include/dma.h

   1 /* SPDX-License-Identifier: GPL-2.0+ */
   2 /*
   3  * Copyright (C) 2018 Álvaro Fernández Rojas <noltari@gmail.com>
   4  * Copyright (C) 2015 - 2018 Texas Instruments Incorporated <www.ti.com>
   5  * Written by Mugunthan V N <mugunthanvnm@ti.com>
   6  *
   7  */
   8
   9 #ifndef _DMA_H_
  10 #define _DMA_H_
  11
  12 #include <linux/bitops.h>
  13 #include <linux/errno.h>
  14 #include <linux/types.h>
  15
  16 /*
  17  * enum dma_direction - dma transfer direction indicator
  18  * @DMA_MEM_TO_MEM: Memcpy mode
  19  * @DMA_MEM_TO_DEV: From Memory to Device
  20  * @DMA_DEV_TO_MEM: From Device to Memory
  21  * @DMA_DEV_TO_DEV: From Device to Device
  22  */
  23 enum dma_direction {
  24         DMA_MEM_TO_MEM,
  25         DMA_MEM_TO_DEV,
  26         DMA_DEV_TO_MEM,
  27         DMA_DEV_TO_DEV,
  28 };
  29
  30 #define DMA_SUPPORTS_MEM_TO_MEM BIT(0)
  31 #define DMA_SUPPORTS_MEM_TO_DEV BIT(1)
  32 #define DMA_SUPPORTS_DEV_TO_MEM BIT(2)
  33 #define DMA_SUPPORTS_DEV_TO_DEV BIT(3)
  34
  35 /*
  36  * struct dma_dev_priv - information about a device used by the uclass
  37  *
  38  * @supported: mode of transfers that DMA can support, should be
  39  *             one/multiple of DMA_SUPPORTS_*
  40  */
  41 struct dma_dev_priv {
  42         u32 supported;
  43 };
  44
  45 #ifdef CONFIG_DMA_CHANNELS
  46 /**
  47  * A DMA is a feature of computer systems that allows certain hardware
  48  * subsystems to access main system memory, independent of the CPU.
  49  * DMA channels are typically generated externally to the HW module
  50  * consuming them, by an entity this API calls a DMA provider. This API
  51  * provides a standard means for drivers to enable and disable DMAs, and to
  52  * copy, send and receive data using DMA.
  53  *
  54  * A driver that implements UCLASS_DMA is a DMA provider. A provider will
  55  * often implement multiple separate DMAs, since the hardware it manages
  56  * often has this capability. dma_uclass.h describes the interface which
  57  * DMA providers must implement.
  58  *
  59  * DMA consumers/clients are the HW modules driven by the DMA channels. This
  60  * header file describes the API used by drivers for those HW modules.
  61  *
  62  * DMA consumer DMA_MEM_TO_DEV (transmit) usage example (based on networking).
  63  * Note. dma_send() is sync operation always -  it'll start transfer and will
  64  * poll for it to complete:
  65  *      - get/request dma channel
  66  *      struct dma dma_tx;
  67  *      ret = dma_get_by_name(common->dev, "tx0", &dma_tx);
  68  *      if (ret) ...
  69  *
  70  *      - enable dma channel
  71  *      ret = dma_enable(&dma_tx);
  72  *      if (ret) ...
  73  *
  74  *      - dma transmit DMA_MEM_TO_DEV.
  75  *      struct ti_drv_packet_data packet_data;
  76  *
  77  *      packet_data.opt1 = val1;
  78  *      packet_data.opt2 = val2;
  79  *      ret = dma_send(&dma_tx, packet, length, &packet_data);
  80  *      if (ret) ..
  81  *
  82  * DMA consumer DMA_DEV_TO_MEM (receive) usage example (based on networking).
  83  * Note. dma_receive() is sync operation always - it'll start transfer
  84  * (if required) and will poll for it to complete (or for any previously
  85  * configured dev2mem transfer to complete):
  86  *      - get/request dma channel
  87  *      struct dma dma_rx;
  88  *      ret = dma_get_by_name(common->dev, "rx0", &dma_rx);
  89  *      if (ret) ...
  90  *
  91  *      - enable dma channel
  92  *      ret = dma_enable(&dma_rx);
  93  *      if (ret) ...
  94  *
  95  *      - dma receive DMA_DEV_TO_MEM.
  96  *      struct ti_drv_packet_data packet_data;
  97  *
  98  *      len = dma_receive(&dma_rx, (void **)packet, &packet_data);
  99  *      if (ret < 0) ...
 100  *
 101  * DMA consumer DMA_DEV_TO_MEM (receive) zero-copy usage example (based on
 102  * networking). Networking subsystem allows to configure and use few receive
 103  * buffers (dev2mem), as Networking RX DMA channels usually implemented
 104  * as streaming interface
 105  *      - get/request dma channel
 106  *      struct dma dma_rx;
 107  *      ret = dma_get_by_name(common->dev, "rx0", &dma_rx);
 108  *      if (ret) ...
