1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Device tree helpers for DMA request / controller 4 * 5 * Based on of_gpio.c 6 * 7 * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/ 8 */ 9 10 #include <linux/device.h> 11 #include <linux/err.h> 12 #include <linux/module.h> 13 #include <linux/mutex.h> 14 #include <linux/slab.h> 15 #include <linux/of.h> 16 #include <linux/of_dma.h> 17 18 #include "dmaengine.h" 19 20 static LIST_HEAD(of_dma_list); 21 static DEFINE_MUTEX(of_dma_lock); 22 23 /** 24 * of_dma_find_controller - Get a DMA controller in DT DMA helpers list 25 * @dma_spec: pointer to DMA specifier as found in the device tree 26 * 27 * Finds a DMA controller with matching device node and number for dma cells 28 * in a list of registered DMA controllers. If a match is found a valid pointer 29 * to the DMA data stored is retuned. A NULL pointer is returned if no match is 30 * found. 31 */ 32 static struct of_dma *of_dma_find_controller(struct of_phandle_args *dma_spec) 33 { 34 struct of_dma *ofdma; 35 36 list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) 37 if (ofdma->of_node == dma_spec->np) 38 return ofdma; 39 40 pr_debug("%s: can't find DMA controller %pOF\n", __func__, 41 dma_spec->np); 42 43 return NULL; 44 } 45 46 /** 47 * of_dma_router_xlate - translation function for router devices 48 * @dma_spec: pointer to DMA specifier as found in the device tree 49 * @ofdma: pointer to DMA controller data (router information) 50 * 51 * The function creates new dma_spec to be passed to the router driver's 52 * of_dma_route_allocate() function to prepare a dma_spec which will be used 53 * to request channel from the real DMA controller. 54 */ 55 static struct dma_chan *of_dma_router_xlate(struct of_phandle_args *dma_spec, 56 struct of_dma *ofdma) 57 { 58 struct dma_chan *chan; 59 struct of_dma *ofdma_target; 60 struct of_phandle_args dma_spec_target; 61 void *route_data; 62 63 /* translate the request for the real DMA controller */ 64 memcpy(&dma_spec_target, dma_spec, sizeof(dma_spec_target)); 65 route_data = ofdma->of_dma_route_allocate(&dma_spec_target, ofdma); 66 if (IS_ERR(route_data)) 67 return NULL; 68 69 ofdma_target = of_dma_find_controller(&dma_spec_target); 70 if (!ofdma_target) { 71 ofdma->dma_router->route_free(ofdma->dma_router->dev, 72 route_data); 73 chan = ERR_PTR(-EPROBE_DEFER); 74 goto err; 75 } 76 77 chan = ofdma_target->of_dma_xlate(&dma_spec_target, ofdma_target); 78 if (IS_ERR_OR_NULL(chan)) { 79 ofdma->dma_router->route_free(ofdma->dma_router->dev, 80 route_data); 81 } else { 82 int ret = 0; 83 84 chan->router = ofdma->dma_router; 85 chan->route_data = route_data; 86 87 if (chan->device->device_router_config) 88 ret = chan->device->device_router_config(chan); 89 90 if (ret) { 91 dma_release_channel(chan); 92 chan = ERR_PTR(ret); 93 } 94 } 95 96 err: 97 /* 98 * Need to put the node back since the ofdma->of_dma_route_allocate 99 * has taken it for generating the new, translated dma_spec 100 */ 101 of_node_put(dma_spec_target.np); 102 return chan; 103 } 104 105 /** 106 * of_dma_controller_register - Register a DMA controller to DT DMA helpers 107 * @np: device node of DMA controller 108 * @of_dma_xlate: translation function which converts a phandle 109 * arguments list into a dma_chan structure 110 * @data: pointer to controller specific data to be used by 111 * translation function 112 * 113 * Returns 0 on success or appropriate errno value on error. 