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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(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 return NULL;
72
73 chan = ofdma_target->of_dma_xlate(&dma_spec_target, ofdma_target);
74 if (IS_ERR_OR_NULL(chan)) {
75 ofdma->dma_router->route_free(ofdma->dma_router->dev,
76 route_data);
77 } else {
78 chan->router = ofdma->dma_router;
79 chan->route_data = route_data;
80 }
81
82 /*
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
85 */
86 of_node_put(dma_spec_target.np);
87 return chan;
88}
89
90/**
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
97 *
98 * Returns 0 on success or appropriate errno value on error.
99 *
100 * Allocated memory should be freed with appropriate of_dma_controller_free()
101 * call.
102 */
103int of_dma_controller_register(struct device_node *np,
104 struct dma_chan *(*of_dma_xlate)
105 (struct of_phandle_args *, struct of_dma *),
106 void *data)
107{
108 struct of_dma *ofdma;
109
110 if (!np || !of_dma_xlate) {
111 pr_err("%s: not enough information provided\n", __func__);
112 return -EINVAL;
113 }
114
115 ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
116 if (!ofdma)
117 return -ENOMEM;
118
119 ofdma->of_node = np;
120 ofdma->of_dma_xlate = of_dma_xlate;
121 ofdma->of_dma_data = data;
122
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);
127
128 return 0;
129}
130EXPORT_SYMBOL_GPL(of_dma_controller_register);
131
132/**
133 * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list
134 * @np: device node of DMA controller
135 *
136 * Memory allocated by of_dma_controller_register() is freed here.
137 */
138void of_dma_controller_free(struct device_node *np)
139{
140 struct of_dma *ofdma;
141
142 mutex_lock(&of_dma_lock);
143
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);
147 kfree(ofdma);
148 break;
149 }
150
151 mutex_unlock(&of_dma_lock);
152}
153EXPORT_SYMBOL_GPL(of_dma_controller_free);
154
155/**
156 * of_dma_router_register - Register a DMA router to DT DMA helpers as a
157 * controller
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.
164 *
165 * Returns 0 on success or appropriate errno value on error.
166 *
167 * Allocated memory should be freed with appropriate of_dma_controller_free()
168 * call.
169 */
170int 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)
174{
175 struct of_dma *ofdma;
176
177 if (!np || !of_dma_route_allocate || !dma_router) {
178 pr_err("%s: not enough information provided\n", __func__);
179 return -EINVAL;
180 }
181
182 ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
183 if (!ofdma)
184 return -ENOMEM;
185
186 ofdma->of_node = np;
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;
190
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);
195
196 return 0;
197}
198EXPORT_SYMBOL_GPL(of_dma_router_register);
199
200/**
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
206 *
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.
210 */
211static int of_dma_match_channel(struct device_node *np, const char *name,
212 int index, struct of_phandle_args *dma_spec)
213{
214 const char *s;
215
216 if (of_property_read_string_index(np, "dma-names", index, &s))
217 return -ENODEV;
218
219 if (strcmp(name, s))
220 return -ENODEV;
221
222 if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index,
223 dma_spec))
224 return -ENODEV;
225
226 return 0;
227}
228
229/**
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
233 *
234 * Returns pointer to appropriate DMA channel on success or an error pointer.