 109  *
 110  *      for (i = 0; i < RX_DESC_NUM; i++) {
 111  *              ret = dma_prepare_rcv_buf(&dma_rx,
 112  *                                        net_rx_packets[i],
 113  *                                        RX_BUF_SIZE);
 114  *              if (ret) ...
 115  *      }
 116  *
 117  *      - enable dma channel
 118  *      ret = dma_enable(&dma_rx);
 119  *      if (ret) ...
 120  *
 121  *      - dma receive DMA_DEV_TO_MEM.
 122  *      struct ti_drv_packet_data packet_data;
 123  *
 124  *      len = dma_receive(&dma_rx, (void **)packet, &packet_data);
 125  *      if (ret < 0) ..
 126  *
 127  *      -- process packet --
 128  *
 129  *      - return buffer back to DAM channel
 130  *      ret = dma_prepare_rcv_buf(&dma_rx,
 131  *                                net_rx_packets[rx_next],
 132  *                                RX_BUF_SIZE);
 133  */
 134
 135 struct udevice;
 136
 137 /**
 138  * struct dma - A handle to (allowing control of) a single DMA.
 139  *
 140  * Clients provide storage for DMA handles. The content of the structure is
 141  * managed solely by the DMA API and DMA drivers. A DMA struct is
 142  * initialized by "get"ing the DMA struct. The DMA struct is passed to all
 143  * other DMA APIs to identify which DMA channel to operate upon.
 144  *
 145  * @dev: The device which implements the DMA channel.
 146  * @id: The DMA channel ID within the provider.
 147  *
 148  * Currently, the DMA API assumes that a single integer ID is enough to
 149  * identify and configure any DMA channel for any DMA provider. If this
 150  * assumption becomes invalid in the future, the struct could be expanded to
 151  * either (a) add more fields to allow DMA providers to store additional
 152  * information, or (b) replace the id field with an opaque pointer, which the
 153  * provider would dynamically allocated during its .of_xlate op, and process
 154  * during is .request op. This may require the addition of an extra op to clean
 155  * up the allocation.
 156  */
 157 struct dma {
 158         struct udevice *dev;
 159         /*
 160          * Written by of_xlate. We assume a single id is enough for now. In the
 161          * future, we might add more fields here.
 162          */
 163         unsigned long id;
 164 };
 165
 166 # if CONFIG_IS_ENABLED(OF_CONTROL) && CONFIG_IS_ENABLED(DMA)
 167 /**
 168  * dma_get_by_index - Get/request a DMA by integer index.
 169  *
 170  * This looks up and requests a DMA. The index is relative to the client
 171  * device; each device is assumed to have n DMAs associated with it somehow,
 172  * and this function finds and requests one of them. The mapping of client
 173  * device DMA indices to provider DMAs may be via device-tree properties,
 174  * board-provided mapping tables, or some other mechanism.
 175  *
 176  * @dev:        The client device.
 177  * @index:      The index of the DMA to request, within the client's list of
 178  *              DMA channels.
 179  * @dma:        A pointer to a DMA struct to initialize.
 180  * @return 0 if OK, or a negative error code.
 181  */
 182 int dma_get_by_index(struct udevice *dev, int index, struct dma *dma);
 183
 184 /**
 185  * dma_get_by_name - Get/request a DMA by name.
 186  *
 187  * This looks up and requests a DMA. The name is relative to the client
 188  * device; each device is assumed to have n DMAs associated with it somehow,
 189  * and this function finds and requests one of them. The mapping of client
 190  * device DMA names to provider DMAs may be via device-tree properties,
 191  * board-provided mapping tables, or some other mechanism.
 192  *
 193  * @dev:        The client device.
 194  * @name:       The name of the DMA to request, within the client's list of
 195  *              DMA channels.
 196  * @dma:        A pointer to a DMA struct to initialize.
 197  * @return 0 if OK, or a negative error code.
 198  */
 199 int dma_get_by_name(struct udevice *dev, const char *name, struct dma *dma);
 200 # else
 201 static inline int dma_get_by_index(struct udevice *dev, int index,
 202                                    struct dma *dma)
 203 {
 204         return -ENOSYS;
 205 }
 206
 207 static inline int dma_get_by_name(struct udevice *dev, const char *name,
 208                                   struct dma *dma)
 209 {
 210         return -ENOSYS;
 211 }
 212 # endif
 213
 214 /**
 215  * dma_request - Request a DMA by provider-specific ID.
 216  *
 217  * This requests a DMA using a provider-specific ID. Generally, this function
 218  * should not be used, since dma_get_by_index/name() provide an interface that
 219  * better separates clients from intimate knowledge of DMA providers.
