drivers/dma/of-dma.c

   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);