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- /* SPDX-License-Identifier: GPL-2.0+ */
- /*
- * Copyright (C) 2018 Álvaro Fernández Rojas <noltari@gmail.com>
- * Copyright (C) 2015 - 2018 Texas Instruments Incorporated <www.ti.com>
- * Written by Mugunthan V N <mugunthanvnm@ti.com>
- *
- */
- #ifndef _DMA_H_
- #define _DMA_H_
- #include <linux/errno.h>
- #include <linux/types.h>
- /*
- * enum dma_direction - dma transfer direction indicator
- * @DMA_MEM_TO_MEM: Memcpy mode
- * @DMA_MEM_TO_DEV: From Memory to Device
- * @DMA_DEV_TO_MEM: From Device to Memory
- * @DMA_DEV_TO_DEV: From Device to Device
- */
- enum dma_direction {
- DMA_MEM_TO_MEM,
- DMA_MEM_TO_DEV,
- DMA_DEV_TO_MEM,
- DMA_DEV_TO_DEV,
- };
- #define DMA_SUPPORTS_MEM_TO_MEM BIT(0)
- #define DMA_SUPPORTS_MEM_TO_DEV BIT(1)
- #define DMA_SUPPORTS_DEV_TO_MEM BIT(2)
- #define DMA_SUPPORTS_DEV_TO_DEV BIT(3)
- /*
- * struct dma_dev_priv - information about a device used by the uclass
- *
- * @supported: mode of transfers that DMA can support, should be
- * one/multiple of DMA_SUPPORTS_*
- */
- struct dma_dev_priv {
- u32 supported;
- };
- #ifdef CONFIG_DMA_CHANNELS
- /**
- * A DMA is a feature of computer systems that allows certain hardware
- * subsystems to access main system memory, independent of the CPU.
- * DMA channels are typically generated externally to the HW module
- * consuming them, by an entity this API calls a DMA provider. This API
- * provides a standard means for drivers to enable and disable DMAs, and to
- * copy, send and receive data using DMA.
- *
- * A driver that implements UCLASS_DMA is a DMA provider. A provider will
- * often implement multiple separate DMAs, since the hardware it manages
- * often has this capability. dma_uclass.h describes the interface which
- * DMA providers must implement.
- *
- * DMA consumers/clients are the HW modules driven by the DMA channels. This
- * header file describes the API used by drivers for those HW modules.
- *
- * DMA consumer DMA_MEM_TO_DEV (transmit) usage example (based on networking).
- * Note. dma_send() is sync operation always - it'll start transfer and will
- * poll for it to complete:
- * - get/request dma channel
- * struct dma dma_tx;
- * ret = dma_get_by_name(common->dev, "tx0", &dma_tx);
- * if (ret) ...
- *
- * - enable dma channel
- * ret = dma_enable(&dma_tx);
- * if (ret) ...
- *
- * - dma transmit DMA_MEM_TO_DEV.
- * struct ti_drv_packet_data packet_data;
- *
- * packet_data.opt1 = val1;
- * packet_data.opt2 = val2;
- * ret = dma_send(&dma_tx, packet, length, &packet_data);
- * if (ret) ..
- *
- * DMA consumer DMA_DEV_TO_MEM (receive) usage example (based on networking).
- * Note. dma_receive() is sync operation always - it'll start transfer
- * (if required) and will poll for it to complete (or for any previously
- * configured dev2mem transfer to complete):
- * - get/request dma channel
- * struct dma dma_rx;
- * ret = dma_get_by_name(common->dev, "rx0", &dma_rx);
- * if (ret) ...
- *
- * - enable dma channel
- * ret = dma_enable(&dma_rx);
- * if (ret) ...
- *
- * - dma receive DMA_DEV_TO_MEM.
- * struct ti_drv_packet_data packet_data;
- *
- * len = dma_receive(&dma_rx, (void **)packet, &packet_data);
- * if (ret < 0) ...
