1 // SPDX-License-Identifier: GPL-2.0-only
3 * Device tree helpers for DMA request / controller
7 * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
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>
16 #include <linux/of_dma.h>
18 #include "dmaengine.h"
20 static LIST_HEAD(of_dma_list
);
21 static DEFINE_MUTEX(of_dma_lock
);
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
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
32 static struct of_dma
*of_dma_find_controller(struct of_phandle_args
*dma_spec
)
36 list_for_each_entry(ofdma
, &of_dma_list
, of_dma_controllers
)
37 if (ofdma
->of_node
== dma_spec
->np
)
40 pr_debug("%s: can't find DMA controller %pOF\n", __func__
,
47 * of_dma_router_xlate - translation function for router devices
48 * @dma_spec: pointer to DMA specifier as found in the device tree
49 * @of_dma: pointer to DMA controller data (router information)
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.
55 static struct dma_chan
*of_dma_router_xlate(struct of_phandle_args
*dma_spec
,
58 struct dma_chan
*chan
;
59 struct of_dma
*ofdma_target
;
60 struct of_phandle_args dma_spec_target
;
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
))
69 ofdma_target
= of_dma_find_controller(&dma_spec_target
);
73 chan
= ofdma_target
->of_dma_xlate(&dma_spec_target
, ofdma_target
);
75 chan
->router
= ofdma
->dma_router
;
76 chan
->route_data
= route_data
;
78 ofdma
->dma_router
->route_free(ofdma
->dma_router
->dev
,
83 * Need to put the node back since the ofdma->of_dma_route_allocate
84 * has taken it for generating the new, translated dma_spec
86 of_node_put(dma_spec_target
.np
);
91 * of_dma_controller_register - Register a DMA controller to DT DMA helpers
92 * @np: device node of DMA controller
93 * @of_dma_xlate: translation function which converts a phandle
94 * arguments list into a dma_chan structure
95 * @data pointer to controller specific data to be used by
96 * translation function
98 * Returns 0 on success or appropriate errno value on error.
100 * Allocated memory should be freed with appropriate of_dma_controller_free()
103 int of_dma_controller_register(struct device_node
*np
,
104 struct dma_chan
*(*of_dma_xlate
)
105 (struct of_phandle_args
*, struct of_dma
*),
108 struct of_dma
*ofdma
;
110 if (!np
|| !of_dma_xlate
) {
111 pr_err("%s: not enough information provided\n", __func__
);
115 ofdma
= kzalloc(sizeof(*ofdma
), GFP_KERNEL
);
120 ofdma
->of_dma_xlate
= of_dma_xlate
;
121 ofdma
->of_dma_data
= data
;
123 /* Now queue of_dma controller structure in list */
124 mutex_lock(&of_dma_lock
);
125 list_add_tail(&ofdma
->of_dma_controllers
, &of_dma_list
);
126 mutex_unlock(&of_dma_lock
);
130 EXPORT_SYMBOL_GPL(of_dma_controller_register
);
133 * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list
134 * @np: device node of DMA controller
136 * Memory allocated by of_dma_controller_register() is freed here.
138 void of_dma_controller_free(struct device_node
*np
)
140 struct of_dma
*ofdma
;
142 mutex_lock(&of_dma_lock
);
144 list_for_each_entry(ofdma
, &of_dma_list
, of_dma_controllers
)
145 if (ofdma
->of_node
== np
) {
146 list_del(&ofdma
->of_dma_controllers
);
151 mutex_unlock(&of_dma_lock
);
153 EXPORT_SYMBOL_GPL(of_dma_controller_free
);
156 * of_dma_router_register - Register a DMA router to DT DMA helpers as a
158 * @np: device node of DMA router
159 * @of_dma_route_allocate: setup function for the router which need to
160 * modify the dma_spec for the DMA controller to
161 * use and to set up the requested route.
162 * @dma_router: pointer to dma_router structure to be used when
163 * the route need to be free up.
165 * Returns 0 on success or appropriate errno value on error.
167 * Allocated memory should be freed with appropriate of_dma_controller_free()
170 int of_dma_router_register(struct device_node
*np
,
171 void *(*of_dma_route_allocate
)
172 (struct of_phandle_args
*, struct of_dma
*),
173 struct dma_router
*dma_router
)
175 struct of_dma
*ofdma
;
177 if (!np
|| !of_dma_route_allocate
|| !dma_router
) {
178 pr_err("%s: not enough information provided\n", __func__
);
182 ofdma
= kzalloc(sizeof(*ofdma
), GFP_KERNEL
);
187 ofdma
->of_dma_xlate
= of_dma_router_xlate
;
188 ofdma
->of_dma_route_allocate
= of_dma_route_allocate
;
189 ofdma
->dma_router
= dma_router
;
191 /* Now queue of_dma controller structure in list */
192 mutex_lock(&of_dma_lock
);
193 list_add_tail(&ofdma
->of_dma_controllers
, &of_dma_list
);
194 mutex_unlock(&of_dma_lock
);
198 EXPORT_SYMBOL_GPL(of_dma_router_register
);
201 * of_dma_match_channel - Check if a DMA specifier matches name
202 * @np: device node to look for DMA channels
203 * @name: channel name to be matched
204 * @index: index of DMA specifier in list of DMA specifiers
205 * @dma_spec: pointer to DMA specifier as found in the device tree
207 * Check if the DMA specifier pointed to by the index in a list of DMA
208 * specifiers, matches the name provided. Returns 0 if the name matches and
209 * a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV.