114 * 115 * Allocated memory should be freed with appropriate of_dma_controller_free() 116 * call. 117 */ 118 int of_dma_controller_register(struct device_node *np, 119 struct dma_chan *(*of_dma_xlate) 120 (struct of_phandle_args *, struct of_dma *), 121 void *data) 122 { 123 struct of_dma *ofdma; 124 125 if (!np || !of_dma_xlate) { 126 pr_err("%s: not enough information provided\n", __func__); 127 return -EINVAL; 128 } 129 130 ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL); 131 if (!ofdma) 132 return -ENOMEM; 133 134 ofdma->of_node = np; 135 ofdma->of_dma_xlate = of_dma_xlate; 136 ofdma->of_dma_data = data; 137 138 /* Now queue of_dma controller structure in list */ 139 mutex_lock(&of_dma_lock); 140 list_add_tail(&ofdma->of_dma_controllers, &of_dma_list); 141 mutex_unlock(&of_dma_lock); 142 143 return 0; 144 } 145 EXPORT_SYMBOL_GPL(of_dma_controller_register); 146 147 /** 148 * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list 149 * @np: device node of DMA controller 150 * 151 * Memory allocated by of_dma_controller_register() is freed here. 152 */ 153 void of_dma_controller_free(struct device_node *np) 154 { 155 struct of_dma *ofdma; 156 157 mutex_lock(&of_dma_lock); 158 159 list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) 160 if (ofdma->of_node == np) { 161 list_del(&ofdma->of_dma_controllers); 162 kfree(ofdma); 163 break; 164 } 165 166 mutex_unlock(&of_dma_lock); 167 } 168 EXPORT_SYMBOL_GPL(of_dma_controller_free); 169 170 /** 171 * of_dma_router_register - Register a DMA router to DT DMA helpers as a 172 * controller 173 * @np: device node of DMA router 174 * @of_dma_route_allocate: setup function for the router which need to 175 * modify the dma_spec for the DMA controller to 176 * use and to set up the requested route. 177 * @dma_router: pointer to dma_router structure to be used when 178 * the route need to be free up. 179 * 180 * Returns 0 on success or appropriate errno value on error. 181 * 182 * Allocated memory should be freed with appropriate of_dma_controller_free() 183 * call. 184 */ 185 int of_dma_router_register(struct device_node *np, 186 void *(*of_dma_route_allocate) 187 (struct of_phandle_args *, struct of_dma *), 188 struct dma_router *dma_router) 189 { 190 struct of_dma *ofdma; 191 192 if (!np || !of_dma_route_allocate || !dma_router) { 193 pr_err("%s: not enough information provided\n", __func__); 194 return -EINVAL; 195 } 196 197 ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL); 198 if (!ofdma) 199 return -ENOMEM; 200 201 ofdma->of_node = np; 202 ofdma->of_dma_xlate = of_dma_router_xlate; 203 ofdma->of_dma_route_allocate = of_dma_route_allocate; 204 ofdma->dma_router = dma_router; 205 206 /* Now queue of_dma controller structure in list */ 207 mutex_lock(&of_dma_lock); 208 list_add_tail(&ofdma->of_dma_controllers, &of_dma_list); 209 mutex_unlock(&of_dma_lock); 210 211 return 0; 212 } 213 EXPORT_SYMBOL_GPL(of_dma_router_register); 214 215 /** 216 * of_dma_match_channel - Check if a DMA specifier matches name 217 * @np: device node to look for DMA channels 218 * @name: channel name to be matched 219 * @index: index of DMA specifier in list of DMA specifiers 220 * @dma_spec: pointer to DMA specifier as found in the device tree 221 * 222 * Check if the DMA specifier pointed to by the index in a list of DMA 223 * specifiers, matches the name provided. Returns 0 if the name matches and 224 * a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV. 225 */ 226 static int of_dma_match_channel(struct device_node *np, const char *name, 227 int index, struct of_phandle_args *dma_spec) 228 { 229 const char *s; 230 231 if (of_property_read_string_index(np, "dma-names", index, &s)) 232 return -ENODEV; 233 234 if (strcmp(name, s)) 235 return -ENODEV; 236 237 if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index, 238 dma_spec)) 239 return -ENODEV; 240 241 return 0; 242 } 243 244 /** 245 * of_dma_request_slave_channel - Get the DMA slave channel 246 * @np: device node to get DMA request from 247 * @name: name of desired channel 248 * 249 * Returns pointer to appropriate DMA channel on success or an error pointer. 