| 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/mutex.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 | static DEFINE_MUTEX(of_dma_lock); |
| 23 | |
| 24 | /** |
| 25 | * of_dma_find_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 a valid pointer |
| 30 | * to the DMA data stored is retuned. A NULL pointer is returned if no match is |
| 31 | * found. |
| 32 | */ |
| 33 | static struct of_dma *of_dma_find_controller(struct of_phandle_args *dma_spec) |
| 34 | { |
| 35 | struct of_dma *ofdma; |
| 36 | |
| 37 | list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) |
| 38 | if ((ofdma->of_node == dma_spec->np) && |
| 39 | (ofdma->of_dma_nbcells == dma_spec->args_count)) |
| 40 | return ofdma; |
| 41 | |
| 42 | pr_debug("%s: can't find DMA controller %s\n", __func__, |
| 43 | dma_spec->np->full_name); |
| 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 | const __be32 *prop; |
| 68 | |
| 69 | if (!np || !of_dma_xlate) { |
| 70 | pr_err("%s: not enough information provided\n", __func__); |
| 71 | return -EINVAL; |
| 72 | } |
| 73 | |
| 74 | ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL); |
| 75 | if (!ofdma) |
| 76 | return -ENOMEM; |
| 77 | |
| 78 | prop = of_get_property(np, "#dma-cells", NULL); |
| 79 | if (!prop) { |
| 80 | pr_err("%s: #dma-cells property is missing\n", |
| 81 | __func__); |
| 82 | kfree(ofdma); |
| 83 | return -EINVAL; |
| 84 | } |
| 85 | |
| 86 | |
| 87 | ofdma->of_node = np; |
| 88 | ofdma->of_dma_nbcells = be32_to_cpup(prop); |
| 89 | ofdma->of_dma_xlate = of_dma_xlate; |
| 90 | ofdma->of_dma_data = data; |
| 91 | |
| 92 | /* Now queue of_dma controller structure in list */ |
| 93 | mutex_lock(&of_dma_lock); |
| 94 | list_add_tail(&ofdma->of_dma_controllers, &of_dma_list); |
| 95 | mutex_unlock(&of_dma_lock); |
| 96 | |
| 97 | return 0; |
| 98 | } |
| 99 | EXPORT_SYMBOL_GPL(of_dma_controller_register); |
| 100 | |
| 101 | /** |
| 102 | * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list |
| 103 | * @np: device node of DMA controller |
| 104 | * |
| 105 | * Memory allocated by of_dma_controller_register() is freed here. |
| 106 | */ |
| 107 | void of_dma_controller_free(struct device_node *np) |
| 108 | { |
| 109 | struct of_dma *ofdma; |
| 110 | |
| 111 | mutex_lock(&of_dma_lock); |
| 112 | |
| 113 | list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) |
| 114 | if (ofdma->of_node == np) { |
| 115 | list_del(&ofdma->of_dma_controllers); |
| 116 | kfree(ofdma); |
| 117 | break; |
| 118 | } |
| 119 | |
| 120 | mutex_unlock(&of_dma_lock); |
| 121 | } |
| 122 | EXPORT_SYMBOL_GPL(of_dma_controller_free); |
| 123 | |
| 124 | /** |
| 125 | * of_dma_match_channel - Check if a DMA specifier matches name |
| 126 | * @np: device node to look for DMA channels |
| 127 | * @name: channel name to be matched |
| 128 | * @index: index of DMA specifier in list of DMA specifiers |
| 129 | * @dma_spec: pointer to DMA specifier as found in the device tree |
| 130 | * |
| 131 | * Check if the DMA specifier pointed to by the index in a list of DMA |
| 132 | * specifiers, matches the name provided. Returns 0 if the name matches and |
| 133 | * a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV. |
| 134 | */ |
| 135 | static int of_dma_match_channel(struct device_node *np, const char *name, |
| 136 | int index, struct of_phandle_args *dma_spec) |
| 137 | { |
| 138 | const char *s; |
| 139 | |
| 140 | if (of_property_read_string_index(np, "dma-names", index, &s)) |
| 141 | return -ENODEV; |
| 142 | |
| 143 | if (strcmp(name, s)) |
| 144 | return -ENODEV; |
| 145 | |
| 146 | if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index, |
| 147 | dma_spec)) |
| 148 | return -ENODEV; |
| 149 | |
| 150 | return 0; |
| 151 | } |
| 152 | |
| 153 | /** |
| 154 | * of_dma_request_slave_channel - Get the DMA slave channel |
| 155 | * @np: device node to get DMA request from |
| 156 | * @name: name of desired channel |
| 157 | * |
| 158 | * Returns pointer to appropriate dma channel on success or NULL on error. |
| 159 | */ |
| 160 | struct dma_chan *of_dma_request_slave_channel(struct device_node *np, |
| 161 | const char *name) |
| 162 | { |
| 163 | struct of_phandle_args dma_spec; |
| 164 | struct of_dma *ofdma; |
| 165 | struct dma_chan *chan; |
| 166 | int count, i; |
| 167 | |
| 168 | if (!np || !name) { |
| 169 | pr_err("%s: not enough information provided\n", __func__); |
| 170 | return NULL; |
| 171 | } |
| 172 | |
| 173 | count = of_property_count_strings(np, "dma-names"); |
| 174 | if (count < 0) { |
| 175 | pr_err("%s: dma-names property missing or empty\n", __func__); |
| 176 | return NULL; |
| 177 | } |
| 178 | |
| 179 | for (i = 0; i < count; i++) { |
| 180 | if (of_dma_match_channel(np, name, i, &dma_spec)) |
| 181 | continue; |
| 182 | |
| 183 | mutex_lock(&of_dma_lock); |
| 184 | ofdma = of_dma_find_controller(&dma_spec); |
| 185 | |
| 186 | if (ofdma) |
| 187 | chan = ofdma->of_dma_xlate(&dma_spec, ofdma); |
| 188 | else |
| 189 | chan = NULL; |
| 190 | |
| 191 | mutex_unlock(&of_dma_lock); |
| 192 | |
| 193 | of_node_put(dma_spec.np); |
| 194 | |
| 195 | if (chan) |
| 196 | return chan; |
| 197 | } |
| 198 | |
| 199 | return NULL; |
| 200 | } |
| 201 | |
| 202 | /** |
| 203 | * of_dma_simple_xlate - Simple DMA engine translation function |
| 204 | * @dma_spec: pointer to DMA specifier as found in the device tree |
| 205 | * @of_dma: pointer to DMA controller data |
| 206 | * |
| 207 | * A simple translation function for devices that use a 32-bit value for the |
| 208 | * filter_param when calling the DMA engine dma_request_channel() function. |
| 209 | * Note that this translation function requires that #dma-cells is equal to 1 |
| 210 | * and the argument of the dma specifier is the 32-bit filter_param. Returns |
| 211 | * pointer to appropriate dma channel on success or NULL on error. |
| 212 | */ |
| 213 | struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec, |
| 214 | struct of_dma *ofdma) |
| 215 | { |
| 216 | int count = dma_spec->args_count; |
| 217 | struct of_dma_filter_info *info = ofdma->of_dma_data; |
| 218 | |
| 219 | if (!info || !info->filter_fn) |
| 220 | return NULL; |
| 221 | |
| 222 | if (count != 1) |
| 223 | return NULL; |
| 224 | |
| 225 | return dma_request_channel(info->dma_cap, info->filter_fn, |
| 226 | &dma_spec->args[0]); |
| 227 | } |
| 228 | EXPORT_SYMBOL_GPL(of_dma_simple_xlate); |