211 static int of_dma_match_channel(struct device_node
*np
, const char *name
,
212 int index
, struct of_phandle_args
*dma_spec
)
216 if (of_property_read_string_index(np
, "dma-names", index
, &s
))
222 if (of_parse_phandle_with_args(np
, "dmas", "#dma-cells", index
,
230 * of_dma_request_slave_channel - Get the DMA slave channel
231 * @np: device node to get DMA request from
232 * @name: name of desired channel
234 * Returns pointer to appropriate DMA channel on success or an error pointer.
236 struct dma_chan
*of_dma_request_slave_channel(struct device_node
*np
,
239 struct of_phandle_args dma_spec
;
240 struct of_dma
*ofdma
;
241 struct dma_chan
*chan
;
243 int ret_no_channel
= -ENODEV
;
244 static atomic_t last_index
;
247 pr_err("%s: not enough information provided\n", __func__
);
248 return ERR_PTR(-ENODEV
);
251 /* Silently fail if there is not even the "dmas" property */
252 if (!of_find_property(np
, "dmas", NULL
))
253 return ERR_PTR(-ENODEV
);
255 count
= of_property_count_strings(np
, "dma-names");
257 pr_err("%s: dma-names property of node '%pOF' missing or empty\n",
259 return ERR_PTR(-ENODEV
);
263 * approximate an average distribution across multiple
264 * entries with the same name
266 start
= atomic_inc_return(&last_index
);
267 for (i
= 0; i
< count
; i
++) {
268 if (of_dma_match_channel(np
, name
,
273 mutex_lock(&of_dma_lock
);
274 ofdma
= of_dma_find_controller(&dma_spec
);
277 chan
= ofdma
->of_dma_xlate(&dma_spec
, ofdma
);
279 ret_no_channel
= -EPROBE_DEFER
;
283 mutex_unlock(&of_dma_lock
);
285 of_node_put(dma_spec
.np
);
291 return ERR_PTR(ret_no_channel
);
293 EXPORT_SYMBOL_GPL(of_dma_request_slave_channel
);
296 * of_dma_simple_xlate - Simple DMA engine translation function
297 * @dma_spec: pointer to DMA specifier as found in the device tree
298 * @of_dma: pointer to DMA controller data
300 * A simple translation function for devices that use a 32-bit value for the
301 * filter_param when calling the DMA engine dma_request_channel() function.
302 * Note that this translation function requires that #dma-cells is equal to 1
303 * and the argument of the dma specifier is the 32-bit filter_param. Returns
304 * pointer to appropriate dma channel on success or NULL on error.
306 struct dma_chan
*of_dma_simple_xlate(struct of_phandle_args
*dma_spec
,
307 struct of_dma
*ofdma
)
309 int count
= dma_spec
->args_count
;
310 struct of_dma_filter_info
*info
= ofdma
->of_dma_data
;
312 if (!info
|| !info
->filter_fn
)
318 return __dma_request_channel(&info
->dma_cap
, info
->filter_fn
,
319 &dma_spec
->args
[0], dma_spec
->np
);
321 EXPORT_SYMBOL_GPL(of_dma_simple_xlate
);
324 * of_dma_xlate_by_chan_id - Translate dt property to DMA channel by channel id
325 * @dma_spec: pointer to DMA specifier as found in the device tree
326 * @of_dma: pointer to DMA controller data
328 * This function can be used as the of xlate callback for DMA driver which wants
329 * to match the channel based on the channel id. When using this xlate function
330 * the #dma-cells propety of the DMA controller dt node needs to be set to 1.
331 * The data parameter of of_dma_controller_register must be a pointer to the
332 * dma_device struct the function should match upon.
334 * Returns pointer to appropriate dma channel on success or NULL on error.
336 struct dma_chan
*of_dma_xlate_by_chan_id(struct of_phandle_args
*dma_spec
,
337 struct of_dma
*ofdma
)
339 struct dma_device
*dev
= ofdma
->of_dma_data
;
340 struct dma_chan
*chan
, *candidate
= NULL
;
342 if (!dev
|| dma_spec
->args_count
!= 1)
345 list_for_each_entry(chan
, &dev
->channels
, device_node
)
346 if (chan
->chan_id
== dma_spec
->args
[0]) {
354 return dma_get_slave_channel(candidate
);
356 EXPORT_SYMBOL_GPL(of_dma_xlate_by_chan_id
);