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> | |
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); | |
9743a3b6 | 22 | static DEFINE_SPINLOCK(of_dma_lock); |
aa3da644 JH |
23 | |
24 | /** | |
9743a3b6 JH |
25 | * of_dma_get_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 the use_count | |
30 | * variable is increased and a valid pointer to the DMA data stored is retuned. | |
31 | * A NULL pointer is returned if no match is found. | |
aa3da644 | 32 | */ |
9743a3b6 | 33 | static struct of_dma *of_dma_get_controller(struct of_phandle_args *dma_spec) |
aa3da644 JH |
34 | { |
35 | struct of_dma *ofdma; | |
36 | ||
9743a3b6 JH |
37 | spin_lock(&of_dma_lock); |
38 | ||
9743a3b6 JH |
39 | list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) |
40 | if ((ofdma->of_node == dma_spec->np) && | |
41 | (ofdma->of_dma_nbcells == dma_spec->args_count)) { | |
42 | ofdma->use_count++; | |
43 | spin_unlock(&of_dma_lock); | |
aa3da644 | 44 | return ofdma; |
9743a3b6 JH |
45 | } |
46 | ||
47 | spin_unlock(&of_dma_lock); | |
48 | ||
49 | pr_debug("%s: can't find DMA controller %s\n", __func__, | |
50 | dma_spec->np->full_name); | |
aa3da644 JH |
51 | |
52 | return NULL; | |
53 | } | |
54 | ||
9743a3b6 JH |
55 | /** |
56 | * of_dma_put_controller - Decrement use count for a registered DMA controller | |
57 | * @of_dma: pointer to DMA controller data | |
58 | * | |
59 | * Decrements the use_count variable in the DMA data structure. This function | |
60 | * should be called only when a valid pointer is returned from | |
61 | * of_dma_get_controller() and no further accesses to data referenced by that | |
62 | * pointer are needed. | |
63 | */ | |
64 | static void of_dma_put_controller(struct of_dma *ofdma) | |
65 | { | |
66 | spin_lock(&of_dma_lock); | |
67 | ofdma->use_count--; | |
68 | spin_unlock(&of_dma_lock); | |
69 | } | |
70 | ||
aa3da644 JH |
71 | /** |
72 | * of_dma_controller_register - Register a DMA controller to DT DMA helpers | |
73 | * @np: device node of DMA controller | |
74 | * @of_dma_xlate: translation function which converts a phandle | |
75 | * arguments list into a dma_chan structure | |
76 | * @data pointer to controller specific data to be used by | |
77 | * translation function | |
78 | * | |
79 | * Returns 0 on success or appropriate errno value on error. | |
80 | * | |
81 | * Allocated memory should be freed with appropriate of_dma_controller_free() | |
82 | * call. | |
83 | */ | |
84 | int of_dma_controller_register(struct device_node *np, | |
85 | struct dma_chan *(*of_dma_xlate) | |
86 | (struct of_phandle_args *, struct of_dma *), | |
87 | void *data) | |
88 | { | |
89 | struct of_dma *ofdma; | |
90 | int nbcells; | |
9a188eb1 | 91 | const __be32 *prop; |
aa3da644 JH |
92 | |
93 | if (!np || !of_dma_xlate) { | |
94 | pr_err("%s: not enough information provided\n", __func__); | |
95 | return -EINVAL; | |
96 | } | |
97 | ||
98 | ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL); | |
99 | if (!ofdma) | |
100 | return -ENOMEM; | |
101 | ||
9a188eb1 VK |
102 | prop = of_get_property(np, "#dma-cells", NULL); |
103 | if (prop) | |
104 | nbcells = be32_to_cpup(prop); | |
105 | ||
106 | if (!prop || !nbcells) { | |
aa3da644 JH |
107 | pr_err("%s: #dma-cells property is missing or invalid\n", |
108 | __func__); | |
e68b1130 | 109 | kfree(ofdma); |
aa3da644 JH |
110 | return -EINVAL; |
111 | } | |
112 | ||
113 | ofdma->of_node = np; | |
114 | ofdma->of_dma_nbcells = nbcells; | |
115 | ofdma->of_dma_xlate = of_dma_xlate; | |
116 | ofdma->of_dma_data = data; | |
9743a3b6 | 117 | ofdma->use_count = 0; |
aa3da644 JH |
118 | |
119 | /* Now queue of_dma controller structure in list */ | |
88b386c0 | 120 | spin_lock(&of_dma_lock); |
9743a3b6 | 121 | list_add_tail(&ofdma->of_dma_controllers, &of_dma_list); |
88b386c0 | 122 | spin_unlock(&of_dma_lock); |
aa3da644 JH |
123 | |
124 | return 0; | |
125 | } | |
126 | EXPORT_SYMBOL_GPL(of_dma_controller_register); | |
127 | ||
128 | /** | |
129 | * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list | |
130 | * @np: device node of DMA controller | |
131 | * | |
132 | * Memory allocated by of_dma_controller_register() is freed here. | |
133 | */ | |
9743a3b6 | 134 | int of_dma_controller_free(struct device_node *np) |
aa3da644 JH |
135 | { |
136 | struct of_dma *ofdma; | |
137 | ||
9743a3b6 JH |
138 | spin_lock(&of_dma_lock); |
139 | ||
140 | if (list_empty(&of_dma_list)) { | |
141 | spin_unlock(&of_dma_lock); | |
142 | return -ENODEV; | |
aa3da644 | 143 | } |
9743a3b6 JH |
144 | |
145 | list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) | |