250 */ 251 struct dma_chan *of_dma_request_slave_channel(struct device_node *np, 252 const char *name) 253 { 254 struct of_phandle_args dma_spec; 255 struct of_dma *ofdma; 256 struct dma_chan *chan; 257 int count, i, start; 258 int ret_no_channel = -ENODEV; 259 static atomic_t last_index; 260 261 if (!np || !name) { 262 pr_err("%s: not enough information provided\n", __func__); 263 return ERR_PTR(-ENODEV); 264 } 265 266 /* Silently fail if there is not even the "dmas" property */ 267 if (!of_property_present(np, "dmas")) 268 return ERR_PTR(-ENODEV); 269 270 count = of_property_count_strings(np, "dma-names"); 271 if (count < 0) { 272 pr_err("%s: dma-names property of node '%pOF' missing or empty\n", 273 __func__, np); 274 return ERR_PTR(-ENODEV); 275 } 276 277 /* 278 * approximate an average distribution across multiple 279 * entries with the same name 280 */ 281 start = atomic_inc_return(&last_index); 282 for (i = 0; i < count; i++) { 283 if (of_dma_match_channel(np, name, 284 (i + start) % count, 285 &dma_spec)) 286 continue; 287 288 mutex_lock(&of_dma_lock); 289 ofdma = of_dma_find_controller(&dma_spec); 290 291 if (ofdma) { 292 chan = ofdma->of_dma_xlate(&dma_spec, ofdma); 293 } else { 294 ret_no_channel = -EPROBE_DEFER; 295 chan = NULL; 296 } 297 298 mutex_unlock(&of_dma_lock); 299 300 of_node_put(dma_spec.np); 301 302 if (chan) 303 return chan; 304 } 305 306 return ERR_PTR(ret_no_channel); 307 } 308 EXPORT_SYMBOL_GPL(of_dma_request_slave_channel); 309 310 /** 311 * of_dma_simple_xlate - Simple DMA engine translation function 312 * @dma_spec: pointer to DMA specifier as found in the device tree 313 * @ofdma: pointer to DMA controller data 314 * 315 * A simple translation function for devices that use a 32-bit value for the 316 * filter_param when calling the DMA engine dma_request_channel() function. 317 * Note that this translation function requires that #dma-cells is equal to 1 318 * and the argument of the dma specifier is the 32-bit filter_param. Returns 319 * pointer to appropriate dma channel on success or NULL on error. 320 */ 321 struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec, 322 struct of_dma *ofdma) 323 { 324 int count = dma_spec->args_count; 325 struct of_dma_filter_info *info = ofdma->of_dma_data; 326 327 if (!info || !info->filter_fn) 328 return NULL; 329 330 if (count != 1) 331 return NULL; 332 333 return __dma_request_channel(&info->dma_cap, info->filter_fn, 334 &dma_spec->args[0], dma_spec->np); 335 } 336 EXPORT_SYMBOL_GPL(of_dma_simple_xlate); 337 338 /** 339 * of_dma_xlate_by_chan_id - Translate dt property to DMA channel by channel id 340 * @dma_spec: pointer to DMA specifier as found in the device tree 341 * @ofdma: pointer to DMA controller data 342 * 343 * This function can be used as the of xlate callback for DMA driver which wants 344 * to match the channel based on the channel id. When using this xlate function 345 * the #dma-cells propety of the DMA controller dt node needs to be set to 1. 346 * The data parameter of of_dma_controller_register must be a pointer to the 347 * dma_device struct the function should match upon. 348 * 349 * Returns pointer to appropriate dma channel on success or NULL on error. 350 */ 351 struct dma_chan *of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec, 352 struct of_dma *ofdma) 353 { 354 struct dma_device *dev = ofdma->of_dma_data; 355 struct dma_chan *chan, *candidate = NULL; 356 357 if (!dev || dma_spec->args_count != 1) 358 return NULL; 359 360 list_for_each_entry(chan, &dev->channels, device_node) 361 if (chan->chan_id == dma_spec->args[0]) { 362 candidate = chan; 363 break; 364 } 365 366 if (!candidate) 367 return NULL; 368 369 return dma_get_slave_channel(candidate); 370 } 371 EXPORT_SYMBOL_GPL(of_dma_xlate_by_chan_id); 372