Commit | Line | Data |
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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 JH |
37 | list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) |
38 | if ((ofdma->of_node == dma_spec->np) && | |
de61608a | 39 | (ofdma->of_dma_nbcells == dma_spec->args_count)) |
aa3da644 | 40 | return ofdma; |
9743a3b6 JH |
41 | |
42 | pr_debug("%s: can't find DMA controller %s\n", __func__, | |
43 | dma_spec->np->full_name); | |
aa3da644 JH |
44 | |
45 | return NULL; | |
46 | } | |
47 | ||
48 | /** | |
49 | * of_dma_controller_register - Register a DMA controller to DT DMA helpers | |
50 | * @np: device node of DMA controller | |
51 | * @of_dma_xlate: translation function which converts a phandle | |
52 | * arguments list into a dma_chan structure | |
53 | * @data pointer to controller specific data to be used by | |
54 | * translation function | |
55 | * | |
56 | * Returns 0 on success or appropriate errno value on error. | |
57 | * | |
58 | * Allocated memory should be freed with appropriate of_dma_controller_free() | |
59 | * call. | |
60 | */ | |
61 | int of_dma_controller_register(struct device_node *np, | |
62 | struct dma_chan *(*of_dma_xlate) | |
63 | (struct of_phandle_args *, struct of_dma *), | |
64 | void *data) | |
65 | { | |
66 | struct of_dma *ofdma; | |
67 | int nbcells; | |
9a188eb1 | 68 | const __be32 *prop; |
aa3da644 JH |
69 | |
70 | if (!np || !of_dma_xlate) { | |
71 | pr_err("%s: not enough information provided\n", __func__); | |
72 | return -EINVAL; | |
73 | } | |
74 | ||
75 | ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL); | |
76 | if (!ofdma) | |
77 | return -ENOMEM; | |
78 | ||
9a188eb1 VK |
79 | prop = of_get_property(np, "#dma-cells", NULL); |
80 | if (prop) | |
81 | nbcells = be32_to_cpup(prop); | |
82 | ||
83 | if (!prop || !nbcells) { | |
aa3da644 JH |
84 | pr_err("%s: #dma-cells property is missing or invalid\n", |
85 | __func__); | |
e68b1130 | 86 | kfree(ofdma); |
aa3da644 JH |
87 | return -EINVAL; |
88 | } | |
89 | ||
90 | ofdma->of_node = np; | |
91 | ofdma->of_dma_nbcells = nbcells; | |
92 | ofdma->of_dma_xlate = of_dma_xlate; | |
93 | ofdma->of_dma_data = data; | |
94 | ||
95 | /* Now queue of_dma controller structure in list */ | |
de61608a | 96 | mutex_lock(&of_dma_lock); |
9743a3b6 | 97 | list_add_tail(&ofdma->of_dma_controllers, &of_dma_list); |
de61608a | 98 | mutex_unlock(&of_dma_lock); |
aa3da644 JH |
99 | |
100 | return 0; | |
101 | } | |
102 | EXPORT_SYMBOL_GPL(of_dma_controller_register); | |
103 | ||
104 | /** | |
105 | * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list | |
106 | * @np: device node of DMA controller | |
107 | * | |
108 | * Memory allocated by of_dma_controller_register() is freed here. | |
109 | */ | |
de61608a | 110 | void of_dma_controller_free(struct device_node *np) |
aa3da644 JH |
111 | { |
112 | struct of_dma *ofdma; | |
113 | ||
de61608a | 114 | mutex_lock(&of_dma_lock); |
9743a3b6 JH |
115 | |
116 | list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) | |
117 | if (ofdma->of_node == np) { | |
9743a3b6 | 118 | list_del(&ofdma->of_dma_controllers); |
9743a3b6 | 119 | kfree(ofdma); |
de61608a | 120 | break; |
9743a3b6 JH |
121 | } |
122 | ||
de61608a | 123 | mutex_unlock(&of_dma_lock); |
aa3da644 JH |
124 | } |
125 | EXPORT_SYMBOL_GPL(of_dma_controller_free); | |
126 | ||
127 | /** | |
5ca7c109 | 128 | * of_dma_match_channel - Check if a DMA specifier matches name |
aa3da644 | 129 | * @np: device node to look for DMA channels |
5ca7c109 JH |
130 | * @name: channel name to be matched |
131 | * @index: index of DMA specifier in list of DMA specifiers | |
aa3da644 JH |
132 | * @dma_spec: pointer to DMA specifier as found in the device tree |
133 | * | |
