include/linux/dmaengine.h

   1 /*
   2  * Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License as published by the Free
   6  * Software Foundation; either version 2 of the License, or (at your option)
   7  * any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along with
  15  * this program; if not, write to the Free Software Foundation, Inc., 59
  16  * Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  17  *
  18  * The full GNU General Public License is included in this distribution in the
  19  * file called COPYING.
  20  */
  21 #ifndef DMAENGINE_H
  22 #define DMAENGINE_H
  23
  24 #ifdef CONFIG_DMA_ENGINE
  25
  26 #include <linux/device.h>
  27 #include <linux/uio.h>
  28 #include <linux/kref.h>
  29 #include <linux/completion.h>
  30 #include <linux/rcupdate.h>
  31
  32 /**
  33  * enum dma_event - resource PNP/power managment events
  34  * @DMA_RESOURCE_SUSPEND: DMA device going into low power state
  35  * @DMA_RESOURCE_RESUME: DMA device returning to full power
  36  * @DMA_RESOURCE_ADDED: DMA device added to the system
  37  * @DMA_RESOURCE_REMOVED: DMA device removed from the system
  38  */
  39 enum dma_event {
  40         DMA_RESOURCE_SUSPEND,
  41         DMA_RESOURCE_RESUME,
  42         DMA_RESOURCE_ADDED,
  43         DMA_RESOURCE_REMOVED,
  44 };
  45
  46 /**
  47  * typedef dma_cookie_t - an opaque DMA cookie
  48  *
  49  * if dma_cookie_t is >0 it's a DMA request cookie, <0 it's an error code
  50  */
  51 typedef s32 dma_cookie_t;
  52
  53 #define dma_submit_error(cookie) ((cookie) < 0 ? 1 : 0)
  54
  55 /**
  56  * enum dma_status - DMA transaction status
  57  * @DMA_SUCCESS: transaction completed successfully
  58  * @DMA_IN_PROGRESS: transaction not yet processed
  59  * @DMA_ERROR: transaction failed
  60  */
  61 enum dma_status {
  62         DMA_SUCCESS,
  63         DMA_IN_PROGRESS,
  64         DMA_ERROR,
  65 };
  66
  67 /**
  68  * struct dma_chan_percpu - the per-CPU part of struct dma_chan
  69  * @refcount: local_t used for open-coded "bigref" counting
  70  * @memcpy_count: transaction counter
  71  * @bytes_transferred: byte counter
  72  */
  73
  74 struct dma_chan_percpu {
  75         local_t refcount;
  76         /* stats */
  77         unsigned long memcpy_count;
  78         unsigned long bytes_transferred;
  79 };
  80
  81 /**
  82  * struct dma_chan - devices supply DMA channels, clients use them
  83  * @client: ptr to the client user of this chan, will be %NULL when unused
  84  * @device: ptr to the dma device who supplies this channel, always !%NULL
  85  * @cookie: last cookie value returned to client
  86  * @chan_id: channel ID for sysfs
  87  * @class_dev: class device for sysfs
  88  * @refcount: kref, used in "bigref" slow-mode
  89  * @slow_ref: indicates that the DMA channel is free
  90  * @rcu: the DMA channel's RCU head
  91  * @client_node: used to add this to the client chan list
  92  * @device_node: used to add this to the device chan list
  93  * @local: per-cpu pointer to a struct dma_chan_percpu
  94  */
  95 struct dma_chan {
  96         struct dma_client *client;
  97         struct dma_device *device;
  98         dma_cookie_t cookie;
  99
 100         /* sysfs */
 101         int chan_id;
 102         struct class_device class_dev;
 103
 104         struct kref refcount;
 105         int slow_ref;
 106         struct rcu_head rcu;
 107
 108         struct list_head client_node;
 109         struct list_head device_node;
 110         struct dma_chan_percpu *local;
 111 };
 112
 113 void dma_chan_cleanup(struct kref *kref);
 114
 115 static inline void dma_chan_get(struct dma_chan *chan)
 116 {
 117         if (unlikely(chan->slow_ref))
 118                 kref_get(&chan->refcount);
 119         else {
 120                 local_inc(&(per_cpu_ptr(chan->local, get_cpu())->refcount));
 121                 put_cpu();
 122         }
 123 }
 124
 125 static inline void dma_chan_put(struct dma_chan *chan)
 126 {
 127         if (unlikely(chan->slow_ref))
 128                 kref_put(&chan->refcount, dma_chan_cleanup);
 129         else {
 130                 local_dec(&(per_cpu_ptr(chan->local, get_cpu())->refcount));
 131                 put_cpu();
 132         }
 133 }
 134
 135 /*
 136  * typedef dma_event_callback - function pointer to a DMA event callback
 137  */
 138 typedef void (*dma_event_callback) (struct dma_client *client,
 139                 struct dma_chan *chan, enum dma_event event);
 140
 141 /**
 142  * struct dma_client - info on the entity making use of DMA services