235 */
236struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
237 const char *name)
238{
239 struct of_phandle_args dma_spec;
240 struct of_dma *ofdma;
241 struct dma_chan *chan;
242 int count, i, start;
243 int ret_no_channel = -ENODEV;
244 static atomic_t last_index;
245
246 if (!np || !name) {
247 pr_err("%s: not enough information provided\n", __func__);
248 return ERR_PTR(-ENODEV);
249 }
250
251 /* Silently fail if there is not even the "dmas" property */
252 if (!of_find_property(np, "dmas", NULL))
253 return ERR_PTR(-ENODEV);
254
255 count = of_property_count_strings(np, "dma-names");
256 if (count < 0) {
257 pr_err("%s: dma-names property of node '%pOF' missing or empty\n",
258 __func__, np);
259 return ERR_PTR(-ENODEV);
260 }
261
262 /*
263 * approximate an average distribution across multiple
264 * entries with the same name
265 */
266 start = atomic_inc_return(&last_index);
267 for (i = 0; i < count; i++) {
268 if (of_dma_match_channel(np, name,
269 (i + start) % count,
270 &dma_spec))
271 continue;
272
273 mutex_lock(&of_dma_lock);
274 ofdma = of_dma_find_controller(&dma_spec);
275
276 if (ofdma) {
277 chan = ofdma->of_dma_xlate(&dma_spec, ofdma);
278 } else {
279 ret_no_channel = -EPROBE_DEFER;
280 chan = NULL;
281 }
282
283 mutex_unlock(&of_dma_lock);
284
285 of_node_put(dma_spec.np);
286
287 if (chan)
288 return chan;
289 }
290
291 return ERR_PTR(ret_no_channel);
292}
293EXPORT_SYMBOL_GPL(of_dma_request_slave_channel);
294
295/**
296 * of_dma_simple_xlate - Simple DMA engine translation function
297 * @dma_spec: pointer to DMA specifier as found in the device tree
298 * @ofdma: pointer to DMA controller data
299 *
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.
305 */
306struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
307 struct of_dma *ofdma)
308{
309 int count = dma_spec->args_count;
310 struct of_dma_filter_info *info = ofdma->of_dma_data;
311
312 if (!info || !info->filter_fn)
313 return NULL;
314
315 if (count != 1)
316 return NULL;
317
318 return __dma_request_channel(&info->dma_cap, info->filter_fn,
319 &dma_spec->args[0], dma_spec->np);
320}
321EXPORT_SYMBOL_GPL(of_dma_simple_xlate);
322
323/**
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 * @ofdma: pointer to DMA controller data
327 *
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.
333 *
334 * Returns pointer to appropriate dma channel on success or NULL on error.
335 */
336struct dma_chan *of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec,
337 struct of_dma *ofdma)
338{
339 struct dma_device *dev = ofdma->of_dma_data;
340 struct dma_chan *chan, *candidate = NULL;
341
342 if (!dev || dma_spec->args_count != 1)
343 return NULL;
344
345 list_for_each_entry(chan, &dev->channels, device_node)
346 if (chan->chan_id == dma_spec->args[0]) {
347 candidate = chan;
348 break;
349 }
350
351 if (!candidate)
352 return NULL;
353
354 return dma_get_slave_channel(candidate);
355}
356EXPORT_SYMBOL_GPL(of_dma_xlate_by_chan_id);
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
21static LIST_HEAD(of_dma_list);
22static 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 */
33static 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_controller_register - Register a DMA controller to DT DMA helpers
49 * @np: device node of DMA controller
50 * @of_dma_xlate: translation function which converts a phandle
51 * arguments list into a dma_chan structure
52 * @data pointer to controller specific data to be used by
53 * translation function
54 *
55 * Returns 0 on success or appropriate errno value on error.
56 *
57 * Allocated memory should be freed with appropriate of_dma_controller_free()
58 * call.
59 */
60int of_dma_controller_register(struct device_node *np,
61 struct dma_chan *(*of_dma_xlate)
62 (struct of_phandle_args *, struct of_dma *),
63 void *data)
64{
65 struct of_dma *ofdma;
66
67 if (!np || !of_dma_xlate) {
68 pr_err("%s: not enough information provided\n", __func__);
69 return -EINVAL;
70 }
71
72 ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
73 if (!ofdma)
74 return -ENOMEM;
75
76 ofdma->of_node = np;
77 ofdma->of_dma_xlate = of_dma_xlate;
78 ofdma->of_dma_data = data;
79
80 /* Now queue of_dma controller structure in list */
81 mutex_lock(&of_dma_lock);
82 list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
83 mutex_unlock(&of_dma_lock);
84
85 return 0;
86}
87EXPORT_SYMBOL_GPL(of_dma_controller_register);
88
89/**
90 * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list
91 * @np: device node of DMA controller
92 *
93 * Memory allocated by of_dma_controller_register() is freed here.