 220  * However, this function may be useful in core SoC-specific code.
 221  *
 222  * @dev: The DMA provider device.
 223  * @dma: A pointer to a DMA struct to initialize. The caller must
 224  *       have already initialized any field in this struct which the
 225  *       DMA provider uses to identify the DMA channel.
 226  * @return 0 if OK, or a negative error code.
 227  */
 228 int dma_request(struct udevice *dev, struct dma *dma);
 229
 230 /**
 231  * dma_free - Free a previously requested DMA.
 232  *
 233  * @dma: A DMA struct that was previously successfully requested by
 234  *       dma_request/get_by_*().
 235  * @return 0 if OK, or a negative error code.
 236  */
 237 int dma_free(struct dma *dma);
 238
 239 /**
 240  * dma_enable() - Enable (turn on) a DMA channel.
 241  *
 242  * @dma: A DMA struct that was previously successfully requested by
 243  *       dma_request/get_by_*().
 244  * @return zero on success, or -ve error code.
 245  */
 246 int dma_enable(struct dma *dma);
 247
 248 /**
 249  * dma_disable() - Disable (turn off) a DMA channel.
 250  *
 251  * @dma: A DMA struct that was previously successfully requested by
 252  *       dma_request/get_by_*().
 253  * @return zero on success, or -ve error code.
 254  */
 255 int dma_disable(struct dma *dma);
 256
 257 /**
 258  * dma_prepare_rcv_buf() - Prepare/add receive DMA buffer.
 259  *
 260  * It allows to implement zero-copy async DMA_DEV_TO_MEM (receive) transactions
 261  * if supported by DMA providers.
 262  *
 263  * @dma: A DMA struct that was previously successfully requested by
 264  *       dma_request/get_by_*().
 265  * @dst: The receive buffer pointer.
 266  * @size: The receive buffer size
 267  * @return zero on success, or -ve error code.
 268  */
 269 int dma_prepare_rcv_buf(struct dma *dma, void *dst, size_t size);
 270
 271 /**
 272  * dma_receive() - Receive a DMA transfer.
 273  *
 274  * @dma: A DMA struct that was previously successfully requested by
 275  *       dma_request/get_by_*().
 276  * @dst: The destination pointer.
 277  * @metadata: DMA driver's channel specific data
 278  * @return length of received data on success, or zero - no data,
 279  * or -ve error code.
 280  */
 281 int dma_receive(struct dma *dma, void **dst, void *metadata);
 282
 283 /**
 284  * dma_send() - Send a DMA transfer.
 285  *
 286  * @dma: A DMA struct that was previously successfully requested by
 287  *       dma_request/get_by_*().
 288  * @src: The source pointer.
 289  * @len: Length of the data to be sent (number of bytes).
 290  * @metadata: DMA driver's channel specific data
 291  * @return zero on success, or -ve error code.
 292  */
 293 int dma_send(struct dma *dma, void *src, size_t len, void *metadata);
 294
 295 /**
 296  * dma_get_cfg() - Get DMA channel configuration for client's use
 297  *
 298  * @dma:      The DMA Channel to manipulate
 299  * @cfg_id:   DMA provider specific ID to identify what
 300  *            configuration data client needs
 301  * @cfg_data: Pointer to store pointer to DMA driver specific
 302  *            configuration data for the given cfg_id (output param)
 303  * @return zero on success, or -ve error code.
 304  */
 305 int dma_get_cfg(struct dma *dma, u32 cfg_id, void **cfg_data);
 306 #endif /* CONFIG_DMA_CHANNELS */
 307
 308 #if CONFIG_IS_ENABLED(DMA)
 309 /*
 310  * dma_get_device - get a DMA device which supports transfer
 311  * type of transfer_type
 312  *
 313  * @transfer_type - transfer type should be one/multiple of
 314  *                  DMA_SUPPORTS_*
 315  * @devp - udevice pointer to return the found device
 316  * @return - will return on success and devp will hold the
 317  *           pointer to the device
 318  */
 319 int dma_get_device(u32 transfer_type, struct udevice **devp);
 320
 321 /*
 322  * dma_memcpy - try to use DMA to do a mem copy which will be
 323  *              much faster than CPU mem copy
 324  *
 325  * @dst - destination pointer
 326  * @src - souce pointer
 327  * @len - data length to be copied
 328  * @return - on successful transfer returns no of bytes
 329              transferred and on failure return error code.
 330  */
 331 int dma_memcpy(void *dst, void *src, size_t len);
 332 #else
 333 static inline int dma_get_device(u32 transfer_type, struct udevice **devp)
 334 {
 335         return -ENOSYS;
 336 }
 337
 338 static inline int dma_memcpy(void *dst, void *src, size_t len)
 339 {
 340         return -ENOSYS;
 341 }
 342 #endif /* CONFIG_DMA */
 343 #endif  /* _DMA_H_ */