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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Device tree helpers for DMA request / controller4 *5 * Based on of_gpio.c6 *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 20static LIST_HEAD(of_dma_list);21static DEFINE_MUTEX(of_dma_lock);22 23/**24 * of_dma_find_controller - Get a DMA controller in DT DMA helpers list25 * @dma_spec: pointer to DMA specifier as found in the device tree26 *27 * Finds a DMA controller with matching device node and number for dma cells28 * in a list of registered DMA controllers. If a match is found a valid pointer29 * to the DMA data stored is returned. A NULL pointer is returned if no match is30 * found.31 */32static struct of_dma *of_dma_find_controller(const 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 devices48 * @dma_spec: pointer to DMA specifier as found in the device tree49 * @ofdma: pointer to DMA controller data (router information)50 *51 * The function creates new dma_spec to be passed to the router driver's52 * of_dma_route_allocate() function to prepare a dma_spec which will be used53 * to request channel from the real DMA controller.54 */55static 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 96err:97 /*98 * Need to put the node back since the ofdma->of_dma_route_allocate99 * has taken it for generating the new, translated dma_spec100 */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 helpers107 * @np: device node of DMA controller108 * @of_dma_xlate: translation function which converts a phandle109 * arguments list into a dma_chan structure110 * @data: pointer to controller specific data to be used by111 * translation function112 *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 */118int 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}145EXPORT_SYMBOL_GPL(of_dma_controller_register);146 147/**148 * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list149 * @np: device node of DMA controller150 *151 * Memory allocated by of_dma_controller_register() is freed here.152 */153void 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}168EXPORT_SYMBOL_GPL(of_dma_controller_free);169 170/**171 * of_dma_router_register - Register a DMA router to DT DMA helpers as a172 * controller173 * @np: device node of DMA router174 * @of_dma_route_allocate: setup function for the router which need to175 * modify the dma_spec for the DMA controller to176 * use and to set up the requested route.177 * @dma_router: pointer to dma_router structure to be used when178 * 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 */185int 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}213EXPORT_SYMBOL_GPL(of_dma_router_register);214 215/**216 * of_dma_match_channel - Check if a DMA specifier matches name217 * @np: device node to look for DMA channels218 * @name: channel name to be matched219 * @index: index of DMA specifier in list of DMA specifiers220 * @dma_spec: pointer to DMA specifier as found in the device tree221 *222 * Check if the DMA specifier pointed to by the index in a list of DMA223 * specifiers, matches the name provided. Returns 0 if the name matches and224 * a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV.225 */226static 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 channel246 * @np: device node to get DMA request from247 * @name: name of desired channel248 *249 * Returns pointer to appropriate DMA channel on success or an error pointer.250 */251struct 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 multiple279 * entries with the same name280 */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}308EXPORT_SYMBOL_GPL(of_dma_request_slave_channel);309 310/**311 * of_dma_simple_xlate - Simple DMA engine translation function312 * @dma_spec: pointer to DMA specifier as found in the device tree313 * @ofdma: pointer to DMA controller data314 *315 * A simple translation function for devices that use a 32-bit value for the316 * filter_param when calling the DMA engine dma_request_channel() function.317 * Note that this translation function requires that #dma-cells is equal to 1318 * and the argument of the dma specifier is the 32-bit filter_param. Returns319 * pointer to appropriate dma channel on success or NULL on error.320 */321struct 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}336EXPORT_SYMBOL_GPL(of_dma_simple_xlate);337 338/**339 * of_dma_xlate_by_chan_id - Translate dt property to DMA channel by channel id340 * @dma_spec: pointer to DMA specifier as found in the device tree341 * @ofdma: pointer to DMA controller data342 *343 * This function can be used as the of xlate callback for DMA driver which wants344 * to match the channel based on the channel id. When using this xlate function345 * the #dma-cells property 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 the347 * dma_device struct the function should match upon.348 *349 * Returns pointer to appropriate dma channel on success or NULL on error.350 */351struct 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}371EXPORT_SYMBOL_GPL(of_dma_xlate_by_chan_id);372