dma: add channels support

This adds channels support for dma controllers that have multiple channels
which can transfer data to/from different devices (enet, usb...).

DMA channle API:
 dma_get_by_index()
 dma_get_by_name()
 dma_request()
 dma_free()
 dma_enable()
 dma_disable()
 dma_prepare_rcv_buf()
 dma_receive()
 dma_send()

Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
[grygorii.strashko@ti.com: drop unused dma_get_by_index_platdata(),
 add metadata to send/receive ops, add dma_prepare_rcv_buf(),
 minor clean up]
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

1 files changed, 258 insertions, 2 deletions

diff --git a/include/dma.h b/include/dma.h
index 97fa0cf695b..d1c3d0df7d9 100644
--- a/include/dma.h
+++ b/include/dma.h
@@ -1,12 +1,17 @@
 /* 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
@@ -36,6 +41,257 @@ 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