146 | if (ofdma->of_node == np) { | |
147 | if (ofdma->use_count) { | |
148 | spin_unlock(&of_dma_lock); | |
149 | return -EBUSY; | |
150 | } | |
151 | ||
152 | list_del(&ofdma->of_dma_controllers); | |
153 | spin_unlock(&of_dma_lock); | |
154 | kfree(ofdma); | |
155 | return 0; | |
156 | } | |
157 | ||
158 | spin_unlock(&of_dma_lock); | |
159 | return -ENODEV; | |
aa3da644 JH |
160 | } |
161 | EXPORT_SYMBOL_GPL(of_dma_controller_free); | |
162 | ||
163 | /** | |
5ca7c109 | 164 | * of_dma_match_channel - Check if a DMA specifier matches name |
aa3da644 | 165 | * @np: device node to look for DMA channels |
5ca7c109 JH |
166 | * @name: channel name to be matched |
167 | * @index: index of DMA specifier in list of DMA specifiers | |
aa3da644 JH |
168 | * @dma_spec: pointer to DMA specifier as found in the device tree |
169 | * | |
5ca7c109 JH |
170 | * Check if the DMA specifier pointed to by the index in a list of DMA |
171 | * specifiers, matches the name provided. Returns 0 if the name matches and | |
172 | * a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV. | |
aa3da644 | 173 | */ |
bef29ec5 MP |
174 | static int of_dma_match_channel(struct device_node *np, const char *name, |
175 | int index, struct of_phandle_args *dma_spec) | |
aa3da644 | 176 | { |
aa3da644 JH |
177 | const char *s; |
178 | ||
5ca7c109 JH |
179 | if (of_property_read_string_index(np, "dma-names", index, &s)) |
180 | return -ENODEV; | |
aa3da644 | 181 | |
5ca7c109 JH |
182 | if (strcmp(name, s)) |
183 | return -ENODEV; | |
aa3da644 | 184 | |
5ca7c109 JH |
185 | if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index, |
186 | dma_spec)) | |
187 | return -ENODEV; | |
aa3da644 | 188 | |
5ca7c109 | 189 | return 0; |
aa3da644 JH |
190 | } |
191 | ||
192 | /** | |
193 | * of_dma_request_slave_channel - Get the DMA slave channel | |
194 | * @np: device node to get DMA request from | |
195 | * @name: name of desired channel | |
196 | * | |
197 | * Returns pointer to appropriate dma channel on success or NULL on error. | |
198 | */ | |
199 | struct dma_chan *of_dma_request_slave_channel(struct device_node *np, | |
bef29ec5 | 200 | const char *name) |
aa3da644 JH |
201 | { |
202 | struct of_phandle_args dma_spec; | |
203 | struct of_dma *ofdma; | |
204 | struct dma_chan *chan; | |
5ca7c109 | 205 | int count, i; |
aa3da644 JH |
206 | |
207 | if (!np || !name) { | |
208 | pr_err("%s: not enough information provided\n", __func__); | |
209 | return NULL; | |
210 | } | |
211 | ||
5ca7c109 JH |
212 | count = of_property_count_strings(np, "dma-names"); |
213 | if (count < 0) { | |
214 | pr_err("%s: dma-names property missing or empty\n", __func__); | |
215 | return NULL; | |
216 | } | |
217 | ||
218 | for (i = 0; i < count; i++) { | |
219 | if (of_dma_match_channel(np, name, i, &dma_spec)) | |
220 | continue; | |
aa3da644 | 221 | |
9743a3b6 | 222 | ofdma = of_dma_get_controller(&dma_spec); |
aa3da644 | 223 | |
f22eb140 LPC |
224 | if (ofdma) { |
225 | chan = ofdma->of_dma_xlate(&dma_spec, ofdma); | |
aa3da644 | 226 | |
f22eb140 LPC |
227 | of_dma_put_controller(ofdma); |
228 | } else { | |
229 | chan = NULL; | |
230 | } | |
9743a3b6 | 231 | |
aa3da644 JH |
232 | of_node_put(dma_spec.np); |
233 | ||
5ca7c109 JH |
234 | if (chan) |
235 | return chan; | |
236 | } | |
aa3da644 | 237 | |
5ca7c109 | 238 | return NULL; |
aa3da644 JH |
239 | } |
240 | ||
241 | /** | |
242 | * of_dma_simple_xlate - Simple DMA engine translation function | |
243 | * @dma_spec: pointer to DMA specifier as found in the device tree | |
244 | * @of_dma: pointer to DMA controller data | |
245 | * | |
246 | * A simple translation function for devices that use a 32-bit value for the | |
247 | * filter_param when calling the DMA engine dma_request_channel() function. | |
248 | * Note that this translation function requires that #dma-cells is equal to 1 | |
249 | * and the argument of the dma specifier is the 32-bit filter_param. Returns | |
250 | * pointer to appropriate dma channel on success or NULL on error. | |
251 | */ | |
252 | struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec, | |
253 | struct of_dma *ofdma) | |
254 | { | |
255 | int count = dma_spec->args_count; | |
256 | struct of_dma_filter_info *info = ofdma->of_dma_data; | |
257 | ||
258 | if (!info || !info->filter_fn) | |
259 | return NULL; | |
260 | ||
261 | if (count != 1) | |
262 | return NULL; | |
263 | ||
264 | return dma_request_channel(info->dma_cap, info->filter_fn, | |
265 | &dma_spec->args[0]); | |
266 | } | |
267 | EXPORT_SYMBOL_GPL(of_dma_simple_xlate); |