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