/* SPDX-License-Identifier: GPL-2.0+ */
/*
- * (C) Copyright 2015
- * Texas Instruments Incorporated, <www.ti.com>
+ * 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
#define DMA_SUPPORTS_DEV_TO_MEM BIT(2)
#define DMA_SUPPORTS_DEV_TO_DEV BIT(3)
-/*
- * struct dma_ops - Driver model DMA operations
- *
- * The uclass interface is implemented by all DMA devices which use
- * driver model.
- */
-struct dma_ops {
- /*
- * Get the current timer count
- *
- * @dev: The DMA device
- * @direction: direction of data transfer should be one from
- enum dma_direction
- * @dst: Destination pointer
- * @src: Source pointer
- * @len: Length of the data to be copied.
- * @return: 0 if OK, -ve on error
- */
- int (*transfer)(struct udevice *dev, int direction, void *dst,
- void *src, size_t len);
-};
-
/*
* struct dma_dev_priv - information about a device used by the uclass
*
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
projects / oweals / u-boot.git / blobdiff