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Jon Hunteraa3da642012-09-14 17:41:56 -05001/*
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>
Lars-Peter Clausende616082013-04-19 11:42:14 +020016#include <linux/mutex.h>
Jon Hunteraa3da642012-09-14 17:41:56 -050017#include <linux/slab.h>
18#include <linux/of.h>
19#include <linux/of_dma.h>
20
21static LIST_HEAD(of_dma_list);
Lars-Peter Clausende616082013-04-19 11:42:14 +020022static DEFINE_MUTEX(of_dma_lock);
Jon Hunteraa3da642012-09-14 17:41:56 -050023
24/**
Lars-Peter Clausende616082013-04-19 11:42:14 +020025 * of_dma_find_controller - Get a DMA controller in DT DMA helpers list
Jon Hunter9743a3b2012-10-11 14:43:01 -050026 * @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
Lars-Peter Clausende616082013-04-19 11:42:14 +020029 * 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.
Jon Hunteraa3da642012-09-14 17:41:56 -050032 */
Lars-Peter Clausende616082013-04-19 11:42:14 +020033static struct of_dma *of_dma_find_controller(struct of_phandle_args *dma_spec)
Jon Hunteraa3da642012-09-14 17:41:56 -050034{
35 struct of_dma *ofdma;
36
Jon Hunter9743a3b2012-10-11 14:43:01 -050037 list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
Lars-Peter Clausen8552bb42013-04-22 10:33:33 +020038 if (ofdma->of_node == dma_spec->np)
Jon Hunteraa3da642012-09-14 17:41:56 -050039 return ofdma;
Jon Hunter9743a3b2012-10-11 14:43:01 -050040
41 pr_debug("%s: can't find DMA controller %s\n", __func__,
42 dma_spec->np->full_name);
Jon Hunteraa3da642012-09-14 17:41:56 -050043
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;
Jon Hunteraa3da642012-09-14 17:41:56 -050066
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
Jon Hunteraa3da642012-09-14 17:41:56 -050076 ofdma->of_node = np;
Jon Hunteraa3da642012-09-14 17:41:56 -050077 ofdma->of_dma_xlate = of_dma_xlate;
78 ofdma->of_dma_data = data;
79
80 /* Now queue of_dma controller structure in list */
Lars-Peter Clausende616082013-04-19 11:42:14 +020081 mutex_lock(&of_dma_lock);
Jon Hunter9743a3b2012-10-11 14:43:01 -050082 list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
Lars-Peter Clausende616082013-04-19 11:42:14 +020083 mutex_unlock(&of_dma_lock);
Jon Hunteraa3da642012-09-14 17:41:56 -050084
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 */
Lars-Peter Clausende616082013-04-19 11:42:14 +020095void of_dma_controller_free(struct device_node *np)
Jon Hunteraa3da642012-09-14 17:41:56 -050096{
97 struct of_dma *ofdma;
98
Lars-Peter Clausende616082013-04-19 11:42:14 +020099 mutex_lock(&of_dma_lock);
Jon Hunter9743a3b2012-10-11 14:43:01 -0500100
101 list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
102 if (ofdma->of_node == np) {
Jon Hunter9743a3b2012-10-11 14:43:01 -0500103 list_del(&ofdma->of_dma_controllers);
Jon Hunter9743a3b2012-10-11 14:43:01 -0500104 kfree(ofdma);
Lars-Peter Clausende616082013-04-19 11:42:14 +0200105 break;
Jon Hunter9743a3b2012-10-11 14:43:01 -0500106 }
107
Lars-Peter Clausende616082013-04-19 11:42:14 +0200108 mutex_unlock(&of_dma_lock);
Jon Hunteraa3da642012-09-14 17:41:56 -0500109}
110EXPORT_SYMBOL_GPL(of_dma_controller_free);
111
112/**
Jon Hunter5ca7c102012-09-25 13:59:31 -0500113 * of_dma_match_channel - Check if a DMA specifier matches name
Jon Hunteraa3da642012-09-14 17:41:56 -0500114 * @np: device node to look for DMA channels
Jon Hunter5ca7c102012-09-25 13:59:31 -0500115 * @name: channel name to be matched
116 * @index: index of DMA specifier in list of DMA specifiers
Jon Hunteraa3da642012-09-14 17:41:56 -0500117 * @dma_spec: pointer to DMA specifier as found in the device tree
118 *
Jon Hunter5ca7c102012-09-25 13:59:31 -0500119 * 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.
