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@@ -1,12 +1,17 @@
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/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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- * (C) Copyright 2015
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- * Texas Instruments Incorporated, <www.ti.com>
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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/errno.h>
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+#include <linux/types.h>
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+
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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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@@ -36,6 +41,257 @@ 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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+
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+struct udevice;
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+
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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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+
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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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+/**
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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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+
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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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+/**
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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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+/**
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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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+/**
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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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+/**
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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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+/**
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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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+/**
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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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+/**
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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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+#endif /* CONFIG_DMA_CHANNELS */
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+
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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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