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Diffstat (limited to 'include/dma.h')
| -rw-r--r-- | include/dma.h | 319 |
1 files changed, 319 insertions, 0 deletions
diff --git a/include/dma.h b/include/dma.h new file mode 100644 index 0000000..d1c3d0d --- /dev/null +++ b/include/dma.h @@ -0,0 +1,319 @@ +/* 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_ */ |