the index in a list of DMA
209 * specifiers, matches the name provided. Returns 0 if the name matches and
210 * a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV.
212 static int of_dma_match_channel(struct device_node *np, const char *name,
213 int index, struct of_phandle_args *dma_spec)
217 if (of_property_read_string_index(np, "dma-names", index, &s))
223 if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index,
231 * of_dma_request_slave_channel - Get the DMA slave channel
232 * @np: device node to get DMA request from
233 * @name: name of desired channel
235 * Returns pointer to appropriate DMA channel on success or an error pointer.
237 struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
240 struct of_phandle_args dma_spec;
241 struct of_dma *ofdma;
242 struct dma_chan *chan;
244 int ret_no_channel = -ENODEV;
245 static atomic_t last_index;
248 pr_err("%s: not enough information provided\n", __func__);
249 return ERR_PTR(-ENODEV);
252 /* Silently fail if there is not even the "dmas" property */
253 if (!of_find_property(np, "dmas", NULL))
254 return ERR_PTR(-ENODEV);
256 count = of_property_count_strings(np, "dma-names");
258 pr_err("%s: dma-names property of node '%pOF' missing or empty\n",
260 return ERR_PTR(-ENODEV);
264 * approximate an average distribution across multiple
265 * entries with the same name
267 start = atomic_inc_return(&last_index);
268 for (i = 0; i < count; i++) {
269 if (of_dma_match_channel(np, name,
274 mutex_lock(&of_dma_lock);
275 ofdma = of_dma_find_controller(&dma_spec);
278 chan = ofdma->of_dma_xlate(&dma_spec, ofdma);
280 ret_no_channel = -EPROBE_DEFER;
284 mutex_unlock(&of_dma_lock);
286 of_node_put(dma_spec.np);
292 return ERR_PTR(ret_no_channel);
294 EXPORT_SYMBOL_GPL(of_dma_request_slave_channel);
297 * of_dma_simple_xlate - Simple DMA engine translation function
298 * @dma_spec: pointer to DMA specifier as found in the device tree
299 * @of_dma: pointer to DMA controller data
301 * A simple translation function for devices that use a 32-bit value for the
302 * filter_param when calling the DMA engine dma_request_channel() function.
303 * Note that this translation function requires that #dma-cells is equal to 1
304 * and the argument of the dma specifier is the 32-bit filter_param. Returns
305 * pointer to appropriate dma channel on success or NULL on error.
307 struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
308 struct of_dma *ofdma)
310 int count = dma_spec->args_count;
311 struct of_dma_filter_info *info = ofdma->of_dma_data;
313 if (!info || !info->filter_fn)
319 return dma_request_channel(info->dma_cap, info->filter_fn,
322 EXPORT_SYMBOL_GPL(of_dma_simple_xlate);
325 * of_dma_xlate_by_chan_id - Translate dt property to DMA channel by channel id
326 * @dma_spec: pointer to DMA specifier as found in the device tree
327 * @of_dma: pointer to DMA controller data
329 * This function can be used as the of xlate callback for DMA driver which wants
330 * to match the channel based on the channel id. When using this xlate function
331 * the #dma-cells propety of the DMA controller dt node needs to be set to 1.
332 * The data parameter of of_dma_controller_register must be a pointer to the
333 * dma_device struct the function should match upon.
335 * Returns pointer to appropriate dma channel on success or NULL on error.
337 struct dma_chan *of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec,
338 struct of_dma *ofdma)
340 struct dma_device *dev = ofdma->of_dma_data;
341 struct dma_chan *chan, *candidate = NULL;
343 if (!dev || dma_spec->args_count != 1)
346 list_for_each_entry(chan, &dev->channels, device_node)
347 if (chan->chan_id == dma_spec->args[0]) {
355 return dma_get_slave_channel(candidate);
357 EXPORT_SYMBOL_GPL(of_dma_xlate_by_chan_id);