- *
- * DMA consumer DMA_DEV_TO_MEM (receive) zero-copy usage example (based on
- * networking). Networking subsystem allows to configure and use few receive
- * buffers (dev2mem), as Networking RX DMA channels usually implemented
- * as streaming interface
- * - get/request dma channel
- * struct dma dma_rx;
- * ret = dma_get_by_name(common->dev, "rx0", &dma_rx);
- * if (ret) ...
- *
- * for (i = 0; i < RX_DESC_NUM; i++) {
- * ret = dma_prepare_rcv_buf(&dma_rx,
- * net_rx_packets[i],
- * RX_BUF_SIZE);
- * if (ret) ...
- * }
- *
- * - enable dma channel
- * ret = dma_enable(&dma_rx);
- * if (ret) ...
- *
- * - dma receive DMA_DEV_TO_MEM.
- * struct ti_drv_packet_data packet_data;
- *
- * len = dma_receive(&dma_rx, (void **)packet, &packet_data);
- * if (ret < 0) ..
- *
- * -- process packet --
- *
- * - return buffer back to DAM channel
- * ret = dma_prepare_rcv_buf(&dma_rx,
- * net_rx_packets[rx_next],
- * RX_BUF_SIZE);
- */
- struct udevice;
- /**
- * struct dma - A handle to (allowing control of) a single DMA.
- *
- * Clients provide storage for DMA handles. The content of the structure is
- * managed solely by the DMA API and DMA drivers. A DMA struct is
- * initialized by "get"ing the DMA struct. The DMA struct is passed to all
- * other DMA APIs to identify which DMA channel to operate upon.
- *
- * @dev: The device which implements the DMA channel.
- * @id: The DMA channel ID within the provider.
- *
- * Currently, the DMA API assumes that a single integer ID is enough to
- * identify and configure any DMA channel for any DMA provider. If this
- * assumption becomes invalid in the future, the struct could be expanded to
- * either (a) add more fields to allow DMA providers to store additional
- * information, or (b) replace the id field with an opaque pointer, which the
- * provider would dynamically allocated during its .of_xlate op, and process
- * during is .request op. This may require the addition of an extra op to clean
- * up the allocation.
- */
- struct dma {
- struct udevice *dev;
- /*
- * Written by of_xlate. We assume a single id is enough for now. In the
- * future, we might add more fields here.
- */
- unsigned long id;
- };
- # if CONFIG_IS_ENABLED(OF_CONTROL) && CONFIG_IS_ENABLED(DMA)
- /**
- * dma_get_by_index - Get/request a DMA by integer index.
- *
- * This looks up and requests a DMA. The index is relative to the client
- * device; each device is assumed to have n DMAs associated with it somehow,
- * and this function finds and requests one of them. The mapping of client
- * device DMA indices to provider DMAs may be via device-tree properties,
- * board-provided mapping tables, or some other mechanism.
- *
- * @dev: The client device.
- * @index: The index of the DMA to request, within the client's list of
- * DMA channels.
- * @dma: A pointer to a DMA struct to initialize.
- * @return 0 if OK, or a negative error code.
- */
- int dma_get_by_index(struct udevice *dev, int index, struct dma *dma);
- /**
- * dma_get_by_name - Get/request a DMA by name.
- *
- * This looks up and requests a DMA. The name is relative to the client
- * device; each device is assumed to have n DMAs associated with it somehow,
- * and this function finds and requests one of them. The mapping of client
- * device DMA names to provider DMAs may be via device-tree properties,
- * board-provided mapping tables, or some other mechanism.
- *
- * @dev: The client device.
- * @name: The name of the DMA to request, within the client's list of
- * DMA channels.
- * @dma: A pointer to a DMA struct to initialize.
- * @return 0 if OK, or a negative error code.
