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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> | |
16 | #include <linux/rculist.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 | ||
23 | /** | |
24 | * of_dma_find_controller - Find a DMA controller in DT DMA helpers list | |
25 | * @np: device node of DMA controller | |
26 | */ | |
27 | static struct of_dma *of_dma_find_controller(struct device_node *np) | |
28 | { | |
29 | struct of_dma *ofdma; | |
30 | ||
31 | if (list_empty(&of_dma_list)) { | |
32 | pr_err("empty DMA controller list\n"); | |
33 | return NULL; | |
34 | } | |
35 | ||
36 | list_for_each_entry_rcu(ofdma, &of_dma_list, of_dma_controllers) | |
37 | if (ofdma->of_node == np) | |
38 | return ofdma; | |
39 | ||
40 | return NULL; | |
41 | } | |
42 | ||
43 | /** | |
44 | * of_dma_controller_register - Register a DMA controller to DT DMA helpers | |
45 | * @np: device node of DMA controller | |
46 | * @of_dma_xlate: translation function which converts a phandle | |
47 | * arguments list into a dma_chan structure | |
48 | * @data pointer to controller specific data to be used by | |
49 | * translation function | |
50 | * | |
51 | * Returns 0 on success or appropriate errno value on error. | |
52 | * | |
53 | * Allocated memory should be freed with appropriate of_dma_controller_free() | |
54 | * call. | |
55 | */ | |
56 | int of_dma_controller_register(struct device_node *np, | |
57 | struct dma_chan *(*of_dma_xlate) | |
58 | (struct of_phandle_args *, struct of_dma *), | |
59 | void *data) | |
60 | { | |
61 | struct of_dma *ofdma; | |
62 | int nbcells; | |
63 | ||
64 | if (!np || !of_dma_xlate) { | |
65 | pr_err("%s: not enough information provided\n", __func__); | |
66 | return -EINVAL; | |
67 | } | |
68 | ||
69 | ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL); | |
70 | if (!ofdma) | |
71 | return -ENOMEM; | |
72 | ||
73 | nbcells = be32_to_cpup(of_get_property(np, "#dma-cells", NULL)); | |
74 | if (!nbcells) { | |
75 | pr_err("%s: #dma-cells property is missing or invalid\n", | |
76 | __func__); | |
77 | return -EINVAL; | |
78 | } | |
79 | ||
80 | ofdma->of_node = np; | |
81 | ofdma->of_dma_nbcells = nbcells; | |
82 | ofdma->of_dma_xlate = of_dma_xlate; | |
83 | ofdma->of_dma_data = data; | |
84 | ||
85 | /* Now queue of_dma controller structure in list */ | |
86 | list_add_tail_rcu(&ofdma->of_dma_controllers, &of_dma_list); | |
87 | ||
88 | return 0; | |
89 | } | |
90 | EXPORT_SYMBOL_GPL(of_dma_controller_register); | |
91 | ||
92 | /** | |
93 | * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list | |
94 | * @np: device node of DMA controller | |
95 | * | |
96 | * Memory allocated by of_dma_controller_register() is freed here. | |
97 | */ | |
98 | void of_dma_controller_free(struct device_node *np) | |
99 | { | |
100 | struct of_dma *ofdma; | |
101 | ||
102 | ofdma = of_dma_find_controller(np); | |
103 | if (ofdma) { | |
104 | list_del_rcu(&ofdma->of_dma_controllers); | |
105 | kfree(ofdma); | |
106 | } | |
107 | } | |
108 | EXPORT_SYMBOL_GPL(of_dma_controller_free); | |
109 | ||
110 | /** | |
5ca7c109 | 111 | * of_dma_match_channel - Check if a DMA specifier matches name |
aa3da644 | 112 | * @np: device node to look for DMA channels |
5ca7c109 JH |
113 | * @name: channel name to be matched |
114 | * @index: index of DMA specifier in list of DMA specifiers | |
aa3da644 JH |
115 | * @dma_spec: pointer to DMA specifier as found in the device tree |
116 | * | |
5ca7c109 JH |
117 | * Check if the DMA specifier pointed to by the index in a list of DMA |
118 | * specifiers, matches the name provided. Returns 0 if the name matches and | |
