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 return NULL; 72 73 chan = ofdma_target->of_dma_xlate(&dma_spec_target, ofdma_target); 74 if (IS_ERR_OR_NULL(chan)) { 75 ofdma->dma_router->route_free(ofdma->dma_router->dev, 76 route_data); 77 } else { 78 int ret = 0; 79 80 chan->router = ofdma->dma_router; 81 chan->route_data = route_data; 82 83 if (chan->device->device_router_config) 84 ret = chan->device->device_router_config(chan); 85 86 if (ret) { 87 dma_release_channel(chan); 88 chan = ERR_PTR(ret); 89 } 90 } 91 92 /* 93 * Need to put the node back since the ofdma->of_dma_route_allocate 94 * has taken it for generating the new, translated dma_spec 95 */ 96 of_node_put(dma_spec_target.np); 97 return chan; 98 } 99 100 /** 101 * of_dma_controller_register - Register a DMA controller to DT DMA helpers 102 * @np: device node of DMA controller 103 * @of_dma_xlate: translation function which converts a phandle 104 * arguments list into a dma_chan structure 105 * @data: pointer to controller specific data to be used by 106 * translation function 107 * 108 * Returns 0 on success or appropriate errno value on error. 109 * 110 * Allocated memory should be freed with appropriate of_dma_controller_free() 111 * call. 112 */ 113 int of_dma_controller_register(struct device_node *np, 114 struct dma_chan *(*of_dma_xlate) 115 (struct of_phandle_args *, struct of_dma *), 116 void *data) 117 { 118 struct of_dma *ofdma; 119 120 if (!np || !of_dma_xlate) { 121 pr_err("%s: not enough information provided\n", __func__); 122 return -EINVAL; 123 } 124 125 ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL); 126 if (!ofdma) 127 return -ENOMEM; 128 129 ofdma->of_node = np; 130 ofdma->of_dma_xlate = of_dma_xlate; 131 ofdma->of_dma_data = data; 132 133 /* Now queue of_dma controller structure in list */ 134 mutex_lock(&of_dma_lock); 135 list_add_tail(&ofdma->of_dma_controllers, &of_dma_list); 136 mutex_unlock(&of_dma_lock); 137 138 return 0; 139 } 140 EXPORT_SYMBOL_GPL(of_dma_controller_register); 141 142 /** 143 * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list 144 * @np: device node of DMA controller 145 * 146 * Memory allocated by of_dma_controller_register() is freed here. 147 */ 148 void of_dma_controller_free(struct device_node *np) 149 { 150 struct of_dma *ofdma; 151 152 mutex_lock(&of_dma_lock); 153 154 list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) 155 if (ofdma->of_node == np) { 156 list_del(&ofdma->of_dma_controllers); 157 kfree(ofdma); 158 break; 159 } 160 161 mutex_unlock(&of_dma_lock); 162 } 163 EXPORT_SYMBOL_GPL(of_dma_controller_free); 164 165 /** 166 * of_dma_router_register - Register a DMA router to DT DMA helpers as a 167 * controller 168 * @np: device node of DMA router 169 * @of_dma_route_allocate: setup function for the router which need to 170 * modify the dma_spec for the DMA controller to 171 * use and to set up the requested route. 172 * @dma_router: pointer to dma_router structure to be used when 173 * the route need to be free up. 174 * 175 * Returns 0 on success or appropriate errno value on error. 176 * 177 * Allocated memory should be freed with appropriate of_dma_controller_free() 178 * call. 179 */ 180 int of_dma_router_register(struct device_node *np, 181 void *(*of_dma_route_allocate) 182 (struct of_phandle_args *, struct of_dma *), 183 struct dma_router *dma_router) 184 { 185 struct of_dma *ofdma; 186 187 if (!np || !of_dma_route_allocate || !dma_router) { 188 pr_err("%s: not enough information provided\n", __func__); 189 return -EINVAL; 190 } 191 192 ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL); 193 if (!ofdma) 194 return -ENOMEM; 195 196 ofdma->of_node = np; 197 ofdma->of_dma_xlate = of_dma_router_xlate; 198 ofdma->of_dma_route_allocate = of_dma_route_allocate; 199 ofdma->dma_router = dma_router; 200 201 /* Now queue of_dma controller structure in list */ 202 mutex_lock(&of_dma_lock); 203 list_add_tail(&ofdma->of_dma_controllers, &of_dma_list); 204 mutex_unlock(&of_dma_lock); 205 206 return 0; 207 } 208 EXPORT_SYMBOL_GPL(of_dma_router_register); 209 210 /** 211 * of_dma_match_channel - Check if a DMA specifier matches name 212 * @np: device node to look for DMA channels 213 * @name: channel name to be matched 214 * @index: index of DMA specifier in list of DMA specifiers 215 * @dma_spec: pointer to DMA specifier as found in the device tree 216 * 217 * Check if the DMA specifier pointed to by the index in a list of DMA 218 * specifiers, matches the name provided. Returns 0 if the name matches