 143  * @event_callback: func ptr to call when something happens
 144  * @chan_count: number of chans allocated
 145  * @chans_desired: number of chans requested. Can be +/- chan_count
 146  * @lock: protects access to the channels list
 147  * @channels: the list of DMA channels allocated
 148  * @global_node: list_head for global dma_client_list
 149  */
 150 struct dma_client {
 151         dma_event_callback      event_callback;
 152         unsigned int            chan_count;
 153         unsigned int            chans_desired;
 154
 155         spinlock_t              lock;
 156         struct list_head        channels;
 157         struct list_head        global_node;
 158 };
 159
 160 /**
 161  * struct dma_device - info on the entity supplying DMA services
 162  * @chancnt: how many DMA channels are supported
 163  * @channels: the list of struct dma_chan
 164  * @global_node: list_head for global dma_device_list
 165  * @refcount: reference count
 166  * @done: IO completion struct
 167  * @dev_id: unique device ID
 168  * @device_alloc_chan_resources: allocate resources and return the
 169  *      number of allocated descriptors
 170  * @device_free_chan_resources: release DMA channel's resources
 171  * @device_memcpy_buf_to_buf: memcpy buf pointer to buf pointer
 172  * @device_memcpy_buf_to_pg: memcpy buf pointer to struct page
 173  * @device_memcpy_pg_to_pg: memcpy struct page/offset to struct page/offset
 174  * @device_memcpy_complete: poll the status of an IOAT DMA transaction
 175  * @device_memcpy_issue_pending: push appended descriptors to hardware
 176  */
 177 struct dma_device {
 178
 179         unsigned int chancnt;
 180         struct list_head channels;
 181         struct list_head global_node;
 182
 183         struct kref refcount;
 184         struct completion done;
 185
 186         int dev_id;
 187
 188         int (*device_alloc_chan_resources)(struct dma_chan *chan);
 189         void (*device_free_chan_resources)(struct dma_chan *chan);
 190         dma_cookie_t (*device_memcpy_buf_to_buf)(struct dma_chan *chan,
 191                         void *dest, void *src, size_t len);
 192         dma_cookie_t (*device_memcpy_buf_to_pg)(struct dma_chan *chan,
 193                         struct page *page, unsigned int offset, void *kdata,
 194                         size_t len);
 195         dma_cookie_t (*device_memcpy_pg_to_pg)(struct dma_chan *chan,
 196                         struct page *dest_pg, unsigned int dest_off,
 197                         struct page *src_pg, unsigned int src_off, size_t len);
 198         enum dma_status (*device_memcpy_complete)(struct dma_chan *chan,
 199                         dma_cookie_t cookie, dma_cookie_t *last,
 200                         dma_cookie_t *used);
 201         void (*device_memcpy_issue_pending)(struct dma_chan *chan);
 202 };
 203
 204 /* --- public DMA engine API --- */
 205
 206 struct dma_client *dma_async_client_register(dma_event_callback event_callback);
 207 void dma_async_client_unregister(struct dma_client *client);
 208 void dma_async_client_chan_request(struct dma_client *client,
 209                 unsigned int number);
 210
 211 /**
 212  * dma_async_memcpy_buf_to_buf - offloaded copy between virtual addresses
 213  * @chan: DMA channel to offload copy to
 214  * @dest: destination address (virtual)
 215  * @src: source address (virtual)
 216  * @len: length
 217  *
 218  * Both @dest and @src must be mappable to a bus address according to the
 219  * DMA mapping API rules for streaming mappings.
 220  * Both @dest and @src must stay memory resident (kernel memory or locked
 221  * user space pages).
 222  */
 223 static inline dma_cookie_t dma_async_memcpy_buf_to_buf(struct dma_chan *chan,
 224         void *dest, void *src, size_t len)
 225 {
 226         int cpu = get_cpu();
 227         per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
 228         per_cpu_ptr(chan->local, cpu)->memcpy_count++;
 229         put_cpu();
 230
 231         return chan->device->device_memcpy_buf_to_buf(chan, dest, src, len);
 232 }
 233
 234 /**
 235  * dma_async_memcpy_buf_to_pg - offloaded copy from address to page
 236  * @chan: DMA channel to offload copy to
 237  * @page: destination page
 238  * @offset: offset in page to copy to
 239  * @kdata: source address (virtual)
 240  * @len: length
 241  *
 242  * Both @page/@offset and @kdata must be mappable to a bus address according
 243  * to the DMA mapping API rules for streaming mappings.