119 | * a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV. | |
aa3da644 | 120 | */ |
5ca7c109 JH |
121 | static int of_dma_match_channel(struct device_node *np, char *name, int index, |
122 | struct of_phandle_args *dma_spec) | |
aa3da644 | 123 | { |
aa3da644 JH |
124 | const char *s; |
125 | ||
5ca7c109 JH |
126 | if (of_property_read_string_index(np, "dma-names", index, &s)) |
127 | return -ENODEV; | |
aa3da644 | 128 | |
5ca7c109 JH |
129 | if (strcmp(name, s)) |
130 | return -ENODEV; | |
aa3da644 | 131 | |
5ca7c109 JH |
132 | if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index, |
133 | dma_spec)) | |
134 | return -ENODEV; | |
aa3da644 | 135 | |
5ca7c109 | 136 | return 0; |
aa3da644 JH |
137 | } |
138 | ||
139 | /** | |
140 | * of_dma_request_slave_channel - Get the DMA slave channel | |
141 | * @np: device node to get DMA request from | |
142 | * @name: name of desired channel | |
143 | * | |
144 | * Returns pointer to appropriate dma channel on success or NULL on error. | |
145 | */ | |
146 | struct dma_chan *of_dma_request_slave_channel(struct device_node *np, | |
147 | char *name) | |
148 | { | |
149 | struct of_phandle_args dma_spec; | |
150 | struct of_dma *ofdma; | |
151 | struct dma_chan *chan; | |
5ca7c109 | 152 | int count, i; |
aa3da644 JH |
153 | |
154 | if (!np || !name) { | |
155 | pr_err("%s: not enough information provided\n", __func__); | |
156 | return NULL; | |
157 | } | |
158 | ||
5ca7c109 JH |
159 | count = of_property_count_strings(np, "dma-names"); |
160 | if (count < 0) { | |
161 | pr_err("%s: dma-names property missing or empty\n", __func__); | |
162 | return NULL; | |
163 | } | |
164 | ||
165 | for (i = 0; i < count; i++) { | |
166 | if (of_dma_match_channel(np, name, i, &dma_spec)) | |
167 | continue; | |
aa3da644 JH |
168 | |
169 | ofdma = of_dma_find_controller(dma_spec.np); | |
170 | if (!ofdma) { | |
171 | pr_debug("%s: can't find DMA controller %s\n", | |
172 | np->full_name, dma_spec.np->full_name); | |
173 | continue; | |
174 | } | |
175 | ||
176 | if (dma_spec.args_count != ofdma->of_dma_nbcells) { | |
177 | pr_debug("%s: wrong #dma-cells for %s\n", np->full_name, | |
178 | dma_spec.np->full_name); | |
179 | continue; | |
180 | } | |
181 | ||
182 | chan = ofdma->of_dma_xlate(&dma_spec, ofdma); | |
183 | ||
184 | of_node_put(dma_spec.np); | |
185 | ||
5ca7c109 JH |
186 | if (chan) |
187 | return chan; | |
188 | } | |
aa3da644 | 189 | |
5ca7c109 | 190 | return NULL; |
aa3da644 JH |
191 | } |
192 | ||
193 | /** | |
194 | * of_dma_simple_xlate - Simple DMA engine translation function | |
195 | * @dma_spec: pointer to DMA specifier as found in the device tree | |
196 | * @of_dma: pointer to DMA controller data | |
197 | * | |
198 | * A simple translation function for devices that use a 32-bit value for the | |
199 | * filter_param when calling the DMA engine dma_request_channel() function. | |
200 | * Note that this translation function requires that #dma-cells is equal to 1 | |
201 | * and the argument of the dma specifier is the 32-bit filter_param. Returns | |
202 | * pointer to appropriate dma channel on success or NULL on error. | |
203 | */ | |
204 | struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec, | |
205 | struct of_dma *ofdma) | |
206 | { | |
207 | int count = dma_spec->args_count; | |
208 | struct of_dma_filter_info *info = ofdma->of_dma_data; | |
209 | ||
210 | if (!info || !info->filter_fn) | |
211 | return NULL; | |
212 | ||
213 | if (count != 1) | |
214 | return NULL; | |
215 | ||
216 | return dma_request_channel(info->dma_cap, info->filter_fn, | |
217 | &dma_spec->args[0]); | |
218 | } | |
219 | EXPORT_SYMBOL_GPL(of_dma_simple_xlate); |