and 219 * a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV. 220 */ 221 static int of_dma_match_channel(struct device_node *np, const char *name, 222 int index, struct of_phandle_args *dma_spec) 223 { 224 const char *s; 225 226 if (of_property_read_string_index(np, "dma-names", index, &s)) 227 return -ENODEV; 228 229 if (strcmp(name, s)) 230 return -ENODEV; 231 232 if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index, 233 dma_spec)) 234 return -ENODEV; 235 236 return 0; 237 } 238 239 /** 240 * of_dma_request_slave_channel - Get the DMA slave channel 241 * @np: device node to get DMA request from 242 * @name: name of desired channel 243 * 244 * Returns pointer to appropriate DMA channel on success or an error pointer. 245 */ 246 struct dma_chan *of_dma_request_slave_channel(struct device_node *np, 247 const char *name) 248 { 249 struct of_phandle_args dma_spec; 250 struct of_dma *ofdma; 251 struct dma_chan *chan; 252 int count, i, start; 253 int ret_no_channel = -ENODEV; 254 static atomic_t last_index; 255 256 if (!np || !name) { 257 pr_err("%s: not enough information provided\n", __func__); 258 return ERR_PTR(-ENODEV); 259 } 260 261 /* Silently fail if there is not even the "dmas" property */ 262 if (!of_find_property(np, "dmas", NULL)) 263 return ERR_PTR(-ENODEV); 264 265 count = of_property_count_strings(np, "dma-names"); 266 if (count < 0) { 267 pr_err("%s: dma-names property of node '%pOF' missing or empty\n", 268 __func__, np); 269 return ERR_PTR(-ENODEV); 270 } 271 272 /* 273 * approximate an average distribution across multiple 274 * entries with the same name 275 */ 276 start = atomic_inc_return(&last_index); 277 for (i = 0; i < count; i++) { 278 if (of_dma_match_channel(np, name, 279 (i + start) % count, 280 &dma_spec)) 281 continue; 282 283 mutex_lock(&of_dma_lock); 284 ofdma = of_dma_find_controller(&dma_spec); 285 286 if (ofdma) { 287 chan = ofdma->of_dma_xlate(&dma_spec, ofdma); 288 } else { 289 ret_no_channel = -EPROBE_DEFER; 290 chan = NULL; 291 } 292 293 mutex_unlock(&of_dma_lock); 294 295 of_node_put(dma_spec.np); 296 297 if (chan) 298 return chan; 299 } 300 301 return ERR_PTR(ret_no_channel); 302 } 303 EXPORT_SYMBOL_GPL(of_dma_request_slave_channel); 304 305 /** 306 * of_dma_simple_xlate - Simple DMA engine translation function 307 * @dma_spec: pointer to DMA specifier as found in the device tree 308 * @ofdma: pointer to DMA controller data 309 * 310 * A simple translation function for devices that use a 32-bit value for the 311 * filter_param when calling the DMA engine dma_request_channel() function. 312 * Note that this translation function requires that #dma-cells is equal to 1 313 * and the argument of the dma specifier is the 32-bit filter_param. Returns 314 * pointer to appropriate dma channel on success or NULL on error. 315 */ 316 struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec, 317 struct of_dma *ofdma) 318 { 319 int count = dma_spec->args_count; 320 struct of_dma_filter_info *info = ofdma->of_dma_data; 321 322 if (!info || !info->filter_fn) 323 return NULL; 324 325 if (count != 1) 326 return NULL; 327 328 return __dma_request_channel(&info->dma_cap, info->filter_fn, 329 &dma_spec->args[0], dma_spec->np); 330 } 331 EXPORT_SYMBOL_GPL(of_dma_simple_xlate); 332 333 /** 334 * of_dma_xlate_by_chan_id - Translate dt property to DMA channel by channel id 335 * @dma_spec: pointer to DMA specifier as found in the device tree 336 * @ofdma: pointer to DMA controller data 337 * 338 * This function can be used as the of xlate callback for DMA driver which wants 339 * to match the channel based on the channel id. When using this xlate function 340 * the #dma-cells propety of the DMA controller dt node needs to be set to 1. 341 * The data parameter of of_dma_controller_register must be a pointer to the 342 * dma_device struct the function should match upon. 343 * 344 * Returns pointer to appropriate dma channel on success or NULL on error. 345 */ 346 struct dma_chan *of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec, 347 struct of_dma *ofdma) 348 { 349 struct dma_device *dev = ofdma->of_dma_data; 350 struct dma_chan *chan, *candidate = NULL; 351 352 if (!dev || dma_spec->args_count != 1) 353 return NULL; 354 355 list_for_each_entry(chan, &dev->channels, device_node) 356 if (chan->chan_id == dma_spec->args[0]) { 357 candidate = chan; 358 break; 359 } 360 361 if (!candidate) 362 return NULL; 363 364 return dma_get_slave_channel(candidate); 365 } 366 EXPORT_SYMBOL_GPL(of_dma_xlate_by_chan_id); 367