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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_ */