Jon Hunteraa3da642012-09-14 17:41:56 -0500122 */
Markus Pargmannbef29ec2013-02-24 16:36:09 +0100123static int of_dma_match_channel(struct device_node *np, const char *name,
124 int index, struct of_phandle_args *dma_spec)
Jon Hunteraa3da642012-09-14 17:41:56 -0500125{
Jon Hunteraa3da642012-09-14 17:41:56 -0500126 const char *s;
127
Jon Hunter5ca7c102012-09-25 13:59:31 -0500128 if (of_property_read_string_index(np, "dma-names", index, &s))
129 return -ENODEV;
Jon Hunteraa3da642012-09-14 17:41:56 -0500130
Jon Hunter5ca7c102012-09-25 13:59:31 -0500131 if (strcmp(name, s))
132 return -ENODEV;
Jon Hunteraa3da642012-09-14 17:41:56 -0500133
Jon Hunter5ca7c102012-09-25 13:59:31 -0500134 if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index,
135 dma_spec))
136 return -ENODEV;
Jon Hunteraa3da642012-09-14 17:41:56 -0500137
Jon Hunter5ca7c102012-09-25 13:59:31 -0500138 return 0;
Jon Hunteraa3da642012-09-14 17:41:56 -0500139}
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 *
Stephen Warren0ad7c002013-11-26 10:04:22 -0700146 * Returns pointer to appropriate DMA channel on success or an error pointer.
Jon Hunteraa3da642012-09-14 17:41:56 -0500147 */
148struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
Markus Pargmannbef29ec2013-02-24 16:36:09 +0100149 const char *name)
Jon Hunteraa3da642012-09-14 17:41:56 -0500150{
151 struct of_phandle_args dma_spec;
152 struct of_dma *ofdma;
153 struct dma_chan *chan;
Jon Hunter5ca7c102012-09-25 13:59:31 -0500154 int count, i;
Stephen Warren0ad7c002013-11-26 10:04:22 -0700155 int ret_no_channel = -ENODEV;
Jon Hunteraa3da642012-09-14 17:41:56 -0500156
157 if (!np || !name) {
158 pr_err("%s: not enough information provided\n", __func__);
Stephen Warren0ad7c002013-11-26 10:04:22 -0700159 return ERR_PTR(-ENODEV);
Jon Hunteraa3da642012-09-14 17:41:56 -0500160 }
161
Jon Hunter5ca7c102012-09-25 13:59:31 -0500162 count = of_property_count_strings(np, "dma-names");
163 if (count < 0) {
Lothar Waßmann303fd712013-07-31 16:14:35 +0200164 pr_err("%s: dma-names property of node '%s' missing or empty\n",
165 __func__, np->full_name);
Stephen Warren0ad7c002013-11-26 10:04:22 -0700166 return ERR_PTR(-ENODEV);
Jon Hunter5ca7c102012-09-25 13:59:31 -0500167 }
168
169 for (i = 0; i < count; i++) {
170 if (of_dma_match_channel(np, name, i, &dma_spec))
171 continue;
Jon Hunteraa3da642012-09-14 17:41:56 -0500172
Lars-Peter Clausende616082013-04-19 11:42:14 +0200173 mutex_lock(&of_dma_lock);
174 ofdma = of_dma_find_controller(&dma_spec);
Jon Hunteraa3da642012-09-14 17:41:56 -0500175
Stephen Warren0ad7c002013-11-26 10:04:22 -0700176 if (ofdma) {
Lars-Peter Clausenf22eb142013-04-19 11:42:13 +0200177 chan = ofdma->of_dma_xlate(&dma_spec, ofdma);
Stephen Warren0ad7c002013-11-26 10:04:22 -0700178 } else {
179 ret_no_channel = -EPROBE_DEFER;
Lars-Peter Clausenf22eb142013-04-19 11:42:13 +0200180 chan = NULL;
Stephen Warren0ad7c002013-11-26 10:04:22 -0700181 }
Lars-Peter Clausende616082013-04-19 11:42:14 +0200182
183 mutex_unlock(&of_dma_lock);
Jon Hunter9743a3b2012-10-11 14:43:01 -0500184
Jon Hunteraa3da642012-09-14 17:41:56 -0500185 of_node_put(dma_spec.np);
186
Jon Hunter5ca7c102012-09-25 13:59:31 -0500187 if (chan)
188 return chan;
189 }
Jon Hunteraa3da642012-09-14 17:41:56 -0500190
Stephen Warren0ad7c002013-11-26 10:04:22 -0700191 return ERR_PTR(ret_no_channel);
Jon Hunteraa3da642012-09-14 17:41:56 -0500192}
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);