- */
- int dma_get_by_name(struct udevice *dev, const char *name, struct dma *dma);
- # else
- static inline int dma_get_by_index(struct udevice *dev, int index,
- struct dma *dma)
- {
- return -ENOSYS;
- }
- static inline int dma_get_by_name(struct udevice *dev, const char *name,
- struct dma *dma)
- {
- return -ENOSYS;
- }
- # endif
- /**
- * dma_request - Request a DMA by provider-specific ID.
- *
- * This requests a DMA using a provider-specific ID. Generally, this function
- * should not be used, since dma_get_by_index/name() provide an interface that
- * better separates clients from intimate knowledge of DMA providers.
- * However, this function may be useful in core SoC-specific code.
- *
- * @dev: The DMA provider device.
- * @dma: A pointer to a DMA struct to initialize. The caller must
- * have already initialized any field in this struct which the
- * DMA provider uses to identify the DMA channel.
- * @return 0 if OK, or a negative error code.
- */
- int dma_request(struct udevice *dev, struct dma *dma);
- /**
- * dma_free - Free a previously requested DMA.
- *
- * @dma: A DMA struct that was previously successfully requested by
- * dma_request/get_by_*().
- * @return 0 if OK, or a negative error code.
- */
- int dma_free(struct dma *dma);
- /**
- * dma_enable() - Enable (turn on) a DMA channel.
- *
- * @dma: A DMA struct that was previously successfully requested by
- * dma_request/get_by_*().
- * @return zero on success, or -ve error code.
- */
- int dma_enable(struct dma *dma);
- /**
- * dma_disable() - Disable (turn off) a DMA channel.
- *
- * @dma: A DMA struct that was previously successfully requested by
- * dma_request/get_by_*().
- * @return zero on success, or -ve error code.
- */
- int dma_disable(struct dma *dma);
- /**
- * dma_prepare_rcv_buf() - Prepare/add receive DMA buffer.
- *
- * It allows to implement zero-copy async DMA_DEV_TO_MEM (receive) transactions
- * if supported by DMA providers.
- *
- * @dma: A DMA struct that was previously successfully requested by
- * dma_request/get_by_*().
- * @dst: The receive buffer pointer.
- * @size: The receive buffer size
- * @return zero on success, or -ve error code.
- */
- int dma_prepare_rcv_buf(struct dma *dma, void *dst, size_t size);
- /**
- * dma_receive() - Receive a DMA transfer.
- *
- * @dma: A DMA struct that was previously successfully requested by
- * dma_request/get_by_*().
- * @dst: The destination pointer.
- * @metadata: DMA driver's channel specific data
- * @return length of received data on success, or zero - no data,
- * or -ve error code.
- */
- int dma_receive(struct dma *dma, void **dst, void *metadata);
- /**
- * dma_send() - Send a DMA transfer.
- *
- * @dma: A DMA struct that was previously successfully requested by
- * dma_request/get_by_*().
- * @src: The source pointer.
- * @len: Length of the data to be sent (number of bytes).
- * @metadata: DMA driver's channel specific data
- * @return zero on success, or -ve error code.
- */
- int dma_send(struct dma *dma, void *src, size_t len, void *metadata);
- #endif /* CONFIG_DMA_CHANNELS */
- /*
- * dma_get_device - get a DMA device which supports transfer
- * type of transfer_type
- *
- * @transfer_type - transfer type should be one/multiple of
- * DMA_SUPPORTS_*
- * @devp - udevice pointer to return the found device
- * @return - will return on success and devp will hold the
- * pointer to the device
- */
- int dma_get_device(u32 transfer_type, struct udevice **devp);
- /*
- * dma_memcpy - try to use DMA to do a mem copy which will be
- * much faster than CPU mem copy
- *
- * @dst - destination pointer
- * @src - souce pointer
- * @len - data length to be copied
- * @return - on successful transfer returns no of bytes
- transferred and on failure return error code.
- */
- int dma_memcpy(void *dst, void *src, size_t len);
- #endif /* _DMA_H_ */
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