94 */
95void of_dma_controller_free(struct device_node *np)
96{
97 struct of_dma *ofdma;
98
99 mutex_lock(&of_dma_lock);
100
101 list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
102 if (ofdma->of_node == np) {
103 list_del(&ofdma->of_dma_controllers);
104 kfree(ofdma);
105 break;
106 }
107
108 mutex_unlock(&of_dma_lock);
109}
110EXPORT_SYMBOL_GPL(of_dma_controller_free);
111
112/**
113 * of_dma_match_channel - Check if a DMA specifier matches name
114 * @np: device node to look for DMA channels
115 * @name: channel name to be matched
116 * @index: index of DMA specifier in list of DMA specifiers
117 * @dma_spec: pointer to DMA specifier as found in the device tree
118 *
119 * Check if the DMA specifier pointed to by the index in a list of DMA
120 * specifiers, matches the name provided. Returns 0 if the name matches and
121 * a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV.
122 */
123static int of_dma_match_channel(struct device_node *np, const char *name,
124 int index, struct of_phandle_args *dma_spec)
125{
126 const char *s;
127
128 if (of_property_read_string_index(np, "dma-names", index, &s))
129 return -ENODEV;
130
131 if (strcmp(name, s))
132 return -ENODEV;
133
134 if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index,
135 dma_spec))
136 return -ENODEV;
137
138 return 0;
139}
140
141/**
142 * of_dma_request_slave_channel - Get the DMA slave channel
143 * @np: device node to get DMA request from
144 * @name: name of desired channel
145 *
146 * Returns pointer to appropriate DMA channel on success or an error pointer.
147 */
148struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
149 const char *name)
150{
151 struct of_phandle_args dma_spec;
152 struct of_dma *ofdma;
153 struct dma_chan *chan;
154 int count, i;
155 int ret_no_channel = -ENODEV;
156
157 if (!np || !name) {
158 pr_err("%s: not enough information provided\n", __func__);
159 return ERR_PTR(-ENODEV);
160 }
161
162 count = of_property_count_strings(np, "dma-names");
163 if (count < 0) {
164 pr_err("%s: dma-names property of node '%s' missing or empty\n",
165 __func__, np->full_name);
166 return ERR_PTR(-ENODEV);
167 }
168
169 for (i = 0; i < count; i++) {
170 if (of_dma_match_channel(np, name, i, &dma_spec))
171 continue;
172
173 mutex_lock(&of_dma_lock);
174 ofdma = of_dma_find_controller(&dma_spec);
175
176 if (ofdma) {
177 chan = ofdma->of_dma_xlate(&dma_spec, ofdma);
178 } else {
179 ret_no_channel = -EPROBE_DEFER;
180 chan = NULL;
181 }
182
183 mutex_unlock(&of_dma_lock);
184
185 of_node_put(dma_spec.np);
186
187 if (chan)
188 return chan;
189 }
190
191 return ERR_PTR(ret_no_channel);
192}
193
194/**
195 * of_dma_simple_xlate - Simple DMA engine translation function
196 * @dma_spec: pointer to DMA specifier as found in the device tree
197 * @of_dma: pointer to DMA controller data
198 *
199 * A simple translation function for devices that use a 32-bit value for the
200 * filter_param when calling the DMA engine dma_request_channel() function.
201 * Note that this translation function requires that #dma-cells is equal to 1
202 * and the argument of the dma specifier is the 32-bit filter_param. Returns
203 * pointer to appropriate dma channel on success or NULL on error.
204 */
205struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
206 struct of_dma *ofdma)
207{
208 int count = dma_spec->args_count;
209 struct of_dma_filter_info *info = ofdma->of_dma_data;
210
211 if (!info || !info->filter_fn)
212 return NULL;
213
214 if (count != 1)
215 return NULL;
216
217 return dma_request_channel(info->dma_cap, info->filter_fn,
218 &dma_spec->args[0]);
219}
220EXPORT_SYMBOL_GPL(of_dma_simple_xlate);