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aa3da644 JH |
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> | |
de61608a | 16 | #include <linux/mutex.h> |
aa3da644 JH |
17 | #include <linux/slab.h> |
18 | #include <linux/of.h> | |
19 | #include <linux/of_dma.h> | |
20 | ||
21 | static LIST_HEAD(of_dma_list); | |
de61608a | 22 | static DEFINE_MUTEX(of_dma_lock); |
aa3da644 JH |
23 | |
24 | /** | |
de61608a | 25 | * of_dma_find_controller - Get a DMA controller in DT DMA helpers list |
9743a3b6 JH |
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 | |
de61608a LPC |
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. | |
aa3da644 | 32 | */ |
de61608a | 33 | static struct of_dma *of_dma_find_controller(struct of_phandle_args *dma_spec) |
aa3da644 JH |
34 | { |
35 | struct of_dma *ofdma; | |
36 | ||
9743a3b6 | 37 | list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) |
8552bb4f | 38 | if (ofdma->of_node == dma_spec->np) |
aa3da644 | 39 | return ofdma; |
9743a3b6 JH |
40 | |
41 | pr_debug("%s: can't find DMA controller %s\n", __func__, | |
42 | dma_spec->np->full_name); | |
aa3da644 JH |
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 | */ | |
60 | int 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; | |
aa3da644 JH |
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 | ||
aa3da644 | 76 | ofdma->of_node = np; |
aa3da644 JH |
77 | ofdma->of_dma_xlate = of_dma_xlate; |
78 | ofdma->of_dma_data = data; | |
79 | ||
80 | /* Now queue of_dma controller structure in list */ | |
de61608a | 81 | mutex_lock(&of_dma_lock); |
9743a3b6 | 82 | list_add_tail(&ofdma->of_dma_controllers, &of_dma_list); |
de61608a | 83 | mutex_unlock(&of_dma_lock); |
aa3da644 JH |
84 | |
85 | return 0; | |
86 | } | |
87 | EXPORT_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 | */ | |
de61608a | 95 | void of_dma_controller_free(struct device_node *np) |
aa3da644 JH |
96 | { |
97 | struct of_dma *ofdma; | |
98 | ||
de61608a | 99 | mutex_lock(&of_dma_lock); |
9743a3b6 JH |
100 | |
101 | list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) | |
102 | if (ofdma->of_node == np) { | |
9743a3b6 | 103 | list_del(&ofdma->of_dma_controllers); |
9743a3b6 | 104 | kfree(ofdma); |
de61608a | 105 | break; |
9743a3b6 JH |
106 | } |
107 | ||
de61608a | 108 | mutex_unlock(&of_dma_lock); |
aa3da644 JH |
109 | } |
110 | EXPORT_SYMBOL_GPL(of_dma_controller_free); | |
111 | ||
112 | /** | |
5ca7c109 | 113 | * of_dma_match_channel - Check if a DMA specifier matches name |
aa3da644 | 114 | * @np: device node to look for DMA channels |
5ca7c109 JH |
115 | * @name: channel name to be matched |
116 | * @index: index of DMA specifier in list of DMA specifiers | |
aa3da644 JH |
117 | * @dma_spec: pointer to DMA specifier as found in the device tree |
118 | * | |
5ca7c109 JH |
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. | |
aa3da644 | 122 | */ |
bef29ec5 MP |
123 | static int of_dma_match_channel(struct device_node *np, const char *name, |
124 | int index, struct of_phandle_args *dma_spec) | |
aa3da644 | 125 | { |
aa3da644 JH |
126 | const char *s; |
127 | ||
5ca7c109 JH |
128 | if (of_property_read_string_index(np, "dma-names", index, &s)) |
129 | return -ENODEV; | |
aa3da644 | 130 | |
5ca7c109 JH |
131 | if (strcmp(name, s)) |
132 | return -ENODEV; | |
aa3da644 | 133 | |
5ca7c109 JH |
134 | if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index, |
135 | dma_spec)) | |
136 | return -ENODEV; | |
aa3da644 | 137 | |