 244  * Both @page/@offset and @kdata must stay memory resident (kernel memory or
 245  * locked user space pages)
 246  */
 247 static inline dma_cookie_t dma_async_memcpy_buf_to_pg(struct dma_chan *chan,
 248         struct page *page, unsigned int offset, void *kdata, size_t len)
 249 {
 250         int cpu = get_cpu();
 251         per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
 252         per_cpu_ptr(chan->local, cpu)->memcpy_count++;
 253         put_cpu();
 254
 255         return chan->device->device_memcpy_buf_to_pg(chan, page, offset,
 256                                                      kdata, len);
 257 }
 258
 259 /**
 260  * dma_async_memcpy_pg_to_pg - offloaded copy from page to page
 261  * @chan: DMA channel to offload copy to
 262  * @dest_pg: destination page
 263  * @dest_off: offset in page to copy to
 264  * @src_pg: source page
 265  * @src_off: offset in page to copy from
 266  * @len: length
 267  *
 268  * Both @dest_page/@dest_off and @src_page/@src_off must be mappable to a bus
 269  * address according to the DMA mapping API rules for streaming mappings.
 270  * Both @dest_page/@dest_off and @src_page/@src_off must stay memory resident
 271  * (kernel memory or locked user space pages).
 272  */
 273 static inline dma_cookie_t dma_async_memcpy_pg_to_pg(struct dma_chan *chan,
 274         struct page *dest_pg, unsigned int dest_off, struct page *src_pg,
 275         unsigned int src_off, size_t len)
 276 {
 277         int cpu = get_cpu();
 278         per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
 279         per_cpu_ptr(chan->local, cpu)->memcpy_count++;
 280         put_cpu();
 281
 282         return chan->device->device_memcpy_pg_to_pg(chan, dest_pg, dest_off,
 283                                                     src_pg, src_off, len);
 284 }
 285
 286 /**
 287  * dma_async_memcpy_issue_pending - flush pending copies to HW
 288  * @chan: target DMA channel
 289  *
 290  * This allows drivers to push copies to HW in batches,
 291  * reducing MMIO writes where possible.
 292  */
 293 static inline void dma_async_memcpy_issue_pending(struct dma_chan *chan)
 294 {
 295         return chan->device->device_memcpy_issue_pending(chan);
 296 }
 297
 298 /**
 299  * dma_async_memcpy_complete - poll for transaction completion
 300  * @chan: DMA channel
 301  * @cookie: transaction identifier to check status of
 302  * @last: returns last completed cookie, can be NULL
 303  * @used: returns last issued cookie, can be NULL
 304  *
 305  * If @last and @used are passed in, upon return they reflect the driver
 306  * internal state and can be used with dma_async_is_complete() to check
 307  * the status of multiple cookies without re-checking hardware state.
 308  */
 309 static inline enum dma_status dma_async_memcpy_complete(struct dma_chan *chan,
 310         dma_cookie_t cookie, dma_cookie_t *last, dma_cookie_t *used)
 311 {
 312         return chan->device->device_memcpy_complete(chan, cookie, last, used);
 313 }
 314
 315 /**
 316  * dma_async_is_complete - test a cookie against chan state
 317  * @cookie: transaction identifier to test status of
 318  * @last_complete: last know completed transaction
 319  * @last_used: last cookie value handed out
 320  *
 321  * dma_async_is_complete() is used in dma_async_memcpy_complete()
 322  * the test logic is seperated for lightweight testing of multiple cookies
 323  */
 324 static inline enum dma_status dma_async_is_complete(dma_cookie_t cookie,
 325                         dma_cookie_t last_complete, dma_cookie_t last_used)
 326 {
 327         if (last_complete <= last_used) {
 328                 if ((cookie <= last_complete) || (cookie > last_used))
 329                         return DMA_SUCCESS;
 330         } else {
 331                 if ((cookie <= last_complete) && (cookie > last_used))
 332                         return DMA_SUCCESS;
 333         }
 334         return DMA_IN_PROGRESS;
 335 }
 336
 337
 338 /* --- DMA device --- */
 339
 340 int dma_async_device_register(struct dma_device *device);
 341 void dma_async_device_unregister(struct dma_device *device);
 342
 343 /* --- Helper iov-locking functions --- */
 344
 345 struct dma_page_list {
 346         char *base_address;
 347         int nr_pages;
 348         struct page **pages;
 349 };
 350
 351 struct dma_pinned_list {
 352         int nr_iovecs;
 353         struct dma_page_list page_list[0];
 354 };
 355
 356 struct dma_pinned_list *dma_pin_iovec_pages(struct iovec *iov, size_t len);
 357 void dma_unpin_iovec_pages(struct dma_pinned_list* pinned_list);
 358
 359 dma_cookie_t dma_memcpy_to_iovec(struct dma_chan *chan, struct iovec *iov,
 360         struct dma_pinned_list *pinned_list, unsigned char *kdata, size_t len);
 361 dma_cookie_t dma_memcpy_pg_to_iovec(struct dma_chan *chan, struct iovec *iov,
 362         struct dma_pinned_list *pinned_list, struct page *page,
 363         unsigned int offset, size_t len);
 364
 365 #endif /* CONFIG_DMA_ENGINE */
 366 #endif /* DMAENGINE_H */