5ca7c109 JH |
134 | * Check if the DMA specifier pointed to by the index in a list of DMA |
135 | * specifiers, matches the name provided. Returns 0 if the name matches and | |
136 | * a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV. | |
aa3da644 | 137 | */ |
bef29ec5 MP |
138 | static int of_dma_match_channel(struct device_node *np, const char *name, |
139 | int index, struct of_phandle_args *dma_spec) | |
aa3da644 | 140 | { |
aa3da644 JH |
141 | const char *s; |
142 | ||
5ca7c109 JH |
143 | if (of_property_read_string_index(np, "dma-names", index, &s)) |
144 | return -ENODEV; | |
aa3da644 | 145 | |
5ca7c109 JH |
146 | if (strcmp(name, s)) |
147 | return -ENODEV; | |
aa3da644 | 148 | |
5ca7c109 JH |
149 | if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index, |
150 | dma_spec)) | |
151 | return -ENODEV; | |
aa3da644 | 152 | |
5ca7c109 | 153 | return 0; |
aa3da644 JH |
154 | } |
155 | ||
156 | /** | |
157 | * of_dma_request_slave_channel - Get the DMA slave channel | |
158 | * @np: device node to get DMA request from | |
159 | * @name: name of desired channel | |
160 | * | |
161 | * Returns pointer to appropriate dma channel on success or NULL on error. | |
162 | */ | |
163 | struct dma_chan *of_dma_request_slave_channel(struct device_node *np, | |
bef29ec5 | 164 | const char *name) |
aa3da644 JH |
165 | { |
166 | struct of_phandle_args dma_spec; | |
167 | struct of_dma *ofdma; | |
168 | struct dma_chan *chan; | |
5ca7c109 | 169 | int count, i; |
aa3da644 JH |
170 | |
171 | if (!np || !name) { | |
172 | pr_err("%s: not enough information provided\n", __func__); | |
173 | return NULL; | |
174 | } | |
175 | ||
5ca7c109 JH |
176 | count = of_property_count_strings(np, "dma-names"); |
177 | if (count < 0) { | |
178 | pr_err("%s: dma-names property missing or empty\n", __func__); | |
179 | return NULL; | |
180 | } | |
181 | ||
182 | for (i = 0; i < count; i++) { | |
183 | if (of_dma_match_channel(np, name, i, &dma_spec)) | |
184 | continue; | |
aa3da644 | 185 | |
de61608a LPC |
186 | mutex_lock(&of_dma_lock); |
187 | ofdma = of_dma_find_controller(&dma_spec); | |
aa3da644 | 188 | |
de61608a | 189 | if (ofdma) |
f22eb140 | 190 | chan = ofdma->of_dma_xlate(&dma_spec, ofdma); |
de61608a | 191 | else |
f22eb140 | 192 | chan = NULL; |
de61608a LPC |
193 | |
194 | mutex_unlock(&of_dma_lock); | |
9743a3b6 | 195 | |
aa3da644 JH |
196 | of_node_put(dma_spec.np); |
197 | ||
5ca7c109 JH |
198 | if (chan) |
199 | return chan; | |
200 | } | |
aa3da644 | 201 | |
5ca7c109 | 202 | return NULL; |
aa3da644 JH |
203 | } |
204 | ||
205 | /** | |
206 | * of_dma_simple_xlate - Simple DMA engine translation function | |
207 | * @dma_spec: pointer to DMA specifier as found in the device tree | |
208 | * @of_dma: pointer to DMA controller data | |
209 | * | |
210 | * A simple translation function for devices that use a 32-bit value for the | |
211 | * filter_param when calling the DMA engine dma_request_channel() function. | |
212 | * Note that this translation function requires that #dma-cells is equal to 1 | |
213 | * and the argument of the dma specifier is the 32-bit filter_param. Returns | |
214 | * pointer to appropriate dma channel on success or NULL on error. | |
215 | */ | |
216 | struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec, | |
217 | struct of_dma *ofdma) | |
218 | { | |
219 | int count = dma_spec->args_count; | |
220 | struct of_dma_filter_info *info = ofdma->of_dma_data; | |
221 | ||
222 | if (!info || !info->filter_fn) | |
223 | return NULL; | |
224 | ||
225 | if (count != 1) | |
226 | return NULL; | |
227 | ||
228 | return dma_request_channel(info->dma_cap, info->filter_fn, | |
229 | &dma_spec->args[0]); | |
230 | } | |
231 | EXPORT_SYMBOL_GPL(of_dma_simple_xlate); |