5ca7c109 | 138 | return 0; |
aa3da644 JH |
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 | * | |
0ad7c000 | 146 | * Returns pointer to appropriate DMA channel on success or an error pointer. |
aa3da644 JH |
147 | */ |
148 | struct dma_chan *of_dma_request_slave_channel(struct device_node *np, | |
bef29ec5 | 149 | const char *name) |
aa3da644 JH |
150 | { |
151 | struct of_phandle_args dma_spec; | |
152 | struct of_dma *ofdma; | |
153 | struct dma_chan *chan; | |
5ca7c109 | 154 | int count, i; |
0ad7c000 | 155 | int ret_no_channel = -ENODEV; |
aa3da644 JH |
156 | |
157 | if (!np || !name) { | |
158 | pr_err("%s: not enough information provided\n", __func__); | |
0ad7c000 | 159 | return ERR_PTR(-ENODEV); |
aa3da644 JH |
160 | } |
161 | ||
5ca7c109 JH |
162 | count = of_property_count_strings(np, "dma-names"); |
163 | if (count < 0) { | |
303fd71d LW |
164 | pr_err("%s: dma-names property of node '%s' missing or empty\n", |
165 | __func__, np->full_name); | |
0ad7c000 | 166 | return ERR_PTR(-ENODEV); |
5ca7c109 JH |
167 | } |
168 | ||
169 | for (i = 0; i < count; i++) { | |
170 | if (of_dma_match_channel(np, name, i, &dma_spec)) | |
171 | continue; | |
aa3da644 | 172 | |
de61608a LPC |
173 | mutex_lock(&of_dma_lock); |
174 | ofdma = of_dma_find_controller(&dma_spec); | |
aa3da644 | 175 | |
0ad7c000 | 176 | if (ofdma) { |
f22eb140 | 177 | chan = ofdma->of_dma_xlate(&dma_spec, ofdma); |
0ad7c000 SW |
178 | } else { |
179 | ret_no_channel = -EPROBE_DEFER; | |
f22eb140 | 180 | chan = NULL; |
0ad7c000 | 181 | } |
de61608a LPC |
182 | |
183 | mutex_unlock(&of_dma_lock); | |
9743a3b6 | 184 | |
aa3da644 JH |
185 | of_node_put(dma_spec.np); |
186 | ||
5ca7c109 JH |
187 | if (chan) |
188 | return chan; | |
189 | } | |
aa3da644 | 190 | |
0ad7c000 | 191 | return ERR_PTR(ret_no_channel); |
aa3da644 JH |
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 | */ | |
205 | struct 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 | } | |
220 | EXPORT_SYMBOL_GPL(of_dma_simple_xlate); | |
16369efb AP |
221 | |
222 | /** | |
223 | * of_dma_xlate_by_chan_id - Translate dt property to DMA channel by channel id | |
224 | * @dma_spec: pointer to DMA specifier as found in the device tree | |
225 | * @of_dma: pointer to DMA controller data | |
226 | * | |
227 | * This function can be used as the of xlate callback for DMA driver which wants | |
228 | * to match the channel based on the channel id. When using this xlate function | |
229 | * the #dma-cells propety of the DMA controller dt node needs to be set to 1. | |
230 | * The data parameter of of_dma_controller_register must be a pointer to the | |
231 | * dma_device struct the function should match upon. | |
232 | * | |
233 | * Returns pointer to appropriate dma channel on success or NULL on error. | |
234 | */ | |
235 | struct dma_chan *of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec, | |
236 | struct of_dma *ofdma) | |
237 | { | |
238 | struct dma_device *dev = ofdma->of_dma_data; | |
239 | struct dma_chan *chan, *candidate = NULL; | |
240 | ||
241 | if (!dev || dma_spec->args_count != 1) | |
242 | return NULL; | |
243 | ||
244 | list_for_each_entry(chan, &dev->channels, device_node) | |
245 | if (chan->chan_id == dma_spec->args[0]) { | |
246 | candidate = chan; | |
247 | break; | |
248 | } | |
249 | ||
250 | if (!candidate) | |
251 | return NULL; | |
252 | ||
253 | return dma_get_slave_channel(candidate); | |
254 | } | |
255 | EXPORT_SYMBOL_GPL(of_dma_xlate_by_chan_id); |