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